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14143387
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Acireductone dioxygenase (iron(II)-requiring)
|
Class of enzymes
Acireductone dioxygenase [iron(II)-requiring] (EC 1.13.11.54) is an enzyme that catalyzes the chemical reaction
1,2-dihydroxy-5-(methylthio)pent-1-en-3-one + O2 formula_0 4-(methylthio)-2-oxobutanoate + formate
Thus, the two substrates of this enzyme are 1,2-dihydroxy-5-(methylthio)pent-1-en-3-one and oxygen, whereas its two products are 4-methylthio-2-oxobutanoate and formate.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O2. The systematic name of this enzyme class is 1,2-dihydroxy-5-(methylthio)pent-1-en-3-one:oxygen oxidoreductase (formate-forming). Other names in common use include ARD', 2-hydroxy-3-keto-5-thiomethylpent-1-ene dioxygenase (ambiguous), acireductone dioxygenase (ambiguous), E-2', and E-3 dioxygenase. This enzyme participates in methionine metabolism.
Structural studies.
As of late 2007, only one structure has been solved for this class of enzymes, with the PDB accession code 2HJI.
References.
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[
{
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14143402
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Acireductone dioxygenase (Ni2+-requiring)
|
Acireductone dioxygenase (Ni2+-requiring) (EC 1.13.11.53) is an enzyme that catalyzes the chemical reaction
1,2-dihydroxy-5-(methylthio)pent-1-en-3-one + O2 formula_0 3-(methylthio)propanoate + formate + CO
Thus, the two substrates of this enzyme are 1,2-dihydroxy-5-(methylthio)pent-1-en-3-one and oxygen, whereas its 3 products are 3-(methylthio)propanoate, formate, and carbon monoxide.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O2. The systematic name of this enzyme class is 1,2-dihydroxy-5-(methylthio)pent-1-en-3-one:oxygen oxidoreductase (formate- and CO-forming). Other names in common use include ARD, 2-hydroxy-3-keto-5-thiomethylpent-1-ene dioxygenase (ambiguous), acireductone dioxygenase (ambiguous), and E-2. This enzyme participates in methionine metabolism.
References.
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[
{
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"text": "\\rightleftharpoons"
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https://en.wikipedia.org/wiki?curid=14143402
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14143423
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Apo-beta-carotenoid-14',13'-dioxygenase
|
Apo-beta-carotenoid-14',13'-dioxygenase (EC 1.13.11.67 is an enzyme that catalyzes the chemical reaction
8'-apo-beta-carotenol + O2 formula_0 14'-apo-beta-carotenal + uncharacterized product
Thus, the two substrates of this enzyme are 8'-apo-beta-carotenol and oxygen, whereas its two products are 14'-apo-beta-carotenal and an uncharacterized product that may be (3E,5E)-7-hydroxy-6-methylhepta-3,5-dien-2-one.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O with incorporation of one atom of oxygen (internal monooxygenases o internal mixed-function oxidases). The systematic name of this enzyme class is 8'-apo-beta-carotenol:O2 oxidoreductase.
References.
<templatestyles src="Reflist/styles.css" />
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
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https://en.wikipedia.org/wiki?curid=14143423
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14143463
|
Arachidonate 8-lipoxygenase
|
Arachidonate 8-lipoxygenase (EC 1.13.11.40) is an enzyme that catalyzes the chemical reaction
arachidonate + O2 formula_0 (5Z,9E,11Z,14Z)-(8R)-8-hydroperoxyicosa-5,9,11,14-tetraenoate
Thus, the two substrates of this enzyme are arachidonate and oxygen, whereas its product is (5Z,9E,11Z,14Z)-(8R)-8-hydroperoxyicosa-5,9,11,14-tetraenoate.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O2. The systematic name of this enzyme class is arachidonate:oxygen 8-oxidoreductase. Other names in common use include 8-lipoxygenase, and 8(R)-lipoxygenase. This enzyme participates in arachidonic acid metabolism.
Structural studies.
As of late 2007, only one structure has been solved for this class of enzymes, with the PDB accession code 2FNQ.
References.
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{
"math_id": 0,
"text": "\\rightleftharpoons"
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https://en.wikipedia.org/wiki?curid=14143463
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14143472
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Arginine 2-monooxygenase
|
Arginine 2-monooxygenase (EC 1.13.12.1) is an enzyme that catalyzes the chemical reaction
L-arginine + O2 formula_0 4-guanidinobutanamide + CO2 + H2O
Thus, the two substrates of this enzyme are L-arginine and oxygen, whereas its 3 products are 4-guanidinobutanamide, carbon dioxide, and water.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O with incorporation of one atom of oxygen (internal monooxygenases o internal mixed-function oxidases). The systematic name of this enzyme class is L-arginine:oxygen 2-oxidoreductase (decarboxylating). Other names in common use include arginine monooxygenase, arginine decarboxylase, arginine oxygenase (decarboxylating), and arginine decarboxy-oxidase. This enzyme participates in urea cycle and metabolism of amino groups. It has one cofactor: the flavin FAD.
References.
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{
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https://en.wikipedia.org/wiki?curid=14143472
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14143490
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Ascorbate 2,3-dioxygenase
|
Obsolete enzyme family
Ascorbate 2,3-dioxygenase (EC 1.13.11.13) is an enzyme that catalyzes the chemical reaction
ascorbate + O2 + H2O formula_0 oxalate + threonate
The 3 substrates of this enzyme are ascorbate, oxygen, and water, whereas its two products are oxalate and threonate.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O2. The systematic name of this enzyme class is ascorbate:oxygen 2,3-oxidoreductase (bond-cleaving). This enzyme is also called AAoxygenase. This enzyme participates in ascorbate and aldarate metabolism. It employs one cofactor, iron.
References.
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{
"math_id": 0,
"text": "\\rightleftharpoons"
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14143504
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Biphenyl-2,3-diol 1,2-dioxygenase
|
Biphenyl-2,3-diol 1,2-dioxygenase (EC 1.13.11.39) is an enzyme that catalyzes the chemical reaction
biphenyl-2,3-diol + O2 formula_0 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate + H2O
Thus, the two substrates of this enzyme are biphenyl-2,3-diol and oxygen, whereas its two products are 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate and water.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O2. The systematic name of this enzyme class is biphenyl-2,3-diol:oxygen 1,2-oxidoreductase (decyclizing). Other names in common use include 2,3-dihydroxybiphenyl dioxygenase, and biphenyl-2,3-diol dioxygenase. This enzyme participates in gamma-hexachlorocyclohexane degradation and biphenyl degradation.
Structural studies.
As of late 2007, 16 structures have been solved for this class of enzymes, with PDB accession codes 1DHY, 1EIL, 1EIQ, 1EIR, 1HAN, 1KMY, 1KND, 1KNF, 1KW3, 1KW6, 1KW8, 1KW9, 1KWB, 1KWC, 1LGT, and 1LKD.
References.
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{
"math_id": 0,
"text": "\\rightleftharpoons"
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14143515
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Caffeate 3,4-dioxygenase
|
Enzyme
Caffeate 3,4-dioxygenase (EC 1.13.11.22) is an enzyme that catalyzes the chemical reaction
3,4-dihydroxy-"trans"-cinnamate + O2 formula_0 3-(2-carboxyethenyl)-"cis","cis"-muconate
Thus, the two substrates of this enzyme are 3,4-dihydroxy-trans-cinnamate (caffeic acid) and oxygen, whereas its product is 3-(2-carboxyethenyl)-cis,cis-muconate.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O2. The systematic name of this enzyme class is 3,4-dihydroxy-trans-cinnamate:oxygen 3,4-oxidoreductase (decyclizing). This enzyme participates in phenylpropanoid biodegradation.
References.
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
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14143537
|
Chloridazon-catechol dioxygenase
|
Class of enzymes
Chloridazon-catechol dioxygenase (EC 1.13.11.36) is an enzyme that catalyzes the chemical reaction
5-amino-4-chloro-2-(2,3-dihydroxyphenyl)-3(2H)-pyridazinone + O2 formula_0 5-amino-4-chloro-2-(2-hydroxymuconoyl)-3(2H)-pyridazinone
Thus, the two substrates of this enzyme are 5-amino-4-chloro-2-(2,3-dihydroxyphenyl)-3(2H)-pyridazinone and oxygen, whereas its product is 5-amino-4-chloro-2-(2-hydroxymuconoyl)-3(2H)-pyridazinone.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O2. The systematic name of this enzyme class is 5-amino-4-chloro-2-(2,3-dihydroxyphenyl)-3(2H)-pyridazinone 1,2-oxidoreductase (decyclizing). It employs one cofactor, iron.
References.
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[
{
"math_id": 0,
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1414360
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MACD
|
Chart indicator of moving average convergence/divergence
MACD, short for moving average convergence/divergence, is a trading indicator used in technical analysis of securities prices, created by Gerald Appel in the late 1970s. It is designed to reveal changes in the strength, direction, momentum, and duration of a trend in a stock's price.
The MACD indicator (or "oscillator") is a collection of three time series calculated from historical price data, most often the closing price. These three series are: the MACD series proper, the "signal" or "average" series, and the "divergence" series which is the difference between the two. The MACD series is the difference between a "fast" (short period) exponential moving average (EMA), and a "slow" (longer period) EMA of the price series. The average series is an EMA of the MACD series itself.
The MACD indicator thus depends on three time parameters, namely the time constants of the three EMAs. The notation "MACD("a","b","c")" usually denotes the indicator where the MACD series is the difference of EMAs with characteristic times "a" and "b", and the average series is an EMA of the MACD series with characteristic time "c". These parameters are usually measured in days. The most commonly used values are 12, 26, and 9 days, that is, MACD(12,26,9). As true with most of the technical indicators, MACD also finds its period settings from the old days when technical analysis used to be mainly based on the daily charts. The reason was the lack of the modern trading platforms which show the changing prices every moment. As the working week used to be 6-days, the period settings of (12, 26, 9) represent 2 weeks, 1 month and one and a half week. Now when the trading weeks have only 5 days, possibilities of changing the period settings cannot be overruled. However, it is always better to stick to the period settings which are used by the majority of traders as the buying and selling decisions based on the standard settings further push the prices in that direction.
Although the MACD and average series are discrete values in nature, but they are customarily displayed as continuous lines in a plot whose horizontal axis is time, whereas the divergence is shown as a bar chart (often called a histogram).
A fast EMA responds more quickly than a slow EMA to recent changes in a stock's price. By comparing EMAs of different periods, the MACD series can indicate changes in the trend of a stock. It is claimed that the divergence series can reveal subtle shifts in the stock's trend.
Since the MACD is based on moving averages, it is a lagging indicator. As a future metric of price trends, the MACD is less useful for stocks that are not trending (trading in a range) or are trading with unpredictable price action. Hence the trends will already be completed or almost done by the time MACD shows the trend.
Terminology.
Over the years, elements of the MACD have become known by multiple and often over-loaded terms. The common definitions of particularly overloaded terms are:
Divergence:
In practice, definition number 2 above is often preferred.
Histogram:
In practice, definition number 2 above is often preferred.
Formula.
The formula for the MACD line is based on two exponential moving averages of the close prices, usually with the periods of 12 and 26:
formula_0
The signal line is then built as the exponential moving average of the MACD line:
formula_1
Mathematical interpretation.
In signal processing terms, the MACD series is a filtered measure of the derivative of the input (price) series with respect to time. (The derivative is called "velocity" in technical stock analysis.) MACD estimates the derivative as if it were calculated and then filtered by the two low-pass filters in tandem, multiplied by a "gain" equal to the difference in their time constants. It also can be seen to approximate the derivative as if it were calculated and then filtered by a single low pass exponential filter (EMA) with time constant equal to the sum of time constants of the two filters, multiplied by the same gain. So, for the standard MACD filter time constants of 12 and 26 days, the MACD derivative estimate is filtered approximately by the equivalent of a low-pass EMA filter of 38 days. The time derivative estimate (per day) is the MACD value divided by 14.
The average series is also a derivative estimate, with an additional low-pass filter in tandem for further smoothing (and additional lag). The difference between the MACD series and the average series (the divergence series) represents a measure of the second derivative of price with respect to time ("acceleration" in technical stock analysis). This estimate has the additional lag of the signal filter and an additional gain factor equal to the signal filter constant.
Classification.
The MACD can be classified as an absolute price oscillator (APO), because it deals with the actual prices of moving averages rather than percentage changes. A percentage price oscillator (PPO), on the other hand, computes the difference between two moving averages of price divided by the longer moving average value.
While an APO will show greater levels for higher priced securities and smaller levels for lower priced securities, a PPO calculates changes relative to price. Subsequently, a PPO is preferred when: comparing oscillator values between different securities, especially those with substantially different prices; or comparing oscillator values for the same security at significantly different times, especially a security whose value has changed greatly.
Another member of the price oscillator family is the detrended price oscillator (DPO), which ignores long term trends while emphasizing short term patterns.
Trading interpretation.
Exponential moving averages highlight recent changes in a stock's price. By comparing EMAs of different lengths, the MACD series gauges changes in the trend of a stock. The difference between the MACD series and its average is claimed to reveal subtle shifts in the strength and direction of a stock's trend. It may be necessary to correlate the signals with the MACD to indicators like RSI power.
Some traders attribute special significance to the MACD line crossing the signal line, or the MACD line crossing the zero axis. Significance is also attributed to disagreements between the MACD line or the difference line and the stock price (specifically, higher highs or lower lows on the price series that are not matched in the indicator series).
Signal-line crossover.
A "signal-line crossover" occurs when the MACD and average lines cross; that is, when the divergence (the bar graph) changes sign. The standard interpretation of such an event is a recommendation to buy if the MACD line crosses up through the average line (a "bullish" crossover), or to sell if it crosses down through the average line (a "bearish" crossover). These events are taken as indications that the trend in the stock is about to accelerate in the direction of the crossover.
Zero crossover.
A "zero crossover" event occurs when the MACD series changes sign, that is, the MACD line crosses the horizontal zero axis. This happens when there is no difference between the fast and slow EMAs of the price series. A change from positive to negative MACD is interpreted as "bearish", and from negative to positive as "bullish". Zero crossovers provide evidence of a change in the direction of a trend but less confirmation of its momentum than a signal line crossover.
Divergence.
A "positive divergence" or "bullish divergence" occurs when the price makes a new low but the MACD does not confirm with a new low of its own. A "negative divergence" or "bearish divergence" occurs when the price makes a new high but the MACD does not confirm with a new high of its own. A divergence with respect to price may occur on the MACD line and/or the MACD Histogram.
Timing.
The MACD is only as useful as the context in which it is applied. An analyst might apply the MACD to a weekly scale before looking at a daily scale, in order to avoid making short term trades against the direction of the intermediate trend. Analysts will also vary the parameters of the MACD to track trends of varying duration. One popular short-term set-up, for example, is the (5,35,5).
False signals.
Like any forecasting algorithm, the MACD can generate false signals. A false positive, for example, would be a bullish crossover followed by a sudden decline in a stock. A false negative would be a situation where there is bearish crossover, yet the stock accelerated suddenly upwards.
A prudent strategy may be to apply a filter to signal line crossovers to ensure that they have held up. An example of a price filter would be to buy if the MACD line breaks above the signal line and then remains above it for three days. As with any filtering strategy, this reduces the probability of false signals but increases the frequency of missed profit.
Analysts use a variety of approaches to filter out false signals and confirm true ones.
A MACD crossover of the signal line indicates that the direction of the acceleration is changing. The MACD line crossing zero suggests that the average velocity is changing direction.
References.
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[
{
"math_id": 0,
"text": "MACD~line = EMA_{12} - EMA_{26}"
},
{
"math_id": 1,
"text": "Signal~line = EMA_9(MACD~line)"
}
] |
https://en.wikipedia.org/wiki?curid=1414360
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14143620
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Coenzyme F420 hydrogenase
|
Class of enzymes
In enzymology, a coenzyme F420 hydrogenase (EC 1.12.98.1) is an enzyme that catalyzes the chemical reaction
H2 + coenzyme F420 formula_0 reduced coenzyme F420
Thus, the two substrates of this enzyme are H2 and coenzyme F420, whereas its product is reduced coenzyme F420.
This enzyme belongs to the family of oxidoreductases, specifically those acting on hydrogen as donor with other, known, acceptors. The systematic name of this enzyme class is hydrogen:coenzyme F420 oxidoreductase. Other names in common use include 8-hydroxy-5-deazaflavin-reducing hydrogenase, F420-reducing hydrogenase, and coenzyme F420-dependent hydrogenase. This enzyme participates in folate biosynthesis and is a critical part of energy conservation in some methanogens such as Methanosarcina barkeri. It has 3 cofactors: iron, nickel, and deazaflavin.
References.
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https://en.wikipedia.org/wiki?curid=14143620
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14143636
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Cypridina-luciferin 2-monooxygenase
|
In enzymology, a Cypridina-luciferin 2-monooxygenase (EC 1.13.12.6) is an enzyme that catalyzes the chemical reaction
Cypridina luciferin + O2 formula_0 oxidized Cypridina luciferin + CO2 + hnu
Thus, the two substrates of this enzyme are Cypridina luciferin and O2, whereas its 3 products are oxidized Cypridina luciferin, CO2, and light.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O with incorporation of one atom of oxygen (internal monooxygenases o internal mixed-function oxidases). The systematic name of this enzyme class is Cypridina-luciferin:oxygen 2-oxidoreductase (decarboxylating). Other names in common use include Cypridina-type luciferase, luciferase (Cypridina luciferin), and Cypridina luciferase.
The primary sequence was determined by cloning the cDNA.
References.
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14143650
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Cysteamine dioxygenase
|
Class of enzymes
In enzymology, a cysteamine dioxygenase (EC 1.13.11.19) is an enzyme that catalyzes the chemical reaction
2-aminoethanethiol + O2 formula_0 hypotaurine
Thus, the two substrates of this enzyme are 2-aminoethanethiol and O2, whereas its product is hypotaurine.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O2. The systematic name of this enzyme class is 2-aminoethanethiol:oxygen oxidoreductase. Other names in common use include persulfurase, cysteamine oxygenase, and cysteamine:oxygen oxidoreductase. This enzyme participates in taurine and hypotaurine metabolism. It employs one cofactor, iron.
References.
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{
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https://en.wikipedia.org/wiki?curid=14143650
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14143666
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Cytochrome-c3 hydrogenase
|
Class of enzymes
In enzymology, a cytochrome-c3 hydrogenase (EC 1.12.2.1) is an enzyme that catalyzes the chemical reaction
2 H2 + ferricytochrome c3 formula_0 4 H+ + ferrocytochrome c3
Thus, the two substrates of this enzyme are H2 and ferricytochrome c3, whereas its two products are H+ and ferrocytochrome c3.
This enzyme belongs to the family of oxidoreductases, specifically those acting on hydrogen as donor with a cytochrome as acceptor. The systematic name of this enzyme class is hydrogen:ferricytochrome-c3 oxidoreductase. Other names in common use include H2:ferricytochrome c3 oxidoreductase, cytochrome c3 reductase, cytochrome hydrogenase, and hydrogenase [ambiguous]. It has 3 cofactors: iron, Nickel, and Iron-sulfur.
Structural studies.
As of late 2007, 19 structures have been solved for this class of enzymes, with PDB accession codes 1FRV, 1H2R, 1UBH, 1UBJ, 1UBK, 1UBL, 1UBM, 1UBO, 1UBR, 1UBT, 1UBU, 1WUH, 1WUI, 1WUJ, 1WUK, 1WUL, 1YQ9, 1YQW, and 1YRQ.
References.
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{
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https://en.wikipedia.org/wiki?curid=14143666
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14143688
|
Fatty-acid peroxidase
|
In enzymology, a fatty-acid peroxidase (EC 1.11.1.3) is an enzyme that catalyzes the chemical reaction
palmitate + 2 H2O2 formula_0 pentadecanal + CO2 + 3 H2O
Thus, the two substrates of this enzyme are palmitate and H2O2, whereas its 3 products are pentadecanal, CO2, and H2O.
This enzyme belongs to the family of oxidoreductases, specifically those acting on a peroxide as acceptor (peroxidases). The systematic name of this enzyme class is hexadecanoate:hydrogen-peroxide oxidoreductase. This enzyme is also called long chain fatty acid peroxidase.
References.
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[
{
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"text": "\\rightleftharpoons"
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https://en.wikipedia.org/wiki?curid=14143688
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14143707
|
Ferredoxin hydrogenase
|
Class of enzymes
In enzymology, ferredoxin hydrogenase (EC 1.12.7.2), also referred to as [Fe-Fe] hydrogenase, H2 oxidizing hydrogenase, H2 producing hydrogenase, bidirectional hydrogenase, hydrogenase (ferredoxin), hydrogenlyase, and uptake hydrogenase, is found in "Clostridium pasteurianum, Clostridium acetobutylicum," "Chlamydomonas reinhardtii", and other organisms. The systematic name of this enzyme is hydrogen:ferredoxin oxidoreductase
Ferredoxin hydrogenase belongs to the family of oxidoreductases, specifically those acting on hydrogen as donor with an iron-sulfur protein as acceptor. Ferredoxin hydrogenase has an active metallocluster site referred to as an "H-cluster" or "H domain" that is involved in the inter-conversion of protons and electrons with hydrogen gas.
Ferredoxin hydrogenase catalyzes the following reversible reaction:
H2 + 2 oxidized ferredoxin formula_0 2 reduced ferredoxin + 2 H+
Enzyme reaction and mechanism.
The exact mechanism by which this reaction occurs is still not entirely known; however, several intermediates have been identified in steady-state conditions. A proposed mechanism for the catalyzed reaction by ferredoxin hydrogenase is:
The two substrates of this enzyme are H2 and oxidized ferredoxin, whereas its two products are reduced ferredoxin and H+. During the hydrogen gas turnover, the H-cluster undergoes a series of redox transitions as protons are translocated. The reaction rate is dependent on the environment pH and sees an activity increase in pH environments between 7–9. Accessory clusters allow for the enzyme to retain full enzyme activity at potentials around and higher than the equilibrium potential. However, it is important to note that the accessory clusters are not as effective at extremely low potentials.
Enzyme structure.
The reaction occurs in the [2Fe] moiety of the active H cluster site, which also includes a [4Fe4S] cluster covalently bonded via a cysteinyl thiolate. An additional accessory site known as the F-domain, which contains four Fe-S clusters, is known as the main gate for electron transfer to and from the catalytic site. The [2Fe] sub-site is coordinated by several CO and CN ligands and an azadithiolate bridge that allows for proton shuttling. The oxidized state of the sub-site, abbreviated as Hox, includes a paramagnetic, mixed-valence [Fe(I)Fe(II)] moiety and a diamagnetic, oxidized [4Fe4S] 2+ cluster. The single electron reduction of Hox yields two protomers that differ in the localization of the added electron and proton. The addition of the second electron results in the [Fe(I)Fe(II)]-[4Fe4S]+ configuration and a protonated azadithiolate bridge.
Biological function.
Hydrogenases are found in prokaryotes, lower eukaryotes, and archaea. This broad category of metalloenzymes can be divided into [NiFe], [FeFe], and [Fe] variants based on the transition metals found in their active sites. However, the hydrogen gas oxidation and proton reduction activities varies greatly among the variants and even within their own subcategories. Ferredoxin hydrogenase participates in glyoxylate and dicarboxylate metabolism and methane metabolism. It has 3 cofactors: iron, Sulfur, and Nickel.
Ferredoxin hydrogenase found in the green algae "Chlamydomonas reinhardtii" use supplied electrons from photosystem I to reduce protons into hydrogen gas. This electron supply transfer is possible through photosystem I interactions with photosynthetic electron transfer ferredoxin (PetF). The inter-conversion of protons and electrons with hydrogen gas allow organisms to modulate energy input and output, adjust organelle redox potential, and transduce chemical signals.
Industrial significance.
Hydrogen gas is a potential candidate for the partial replacement of fossil fuels as a clean energy carrier in fuel cells. However, because of the gas's weight, it often escapes the Earth's atmosphere into space, making it a scarce resource on Earth.
The hydrogen photo-production in green algae, catalyzed by ferredoxin hydrogenase, is a potential source of hydrogen gas. Unfortunately, the inefficiency of the reaction and enzyme as whole to produce hydrogen places a barrier on the viability of this reaction on an industrial scale. In addition, ferredoxin hydrogenase is sensitive to oxygen; the typical half life for the enzyme under aerobic conditions is on the scale of seconds, rendering it difficult to cultivate and manage commercially.
References.
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{
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https://en.wikipedia.org/wiki?curid=14143707
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14143721
|
Gentisate 1,2-dioxygenase
|
In enzymology, a gentisate 1,2-dioxygenase (EC 1.13.11.4) is an enzyme that catalyzes the chemical reaction
2,5-dihydroxybenzoate + O2 formula_0 maleylpyruvate
Thus, the two substrates of this enzyme are 2,5-dihydroxybenzoate and O2, whereas its product is 3-maleylpyruvate.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O2. The systematic name of this enzyme class is gentisate:oxygen 1,2-oxidoreductase (decyclizing). Other names in common use include gentisate oxygenase, 2,5-dihydroxybenzoate dioxygenase, gentisate dioxygenase, and gentisic acid oxidase. This enzyme participates in tyrosine metabolism. It employs one cofactor, iron.
Structural studies.
As of late 2007, only one structure has been solved for this class of enzymes, with the PDB accession code 2D40.
References.
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{
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https://en.wikipedia.org/wiki?curid=14143721
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14143738
|
Hydrogenase (acceptor)
|
In enzymology, a hydrogenase (acceptor) (EC 1.12.99.6) is an enzyme that catalyzes the chemical reaction
H2 + A formula_0 AH2
Thus, the two substrates of this enzyme are H2 and A, whereas its product is AH2.
This enzyme belongs to the family of oxidoreductases, specifically those acting on hydrogen as donor with other acceptors. The systematic name of this enzyme class is hydrogen:acceptor oxidoreductase. Other names in common use include H2 producing hydrogenase[ambiguous], hydrogen-lyase[ambiguous], hydrogenlyase[ambiguous], uptake hydrogenase[ambiguous], and hydrogen:(acceptor) oxidoreductase.
References.
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[
{
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https://en.wikipedia.org/wiki?curid=14143738
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14143750
|
Hydrogen dehydrogenase
|
In enzymology, a hydrogen dehydrogenase (EC 1.12.1.2) is an enzyme that catalyzes the chemical reaction
H2 + NAD+ formula_0 H+ + NADH
Thus, the two substrates of this enzyme are H2 and NAD+, whereas its two products are H+ and NADH.
This enzyme belongs to the family of oxidoreductases, specifically those acting on hydrogen as donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is hydrogen:NAD+ oxidoreductase. Other names in common use include H2:NAD+ oxidoreductase, NAD+-linked hydrogenase, bidirectional hydrogenase, and hydrogenase. This enzyme participates in glyoxylate and dicarboxylate metabolism and methane metabolism. It has 6 cofactors: FAD, Iron, FMN, Flavin, Nickel, and Iron-sulfur.
References.
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{
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https://en.wikipedia.org/wiki?curid=14143750
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14143771
|
Hydrogen dehydrogenase (NADP+)
|
In enzymology, a hydrogen dehydrogenase (NADP+) (EC 1.12.1.3) is an enzyme that catalyzes the chemical reaction
H2 + NADP+ formula_0 H+ + NADPH
Thus, the two substrates of this enzyme are H2 and NADP+, whereas its two products are H+ and NADPH.
This enzyme belongs to the family of oxidoreductases, specifically those acting on hydrogen as donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is hydrogen:NADP+ oxidoreductase. Other names in common use include NADP+-linked hydrogenase, NADP+-reducing hydrogenase, hydrogen dehydrogenase (NADP+), and simply hydrogenase (which is ambiguous).
Structural studies.
As of late 2007, only one structure has been solved for this class of enzymes, with the PDB accession code 2AUV.
References.
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{
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https://en.wikipedia.org/wiki?curid=14143771
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14143802
|
Hydroxyquinol 1,2-dioxygenase
|
In enzymology, a hydroxyquinol 1,2-dioxygenase (EC 1.13.11.37) is an enzyme that catalyzes the chemical reaction
benzene-1,2,4-triol + O2 formula_0 3-hydroxy-cis,cis-muconate
Thus, the two substrates of this enzyme are benzene-1,2,4-triol (hydroxyquinol) and O2, whereas its product is 3-hydroxy-cis,cis-muconate.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O2. The systematic name of this enzyme class is benzene-1,2,4-triol:oxygen 1,2-oxidoreductase (decyclizing). This enzyme is also called hydroxyquinol dioxygenase. This enzyme participates in benzoate degradation via hydroxylation and 1,4-dichlorobenzene degradation. It employs one cofactor, iron.
Structural studies.
As of late 2007[ [update]], only one structure has been solved for this class of enzymes, with the PDB accession code 1TMX.
References.
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https://en.wikipedia.org/wiki?curid=14143802
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14143815
|
Indole 2,3-dioxygenase
|
In enzymology, an indole 2,3-dioxygenase (EC 1.13.11.17) is an enzyme that catalyzes the chemical reaction
indole + O2 formula_0 2-formylaminobenzaldehyde
Thus, the two substrates of this enzyme are indole and O2, whereas its product is 2-formylaminobenzaldehyde.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O2. The systematic name of this enzyme class is indole:oxygen 2,3-oxidoreductase (decyclizing). Other names in common use include indole oxidase, indoleamine 2,3-dioxygenase (ambiguous), indole:O2 oxidoreductase, indole-oxygen 2,3-oxidoreductase (decyclizing), and IDO (ambiguous). This enzyme participates in tryptophan metabolism. It has 3 cofactors: copper, Flavin, and Flavoprotein.
Indole dioxygenase is not specific to indole but rather operates on a broad range of indole derivatives, including the amino acids tryptophan and 5-hydroxytryptophan (5-HTP), and many indole-analog plant phytochemicals. IDO is a peripheral enzyme, in contrast to tryptophan oxidase, an enzyme of similar amino acid sequence, which is active only in the liver. IDO is induced (produced on demand) by activation of inflammatory processes involving cytokine expression by white blood cells.
References.
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14143838
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Lactate 2-monooxygenase
|
In enzymology, a lactate 2-monooxygenase (EC 1.13.12.4) is an enzyme that catalyzes the chemical reaction
(S)-lactate + O2 formula_0 acetate + CO2 + H2O
Thus, the two substrates of this enzyme are (S)-lactate and O2, whereas its 3 products are acetate, CO2, and H2O.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O with incorporation of one atom of oxygen (internal monooxygenases o internal mixed-function oxidases). The systematic name of this enzyme class is (S)-lactate:oxygen 2-oxidoreductase (decarboxylating). Other names in common use include lactate oxidative decarboxylase, lactate oxidase, lactic oxygenase, lactate oxygenase, lactic oxidase, L-lactate monooxygenase, lactate monooxygenase, and L-lactate-2-monooxygenase. This enzyme participates in pyruvate metabolism. It employs one cofactor, FMN.
Structural studies.
As of late 2007, only one structure has been solved for this class of enzymes, with the PDB accession code 2DU2.
References.
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https://en.wikipedia.org/wiki?curid=14143838
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14143869
|
L-ascorbate oxidase
|
In enzymology, a L-ascorbate oxidase (EC 1.10.3.3) is an enzyme that catalyzes the chemical reaction
2 L-ascorbate + O2 formula_0 2 dehydroascorbate + 2 H2O
Thus, the two substrates of this enzyme are L-ascorbate and O2, whereas its two products are dehydroascorbate and H2O.
Function.
This enzyme belongs to the family of oxidoreductases, specifically those acting on diphenols and related substances as donor with oxygen as acceptor. This enzyme participates in ascorbate metabolism. It employs one cofactor, copper.It has anti-aging effects
Nomenclature.
The systematic name of this enzyme class is L-ascorbate:oxygen oxidoreductase. Other names in common use include ascorbase, ascorbic acid oxidase, ascorbate oxidase, ascorbic oxidase, ascorbate dehydrogenase, L-ascorbic acid oxidase, AAO, L-ascorbate:O2 oxidoreductase, and AA oxidase.
References.
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Further reading.
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14143901
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Lignin peroxidase
|
In enzymology, a lignin peroxidase (EC 1.11.1.14) is an enzyme that catalyzes the chemical reaction
1,2-bis(3,4-dimethoxyphenyl)propane-1,3-diol + H2O2 formula_0 3,4-dimethoxybenzaldehyde + 1-(3,4-dimethoxyphenyl)ethane-1,2-diol + H2O
Thus, the two substrates of this enzyme are 1,2-bis(3,4-dimethoxyphenyl)propane-1,3-diol and H2O2, whereas its 3 products are 3,4-dimethoxybenzaldehyde, 1-(3,4-dimethoxyphenyl)ethane-1,2-diol, and H2O.
This enzyme belongs to the family of oxidoreductases, specifically those acting on a peroxide as acceptor (peroxidases) and can be included in the broad category of ligninases. The systematic name of this enzyme class is 1,2-bis(3,4-dimethoxyphenyl)propane-1,3-diol:hydrogen-peroxide oxidoreductase. Other names in common use include diarylpropane oxygenase, ligninase I, diarylpropane peroxidase, LiP, diarylpropane:oxygen,hydrogen-peroxide oxidoreductase (C-C-bond-cleaving). It employs one cofactor, heme.
Background.
Lignin is highly resistant to biodegradation and only higher fungi and some bacteria are capable of degrading the polymer via an oxidative process. This process has been studied extensively in the past twenty years, but the mechanism has not yet been fully elucidated.
Lignin is found to be degraded by enzyme lignin peroxidases produced by some fungi like "Phanerochaete chrysosporium". The mechanism by which lignin peroxidase (LiP) interacts with the lignin polymer involves veratrole alcohol, which is a secondary metabolite of white rot fungi that acts as a cofactor for the enzyme.
Structural studies.
As of late 2007, 3 structures have been solved for this class of enzymes, with PDB accession codes 1B80, 1B82, and 1B85.
References.
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14143921
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Lignostilbene alphabeta-dioxygenase
|
In enzymology, a lignostilbene alphabeta-dioxygenase (EC 1.13.11.43) is an enzyme that catalyzes the chemical reaction
1,2-bis(4-hydroxy-3-methoxyphenyl)ethylene + O2 formula_0 2 vanillin
Thus, the two substrates of this enzyme are 1,2-bis(4-hydroxy-3-methoxyphenyl)ethylene and O2, whereas its product is vanillin.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O2. The systematic name of this enzyme class is 1,2-bis(4-hydroxy-3-methoxyphenyl)ethylene:oxygen oxidoreductase (alphabeta-bond-cleaving). It employs one cofactor, iron.
References.
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https://en.wikipedia.org/wiki?curid=14143921
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14143931
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Linoleate 11-lipoxygenase
|
In enzymology, a linoleate 11-lipoxygenase (EC 1.13.11.45) is an enzyme that catalyzes the chemical reaction
linoleate + O2 formula_0 (9Z,12Z)-(11S)-11-hydroperoxyoctadeca-9,12-dienoate
Thus, the two substrates of this enzyme are linoleate and O2, whereas its product is (9Z,12Z)-(11S)-11-hydroperoxyoctadeca-9,12-dienoate.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O2. The systematic name of this enzyme class is linoleate:oxygen 11S-oxidoreductase. This enzyme is also called linoleate dioxygenase, manganese lipoxygenase. This enzyme participates in linoleic acid metabolism.
References.
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https://en.wikipedia.org/wiki?curid=14143931
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14143954
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Linoleate diol synthase
|
In enzymology, a linoleate diol synthase (EC 1.13.11.44) is an enzyme that catalyzes the chemical reaction
linoleate + O2 formula_0 (9Z,12Z)-(7S,8S)-dihydroxyoctadeca-9,12-dienoate
Thus, the two substrates of this enzyme are linoleate and O2, whereas its product is (9Z,12Z)-(7S,8S)-dihydroxyoctadeca-9,12-dienoate.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O2. The systematic name of this enzyme class is linoleate:oxygen 7S,8S-oxidoreductase. This enzyme is also called linoleate (8R)-dioxygenase. This enzyme participates in linoleic acid metabolism.
References.
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14143974
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Lysine 2-monooxygenase
|
In enzymology, a lysine 2-monooxygenase (EC 1.13.12.2) is an enzyme that catalyzes the chemical reaction
L-lysine + O2 formula_0 5-aminopentanamide + CO2 + H2O
Thus, the two substrates of this enzyme are L-lysine and O2, whereas its 3 products are 5-aminopentanamide, CO2, and H2O.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O with incorporation of one atom of oxygen (internal monooxygenases o internal mixed-function oxidases). The systematic name of this enzyme class is L-lysine:oxygen 2-oxidoreductase (decarboxylating). Other names in common use include lysine oxygenase, lysine monooxygenase, and L-lysine-2-monooxygenase. This enzyme participates in lysine degradation. It employs one cofactor, FAD.
References.
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14144301
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Manganese peroxidase
|
In enzymology, a manganese peroxidase (EC 1.11.1.13) is an enzyme that catalyzes the chemical reaction
2 Mn(II) + 2 H+ + H2O2 formula_0 2 Mn(III) + 2 H2O
The 3 substrates of this enzyme are Mn(II), H+, and H2O2, whereas its two products are Mn(III) and H2O.
This enzyme belongs to the family of oxidoreductases, to be specific those acting on a peroxide as acceptor (peroxidases). The systematic name of this enzyme class is Mn(II):hydrogen-peroxide oxidoreductase. Other names in common use include peroxidase-M2, and Mn-dependent (NADH-oxidizing) peroxidase. It employs one cofactor, heme. This enzyme needs Ca2+ for activity.
White rot fungi secrete this enzyme to aid lignin degradation.
Discovery and characterization.
Manganese peroxidase (commonly referred to as MnP) was discovered in 1985 simultaneously by the research groups of Michael H. Gold and Ronald Crawford in the fungus "Phanerochaete chrysosporium". The protein was genetically sequenced in "P. chrysoporium" in 1989. The enzyme is thought to be unique to Basidiomycota as no bacterium, yeast, or mold species has yet been found which naturally produces it.
Reaction mechanism.
MnP catalysis occurs in a series of irreversible oxidation-reduction (redox) reactions which follow a ping-pong mechanism with second order kinetics. In the first step of the catalytic cycle, H2O2, or an organic peroxide, enters the active site of MnP. There the oxygen in H2O2 binds to an Fe(III) ion in the heme cofactor to form an iron peroxide complex. Two electrons are transferred from Fe3+ to peroxide, breaking the oxygen-peroxide bond to form H2O and a Fe(IV) oxo-porphyrin radical complex. This oxidized intermediate is known as MnP Compound I. MnP Compound I then binds to a monochelated Mn(II) ion, which donates an electron to quench the radical and form Mn(III) and MnP Compound II, a Fe(IV) oxo-porphyrin complex. MnP Compound II oxidizes another Mn(II) ion to Mn(III) and is reduced by the reaction of two H+ ions and the iron bound oxygen. This reforms the Fe(III) ion in the heme and releases a second water molecule.
There are many deviations from this traditional catalytic cycle. MnP Compound I can be used to oxidize free Mn(II), ferrocyanide, as well as phenolics, and other aromatic compounds.
Chelators.
Mn(III) is unstable in aqueous media, therefore MnP releases it as a Mn(III)-carboxylic acid chelate. There are a variety of carboxylic acid chelators including oxalate, malonate, tartrate, and lactate, however oxalate is the most common. The peroxidase structure favors Mn(III)-chelates over free Mn(III) ions. The Mn(III) chelate interacts with the active site to facilitate product release from the enzyme. The chelator can have an effect on the kinetic rate and even the catalyzed reaction. If the substrate Mn(II) is chelated with lactate, MnP instead catalyzes the evolution of O2. However, this side reaction has little impact on enzymatic activity because it follows slower third order kinetics.
Structural studies.
As of late 2007, 6 structures have been solved for this class of enzymes, with PDB accession codes 1MN1, 1MN2, 1YYD, 1YYG, 1YZP, and 1YZR.
Although MnP, like other lignin peroxidases, is a Class II peroxidase, it has a similar tertiary structure to prokaryotic Class I peroxidases, but contains disulfide bridges like the Class III peroxidases in plants. MnP has a globular structure containing 11-12 α-helices, depending on the species it is produced in. It is stabilized by 10 cystine amino acid residues which form 5 disulfide bridges, one of which is near the C-terminal area. The active site contains a heme cofactor which is bound by two Ca2+ ions, one above and one below the heme. Near the internal heme propionate are three acidic residues which are used to stabilize Mn(II) or Mn(III) when it is bound to the enzyme. The specific residues vary between species, but their number and relative location in the folded protein is conserved. There are a total of 357 amino acid residues in the MnP of "P. chrysosoporium", and a similar number in enzymes produced by other basidiomycetes.
Biochemical significance.
The major function of the Mn(III) ions produced by MnP is oxidation and degradation of lignin. For this purpose, basidiomycetes secrete MnP, rather than Mn(III), and the enzyme functions outside of the fungal cell. Mn(III) ions from MnP can oxidize the phenolic compounds in lignin directly, but they can also oxidize some organic sulfur compounds and unsaturated fatty acids. This oxidation forms thiyl and peroxyl radicals, which in the presence of O2, can oxidize lignin or react with water to form H2O2. The Mn3+ ion itself can degrade lignin by catalyzing alkyl-aryl cleavages and α-carbon oxidation in phenols.
Regulation.
MnP activity is controlled via transcriptional regulation. MnP is up-regulated by increases in extracellular Mn(II) and H2O2 concentrations. It has been found that increased O2 concentration and heat stress also activate MnP.
References.
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Further reading.
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14144321
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Methanosarcina-phenazine hydrogenase
|
In enzymology, a Methanosarcina-phenazine hydrogenase (EC 1.12.98.3) is an enzyme that catalyzes the chemical reaction
H2 + 2-(2,3-dihydropentaprenyloxy)phenazine formula_0 2-dihydropentaprenyloxyphenazine
Thus, the two substrates of this enzyme are H2 and 2-(2,3-dihydropentaprenyloxy)phenazine, whereas its product is 2-dihydropentaprenyloxyphenazine.
This enzyme belongs to the family of oxidoreductases, specifically those acting on hydrogen as donor with other, known, acceptors. The systematic name of this enzyme class is hydrogen:2-(2,3-dihydropentaprenyloxy)phenazine oxidoreductase. Other names in common use include methanophenazine hydrogenase, and methylviologen-reducing hydrogenase.
References.
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14144341
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NADH peroxidase
|
In enzymology, a NADH peroxidase (EC 1.11.1.1) is an enzyme that catalyzes the chemical reaction
NADH + H+ + H2O2 formula_0 NAD+ + 2 H2O
The presumed function of NADH peroxidase is to inactivate H2O2 generated within the cell, for example by glycerol-3-phosphate oxidase during glycerol metabolism or dismutation of superoxide, before the H2O2 causes damage to essential cellular components.
The 3 substrates of this enzyme are NADH, H+, and H2O2, whereas its two products are NAD+ and H2O. It employs one cofactor, FAD, however no discrete FADH2 intermediate has been observed.
This enzyme belongs to the family of oxidoreductases, specifically those acting on a peroxide as acceptor (peroxidases). The systematic name of this enzyme class is NADH:hydrogen-peroxide oxidoreductase. Other names in common use include DPNH peroxidase, NAD peroxidase, diphosphopyridine nucleotide peroxidase, NADH-peroxidase, nicotinamide adenine dinucleotide peroxidase, and NADH2 peroxidase.
Structure.
The crystal structure of NADH peroxidase resembles glutathione reductase with respect to chain fold and location as well as conformation of the prosthetic group FAD
His10 of the NADH peroxidase is located near the N-terminus of the R1 helix within the FAD-binding site. One of the oxygen atoms of Cys42-SO3H is hydrogen-bonded both to the His10 imidazole and to Cys42 N terminus. The His10 functions in part to stabilize the unusual Cys42-SOH redox center. Arg303 also stabilizes the Cys42-SO3H. Glu-14 participates in forming the tight dimer interface that limits solvent accessibility, important for maintaining the oxidation state of the sulfenic acid.
Reaction mechanism.
The NADH peroxidase from Enterococcus faecalis is unique in that it utilizes the Cys42 thiol/sulfenic acid (-SH/-SOH) redox couple in the heterolytic cleavage of the peroxide bond to catalyze the two-electron reduction of hydrogen peroxide to water.
The kinetic mechanism of the wild-type peroxidase involves (1) NADH reduction of E(FAD, Cys42-SOH) to EH2(FAD, Cys42-SH) in an initial priming step; (2) rapid binding of NADH to EH2; (3) reduction of H2O2 by the Cys42-thiolate, yielding E•NADH; and (4) rate-limiting hydride transfer from bound NADH, regenerating EH2. No discrete FADH2 intermediate has been observed, however, and the precise details of Cys42-SOH reduction have not been elucidated.
Inhibitors include Ag+, Cl−, Co2+, Cu2+, Hg2+, NaN3, Pb2+, and SO42−. At suboptimal H2O2 concentrations and concentrations of NADH that are saturating, NADH inhibits the peroxidase activity of the NADH peroxidase by converting the enzyme to an unstable intermediate. NAD+ behaves as an activator by reversing the equilibria that lead to the unstable intermediate, thus converting the enzyme to the kinetically active complex that reduces H2O2.
Biological Function.
NADH eliminates potentially toxic hydrogen peroxide under aerobic growth conditions and represents an enzymatic defense available against H2O2-mediated oxidative stress. Second, the enzyme presents an additional mechanism for regeneration of the NAD+ essential to the strictly fermentative metabolism of this organism. The enzyme may also protect against exogenous H2O2 and contribute to bacterial virulence.
The actual function of NADH peroxidases and oxidases in plants is still unclear, but they could act in early signaling of oxidative stress through producing H2O2.
An alternative role may include regulation of H2O2 formation by NADH peroxidase and oxidase in cell wall loosening and reconstruction.
References.
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14144362
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NADPH peroxidase
|
In enzymology, a NADPH peroxidase (EC 1.11.1.2) is an enzyme that catalyzes the chemical reaction
NADPH + H+ + H2O2 formula_0 NADP+ + 2 H2O
The 3 substrates of this enzyme are NADPH, H+, and H2O2, whereas its two products are NADP+ and H2O.
This enzyme belongs to the family of oxidoreductases, specifically those acting on a peroxide as acceptor (peroxidases). The systematic name of this enzyme class is NADPH:hydrogen-peroxide oxidoreductase. Other names in common use include TPNH peroxidase, NADP peroxidase, nicotinamide adenine dinucleotide phosphate peroxidase, TPN peroxidase, triphosphopyridine nucleotide peroxidase, and NADPH2 peroxidase.
References.
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14144383
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Oplophorus-luciferin 2-monooxygenase
|
In enzymology, an Oplophorus-luciferin 2-monooxygenase (EC 1.13.12.13), also known as "Oplophorus luciferase" (referred in this article as OpLuc) is a luciferase, an enzyme, from the deep-sea shrimp "Oplophorus gracilirostris" [2], belonging to a group of coelenterazine luciferases. Unlike other luciferases, it has a broader substrate specificity [3,4,6] and can also bind to bisdeoxycoelenterazine efficiently [3,4]. It is the third example of a luciferase (Other than "Aequorea" and "Renilla") to be purified in lab [2]. The systematic name of this enzyme class is Oplophorus-luciferin:oxygen 2-oxidoreductase (decarboxylating). This enzyme is also called Oplophorus luciferase.
Chemical reaction.
The two substrates of this enzyme are the luciferin, Coelenterazine and O2 and its 3 products are the oxyluciferin, Coelenteramide, CO2, and light.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O with incorporation of one atom of oxygen (internal monooxygenases o internal mixed-function oxidases). Although the enzyme is part of the group of enzymes that act on coelenterazine, such as "Renilla" and "Gaussia" luciferases, it does not share base pair sequences with these enzymes [3,4,5,7].
OpLuc catalyzes the ATP independent chemical reaction [3,4,5,6]:
coelenterazine ("Oplophorus luciferin") + O2 formula_0 coelenteramide + CO2 + hν
The result of this process in some loss in CO2 as well as a photon of blue light emitted at ~460 nm [2,3,4]. This reaction has an optimal pH of 9, optimal salt concentration of 0.05-0.1 M, and optimal temperature of ~40 C (making it an unusually heat resistant luciferase) [2], although because "O.gracilirostris" are deep sea animals living in below 20 C temperatures, luciferase is normally expressed and folded at low temperatures [6].
Biological Function.
When stimulated in "Oplophorus gracilirostris," OpLuc is secreted from the base of legs and antennae of the deep-sea shrimp as a defense mechanism. This mechanism causes "O.gracilirostris" release a luminous, bright blue luciferase cloud [2].
Enzyme Pathway.
The small protein subunit of OpLuc, 19kda, has an amino terminal peptide sequence that, when stimulated, signals the enzyme to bind to the coelenterazine, "Oplophorus luciferin" (the substrate) [3,7]. Shown in figure 1,the enzyme then oxidizes the coelenterazine in a water medium into the luminescent product, coelenteramide, and releases CO2 as a byproduct [2,3,7].
Structure.
OpLuc is a complex of two covalently bonded [3] protein subunits: two molecules of 19 kDa and two molecules of 35 kDa components, making it a heterotetrameric molecule. The proteins signal the enzyme for secretion in luminescence, catalyzed by the protein 19 kDa [3,4,7]. The luciferase has many cysteine residues that stabilize the enzyme in extracellular environments using disulfide bonds [5].
19 kDa Protein.
This catalytic component of OpLuc has 196 amino acids [3] with one cysteine in the carboxyl terminus and is distinct from proteins found in other luciferases [4]. The protein is made up of two domains with repetitive sequencing of Ia-c and Ila-d in the peptide chain [4]. It is thought to be the protein to cause the bioluminescent reaction of "O.gracilirostris", but functions ineffectively without its larger, subunit counterpart [3,4]. Although the crystal structure of OpLec has yet to be completely analyzed and mapped, 19 kDa experimentally expressed in mammalian cells (regarded as KAZ [7]). The protein was isolated and mutated to catalyze a bright and sustained luminescent reaction to create an engineered luciferase, NanoLuc (NLuc), and a coelenterazine analogue (furimazine) to be used as a cellular reporter [5,8]. A mutated ribbon model of the 19 kDa protein (named nanoKaz) is shown in figure 2.
35 kDa Protein.
The lesser known component of the OpLuc enzyme has 320 amino acids [3] with 11 cysteine and 5 leucine molecules [4]. The amino terminus of the protein was experimentally concluded to begin at 39 amino acids [3]. It is thought to stabilize 19 kDa and is not thought to be affect by substrate specificity [3], however its exact function is not known [3,4,7].
Mechanism.
Although originally thought to have the exact same mechanism as the "Renilla" luciferase [1], this luminescence has two possible reaction routes [2], as shown in figure 3. In the top route, "Oplophorus luciferin" (the coelenterazine displayed as I in the scheme) is oxidized when it combines with O2(radioactively labelled O18 was used in lab experiment) in a water medium and uses a dioxetane peroxide intermediate resulting in a CO2 product and coelenteramide (II in the scheme). The lower pathway does not use an intermediate and has rapid exchanges of oxygen with the water medium. Studies show there is less product yield and is suggested to have partial involvement in the overall reaction [2]. It should be noted, however, it is likely CO2 contamination during experiments demonstrated higher yield than was occurring for the lower pathway, making this pathway highly unlikely in natural conditions [2].
References.
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https://en.wikipedia.org/wiki?curid=14144383
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14144400
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Peptide-tryptophan 2,3-dioxygenase
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In enzymology, a peptide-tryptophan 2,3-dioxygenase (EC 1.13.11.26) is an enzyme that catalyzes the chemical reaction
peptide tryptophan + O2 formula_0 peptide formylkynurenine
Thus, the two substrates of this enzyme are peptide tryptophan and O2, whereas its product is peptide formylkynurenine.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O2. The systematic name of this enzyme class is peptide-tryptophan:oxygen 2,3-oxidoreductase (decyclizing). Other names in common use include pyrrolooxygenase, peptidyltryptophan 2,3-dioxygenase, and tryptophan pyrrolooxygenase.
References.
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{
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https://en.wikipedia.org/wiki?curid=14144400
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14144422
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Phenylalanine 2-monooxygenase
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In enzymology, a phenylalanine 2-monooxygenase (EC 1.13.12.9) is an enzyme that catalyzes the chemical reaction
L-phenylalanine + O2 formula_0 2-phenylacetamide + CO2 + H2O
Thus, the two substrates of this enzyme are L-phenylalanine and O2, whereas its 3 products are 2-phenylacetamide, CO2, and H2O.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O with incorporation of one atom of oxygen (internal monooxygenases o internal mixed-function oxidases). The systematic name of this enzyme class is L-phenylalanine:oxygen 2-oxidoreductase (decarboxylating). Other names in common use include L-phenylalanine oxidase (deaminating and decarboxylating), and phenylalanine (deaminating, decarboxylating)oxidase. This enzyme participates in phenylalanine metabolism.
References.
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[
{
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https://en.wikipedia.org/wiki?curid=14144422
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14144435
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Phospholipid-hydroperoxide glutathione peroxidase
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In enzymology, a phospholipid-hydroperoxide glutathione peroxidase (EC 1.11.1.12) is an enzyme that catalyzes the chemical reaction
2 glutathione + a lipid hydroperoxide formula_0 glutathione disulfide + lipid + 2 H2O
Thus, the two substrates of this enzyme are glutathione and lipid hydroperoxide, whereas its 3 products are glutathione disulfide, lipid, and H2O.
This enzyme belongs to the family of oxidoreductases, to be specific those acting on a peroxide as acceptor (peroxidases). The systematic name of this enzyme class is glutathione:lipid-hydroperoxide oxidoreductase. Other names in common use include peroxidation-inhibiting protein, PHGPX, peroxidation-inhibiting protein: peroxidase, glutathione, (phospholipid hydroperoxide-reducing), phospholipid hydroperoxide glutathione peroxidase, hydroperoxide glutathione peroxidase, or glutathione peroxidase 4 (GPX4). This enzyme participates in glutathione metabolism.
Structural studies.
As of late 2007, two structures have been solved for this class of enzymes, with PDB accession codes 2GS3 and 2OBI.
References.
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[
{
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https://en.wikipedia.org/wiki?curid=14144435
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14144452
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Protocatechuate 3,4-dioxygenase
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In enzymology, a protocatechuate 3,4-dioxygenase (EC 1.13.11.3) is an enzyme that catalyzes the chemical reaction
3,4-dihydroxybenzoate + O2 formula_0 3-carboxy-cis,cis-muconate
Thus, the two substrates of this enzyme are 3,4-dihydroxybenzoate (protocatechuic acid) and O2, whereas its product is 3-carboxy-cis,cis-muconate.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The systematic name of this enzyme class is protocatechuate:oxygen 3,4-oxidoreductase (decyclizing). Other names in common use include protocatechuate oxygenase, protocatechuic acid oxidase, protocatechuic 3,4-dioxygenase, and protocatechuic 3,4-oxygenase. This enzyme participates in benzoate degradation via hydroxylation and 2,4-dichlorobenzoate degradation. It employs one cofactor, iron.
This enzyme has been found effective at improving organic fluorophore-stability in single-molecule experiments. Commercial preps of the enzyme isolated from "Pseudomonas" spp. generally require further purification to remove strong contaminating nuclease activity.
Structural studies.
As of late 2007, 37 structures have been solved for this class of enzymes, with PDB accession codes 1EO2, 1EO9, 1EOA, 1EOB, 1EOC, 1YKK, 1YKL, 1YKM, 1YKN, 1YKO, 1YKP, 2BUM, 2BUQ, 2BUR, 2BUT, 2BUU, 2BUV, 2BUW, 2BUX, 2BUY, 2BUZ, 2BV0, 2PCD, 3PCA, 3PCB, 3PCC, 3PCD, 3PCE, 3PCF, 3PCG, 3PCH, 3PCI, 3PCJ, 3PCK, 3PCL, 3PCM, and 3PCN.
References.
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[
{
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https://en.wikipedia.org/wiki?curid=14144452
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14144474
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Protocatechuate 4,5-dioxygenase
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In enzymology, a protocatechuate 4,5-dioxygenase (EC 1.13.11.8) is an enzyme that catalyzes the chemical reaction
protocatechuate + O2 formula_0 4-carboxy-2-hydroxymuconate semialdehyde
Thus, the two substrates of this enzyme are protocatechuate and O2, whereas its product is 4-carboxy-2-hydroxymuconate semialdehyde.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O2. The systematic name of this enzyme class is protocatechuate:oxygen 4,5-oxidoreductase (decyclizing). Other names in common use include protocatechuate 4,5-oxygenase, protocatechuic 4,5-dioxygenase, and protocatechuic 4,5-oxygenase. This enzyme participates in benzoate degradation via hydroxylation and 2,4-dichlorobenzoate degradation. It employs one cofactor, iron.
Structural studies.
As of late 2007, two structures have been solved for this class of enzymes, with PDB accession codes 1B4U and 1BOU.
References.
<templatestyles src="Reflist/styles.css" />
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[
{
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"text": "\\rightleftharpoons"
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https://en.wikipedia.org/wiki?curid=14144474
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14144490
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Pyrogallol 1,2-oxygenase
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In enzymology, a pyrogallol 1,2-oxygenase (EC 1.13.11.35) is an enzyme that catalyzes the chemical reaction
1,2,3-trihydroxybenzene + O2 formula_0 (Z)-5-oxohex-2-enedioate
Thus, the two substrates of this enzyme are 1,2,3-trihydroxybenzene and O2, whereas its product is (Z)-5-oxohex-2-enedioate.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O2. The systematic name of this enzyme class is 1,2,3-trihydroxybenzene:oxygen 1,2-oxidoreductase (decyclizing). This enzyme is also called pyrogallol 1,2-dioxygenase.
References.
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[
{
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https://en.wikipedia.org/wiki?curid=14144490
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14144510
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Quercetin 2,3-dioxygenase
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In enzymology, a quercetin 2,3-dioxygenase (EC 1.13.11.24) is an enzyme that catalyzes the chemical reaction
quercetin + O2 formula_0 2-(3,4-dihydroxybenzoyloxy)-4,6-dihydroxybenzoate + CO + H+
Thus, the two substrates of this enzyme are quercetin and O2, whereas its three products are 2-(3,4-dihydroxybenzoyloxy)-4,6-dihydroxybenzoate, CO, and H+.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O2. The systematic name of this enzyme class is quercetin:oxygen 2,3-oxidoreductase (decyclizing). Other names in common use include quercetinase and flavonol 2,4-oxygenase. It has two cofactors: iron and copper.
Structural studies.
As of late 2007, six crystal structures have been solved for this class of enzymes, with PDB accession codes 1GQG, 1GQH, 1H1I, 1H1M, 1JUH, and 2H0V.
References.
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[
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https://en.wikipedia.org/wiki?curid=14144510
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14144535
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Renilla-luciferin 2-monooxygenase
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Renilla-luciferin 2-monooxygenase, "Renilla" luciferase, or RLuc, is a bioluminescent enzyme found in "Renilla reniformis", belonging to a group of coelenterazine luciferases. Of this group of enzymes, the luciferase from "Renilla reniformis" has been the most extensively studied, and due to its bioluminescence requiring only molecular oxygen, has a wide range of applications, with uses as a reporter gene probe in cell culture, in vivo imaging, and various other areas of biological research.
Recently, chimeras of RLuc have been developed and demonstrated to be the brightest luminescent proteins to date, and have proved effective in both noninvasive single-cell and whole body imaging.
Note that the EC record also includes other unrelated enzymes that catalyze the same reaction. An example is the calcium-dependent photoprotein aequorin: while Rluc is in the AB hydrolase superfamily, aequorin is an EF hand protein. The name does not specifically refer to "Renilla", but instead refers to Renilla-luciferin, a chemical also known as coelenterazine.
Chemical reaction.
RLuc is an oxidoreductase, specifically acting on single donors with O2 as the oxidant. However, this enzyme appears to be unrelated from most other luciferases that act on coelenterazine, such as those from copepods.
RLuc catalyzes the chemical reaction
Coelenterazine + O2 formula_0 coelenteramide + CO2 + hν
In the process, coelenterazine is oxidized with a concurrent loss of CO2, and a photon of blue light is emitted.
Biological function.
In "Renilla reniformis", RLuc is found in membrane-bound intracellular structures within specialized light emitting cells, and is coupled with a closely interacting green fluorescent protein (RrGFP), and a Ca++ activated luciferin binding protein (RrLBP). Although the luciferase catalyzed oxidation of coelenterazine releases a photon of blue light (480 nm), this is not observed "in vivo". Instead, the energy released by the reaction involving RLuc is passed via resonance energy transfer to the fluorophore of RrGFP and emitted as a green photon (505 nm), resulting in green bioluminescence observed from the animal. This process relies on a Förster resonance energy transfer (FRET) mechanism, increasing the emitted photon number approximately six-fold.
Structure.
Renilla luciferase contains 311 amino acids, and is active as a nearly spherical single polypeptide chain monomer of 36 kDa, which have a tendency for self-association, forming inactive dimers and trimers. Like other dehalogenase-superfamily enzymes, it has a characteristic α/β-hydrolase fold sequence at its core and shares the conserved catalytic triad of residues employed by dehalogenases. In RLuc, the loop containing residues 153 – 163 is structurally flexible, facilitating greater diffusion of solvents into the active site, which contains a highly-conserved catalytic triad consisting of Aspartic Acid at residue 120, Glutamic Acid at residue 144, and Histidine at residue 285.
Enzyme pathway.
Unlike photoproteins which stably bind coelenterazine and emit light upon addition of calcium, coelenterazine is normally bound by RrLBP, the luciferin-binding protein. When stimulated, a Ca2+ ion first interacts with RrLBP, causing it to release coelenterazine. Coelenterazine is then oxidized by RLuc into coelenteramide, releasing a single photon of blue light (480 nm) in the process. This photon is captured by the adjacent GFP, releasing a photon of green light. This pathway is summarized below.
formula_1
formula_2
formula_3
Mechanism.
The RLuc mediated chemical reaction involves the catalytic degradation of coelenterazine, and proceeds through a 1,2-dioxetane (also called dioxetanone or cyclic peroxide) intermediate. Based on studies using radioactively labelled oxygen species within the RLuc complex, it has been determined that the luciferin carbonyl oxygen is exchanged rapidly with oxygen from water prior to incorporation of an oxygen atom from O2 via a dioxetane intermediate. The resultant CO2 also rapidly exchanges its oxygens with those from the surrounding water. The general mechanism is depicted below.
References.
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[
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{
"math_id": 1,
"text": "RrLBP \\ce{->[\\ce{+Ca^{2+}}]} apoRrLBP(+Ca^{2+}) + coelenterazine"
},
{
"math_id": 2,
"text": " coelenterazine + O2 \\ce{->[\\ce{RLuc}]} coelenteramide + CO2 + hv (480 nm)"
},
{
"math_id": 3,
"text": " hv (480 nm) \\ce{->[\\ce{RrGFP}]} hv (505 nm)"
}
] |
https://en.wikipedia.org/wiki?curid=14144535
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14144557
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Ribosyldihydronicotinamide dehydrogenase (quinone)
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In enzymology, a ribosyldihydronicotinamide dehydrogenase (quinone) (EC 1.10.99.2) is an enzyme that catalyzes the chemical reaction
1-(beta-D-ribofuranosyl)-1,4-dihydronicotinamide + a quinone formula_0 1-(beta-D-ribofuranosyl)nicotinamide + a hydroquinone
Thus, the two substrates of this enzyme are 1-(beta-D-ribofuranosyl)-1,4-dihydronicotinamide and quinone, whereas its two products are 1-(beta-D-ribofuranosyl)nicotinamide and hydroquinone.
This enzyme belongs to the family of oxidoreductases, specifically those acting on diphenols and related substances as donor with other acceptors. The systematic name of this enzyme class is 1-(beta-D-ribofuranosyl)-1,4-dihydronicotinamide:quinone oxidoreductase. Other names in common use include NRH:quinone oxidoreductase 2, NQO2, NQO2, NAD(P)H:quinone oxidoreductase-2 (misleading), QR2, quinone reductase 2, N-ribosyldihydronicotinamide dehydrogenase (quinone), and NAD(P)H:quinone oxidoreductase2 (misleading).
References.
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https://en.wikipedia.org/wiki?curid=14144557
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14144577
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Rifamycin-B oxidase
|
Enzyme
In enzymology, a rifamycin-B oxidase (EC 1.10.3.6) is an enzyme that catalyzes the chemical reaction
rifamycin B + O2 formula_0 rifamycin O + H2O2
Thus, the two substrates of this enzyme are rifamycin B and O2, whereas its two products are rifamycin O and H2O2.
This enzyme belongs to the family of oxidoreductases, specifically those acting on diphenols and related substances as donor with oxygen as acceptor. The systematic name of this enzyme class is rifamycin-B:oxygen oxidoreductase. This enzyme is also called rifamycin B oxidase.
References.
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[
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https://en.wikipedia.org/wiki?curid=14144577
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14144593
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Stizolobate synthase
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In enzymology, a stizolobate synthase (EC 1.13.11.29) is an enzyme that catalyzes the chemical reaction
3,4-dihydroxy-L-phenylalanine + O2 formula_0 4-(L-alanin-3-yl)-2-hydroxy-cis,cis-muconate 6-semialdehyde
Thus, the two substrates of this enzyme are 3,4-dihydroxy-L-phenylalanine and O2, whereas its product is 4-(L-alanin-3-yl)-2-hydroxy-cis,cis-muconate 6-semialdehyde.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O2. The systematic name of this enzyme class is 3,4-dihydroxy-L-phenylalanine:oxygen 4,5-oxidoreductase (recyclizing). This enzyme participates in tyrosine metabolism. It employs one cofactor, zinc.
References.
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[
{
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https://en.wikipedia.org/wiki?curid=14144593
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14144612
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Stizolobinate synthase
|
In enzymology, a stizolobinate synthase (EC 1.13.11.30) is an enzyme that catalyzes the chemical reaction
3,4-dihydroxy-L-phenylalanine + O2 formula_0 5-(L-alanin-3-yl)-2-hydroxy-cis,cis-muconate 6-semialdehyde
Thus, the two substrates of this enzyme are 3,4-dihydroxy-L-phenylalanine and O2, whereas its product is 5-(L-alanin-3-yl)-2-hydroxy-cis,cis-muconate 6-semialdehyde.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O2. The systematic name of this enzyme class is 3,4-dihydroxy-L-phenylalanine:oxygen 2,3-oxidoreductase (recyclizing). This enzyme participates in tyrosine metabolism. It employs one cofactor, zinc.
References.
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[
{
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"text": "\\rightleftharpoons"
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https://en.wikipedia.org/wiki?curid=14144612
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14144632
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Sulfur oxygenase/reductase
|
In enzymology, a sulfur oxygenase/reductase (EC 1.13.11.55) is an enzyme that catalyzes the chemical reaction
4 sulfur + 4 H2O + O2 formula_0 2 hydrogen sulfide + 2 bisulfite + 2 H+
The 3 substrates of this enzyme are sulfur, H2O, and O2, whereas its 3 products are hydrogen sulfide, bisulfite, and H+.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O2. The systematic name of this enzyme class is sulfur:oxygen oxidoreductase (hydrogen-sulfide- and sulfite-forming). Other names in common use include SOR, sulfur oxygenase, and sulfur oxygenase reductase.
References.
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[
{
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https://en.wikipedia.org/wiki?curid=14144632
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14144653
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Trans-acenaphthene-1,2-diol dehydrogenase
|
Enzyme
In enzymology, a trans-acenaphthene-1,2-diol dehydrogenase (EC 1.10.1.1) is an enzyme that catalyzes the chemical reaction
(+/-)-trans-acenaphthene-1,2-diol + 2 NADP+ formula_0 acenaphthenequinone + 2 NADPH + 2 H+
Thus, the two substrates of this enzyme are (+/-)-trans-acenaphthene-1,2-diol and NADP+, whereas its 3 products are acenaphthenequinone, NADPH, and H+.
This enzyme belongs to the family of oxidoreductases, specifically those acting on diphenols and related substances as donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is (+/-)-trans-acenaphthene-1,2-diol:NADP+ oxidoreductase. This enzyme is also called trans-1,2-acenaphthenediol dehydrogenase.
References.
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{
"math_id": 0,
"text": "\\rightleftharpoons"
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https://en.wikipedia.org/wiki?curid=14144653
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14144721
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Tryptophan 2-monooxygenase
|
In enzymology, a tryptophan 2-monooxygenase (EC 1.13.12.3) is an enzyme that catalyzes the chemical reaction
L-tryptophan + O2 formula_0 (indol-3-yl)acetamide + CO2 + H2O
Thus, the two substrates of this enzyme are L-tryptophan and O2, and its 3 products are (indol-3-yl)acetamide, CO2, and H2O.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O with incorporation of one atom of oxygen (internal monooxygenases o internal mixed-function oxidases). The systematic name of this enzyme class is L-tryptophan:oxygen 2-oxidoreductase (decarboxylating). This enzyme participates in tryptophan metabolism.
References.
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[
{
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"text": "\\rightleftharpoons"
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https://en.wikipedia.org/wiki?curid=14144721
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14144760
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Watasenia-luciferin 2-monooxygenase
|
In enzymology, a Watasenia-luciferin 2-monooxygenase (EC 1.13.12.8) is an enzyme that catalyzes the chemical reaction
Watasenia luciferin + O2 formula_0 oxidized Watasenia luciferin + CO2 + hnu
Thus, the two substrates of this enzyme are Watasenia luciferin and O2, whereas its 3 products are oxidized Watasenia luciferin, CO2, and hn.
This enzyme belongs to the family of oxidoreductases, specifically, those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O with the incorporation of one atom of oxygen (internal monooxygenases o internal mixed-function oxidases). The systematic name of this enzyme class is Watasenia-luciferin:oxygen 2-oxidoreductase (decarboxylating). This enzyme is also called Watasenia-type luciferase.
References.
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
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https://en.wikipedia.org/wiki?curid=14144760
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14147
|
Harmonic analysis
|
Study of superpositions in mathematics
Harmonic analysis is a branch of mathematics concerned with investigating the connections between a function and its representation in frequency. The frequency representation is found by using the Fourier transform for functions on unbounded domains such as the full real line or by Fourier series for functions on bounded domains, especially periodic functions on finite intervals. Generalizing these transforms to other domains is generally called Fourier analysis, although the term is sometimes used interchangeably with harmonic analysis. Harmonic analysis has become a vast subject with applications in areas as diverse as number theory, representation theory, signal processing, quantum mechanics, tidal analysis and neuroscience.
The term "harmonics" originated from the Ancient Greek word "harmonikos", meaning "skilled in music". In physical eigenvalue problems, it began to mean waves whose frequencies are integer multiples of one another, as are the frequencies of the harmonics of music notes. Still, the term has been generalized beyond its original meaning.
Development of Harmonic Analysis.
Historically, harmonic functions first referred to the solutions of Laplace's equation. This terminology was extended to other special functions that solved related equations, then to eigenfunctions of general elliptic operators, and nowadays harmonic functions are considered as a generalization of periodic functions in function spaces defined on manifolds, for example as solutions of general, not necessarily elliptic, partial differential equations including some boundary conditions that may imply their symmetry or periodicity.
Fourier Analysis.
The classical Fourier transform on R"n" is still an area of ongoing research, particularly concerning Fourier transformation on more general objects such as tempered distributions. For instance, if we impose some requirements on a distribution "f", we can attempt to translate these requirements into the Fourier transform of "f". The Paley–Wiener theorem is an example. The Paley–Wiener theorem immediately implies that if "f" is a nonzero distribution of compact support (these include functions of compact support), then its Fourier transform is never compactly supported (i.e., if a signal is limited in one domain, it is unlimited in the other). This is an elementary form of an uncertainty principle in a harmonic-analysis setting.
Fourier series can be conveniently studied in the context of Hilbert spaces, which provides a connection between harmonic analysis and functional analysis. There are four versions of the Fourier transform, dependent on the spaces that are mapped by the transformation:
Abstract harmonic analysis.
Abstract harmonic analysis is primarily concerned with how real or
complex-valued functions (often on very general domains) can be studied using symmetries such
as translations or rotations (for instance via the Fourier transform and its relatives); this field is of
course related to real-variable harmonic analysis, but is perhaps closer in spirit to representation theory and functional analysis.
One of the most modern branches of harmonic analysis, having its roots in the mid-20th century, is analysis on topological groups. The core motivating ideas are the various Fourier transforms, which can be generalized to a transform of functions defined on Hausdorff locally compact topological groups.
One of the major results in the theory of functions on abelian locally compact groups is called Pontryagin duality.
Harmonic analysis studies the properties of that duality. Different generalization of Fourier transforms attempts to extend those features to different settings, for instance, first to the case of general abelian topological groups and second to the case of non-abelian Lie groups.
Harmonic analysis is closely related to the theory of unitary group representations for general non-abelian locally compact groups. For compact groups, the Peter–Weyl theorem explains how one may get harmonics by choosing one irreducible representation out of each equivalence class of representations. This choice of harmonics enjoys some of the valuable properties of the classical Fourier transform in terms of carrying convolutions to pointwise products or otherwise showing a certain understanding of the underlying group structure. See also: Non-commutative harmonic analysis.
If the group is neither abelian nor compact, no general satisfactory theory is currently known ("satisfactory" means at least as strong as the Plancherel theorem). However, many specific cases have been analyzed, for example, SL"n". In this case, representations in infinite dimensions play a crucial role.
Applied harmonic analysis.
Many applications of harmonic analysis in science and engineering begin with the idea or hypothesis that a phenomenon or signal is composed of a sum of individual oscillatory components. Ocean tides and vibrating strings are common and simple examples. The theoretical approach often tries to describe the system by a differential equation or system of equations to predict the essential features, including the amplitude, frequency, and phases of the oscillatory components. The specific equations depend on the field, but theories generally try to select equations that represent significant principles that are applicable.
The experimental approach is usually to acquire data that accurately quantifies the phenomenon. For example, in a study of tides, the experimentalist would acquire samples of water depth as a function of time at closely enough spaced intervals to see each oscillation and over a long enough duration that multiple oscillatory periods are likely included. In a study on vibrating strings, it is common for the experimentalist to acquire a sound waveform sampled at a rate at least twice that of the highest frequency expected and for a duration many times the period of the lowest frequency expected.
For example, the top signal at the right is a sound waveform of a bass guitar playing an open string corresponding to an A note with a fundamental frequency of 55 Hz. The waveform appears oscillatory, but it is more complex than a simple sine wave, indicating the presence of additional waves. The different wave components contributing to the sound can be revealed by applying a mathematical analysis technique known as the Fourier transform, shown in the lower figure. There is a prominent peak at 55 Hz, but other peaks at 110 Hz, 165 Hz, and at other frequencies corresponding to integer multiples of 55 Hz. In this case, 55 Hz is identified as the fundamental frequency of the string vibration, and the integer multiples are known as harmonics.
References.
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[
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https://en.wikipedia.org/wiki?curid=14147
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14147233
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1,2-dehydroreticulinium reductase (NADPH)
|
Class of enzymes
In enzymology, a 1,2-dehydroreticulinium reductase (NADPH) (EC 1.5.1.27) is an enzyme that catalyzes the chemical reaction
(R)-reticuline + NADP+ formula_0 1,2-dehydroreticulinium + NADPH + H+
Thus, the two substrates of this enzyme are (R)-reticuline and NADP+, whereas its 3 products are 1,2-dehydroreticulinium, NADPH, and H+.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is (R)-reticuline:NADP+ oxidoreductase. This enzyme is also called 1,2-dehydroreticulinium ion reductase. This enzyme participates in alkaloid biosynthesis i.
References.
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[
{
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https://en.wikipedia.org/wiki?curid=14147233
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14147260
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1-Pyrroline-5-carboxylate dehydrogenase
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Class of enzymes
In enzymology, a 1-pyrroline-5-carboxylate dehydrogenase (EC 1.2.1.88) is an enzyme that catalyzes the chemical reaction
(S)-1-pyrroline-5-carboxylate + NAD+ + 2 H2O formula_0 -glutamate + NADH + H+
The three substrates of this enzyme are ("S")-1-pyrroline-5-carboxylate, NAD+, and H2O, whereas its three products are glutamate, NADH, and H+.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is ("S")-1-pyrroline-5-carboxylate:NAD+ oxidoreductase. Other names in common use include delta-1-pyrroline-5-carboxylate dehydrogenase, 1-pyrroline dehydrogenase, pyrroline-5-carboxylate dehydrogenase, pyrroline-5-carboxylic acid dehydrogenase, -pyrroline-5-carboxylate-NAD+ oxidoreductase, and 1-pyrroline-5-carboxylate:NAD+ oxidoreductase. This enzyme participates in glutamate metabolism and arginine and proline metabolism.
Structural studies.
As of late 2007, 14 structures have been solved for this class of enzymes, with PDB accession codes 2BHP, 2BHQ, 2BJA, 2BJK, 2EHQ, 2EHU, 2EII, 2EIT, 2EIW, 2EJ6, 2EJD, 2EJL, 2IY6, and 2J40.
Human gene.
In human, the protein is encoded by "ALDH4A1" gene.
References.
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[
{
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https://en.wikipedia.org/wiki?curid=14147260
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14147280
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2,4-diaminopentanoate dehydrogenase
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Class of enzymes
In enzymology, a 2,4-diaminopentanoate dehydrogenase (EC 1.4.1.12) is an enzyme that catalyzes the chemical reaction
2,4-diaminopentanoate + H2O + NAD(P)+ formula_0 2-amino-4-oxopentanoate + NH3 + NAD(P)H + H+
The 4 substrates of this enzyme are 2,4-diaminopentanoate, H2O, NAD+, and NADP+, whereas its 5 products are 2-amino-4-oxopentanoate, NH3, NADH, NADPH, and H+.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH2 group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is 2,4-diaminopentanoate:NAD(P)+ oxidoreductase (deaminating). This enzyme is also called 2,4-diaminopentanoic acid C4 dehydrogenase. This enzyme participates in 3 metabolic pathways: lysine degradation, arginine and proline metabolism, and d-arginine and d-ornithine metabolism.
References.
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{
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https://en.wikipedia.org/wiki?curid=14147280
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14147300
|
2-hydroxy-1,4-benzoquinone reductase
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Class of enzymes
In enzymology, a 2-hydroxy-1,4-benzoquinone reductase (EC 1.6.5.7) is an enzyme that catalyzes the chemical reaction
2-hydroxy-1,4-benzoquinone + NADH + H+ formula_0 1,2,4-trihydroxybenzene + NAD+
The 3 substrates of this enzyme are 2-hydroxy-1,4-benzoquinone, NADH, and H+, whereas its two products are 1,2,4-trihydroxybenzene and NAD+.
This enzyme participates in gamma-hexachlorocyclohexane degradation and 1,4-dichlorobenzene degradation.
Nomenclature.
This enzyme belongs to the family of oxidoreductases, specifically those acting on NADH or NADPH with a quinone or similar compound as acceptor. The systematic name of this enzyme class is 2-hydroxy-1,4-benzoquinone:NADH oxidoreductase. Other names in common use include hydroxybenzoquinone reductase, 1,2,4-trihydroxybenzene:NAD oxidoreductase, and NADH:2-hydroxy-1,4-benzoquinone oxidoreductase.
References.
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{
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https://en.wikipedia.org/wiki?curid=14147300
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14147323
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2-oxopropyl-CoM reductase (carboxylating)
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Class of enzymes
In enzymology, a 2-oxopropyl-CoM reductase (carboxylating) (EC 1.8.1.5) is an enzyme that catalyzes the chemical reaction
2-mercaptoethanesulfonate + acetoacetate + NADP+ formula_0 2-(2-oxopropylthio)ethanesulfonate + CO2 + NADPH
The 3 substrates of this enzyme are 2-mercaptoethanesulfonate, acetoacetate, and NADP+, whereas its 3 products are 2-(2-oxopropylthio)ethanesulfonate, CO2, and NADPH.
This enzyme belongs to the family of oxidoreductases, specifically those acting on a sulfur group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is 2-mercaptoethanesulfonate, acetoacetate:NADP+ oxidoreductase (decarboxylating). Other names in common use include NADPH:2-(2-ketopropylthio)ethanesulfonate, oxidoreductase/carboxylase, and NADPH:2-ketopropyl-coenzyme M oxidoreductase/carboxylase.
Structural studies.
As of late 2007, two structures have been solved for this class of enzymes, with PDB accession codes 2C3C and 2C3D.
References.
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{
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https://en.wikipedia.org/wiki?curid=14147323
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14147354
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3-aci-nitropropanoate oxidase
|
Class of enzymes
In enzymology, a 3-aci-nitropropanoate oxidase (EC 1.7.3.5) is an enzyme that catalyzes the chemical reaction
3-aci-nitropropanoate + O2 + H2O formula_0 3-oxopropanoate + nitrite + H2O2
The 3 substrates of this enzyme are 3-aci-nitropropanoate, O2, and H2O, whereas its 3 products are 3-oxopropanoate, nitrite, and H2O2.
This enzyme belongs to the family of oxidoreductases, specifically those acting on other nitrogenous compounds as donors with oxygen as acceptor. The systematic name of this enzyme class is 3-aci-nitropropanoate:oxygen oxidoreductase. This enzyme is also called propionate-3-nitronate oxidase. It employs one cofactor, FMN.
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https://en.wikipedia.org/wiki?curid=14147354
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14147479
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4-(dimethylamino)phenylazoxybenzene reductase
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Class of enzymes
In enzymology, a 4-(dimethylamino)phenylazoxybenzene reductase (EC 1.7.1.11) is an enzyme that catalyzes the chemical reaction
4-(dimethylamino)phenylazobenzene + NADP+ formula_0 4-(dimethylamino)phenylazoxybenzene + NADPH + H+
Thus, the two substrates of this enzyme are 4-(dimethylamino)phenylazobenzene and NADP+, whereas its 3 products are 4-(dimethylamino)phenylazoxybenzene, NADPH, and H+.
This enzyme belongs to the family of oxidoreductases, specifically those acting on other nitrogenous compounds as donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is 4-(dimethylamino)phenylazobenzene:NADP+ oxidoreductase. Other names in common use include N,N-dimethyl-p-aminoazobenzene oxide reductase, dimethylaminoazobenzene N-oxide reductase, NADPH-dependent DMAB N-oxide reductase, and NADPH:4-(dimethylamino)phenylazoxybenzene oxidoreductase.
References.
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{
"math_id": 0,
"text": "\\rightleftharpoons"
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https://en.wikipedia.org/wiki?curid=14147479
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14147508
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5,10-methylenetetrahydromethanopterin reductase
|
InterPro Family
In enzymology, a 5,10-methylenetetrahydromethanopterin reductase (EC 1.5.98.2) is an enzyme that catalyzes the chemical reaction
5-methyltetrahydromethanopterin + coenzyme F420 formula_0 5,10-methylenetetrahydromethanopterin + reduced coenzyme F420
Thus, the two substrates of this enzyme are 5-methyltetrahydromethanopterin and coenzyme F420, whereas its two products are 5,10-methylenetetrahydromethanopterin and reduced coenzyme F420.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH group of donors with other acceptors. The systematic name of this enzyme class is 5-methyltetrahydromethanopterin:coenzyme-F420 oxidoreductase. Other names in common use include 5,10-methylenetetrahydromethanopterin cyclohydrolase, N5,N10-methylenetetrahydromethanopterin reductase, methylene-H4MPT reductase, coenzyme F420-dependent N5,N10-methenyltetrahydromethanopterin, reductase, and N5,N10-methylenetetrahydromethanopterin:coenzyme-F420 oxidoreductase. This enzyme participates in folate biosynthesis.
References.
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[
{
"math_id": 0,
"text": "\\rightleftharpoons"
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https://en.wikipedia.org/wiki?curid=14147508
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14147528
|
6,7-dihydropteridine reductase
|
Class of enzymes
In enzymology, 6,7-dihydropteridine reductase (EC 1.5.1.34, also Dihydrobiopterin reductase) is an enzyme that catalyzes the chemical reaction
5,6,7,8-tetrahydropteridine + NAD(P)+ formula_0 6,7-dihydropteridine + NAD(P)H + H+
The four substrates for this enzyme are a 6,7-dihydropteridine (dihydrobiopterin), NADH, NADPH, and H+ and its three products are 5,6,7,8-tetrahydropteridine (tetrahydrobiopterin), NAD+, and NADP+ This enzyme participates in folate biosynthesis. In the human genome, the enzyme is encoded by the QDPR gene.
Nomenclature.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is 5,6,7,8-tetrahydropteridine:NAD(P)+ oxidoreductase. Other names in common use include 6,7-dihydropteridine:NAD(P)H oxidoreductase, DHPR, NAD(P)H:6,7-dihydropteridine oxidoreductase, NADH-dihydropteridine reductase, NADPH-dihydropteridine reductase, NADPH-specific dihydropteridine reductase, dihydropteridine (reduced nicotinamide adenine dinucleotide), reductase, dihydropteridine reductase, dihydropteridine reductase (NADH), and 5,6,7,8-tetrahydropteridine:NAD(P)H+ oxidoreductase.
Clinical significance.
Dihydropteridine reductase deficiency is a defect in the regeneration of tetrahydrobiopterin. Many patients have significant developmental delays despite therapy, develop brain abnormalities, and are prone to sudden death. The reason is not completely clear, but might be related to the accumulation of dihydrobiopterin and abnormal metabolism of folic acid. Response to treatment is variable and the long-term and functional outcome is unknown. To provide a basis for improving the understanding of the epidemiology, genotype/phenotype correlation and outcome of these diseases their impact on the quality of life of patients, and for evaluating diagnostic and therapeutic strategies a patient registry was established by the noncommercial International Working Group on Neurotransmitter Related Disorders (iNTD). Dihydropteridine reductase deficiency is treated with tyrosine supplements, a controlled diet which is lacking in phenylalanine, well as supplementation of L-DOPA.
References.
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Further reading.
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[
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https://en.wikipedia.org/wiki?curid=14147528
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14147556
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Acetylindoxyl oxidase
|
Class of enzymes
Acetylindoxyl oxidase (EC 1.7.3.2) is an enzyme that catalyzes the chemical reaction
N-acetylindoxyl + O2 formula_0 N-acetylisatin + (?)
Thus, the two substrates of this enzyme are N-acetylindoxyl and oxygen, whereas its product is N-acetylisatin.
This enzyme belongs to the family of oxidoreductases, specifically those acting on other nitrogenous compounds as donors with oxygen as acceptor. The systematic name of this enzyme class is N-acetylindoxyl:oxygen oxidoreductase. This enzyme participates in tryptophan metabolism.
References.
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{
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"text": "\\rightleftharpoons"
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https://en.wikipedia.org/wiki?curid=14147556
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14147578
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Adenylyl-sulfate reductase
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Class of enzymes
Adenylyl-sulfate reductase (EC 1.8.99.2) is an enzyme that catalyzes the chemical reaction of the reduction of adenylyl-sulfate/adenosine-5'-phosphosulfate (APS) to sulfite through the use of an electron donor cofactor. The products of the reaction are AMP and sulfite, as well as an oxidized electron donor cofactor.
Nomenclature.
This enzyme belongs to the family of oxidoreductases, specifically those acting on a sulfur group of donors with other acceptors. The systematic name of this enzyme class is AMP, sulfite:acceptor oxidoreductase (adenosine-5'-phosphosulfate-forming). Other names in common use include adenosine phosphosulfate reductase, adenosine 5'-phosphosulfate reductase, APS-reductase, APS reductase, AMP, sulfite:(acceptor) oxidoreductase, and (adenosine-5'-phosphosulfate-forming). This enzyme participates in selenium metabolism and sulfur metabolism.
Mechanism.
APS reductase catalyzes the reversible transformation of APS to sulfite and AMP, which is the rate determining step of the overall reaction. The reaction catalyzed by APS reductase is as follows:
formula_0
Sulfate has to be activated to APS by ATP sulfurylase at the expense of one ATP, hence this reaction requires an input of energy. The reaction above occurs in a strictly anaerobic environment. The two electrons come from a reduced cofactor, in this case reduced FAD. The forward direction requires one AMP molecule; however, research suggests that the reverse reaction requires two AMP molecules (one acting on the substrate and one inhibiting the forward reaction). The reversible reaction occurs when AMP binds to the Arg317 residue, changing the confirmation of Arg317 and APS reductase as a whole, which provides the thermodynamic driving force to go in the reverse direction.
APS reductases are involved in both assimilatory and dissimilatory sulfate reduction. Dissimilatory sulfate reduction takes sulfate and transforms it into sulfide, a sulfur source that can be distributed throughout the body. Assimilatory sulfate reduction takes sulfate and turns it into cysteine. Dissimilatory and assimilatory pathways both use APS reductases as a metabolic tool to produce a sulfur source and amino acids, respectively.
Structure.
As of late 2014, 6 structures have been solved for this class of enzymes, with PDB accession codes 1JNR, 1JNZ, 2FJA, 2FJB, 2FJD, and 2FJE.
The monomer of the enzyme consists of a mix of α-helices and β-sheets (both parallel and antiparallel). The protein cofactor thioredoxin can provide the required reducing equivalents for the reaction in the form of two cysteine residues, which are ultimately oxidized to a disulfide bond. The base active form of APS reductase appears to be a heterodimer, as seen in plants. In both bacteria and plants, two heterodimers tend to form together and produce a heterotetramer.
The active site cleft in bacterial APS reductase has a few key elements. Residue sequences that appear to be necessary for catalysis are the P-loop (residues 60-66), the Arg-loop (residues 162-173), and the LDTG motif (residues 85-88). The P-loop, or phosphate-binding loop, is an especially important consecutive sequence of resides which aids in the recognition of the phosphate group in APS and, as a result, influences the substrate specificity for APS reductase. The C-terminal Cys256 is also catalytically essential, and seems to have a role in changing the conformation of the enzyme during catalysis.
One notable chemical motif that distinguishes APS reductase from the related 3'-phosphoadenosine-5'-phosphosulfate (PAPS) reductase is the presence of a conserved cysteine motif, CC-X~80-CXXC, which occurs in addition to the universally conserved catalytic cysteine residue. This motif is correlated with the presence of a [4Fe-4S] cluster; therefore, these iron-sulfur clusters are not present within PAPS reductase. When the iron-sulfur cluster is present, it is required for catalytic activity and coordinated to the four cysteine residues in the conserved motif on the other side of the active site cleft.
Function.
Sulfur is a vital component in biological life and a key element in amino acids cysteine and methionine. APS reductase controls the rate limiting step of endogenous sulfur assimilation, which is the process of producing hydrogen sulfide from sulfite. Hydrogen sulfite is one of the major sources of sulfur in plants. APS reductase controls the flow of inorganic sulfur to cysteine, which is involved in many biological processes in plants such as growth, development, and responses to biotic and abiotic stresses. In fact, studies have shown that when cells are starved of sulfur, APS reductase gene expression fluctuates, indicating that when the plants are exposed to metabolic and regulatory stress, APS reductase is likely a crucial enzyme in producing hydrogen sulfide and restoring homeostasis.
Bacteria use APS reductases to engage in assimilatory and dissimilatory sulfate reduction, which make them prime candidates to appear in wastewater treatment environments. Biofoulants can contain a number of sulfate reducing bacteria, and studies have shown that if wastewater plants are left untreated sulfate levels will decrease. These studies have further solidified APS reductase’s crucial role in the global sulfur cycle by giving organisms another unique way to obtain sulfur when it's unavailable.
Clinical significance.
APS reductase does not exist within the proteome of human cells; consequently, these enzymes have become the targets of research for various environmental and medical reasons. Competitive inhibitors for the APS reductase in "Mycobacterium tuberculosis" have been studied as a new possible route for TB treatment, especially against drug-resistant and latent TB. Such inhibitors have also been studied in the context of obtaining oil and gas from reservoirs in order to better control the souring of such products.
Some APS reductases have also been investigated for their role in selenium metabolism and reduction due to the chemical similarity between sulfur and selenium. APR2, the dominant APS reductase isozyme in the model plant "Arabidopsis thaliana", has been implicated in the involvement of selenate tolerance and selenite metabolism. Such research may then aid in the goal of enhancing selenium phytoremediation in plants and, as a result, dietary biofortification.
References.
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Further reading.
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[
{
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"text": "APS + 2e^- \\longleftrightarrow AMP +HSO_3^- (E^\\circ = -60 mV)"
}
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https://en.wikipedia.org/wiki?curid=14147578
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14147587
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Adenylyl-sulfate reductase (glutathione)
|
Adenylyl-sulfate reductase (glutathione) (EC 1.8.4.9) is an enzyme that catalyzes the chemical reaction
AMP + sulfite + glutathione disulfide formula_0 adenylyl sulfate + 2 glutathione
The 3 substrates of this enzyme are adenosine monophosphate, sulfite, and glutathione disulfide, whereas its two products are adenylyl sulfate and glutathione.
This enzyme belongs to the family of oxidoreductases, specifically those acting on a sulfur group of donors with a disulfide as acceptor. The systematic name of this enzyme class is AMP,sulfite:glutathione-disulfide oxidoreductase (adenosine-5'-phosphosulfate-forming). Other names in common use include 5'-adenylylsulfate reductase (also used for, internal_xref(ec_num(1,8,99,2))), AMP,sulfite:oxidized-glutathione oxidoreductase, (adenosine-5'-phosphosulfate-forming), and plant-type 5'-adenylylsulfate reductase. In plants, APS is reduced by the plastidic enzyme APS reductase (APR; EC 1.8.4.9) in the presence of physiological concentrations of reduced glutathione (GSH), which acts as an electron donor.
References.
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https://en.wikipedia.org/wiki?curid=14147587
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14147605
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Adenylyl-sulfate reductase (thioredoxin)
|
Adenylyl-sulfate reductase (thioredoxin) (EC 1.8.4.10) is an enzyme that catalyzes the chemical reaction
AMP + sulfite + thioredoxin disulfide formula_0 5'-adenylyl sulfate + thioredoxin
The 3 substrates of this enzyme are adenosine monophosphate, sulfite, and thioredoxin disulfide, whereas its two products are 5'-adenylyl sulfate and thioredoxin.
This enzyme belongs to the family of oxidoreductases, specifically those acting on a sulfur group of donors with a disulfide as acceptor.
This enzyme also assists a feature of the Calvin-Benson cycle's light regulation within the ferredoxin-thioredoxin system in the form of reduced thioredoxin. Thioredoxin-type adenylyl-sulfate reductase also uses thioredoxin as an electron donor in reactions related to protein synthesis. Note this is a general pathway and other resemblances are studied in literature to support this.
The enzyme functions in reactions that in the end stabilize Thiols in related bonds that end up forming a dithiol group as a byproduct.
Nomenclature.
The systematic name of this enzyme class is AMP, sulfite:thioredoxin-disulfide oxidoreductase (adenosine-5'-phosphosulfate-forming). This enzyme is also called thioredoxin-dependent 5'-adenylylsulfate reductase.
Classication.
This enzyme (Adenylyl-sulfate reductase) is an oxidoreductase (Class 1) or more specifically a sulfur oxidoreductase (Sub-Class 8) disulfide (Sub-Subclass 4). The enzyme bears the serial number of 10 under the EC naming system. The primary difference that this particular adenylyl-sulfate reductase from others is it uses thioredoxin as an electron donor instead of other donors such as glutathione (see Adenylyl-sulfate reductase (glutathione)).
Structural studies.
As of late 2011, according to model version updates within the Protein Data Bank, only one structure has been solved for this class of enzymes, with the PDB accession code 2GOY. The structure generally is tetrameric in nature with each monomeric composed of several helical β-sheet proteins with α-helical proteins in tow. The enzyme structure can be viewed on the PDB page.
Active site.
The active site just as its glutaredoxin counterpart, contains a single cysteine based protein where the thioredoxin binds during electron donation. This including most other adenylyl-sulfate reductases The active site cleft is formed in the center of the enzyme's structure and is notably deep allowing for larger internal surface area for thioredoxin or other substrate binding, on any given protein subunit of the tetramer. The substrate binds onto the C-terminal side of the β-chains within the clef mediated by cysteines. There area few other parts of the synaptic cleft formed between certain loops, such as the "P loop" and the "LDTG motif", noted in some literature with these denotation, each of which contain cysteine number 256 which is important in APS initiated analysis although traditionally considered disordered within the context of the adenylyl sulfate-reductase structure.
Species distribution.
Many organisms use this enzyme, primarily plants as mentioned and many microorganisms such as "E. coli" and fungal plant rhizobia.
"E. coli" is experimentally found to harness this enzyme with variants associated with serine and cysteine residues and is inherently involved within its own intermediate and its stabilization with the up-taking of the adenylyl sulfate-reductase and thioredoxin produced by "P. aeruginosa".
This enzyme is also found in several forms of mycobacteria and other fungi including, as mentioned, rhizobia. Rhizobia use the same pathway but some such as "Rhizobium meliloti" have a limited genetic scope that would result in adenylyl-sulfate reductase production with the genes only appearing on a few loci, but is used in primarily the same way as in bacterial organisms for the production of a small selection of amino acids.
Function.
The structure of adenylyl sulfate-reductase (thioredoxin) has been experimentally shown to follow an open-close system during the reaction when binding the substrate into the active site cleft. When the thioredoxin is detected by the enzyme, the C-terminal tail moves over the active site and forms a closed position within the enzyme itself, allowing for the cysteines that are catalytically necessary to move in and make sufficient contact with the thioredoxin. This action only occurs upon substrate binding. It's important to note that further research still is being completed onto the conformational shifts during the reduction reaction upon thioredoxin binding. However, it is suggested that other conformational steps are needed in order for the intermediate to complete binding to the thioredoxin. These evidence-based speculations consider the evolution of other bacteria that may have reacted with this enzyme or another metabolite over time.
In unicellular organisms such as mycobacteria, one use of this enzyme is in the production of certain proteins, primarily types that either involve or lead to the eventual amino acids cysteine and then methionine.
The thioredoxin dependent adenylyl-sulfate reductase's cleaved disulfuric ions are incorporated into the molecular structure of the proto-proteins in the formation of the aforementioned amino acids. In studies such as one published in the Journal of Biological Chemistry experimentally observed the use of this enzyme type and thioredoxin in the synthesis of the above mentioned proteins within mycobacteria. The working pathway that was considered in this study uses thioredoxin dependent adenylyl-sulfate reductase catalyzes the conversion of 5'-adenosinephosphosulfate into 5′-phosphosulfate. The 5'-phosphosulfate is then changed into 3′-phosphoadenosine 5′-phosphate and sulfite similarly to the general pathway that is a result of the combined products mentioned in the general reaction of adenylyl-sulfate reductase, regardless of the electron donor used. The resulting sulfite post-reaction is commonly used in Cysteine/Methionine production within cells utilizing this enzyme.
References.
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Further reading.
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14147626
|
Alanine dehydrogenase
|
Alanine dehydrogenase (EC 1.4.1.1) is an enzyme that catalyzes the chemical reaction
L-alanine + H2O + NAD+ formula_0 pyruvate + NH3 + NADH + H+
The 2 substrates of this enzyme are L-alanine, water, and nicotinamide adenine dinucleotide+ because water is 55M and does not change, whereas its 4 products are pyruvate, ammonia, NADH, and hydrogen ion.
This enzyme participates in taurine and hypotaurine metabolism and reductive carboxylate cycle (CO2 fixation).
Nomenclature.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH2 group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is L-alanine:NAD+ oxidoreductase (deaminating). Other names in common use include AlaDH, L-alanine dehydrogenase, NAD+-linked alanine dehydrogenase, alpha-alanine dehydrogenase, NAD+-dependent alanine dehydrogenase, alanine oxidoreductase, and NADH-dependent alanine dehydrogenase. T
Structure.
Alanine dehydrogenase contains both a N-terminus and C-terminus domains.
References.
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Further reading.
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https://en.wikipedia.org/wiki?curid=14147626
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14147648
|
Alanopine dehydrogenase
|
Alanopine dehydrogenase (EC 1.5.1.17) is an enzyme that catalyzes the chemical reaction
2,2'-iminodipropanoate + NAD+ + H2O formula_0 L-alanine + pyruvate + NADH + H+
The 2 substrates of this enzyme are 2,2'-iminodipropanoate, and nicotinamide adenine dinucleotide+. water is excluded since water is 55M and does not change. Its 4 products are L-alanine, pyruvate, nicotinamide adenine dinucleotide, and hydrogen ion.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is 2,2'-iminodipropanoate:NAD+ oxidoreductase (L-alanine-forming). Other names in common use include ALPDH, alanopine[meso-N-(1-carboxyethyl)-alanine]dehydrogenase, meso-N-(1-carboxyethyl)-alanine:NAD+ oxidoreductase, alanopine: NAD+ oxidoreductase, ADH, and alanopine:NAD+ oxidoreductase.
References.
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{
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https://en.wikipedia.org/wiki?curid=14147648
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14147665
|
Amine oxidase (copper-containing)
|
Amine oxidase (copper-containing) (AOC) (EC 1.4.3.21 and EC 1.4.3.22; formerly EC 1.4.3.6) is a family of amine oxidase enzymes which includes both primary-amine oxidase and diamine oxidase; these enzymes catalyze the oxidation of a wide range of biogenic amines including many neurotransmitters, histamine and xenobiotic amines. They act as a disulphide-linked homodimer. They catalyse the oxidation of primary amines to aldehydes, with the subsequent release of ammonia and hydrogen peroxide, which requires one copper ion per subunit and topaquinone as cofactor:
RCH2NH2 + H2O + O2 formula_0 RCHO + NH3 + H2O2
The 3 substrates of this enzyme are primary amines (RCH2NH2), H2O, and O2, whereas its 3 products are RCHO, NH3, and H2O2.
Copper-containing amine oxidases are found in bacteria, fungi, plants and animals. In prokaryotes, the enzyme enables various amine substrates to be used as sources of carbon and nitrogen.
This enzyme belongs to oxidoreductases, specifically those acting on the CH-NH2 group of donors with oxygen as acceptor. The systematic name of this enzyme class is amine:oxygen oxidoreductase (deaminating) (copper-containing). This enzyme participates in 8 metabolic pathways: urea cycle and metabolism of amino groups, glycine, serine and threonine metabolism, histidine metabolism, tyrosine metabolism, phenylalanine metabolism, tryptophan metabolism, beta-alanine metabolism, and alkaloid biosynthesis ii. It has 2 cofactors: copper, and PQQ.
Structure.
The copper amine oxidase 3-dimensional structure was determined through X-ray crystallography.
The copper amine oxidases occur as mushroom-shaped homodimers of 70-95 kDa, each monomer containing a copper ion and a covalently bound redox cofactor, topaquinone (TPQ). TPQ is formed by post-translational modification of a conserved tyrosine residue. The copper ion is coordinated with three histidine residues and two water molecules in a distorted square pyramidal geometry, and has a dual function in catalysis and TPQ biogenesis. The catalytic domain is the largest of the 3-4 domains found in copper amine oxidases, and consists of a beta sandwich of 18 strands in two sheets. The active site is buried and requires a conformational change to allow the substrate access.
The N2 and N3 N-terminal domains share a common structural fold, its core consisting of alpha-beta(4), where the helix is packed against the coiled anti-parallel beta-sheets. An additional domain is found at the N-terminal of some copper amine oxidases, as well as in related proteins such as cell wall hydrolase and N-acetylmuramoyl-L-alanine amidase. This domain consists of a five-stranded antiparallel beta-sheet twisted around an alpha helix.
Function.
In eukaryotes they have a broader range of functions, including cell differentiation and growth, wound healing, detoxification and cell signalling; one AOC enzyme (AOC3) functions as a vascular adhesion protein (VAP-1) in some mammalian tissues.
References.
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Further reading.
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14147694
|
Asparagusate reductase
|
Asparagusate reductase (EC 1.8.1.11) is an enzyme that catalyzes the chemical reaction
3-mercapto-2-mercaptomethylpropanoate + NAD+ formula_0 asparagusate + NADH + H+
Thus, the two substrates of this enzyme are 3-mercapto-2-mercaptomethylpropanoate and nicotinamide adenine dinucleotide ion, whereas its 3 products are asparagusate, nicotinamide adenine dinucleotide, and hydrogen ion.
This enzyme belongs to the family of oxidoreductases, specifically those acting on a sulfur group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is 3-mercapto-2-mercaptomethylpropanoate:NAD+ oxidoreductase. Other names in common use include asparagusate dehydrogenase, asparagusic dehydrogenase, asparagusate reductase (NADH2), and NADH2:asparagusate oxidoreductase.
References.
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14147712
|
Aspartate dehydrogenase
|
Aspartate dehydrogenase (EC 1.4.1.21) is an enzyme that catalyzes the chemical reaction
L-aspartate + H2O + NAD(P)+ formula_0 oxaloacetate + NH3 + NAD(P)H + H+
The 4 substrates of this enzyme are L-aspartate, water, nicotinamide adenine dinucleotide ion, and nicotinamide adenine dinucleotide phosphate ion, whereas its 5 products are oxaloacetate, ammonia, NADH, nicotinamide adenine dinucleotide phosphate, and hydrogen ion.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH2 group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is L-aspartate:NAD(P)+ oxidoreductase (deaminating). Other names in common use include NAD-dependent aspartate dehydrogenase, NADH2-dependent aspartate dehydrogenase, and NADP+-dependent aspartate dehydrogenase. This enzyme participates in nicotinate and nicotinamide metabolism.
Structural studies.
As of late 2007, only one structure has been solved for this class of enzymes, with the PDB accession code 2DC1.
References.
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https://en.wikipedia.org/wiki?curid=14147712
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14147724
|
Azobenzene reductase
|
Class of enzymes
Azobenzene reductase also known as azoreductase (EC 1.7.1.6) is an enzyme that catalyzes the chemical reaction:
N,N-dimethyl-1,4-phenylenediamine + aniline + NADP+ formula_0 4-(dimethylamino)azobenzene + NADPH + H+
The 3 substrates of this enzyme are N,N-dimethyl-1,4-phenylenediamine, aniline, and nicotinamide adenine dinucleotide phosphate ion, whereas its 3 products are 4-(dimethylamino)azobenzene, nicotinamide adenine dinucleotide phosphate, and hydrogen ion.
This enzyme belongs to the family of oxidoreductases, specifically those acting on other nitrogenous compounds as donors with NAD+ or NADP+ as acceptor.
Mechanism.
The reaction catalyzed by this enzyme proceeds via a ping-pong mechanism by using 2 equivalents of NAD(P)H to reduce one equivalent of the azo compound substrate (for example methyl red where Ar = "p"-dimethylaniline and Ar' = "o"-benzoic acid) into two equivalents of aniline product:
Ar–N=N–Ar' + 2(NAD(P)H + H+) formula_0 Ar–NH2 + NH2–Ar' + 2NAD(P)+
Substrate specificity.
Most azoreductase isoenzymes can reduce methyl red, but are not able to reduce sulfonated azo dyes. The unique azoreductase isozyme from "Bacillus" sp. B29 has the ability to reduce sulfonated azo dyes however.
Nomenclature.
The systematic name of this enzyme class is N,N-dimethyl-1,4-phenylenediamine, aniline:NADP+ oxidoreductase. Other names in common use include:
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Structural studies.
As of late 2007, 3 structures have been solved for this class of enzymes, with PDB accession codes 1NNI, 1V4B, and 2D5I. Please check the last updated data on RCSB PDB site.
References.
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Further reading.
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14147744
|
Berberine reductase
|
Berberine reductase (EC 1.5.1.31) is an enzyme that catalyzes the chemical reaction
(R)-canadine + 2 NADP+ formula_0 berberine + 2 NADPH + H+
Thus, the two substrates of this enzyme are (R)-canadine and nicotinamide adenine dinucleotide phosphate ion, whereas its 3 products are berberine, nicotinamide adenine dinucleotide phosphate, and hydrogen ion.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is (R)-tetrahydroberberine:NADP+ oxidoreductase. This enzyme is also called (R)-canadine synthase.
References.
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14147831
|
Beta-alanopine dehydrogenase
|
Enzyme
Beta-alanopine dehydrogenase (EC 1.5.1.26) is an enzyme that catalyzes the chemical reaction
beta-alanopine + NAD+ + H2O formula_0 beta-alanine + pyruvate + NADH + H+
The 3 substrates of this enzyme are beta-alanopine, nicotinamide adenine dinucleotide ion, and water, whereas its 4 products are beta-alanine, pyruvate, nicotinamide adenine dinucleotide, and hydrogen ion.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is N-(D-1-carboxyethyl)-beta-alanine:NAD+ oxidoreductase (beta-alanine-forming).
References.
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14147850
|
Bis-gamma-glutamylcystine reductase
|
Class of enzymes
Bis-gamma-glutamylcystine reductase (EC 1.8.1.13) is an enzyme that catalyzes the chemical reaction
2 gamma-glutamylcysteine + NADP+ formula_0 bis-gamma-glutamylcystine + NADPH + H+
Thus, the two substrates of this enzyme are gamma-glutamylcysteine and nicotinamide adenine dinucleotide phosphate ion, whereas its 3 products are bis-gamma-glutamylcystine, nicotinamide adenine dinucleotide phosphate, and hydrogen ion.
This enzyme belongs to the family of oxidoreductases, specifically those acting on a sulfur group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is gamma-glutamylcysteine:NADP+ oxidoreductase. This enzyme is also called NADPH2:bis-gamma-glutamylcysteine oxidoreductase. This enzyme participates in glutathione metabolism.
References.
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14147869
|
CoA-disulfide reductase
|
Enzyme
In enzymology, a CoA-disulfide reductase (EC 1.8.1.14) is an enzyme that catalyzes the chemical reaction
2 CoA + NAD(P)+ formula_0 CoA-disulfide + NAD(P)H + H+
The 3 substrates of this enzyme are CoA, NAD+, and NADP+, whereas its 4 products are CoA-disulfide, NADH, NADPH, and H+.
This enzyme belongs to the family of oxidoreductases, specifically those acting on a sulfur group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is CoA:NAD(P)+ oxidoreductase. Other names in common use include CoA-disulfide reductase (NADH2), NADH2:CoA-disulfide oxidoreductase, CoA:NAD+ oxidoreductase, CoADR, and coenzyme A disulfide reductase.
References.
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https://en.wikipedia.org/wiki?curid=14147869
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14147879
|
CoA-glutathione reductase
|
Enzyme
In enzymology, a CoA-glutathione reductase (EC 1.8.1.10) is an enzyme that catalyzes the chemical reaction
CoA + glutathione + NADP+ formula_0 CoA-glutathione + NADPH + H+
The 3 substrates of this enzyme are CoA, glutathione, and NADP+, whereas its 3 products are CoA-glutathione, NADPH, and H+.
This enzyme belongs to the family of oxidoreductases, specifically those acting on a sulfur group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is glutathione:NADP+ oxidoreductase (CoA-acylating). Other names in common use include coenzyme A glutathione disulfide reductase, NADPH-dependent coenzyme A-SS-glutathione reductase, coenzyme A disulfide-glutathione reductase, and NADPH:CoA-glutathione oxidoreductase. This enzyme participates in cysteine metabolism. It employs one cofactor, FAD.
References.
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https://en.wikipedia.org/wiki?curid=14147879
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14147894
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CoB—CoM heterodisulfide reductase
|
In enzymology, a CoB—CoM heterodisulfide reductase (EC 1.8.98.1) is an enzyme that catalyzes the chemical reaction
coenzyme B + coenzyme M + methanophenazine formula_0 N-{7-[(2-sulfoethyl)dithio]heptanoyl}-O3-phospho-L-threonine + dihydromethanophenazine
The 3 substrates of this enzyme are coenzyme B, coenzyme M, and methanophenazine, whereas its two products are N-{7-[(2-sulfoethyl)dithio]heptanoyl}-O3-phospho-L-threonine and dihydromethanophenazine.
This enzyme belongs to the family of oxidoreductases, specifically those acting on a sulfur group of donors with other, known, acceptors. The systematic name of this enzyme class is coenzyme B:coenzyme M:methanophenazine oxidoreductase. Other names in common use include heterodisulfide reductase, and soluble heterodisulfide reductase. This enzyme participates in folate biosynthesis.
References.
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https://en.wikipedia.org/wiki?curid=14147894
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14147906
|
Cyclohexylamine oxidase
|
In enzymology, a cyclohexylamine oxidase (EC 1.4.3.12) is an enzyme that catalyzes the chemical reaction
cyclohexylamine + O2 + H2O formula_0 cyclohexanone + NH3 + H2O2
The 3 substrates of this enzyme are cyclohexylamine, O2, and H2O, whereas its 3 products are cyclohexanone, NH3, and H2O2.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH2 group of donors with oxygen as acceptor. The systematic name of this enzyme class is cyclohexylamine:oxygen oxidoreductase (deaminating). This enzyme participates in caprolactam degradation. It employs one cofactor, FAD.
References.
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https://en.wikipedia.org/wiki?curid=14147906
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14147996
|
Cystine reductase
|
In enzymology, a cystine reductase (EC 1.8.1.6) is an enzyme that catalyzes the chemical reaction
2 L-cysteine + NAD+ formula_0 L-cystine + NADH + H+
Thus, the two substrates of this enzyme are L-cysteine and NAD+, whereas its 3 products are L-cystine, NADH, and H+.
This enzyme belongs to the family of oxidoreductases, specifically those acting on a sulfur group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is L-cysteine:NAD+ oxidoreductase. Other names in common use include cystine reductase (NADH), NADH-dependent cystine reductase, cystine reductase (NADH2), and NADH2:L-cystine oxidoreductase. This enzyme participates in cysteine metabolism.
References.
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14148008
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Cytokinin dehydrogenase
|
In enzymology, a cytokinin dehydrogenase (EC 1.5.99.12) is an enzyme that catalyzes the chemical reaction
"N"6-dimethylallyladenine + electron acceptor + H2O formula_0 adenine + 3-methylbut-2-enal + reduced acceptor
The 3 substrates of this enzyme are cytokinin (here represented by "N"6-dimethylallyladenine), electron acceptor, and H2O, whereas its 3 products are adenine, 3-methylbut-2-enal (or other aldehyde in case of different substrate), and reduced acceptor.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH group of donors with other acceptors. The systematic name of this enzyme class is N"6-dimethylallyladenine:acceptor oxidoreductase. Other names in common use include N"6-dimethylallyladenine:(acceptor) oxidoreductase, 6-N-dimethylallyladenine:acceptor oxidoreductase, and cytokinin oxidase/dehydrogenase abbreviated as CKX.
Structural studies.
As of late 2007, 6 structures have been solved for this class of enzymes, with PDB accession codes 1W1O, 1W1Q, 1W1R, 1W1S, 2EXR, and 2Q4W.
As of March 2016, there have been 18 structures deposited to PDB. 16 of these were of enzymes from maize and two from Arabidopsis.
References.
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14148032
|
D-aspartate oxidase
|
Class of enzymes
In enzymology, a D-aspartate oxidase (EC 1.4.3.1) is an enzyme that catalyzes the chemical reaction
D-aspartate + H2O + O2 formula_0 oxaloacetate + NH3 + H2O2
The 3 substrates of this enzyme are D-aspartate, H2O, and O2, whereas its 3 products are oxaloacetate, NH3, and H2O2.
This enzyme belongs to the FAD dependent oxidoreductase family, specifically those acting on the CH-NH2 group of donors with oxygen as acceptor. The systematic name of this enzyme class is D-aspartate:oxygen oxidoreductase (deaminating). Other names in common use include aspartic oxidase, and D-aspartic oxidase. This enzyme participates in alanine and aspartate metabolism. It employs one cofactor, FAD.
The enzyme is encoded by DDO gene.
References.
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14148047
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Delta1-piperideine-2-carboxylate reductase
|
In enzymology, a Delta1-piperideine-2-carboxylate reductase (EC 1.5.1.21) is an enzyme that catalyzes the chemical reaction
L-pipecolate + NADP+ formula_0 Delta1-piperideine-2-carboxylate + NADPH + H+
Thus, the two substrates of this enzyme are L-pipecolate and NADP+, whereas its 3 products are Delta1-piperideine-2-carboxylate, NADPH, and H+.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is L-pipecolate:NADP+ 2-oxidoreductase. Other names in common use include 1,2-didehydropipecolate reductase, P2C reductase, and 1,2-didehydropipecolic reductase. This enzyme participates in lysine degradation.
References.
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14148054
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D-glutamate(D-aspartate) oxidase
|
In enzymology, a D-glutamate(D-aspartate) oxidase (EC 1.4.3.15) is an enzyme that catalyzes the chemical reaction
D-glutamate + H2O + O2 formula_0 2-oxoglutarate + NH3 + H2O2
The 3 substrates of this enzyme are D-glutamate, H2O, and O2, whereas its 3 products are 2-oxoglutarate, NH3, and H2O2.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH2 group of donors with oxygen as acceptor. The systematic name of this enzyme class is D-glutamate(D-aspartate):oxygen oxidoreductase (deaminating). Other names in common use include D-glutamic-aspartic oxidase, and D-monoaminodicarboxylic acid oxidase. This enzyme participates in alanine and aspartate metabolism. It employs one cofactor, FAD.
References.
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14148065
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D-glutamate oxidase
|
In enzymology, a D-glutamate oxidase (EC 1.4.3.7) is an enzyme that catalyzes the chemical reaction
D-glutamate + H2O + O2 formula_0 2-oxoglutarate + NH3 + H2O2
The 3 substrates of this enzyme are D-glutamate, H2O, and O2, whereas its 3 products are 2-oxoglutarate, NH3, and H2O2.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH2 group of donors with oxygen as acceptor. The systematic name of this enzyme class is D-glutamate:oxygen oxidoreductase (deaminating). Other names in common use include D-glutamic oxidase, and D-glutamic acid oxidase. This enzyme participates in d-glutamine and d-glutamate metabolism.
References.
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14148083
|
Diaminopimelate dehydrogenase
|
In enzymology, a diaminopimelate dehydrogenase (EC 1.4.1.16) is an enzyme that catalyzes the chemical reaction
meso-2,6-diaminoheptanedioate + H2O + NADP+ formula_0 L-2-amino-6-oxoheptanedioate + NH3 + NADPH + H+
The 3 substrates of this enzyme are meso-2,6-diaminoheptanedioate, H2O, and NADP+, whereas its 4 products are L-2-amino-6-oxoheptanedioate, NH3, NADPH, and H+.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH2 group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is meso-2,6-diaminoheptanedioate:NADP+ oxidoreductase (deaminating). Other names in common use include meso-alpha,epsilon-diaminopimelate dehydrogenase, and meso-diaminopimelate dehydrogenase. This enzyme participates in lysine biosynthesis.
Structural studies.
As of late 2007, 4 structures have been solved for this class of enzymes, with PDB accession codes 1DAP, 1F06, 2DAP, and 3DAP.
References.
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14148095
|
Dimethylamine dehydrogenase
|
In enzymology, a dimethylamine dehydrogenase (EC 1.5.8.1) is an enzyme that catalyzes the chemical reaction
dimethylamine + H2O + electron-transferring flavoprotein formula_0 methylamine + formaldehyde + reduced electron-transferring flavoprotein
The 3 substrates of this enzyme are dimethylamine, H2O, and electron-transferring flavoprotein, whereas its 3 products are methylamine, formaldehyde, and reduced electron-transferring flavoprotein.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH group of donors with a flavin as acceptor. The systematic name of this enzyme class is dimethylamine:electron-transferring flavoprotein oxidoreductase. This enzyme participates in methane metabolism. It employs one cofactor, FMN.
References.
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{
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14148106
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Dimethylglycine dehydrogenase
|
In enzymology, a dimethylglycine dehydrogenase (EC 1.5.8.4) is an enzyme that catalyzes the chemical reaction
N,N-dimethylglycine + acceptor + H2O formula_0 sarcosine + formaldehyde + reduced acceptor
The 3 substrates of this enzyme are N,N-dimethylglycine, acceptor, and H2O, whereas its 3 products are sarcosine, formaldehyde, and reduced acceptor.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH group of donors with other acceptors. The systematic name of this enzyme class is N,N-dimethylglycine:acceptor oxidoreductase (demethylating). Other names in common use include N,N-dimethylglycine oxidase, and N,N-dimethylglycine:(acceptor) oxidoreductase (demethylating). This enzyme participates in glycine, serine and threonine metabolism. It employs one cofactor, FAD.
References.
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14148119
|
Dimethylglycine oxidase
|
In enzymology, a dimethylglycine oxidase (EC 1.5.3.10) is an enzyme that catalyzes the chemical reaction
N,N-dimethylglycine + H2O + O2 formula_0 sarcosine + formaldehyde + H2O2
The 3 substrates of this enzyme are N,N-dimethylglycine, H2O, and O2, whereas its 3 products are sarcosine, formaldehyde, and H2O2.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH group of donors with oxygen as acceptor. The systematic name of this enzyme class is N,N-dimethylglycine:oxygen oxidoreductase (demethylating). It employs one cofactor, FAD.
Structural studies.
As of late 2007, 3 structures have been solved for this class of enzymes, with PDB accession codes 1PJ5, 1PJ6, and 1PJ7.
References.
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[
{
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14148140
|
D-lysopine dehydrogenase
|
In enzymology, a D-lysopine dehydrogenase (EC 1.5.1.16) is an enzyme that catalyzes the chemical reaction
N2-(D-1-carboxyethyl)-L-lysine + NADP+ + H2O formula_0 L-lysine + pyruvate + NADPH + H+
The 3 substrates of this enzyme are N2-(D-1-carboxyethyl)-L-lysine, NADP+, and H2O, whereas its 4 products are L-lysine, pyruvate, NADPH, and H+.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is N2-(D-1-carboxyethyl)-L-lysine:NADP+ oxidoreductase (L-lysine-forming). Other names in common use include D-lysopine synthase, lysopine dehydrogenase, D(+)-lysopine dehydrogenase, 2-N-(D-1-carboxyethyl)-L-lysine:NADP+ oxidoreductase, and (L-lysine-forming). This enzyme participates in lysine degradation.
References.
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14148150
|
D-nopaline dehydrogenase
|
In enzymology, a D-nopaline dehydrogenase (EC 1.5.1.19) is an enzyme that catalyzes the chemical reaction
N2-(D-1,3-dicarboxypropyl)-L-arginine + NADP+ + H2O formula_0 L-arginine + 2-oxoglutarate + NADPH + H+
The 3 substrates of this enzyme are N2-(D-1,3-dicarboxypropyl)-L-arginine, NADP+, and H2O, whereas its 4 products are L-arginine, 2-oxoglutarate, NADPH, and H+.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is N2-(D-1,3-dicarboxypropyl)-L-arginine:NADP+ oxidoreductase (L-arginine-forming). Other names in common use include D-nopaline synthase, nopaline dehydrogenase, nopaline synthase, NOS, 2-N-(D-1,3-dicarboxypropyl)-L-arginine:NADP+ oxidoreductase, and (L-arginine-forming). This enzyme participates in arginine and proline metabolism.
References.
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14148161
|
D-octopine dehydrogenase
|
Enzyme
Octopine dehydrogenase (N2-(D-1-carboxyethyl)-L-arginine:NAD+ oxidoreductase, OcDH, ODH) is a dehydrogenase enzyme in the opine dehydrogenase family that helps maintain redox balance under anaerobic conditions. It is found largely in aquatic invertebrates, especially mollusks, sipunculids, and coelenterates, and plays a role analogous to lactate dehydrogenase (found largely in vertebrates)
. In the presence of NADH, OcDH catalyzes the reductive condensation of an α-keto acid with an amino acid to form N-carboxyalkyl-amino acids (opines). The purpose of this reaction is to reoxidize glycolytically formed NADH to NAD+, replenishing this important reductant used in glycolysis and allowing for the continued production of ATP in the absence of oxygen.
-arginine + pyruvate + NADH + H+ formula_0 -octopine + NAD+ + H2O
Structure.
OcDH is a monomer with a molecular weight of 38kD made of two functionally distinct subunits. The first, Domain I, is composed of 199 amino acids and contains a Rossmann fold. Domain II is composed of 204 amino acids and is connected to the Rossmann fold of Domain I via its N-terminus.
Mechanism.
Isothermal titration calorimetry (ITR), nuclear magnetic resonance (NMR)
crystallography, and clonal studies of OcDH and its substrates have led to the identification of the enzyme reaction mechanism. First, the Rossmann fold in Domain I of OcDH binds NADH. Binding of NADH to the Rossmann fold triggers small conformational change typical in the binding of NADH to most dehydrogenases resulting in an interaction between the pyrophosphate moiety of NADH with residue Arg324 on Domain II. This interaction with Arg324 generates and stabilizes the L-arginine binding site and triggers partial domain closure (reduction in the distance between the two domains). The binding of the guanidinium headgroup of L-arginine to the active site of the OcDH:NADH complex (located between the domains) induces a rotational movement of Domain II towards Domain I (via a helix-kink-helix structure in Domain II). This conformational change forms the pyruvate binding site. Binding of pyruvate to the OcDH:NADH:L-arginine complex places the alpha-ketogroup of pyruvate in proximity with the alpha-amino group of L-arginine. The juxtaposition of these groups on the substrates results in the formation of a Schiff base which is subsequently reduced to D-octopine. The priming of the pyruvate site for hydride transfer via a Schiff base through the sequential binding of NADH and L-arginine to OcDH prevents the reduction of pyruvate to lactate.
Substrate specificity.
Octopine dehydrogenase has at least two structural characteristics that contribute to substrate specificity. Upon binding to NADH, amino acid residues lining either side of the active site within the space between the domains of OcDH act as a “molecular ruler”, physically limiting the size of the substrates that can fit into the active site. There is also a negatively charged pocket in the cleft between the two domains that acts an “electrostatic sink” that captures the positively charged side-chain of L-arginine.
Evolution.
Examination of OcDH reaction rates from different organisms in the presence of different substrates has demonstrated a trend of increasing specificity for substrates in animals of increasing complexity. Evolutionary modification in substrate specificity is seen most drastically in the amino acid substrate. OcDH from some sea anemones has been shown to be able to use non-guanidino amino acids whereas OcDH form more complex invertebrates, such as the cuttlefish, can only use L-arginine (a guanidino amino acid).
References.
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{
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14148182
|
Enzyme-thiol transhydrogenase (glutathione-disulfide)
|
In enzymology, an enzyme-thiol transhydrogenase (glutathione-disulfide) (EC 1.8.4.7) is an enzyme that catalyzes the chemical reaction
[xanthine dehydrogenase] + glutathione disulfide formula_0 [xanthine oxidase] + 2 glutathione
Thus, the two substrates of this enzyme are xanthine dehydrogenase and glutathione disulfide, whereas its two products are xanthine oxidase and glutathione.
This enzyme belongs to the family of oxidoreductases, specifically those acting on a sulfur group of donors with a disulfide as acceptor. The systematic name of this enzyme class is [xanthine-dehydrogenase]:glutathione-disulfide S-oxidoreductase. Other names in common use include [xanthine-dehydrogenase]:oxidized-glutathione S-oxidoreductase, enzyme-thiol transhydrogenase (oxidized-glutathione), glutathione-dependent thiol:disulfide oxidoreductase, and thiol:disulfide oxidoreductase. This enzyme participates in glutathione metabolism.
References.
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{
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14148200
|
Ethanolamine oxidase
|
In enzymology, an ethanolamine oxidase (EC 1.4.3.8) is an enzyme that catalyzes the chemical reaction
ethanolamine + H2O + O2 formula_0 glycolaldehyde + NH3 + H2O2
The 3 substrates of this enzyme are ethanolamine, H2O, and O2, whereas its 3 products are glycolaldehyde, NH3, and H2O2.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH2 group of donors with oxygen as acceptor. The systematic name of this enzyme class is ethanolamine:oxygen oxidoreductase (deaminating). It has 2 cofactors: cobalt, and Cobamide.
References.
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{
"math_id": 0,
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14148212
|
Ferredoxin—nitrate reductase
|
Class of enzymes
In enzymology, a ferredoxin—nitrate reductase (EC 1.7.7.2) is an enzyme that catalyzes the chemical reaction
nitrite + H2O + 2 oxidized ferredoxin formula_0 nitrate + 2 reduced ferredoxin + 2 H+
The 3 substrates of this enzyme are nitrite, H2O, and oxidized ferredoxin, whereas its 3 products are nitrate, reduced ferredoxin, and H+. Nitrate Reductase is an essential enzyme present in most biological systems such as green plants, certain fungi, yeasts and bacteria that aids in the reduction of nitrate to ammonium.
This enzyme belongs to the family of oxidoreductases, specifically those acting on other nitrogenous compounds as donors with an iron-sulfur protein as acceptor. The systematic name of this enzyme class is nitrite:ferredoxin oxidoreductase. Other names in common use include assimilatory nitrate reductase, nitrate (ferredoxin) reductase, and assimilatory ferredoxin-nitrate reductase. This enzyme participates in nitrogen metabolism. It has 4 cofactors: iron, Sulfur, Molybdenum, and Iron-sulfur. The Iron-Sulfur cluster ([4FE-4S]) in this enzyme has a variety of different functions that contribute to the growth of aerobic cells. Some of the functions include but are not limited to the following: involved in photosynthetic processes, electron-transfer reactions and the binding of certain substrates, resulting in activation.
Structural studies.
As of late 2007, only one structure has been solved for this class of enzymes, with the PDB accession code 1PFD.
References.
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Further reading.
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14148224
|
Ferredoxin—nitrite reductase
|
Class of enzymes
In enzymology, a ferredoxin—nitrite reductase (EC 1.7.7.1) is an enzyme that catalyzes the chemical reaction
NH3 + 2 H2O + 6 oxidized ferredoxin formula_0 nitrite + 6 reduced ferredoxin + 7 H+
The 3 substrates of this enzyme are NH3, H2O, and oxidized ferredoxin, whereas its 3 products are nitrite, reduced ferredoxin, and H+.
This enzyme belongs to the family of oxidoreductases, specifically those acting on other nitrogenous compounds as donors with an iron-sulfur protein as acceptor. The systematic name of this enzyme class is ammonia:ferredoxin oxidoreductase. This enzyme participates in nitrogen metabolism and nitrogen assimilation. It has 3 cofactors: iron, Siroheme, and Iron-sulfur.
This enzyme can use many different isoforms of ferredoxin. In photosynthesizing tissues, it uses ferredoxin that is reduced by PSI and in the root it uses a form of ferredoxin (FdIII) that has a less negative midpoint potential and can be reduced easily by NADPH.
Structural studies.
As of late 2007, 3 structures have been solved for this class of enzymes, with PDB accession codes 1ZJ8, 1ZJ9, and 2AKJ.
References.
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Literature.
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14148245
|
Flavin reductase
|
Flavin reductase a class of enzymes. There are a variety of flavin reductases, (i.e. FRP, FRE, FRG, etc.) which bind free flavins and through hydrogen bonding, catalyze the reduction of these molecules to a reduced flavin. Riboflavin, or vitamin B, and flavin mononucleotide are two of the most well known flavins in the body and are used in a variety of processes which include metabolism of fat and ketones and the reduction of methemoglobin in erythrocytes. Flavin reductases are similar and often confused for ferric reductases because of their similar catalytic mechanism and structures.
In enzymology, a flavin reductase (EC 1.5.1.30) is an enzyme that catalyzes the chemical reaction
riboflavin + NADPH + H+ formula_0 reduced riboflavin + NADP + H+
Thus, the two products of this enzyme are reduced riboflavin and NADP+, whereas its 3 substrates are riboflavin, NADPH, and H+.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is reduced-riboflavin:NADP+ oxidoreductase. Other names in common use include NADPH:flavin oxidoreductase, riboflavin mononucleotide (reduced nicotinamide adenine dinucleotide, phosphate) reductase, flavin mononucleotide reductase, flavine mononucleotide reductase, FMN reductase (NADPH), NADPH-dependent FMN reductase, NADPH-flavin reductase, NADPH-FMN reductase, NADPH-specific FMN reductase, riboflavin mononucleotide reductase, riboflavine mononucleotide reductase, NADPH2 dehydrogenase (flavin), and NADPH2:riboflavin oxidoreductase.
Structures of reactants and products.
Flavin reductase is a dimer made up of two subunits. Each subunit is similar. Flavin reductase P, FRP, was studied by Tanner, Lei, Tu and Krause and was discovered to have a structure made up of two subunits each containing a sandwich domain and an excursion domain. The excursion domains of each subunit reach out to connect the sandwich domain of the other subunit. This creates a large hydrophobic core in flavin reductase The enzyme has two binding sites, one for NADPH and one for the flavin mononucleotide substrate. The isoalloxazine ring of flavin mononucleotide is where reduction occurs. Therefore, this is where flavin creates a variety of hydrogen bonds to connect to the amino acid side chains of flavin reductase. Side chains 167–169 in FRP block the isoalloxazine ring in FAD from binding the enzyme, making FRP an FMN specific flavin reductase. The placement of methyl groups in the isoalloxazine ring can also have an effect on the binding and specificity of the enzyme for substrate. There is a depletion of a C-terminal extension that allows for the binding of NADPH, and studies show that if it is removed, it is depleted, catalytic activity increases.
Mechanism.
The mechanism of the flavin reductase process is described above and most likely follows the ping pong kinetic pattern. This means that it is a bisubstrate-biproduct mechanism. First the flavin reductase enzyme binds NADPH and stabilizes the release of the hydride. Because of sterics, it is not possible for the enzyme to bind both NADPH and the flavin. For this reason, NADP+ is released and then the flavin substrate is bound to the enzyme. In this step, the hydride attacks Nitrogen on the flavin, which allows for another protonation. Then, reduced flavin is released from flavin reductase as the second product. In this way, the reduction of flavin is dependent on flavin reductase binding first to NADPH, or in some cases NADH.
Biological function.
Flavin reductases exist in a variety of organisms, including animals and bacteria. In luminous organisms, flavin reductase is important in the luciferase process.
In an experiment with "P. fischeri" and "B. harveyi" cells, bioluminescence was increased as the "in vivo" concentration of flavin reductase was increased. This suggests a connection between either a flavin reductase-luciferase complex or reduced flavin and the luminescence process in bacteria. The bacteria oxidize the reduced flavin mononucleotide to oxidized FMN and transfer it through free fusion to generate light.
In humans, flavin reductase often catalyzes an NADPH dependent reduction of flavin mononucleotide which occurs in methemoglobin in erythrocytes and the liver.
It has also been suggested that flavin reductases play a role in the production of hydrogen peroxide. This would be biologically helpful as H2O2 assists the body in maintaining homeostatic microbiota. A study showed that women with lactobacillus that produced hydrogen peroxide were less likely to develop bacterial vaginosis prebirth. It was also seen in Trichomonas vaginalis that decreased levels of flavin reductase increased the cycling of metronidazole because flavin reductase has an antioxidative effect, which decreases oxygen levels, maintaining the metronidazole population.
Future of the enzyme.
Currently, it is seen that bacterial flavin reductase can be used to sensitize carcinomas, or tumors to pro drugs. At first, flavin reductases were used to target the hypoxia of tumors. However, current research is showing an interest in these reductase molecules, specifically, MSuE from "Pseudomonas aeruginosa" which has been shown to increase the effectiveness of the prodrugs for cancerous tumors. A dual flavin reductase has been shown to participate in the activation of anticancer drugs. There are also molecules that when oxidized can be carcinogenic. In this case, it is helpful to have flavin reductase to reduce these molecules, such as carcinogenic chromate.
References.
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14148259
|
FMN reductase
|
In enzymology, an FMN reductase (EC 1.5.1.29) is an enzyme that catalyzes the chemical reaction
FMNH2 + NAD(P)+ formula_0 FMN + NAD(P)H + H+
The 3 substrates of this enzyme are FMNH2, NAD+, and NADP+, whereas its 4 products are FMN, NADH, NADPH, and H+.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is FMNH2:NAD(P)+ oxidoreductase. Other names in common use include NAD(P)H-FMN reductase, NAD(P)H-dependent FMN reductase, NAD(P)H:FMN oxidoreductase, NAD(P)H:flavin oxidoreductase, NAD(P)H2 dehydrogenase (FMN), NAD(P)H2:FMN oxidoreductase, SsuE, riboflavin mononucleotide reductase, flavine mononucleotide reductase, riboflavin mononucleotide (reduced nicotinamide adenine dinucleotide, (phosphate)) reductase, flavin mononucleotide reductase, and riboflavine mononucleotide reductase.
References.
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14148284
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Formyltetrahydrofolate dehydrogenase
|
In enzymology, a formyltetrahydrofolate dehydrogenase (EC 1.5.1.6) is an enzyme that catalyzes the chemical reaction
10-formyltetrahydrofolate + NADP+ + H2O formula_0 tetrahydrofolate + CO2 + NADPH + H+
The 3 substrates of this enzyme are 10-formyltetrahydrofolate, NADP+, and H2O, whereas its 4 products are tetrahydrofolate, CO2, NADPH, and H+.
This enzyme belongs to the family of oxidoreductases, to be specific those acting on the CH-NH group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is 10-formyltetrahydrofolate:NADP+ oxidoreductase. Other names in common use include 10-formyl tetrahydrofolate:NADP oxidoreductase, 10-formyl-H2PtGlu:NADP oxidoreductase, 10-formyl-H4folate dehydrogenase, N10-formyltetrahydrofolate dehydrogenase, and 10-formyltetrahydrofolate dehydrogenase. This enzyme participates in one carbon pool by folate.
Structural studies.
As of late 2007, 7 structures have been solved for this class of enzymes, with PDB accession codes 1S3I, 2BW0, 2CFI, 2CQ8, 2O2P, 2O2Q, and 2O2R.
References.
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14148297
|
Glutamate synthase (ferredoxin)
|
In enzymology, a glutamate synthase (ferredoxin) (EC 1.4.7.1) is an enzyme that catalyzes the chemical reaction
2 L-glutamate + 2 oxidized ferredoxin formula_0 L-glutamine + 2-oxoglutarate + 2 reduced ferredoxin + 2 H+
Thus, the two substrates of this enzyme are L-glutamate and oxidized ferredoxin, whereas its 4 products are L-glutamine, 2-oxoglutarate, reduced ferredoxin, and H+.
Classification.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH2 group of donors with an iron-sulfur protein as acceptor.
Nomenclature.
The systematic name of this enzyme class is L-glutamate:ferredoxin oxidoreductase (transaminating). Other names in common use include:
Biological role.
This enzyme participates in nitrogen metabolism. It has 5 cofactors: FAD, iron, sulfur, iron-sulfur, and flavoprotein.
References.
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{
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14148311
|
Glutamate synthase (NADH)
|
In enzymology, a glutamate synthase (NADH) (EC 1.4.1.14) is an enzyme that catalyzes the chemical reaction
2 L-glutamate + NAD+ formula_0 L-glutamine + 2-oxoglutarate + NADH + H+
Glutamate synthase facilitates the ammonium assimilation pathway, which follows the enzymes, nitrite reductase and glutamine synthase. An ammonium produced by the nitrite reductase reaction will be incorporated into carbon skeleton backbone by glutamine synthase. Glutamine will be produced because of the introduction of ammonium in the carbon backbone, which can be converted into glutamate by glutamate synthase of another pathway.
These processes are common in plant roots due to the fact that if the nitrogen deficient conditions exist (with access to ammonium and nitrate ions), there will be a first priority of ammonium uptake. Thus, the two substrates of this enzyme are L-glutamate and NAD+, whereas its 4 products are L-glutamine, 2-oxoglutarate, NADH, and H+.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH2 group of donors with NAD+ or NADP+ as acceptor. This enzyme participates in glutamate metabolism and nitrogen assimilation. It employs one cofactor, FMN.
Nomenclature.
The systematic name of this enzyme class is L-glutamate:NAD+ oxidoreductase (transaminating). Other names in common use include:
References.
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14148327
|
Glutamate synthase (NADPH)
|
In enzymology, a glutamate synthase (NADPH) (EC 1.4.1.13) is an enzyme that catalyzes the chemical reaction
L-glutamine + 2-oxoglutarate + NADPH + H+ formula_0 2 L-glutamate + NADP+
Thus, the four substrates of this enzyme are L-glutamine, 2-oxoglutarate (α-ketoglutarate), NADPH, and H+, whereas the two products are L-glutamate and NADP+.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH2 group of donors with NAD+ or NADP+ as acceptor. This enzyme participates in glutamate metabolism and nitrogen metabolism. It has 5 cofactors: FAD, Iron, FMN, Sulfur, and Iron-sulfur.
It occurs in bacteria and plants but not animals, and is important as it provides glutamate for the glutamine synthetase reaction.
Nomenclature.
The systematic name of this enzyme class is L-glutamate:NADP+ oxidoreductase (transaminating). Other names in common use include:
<templatestyles src="Div col/styles.css"/>
Structural studies.
As of late 2007, only one structure has been solved for this class of enzymes, with the PDB accession code 1EA0.
References.
<templatestyles src="Reflist/styles.css" />
Further reading.
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