where are unwanted amino acids converted into urea
liver
897334
Deamination Deamination is the removal of an amino group from a molecule. Enzymes that catalyse this reaction are called deaminases. In the human body, deamination takes place primarily in the liver, however glutamate is also deaminated in the kidneys. In situations of excess protein intake, deamination is used to break down amino acids for energy. The amino group is removed from the amino acid and converted to ammonia. The rest of the amino acid is made up of mostly carbon and hydrogen, and is recycled or oxidized for energy. Ammonia is toxic to the human system, and enzymes convert it
Deamination
8548585
process to individual amino acids, which are then absorbed. When amino acids are in excess of needs, the liver takes up the amino acids and deaminates them, a process converting the nitrogen from the amino acids into ammonia, further processed in the liver into urea via the urea cycle. Excretion of urea occurs via the kidneys. Other parts of the amino acid molecules can be converted into glucose and used for fuel. When food protein intake is periodically high or low, the body tries to keep protein levels at an equilibrium by using the "labile protein reserve" to compensate for
Protein (nutrient)
1695228
amino acids so that they can be converted to sugars. The process begins by removing the amino group of the amino acids. The amino group becomes ammonium as it is lost and later undergoes the urea cycle to become urea, in the liver. It is then released into the blood stream, where it is transferred to the kidneys, which will secrete the urea as urine. The remaining portion of the amino acid becomes oxidized, resulting in an alpha-keto acid. The alpha-keto acid will then proceed into the TCA cycle, in order to produce energy. The acid can also enter glycolysis,
Protein catabolism
433178
the urea cycle, either from the oxidation of amino acids or from ammonia. In this cycle, amino groups donated by ammonia and L-aspartate are converted to urea, while L-ornithine, citrulline, L-argininosuccinate, and L-arginine act as intermediates. Urea production occurs in the liver and is regulated by N-acetylglutamate. Urea is then dissolved into the blood (in the reference range of 2.5 to 6.7 mmol/liter) and further transported and excreted by the kidney as a component of urine. In addition, a small amount of urea is excreted (along with sodium chloride and water) in sweat. In water, the amine groups undergo slow
Urea
9912943
(they are only ketogenic). Glucogenic amino acid A glucogenic amino acid is an amino acid that can be converted into glucose through gluconeogenesis. This is in contrast to the ketogenic amino acids, which are converted into ketone bodies. The production of glucose from glucogenic amino acids involves these amino acids being converted to alpha keto acids and then to glucose, with both processes occurring in the liver. This mechanism predominates during catabolysis, rising as fasting and starvation increase in severity. In humans, the glucogenic amino acids are: Amino acids that are both glucogenic and ketogenic (mnemonic "PITTT"): Only leucine and
Glucogenic amino acid
9912942
Glucogenic amino acid A glucogenic amino acid is an amino acid that can be converted into glucose through gluconeogenesis. This is in contrast to the ketogenic amino acids, which are converted into ketone bodies. The production of glucose from glucogenic amino acids involves these amino acids being converted to alpha keto acids and then to glucose, with both processes occurring in the liver. This mechanism predominates during catabolysis, rising as fasting and starvation increase in severity. In humans, the glucogenic amino acids are: Amino acids that are both glucogenic and ketogenic (mnemonic "PITTT"): Only leucine and lysine are not glucogenic
Glucogenic amino acid
1452460
everyday functions and is estimated that per day, a healthy adult excretes about 10 to 30 g of urea. Other than urea being found in urine, it is also present in sweat, blood serum and stomach. Inside the mitochondria of a liver cell, excess ammonia is converted to urea through the urea cycle and if some excess ammonia is still present in the mitochondria, then it gets used up for protein synthesis. There are specific tissues involved during urea processing which are epithelial, extrahepatic and muscle tissues. With the production of ammonia and amino acids, the cell proteins are broken
Urease
433176
from ingested food that are not used for the synthesis of proteins and other biological substances — or produced from catabolism of muscle protein — are oxidized by the body as an alternative source of energy, yielding urea and carbon dioxide. The oxidation pathway starts with the removal of the amino group by a transaminase; the amino group is then fed into the urea cycle. The first step in the conversion of amino acids from protein into metabolic waste in the liver is removal of the alpha-amino nitrogen, which results in ammonia. Because ammonia is toxic, it is excreted immediately
Urea
9636847
Oxidative deamination Oxidative deamination is a form of deamination that generates α-keto acids and other oxidized products from amine-containing compounds, and occurs largely in the liver and kidney. Oxidative deamination is an important step in the catabolism of amino acids, generating a more metabolizable form of the amino acid, and also generating ammonia as a toxic byproduct. The ammonia generated in this process can then be neutralized into urea via the urea cycle. Much of the oxidative deamination occurring in cells involves the amino acid glutamate, which can be oxidatively deaminated by the enzyme glutamate dehydrogenase (GDH), using NAD or
Oxidative deamination
231237
facilitate reactions. Another function is to combine with nitrogen released in the cell, therefore preventing nitrogen overload. α-Ketoglutarate is one of the most important nitrogen transporters in metabolic pathways. The amino groups of amino acids are attached to it (by transamination) and carried to the liver where the urea cycle takes place. α-Ketoglutarate is transaminated, along with glutamine, to form the excitatory neurotransmitter glutamate. Glutamate can then be decarboxylated (requiring vitamin B) into the inhibitory neurotransmitter GABA. It is reported that high ammonia and/or high nitrogen levels may occur with high protein intake, excessive aluminum exposure, Reye's syndrome, cirrhosis, and
Alpha-Ketoglutaric acid
493194
are eggs, chicken, liver, beef, milk, and soybeans. The Food and Nutrition Board (FNB) of the U.S. Institute of Medicine set Recommended Dietary Allowances (RDAs) for essential amino acids in 2002. For phenylalanine plus tyrosine, for adults 19 years and older, 33 mg/kg body weight/day. -Phenylalanine is biologically converted into -tyrosine, another one of the DNA-encoded amino acids. -tyrosine in turn is converted into L-DOPA, which is further converted into dopamine, norepinephrine (noradrenaline), and epinephrine (adrenaline). The latter three are known as the catecholamines. Phenylalanine uses the same active transport channel as tryptophan to cross the blood–brain barrier. In excessive
Phenylalanine
11211643
for the body to keep itself — particularly the nervous system—functional. Protein stores, especially in muscle tissue, provide the amino acids needed for the process. Amino acids are released into the blood and converted in the liver to alpha keto acids. Alpha keto acids can then be converted to glucose to maintain proper blood sugar levels. The situation can become dire when one begins to lose muscle mass; this is a sign that the fat has been expended and the body is now metabolizing the muscle tissue. This results in muscle atrophy, a loss of strength and, ultimately, a depletion
Catabolysis
85532
derived from glutamate or glutamine), having an anaplerotic effect on the cycle, or, in the case of leucine, isoleucine, lysine, phenylalanine, tryptophan, and tyrosine, they are converted into "acetyl-CoA" which can be burned to CO and water, or used to form ketone bodies, which too can only be burned in tissues other than the liver where they are formed, or excreted via the urine or breath. These latter amino acids are therefore termed "ketogenic" amino acids, whereas those that enter the citric acid cycle as intermediates can only be cataplerotically removed by entering the gluconeogenic pathway via "malate" which is
Citric acid cycle
85533
transported out of the mitochondrion to be converted into cytosolic oxaloacetate and ultimately into glucose. These are the so-called "glucogenic" amino acids. De-aminated alanine, cysteine, glycine, serine, and threonine are converted to pyruvate and can consequently either enter the citric acid cycle as "oxaloacetate" (an anaplerotic reaction) or as "acetyl-CoA" to be disposed of as CO and water. In fat catabolism, triglycerides are hydrolyzed to break them into fatty acids and glycerol. In the liver the glycerol can be converted into glucose via dihydroxyacetone phosphate and glyceraldehyde-3-phosphate by way of gluconeogenesis. In many tissues, especially heart and skeletal muscle tissue,
Citric acid cycle
14080355
of coniine alkaloids. When ingested sugars and carbohydrate levels are low, stored fats and proteins are the primary source of energy production. Glucogenic amino acids from proteins are converted to glucose. Ketogenic amino acids can be deaminated to produce alpha keto acids and ketone bodies. Alpha keto acids are used primarily as energy for liver cells and in fatty acid synthesis, also in the liver. Keto acid Keto acids or ketoacids (also called oxo acids or oxoacids) are organic compounds that contain a carboxylic acid group and a ketone group. In several cases, the keto group is hydrated. The alpha-keto
Keto acid
5486119
The ringtail possum recycles 96% of its liver's urea, which is then transferred into the caecum and made into bacterial protein. Only re-ingestion makes this effective and the bacterial protein must be digested in the stomach and the amino acids subsequently absorbed in the small intestine. This recycling also allows the possum to conserve water and urinate less. Reingestion allows the possum to live on low nitrogen eucalyptus leaves which is particularly important during late lactation. Common ringtail possums are nocturnal and are well adapted to arboreal life. They rarely descend to the ground and rely on their prehensile tail.
Common ringtail possum
12739
first pass out of organelles and cells into blood circulation via amino acid transporters, since the amine and carboxylic acid groups are typically ionized. Degradation of an amino acid, occurring in the liver and kidneys, often involves deamination by moving its amino group to alpha-ketoglutarate, forming glutamate. This process involves transaminases, often the same as those used in amination during synthesis. In many vertebrates, the amino group is then removed through the urea cycle and is excreted in the form of urea. However, amino acid degradation can produce uric acid or ammonia instead. For example, serine dehydratase converts serine to
Amino acid
4884804
adult body for 12–18 hours. When fasting continues for more than a few hours, falling insulin levels permit catabolism of muscle protein and triglycerides from adipose tissue. The products of these processes are amino acids (mainly alanine), free fatty acids, and lactic acid. Free fatty acids from triglycerides are converted to ketones, and to acetyl-CoA. Amino acids and lactic acid are used to synthesize new G6P in liver cells by the process of gluconeogenesis. The last step of normal gluconeogenesis, like the last step of glycogenolysis, is the dephosphorylation of G6P by glucose-6-phosphatase to free glucose and . Thus glucose-6-phosphatase
Glycogen storage disease type I
12722
encoded by stop codon and SECIS element. When taken up into the human body from the diet, the 20 standard amino acids either are used to synthesize proteins and other biomolecules or are oxidized to urea and carbon dioxide as a source of energy. The oxidation pathway starts with the removal of the amino group by a transaminase; the amino group is then fed into the urea cycle. The other product of transamidation is a keto acid that enters the citric acid cycle. Glucogenic amino acids can also be converted into glucose, through gluconeogenesis. Of the 20 standard amino acids,
Amino acid
15176091
to these nine essential amino acids, "A. pisum" is unable to synthesize arginine due to missing urea cycle genes. The endosymbiotic relationship with "Buchnera" allows "A. pisum" to overcome this lack of essential amino acids in the phloem sap When provided with nonessential amino acids, "Buchnera" converts nonessential amino acids into essential amino acids to be returned to "A. pisum". This nutritional provisioning has been examined genomically (metabolic complementary, discussed below) and experimentally. Isolated bacteriocytes containing "Buchnera" have been shown to actively take up 14C labeled glutamine (a nonessential amino acid) where it is then converted into glutamic acid. This
Acyrthosiphon pisum
11246581
enzyme experiments. The second and third forward steps cause the formation and release of the reaction's products. Aminoacylases are expressed in the kidney, where they recycle N-acyl-L-amino acids as L-amino acids and aid in urea cycle regulation. N-acyl-L-amino acids are formed when L-amino acids have their N-terminus covalently bonded to an acyl group. The acyl group provides stability for the amino acid, making it more resistant to degradation. Additionally, N-acyl-L-amino acids cannot be used directly as building blocks for proteins and must first be converted to L-amino acids by aminoacylase. Again, the L-amino acid products can be used for biosynthesis
Aminoacylase
984367
acids can be produced from others. The sulfur-containing amino acids, methionine and homocysteine, can be converted into each other but neither can be synthesized "de novo" in humans. Likewise, cysteine can be made from homocysteine but cannot be synthesized on its own. So, for convenience, sulfur-containing amino acids are sometimes considered a single pool of nutritionally equivalent amino acids as are the aromatic amino acid pair, phenylalanine and tyrosine. Likewise arginine, ornithine, and citrulline, which are interconvertible by the urea cycle, are considered a single group. If one of the essential amino acids is less than needed for an individual
Essential amino acid
4338051
into citrulline. After these initial steps the urea cycle continues in the inner membrane space until ornithine once again enters the matrix through a transport channel to continue the first to steps within matrix. α-Ketoglutarate and oxaloacetate can be converted into amino acids within the matrix through the process of transamination. These reactions are facilitated by transaminases in order to produce aspartate and asparagine from oxaloacetate. Transamination of α-ketoglutarate produces glutamate, proline and arginine. These amino acids are then used either within the matrix or transported into the cytosol to produce proteins. Regulation within the matrix is primarily controlled by
Mitochondrial matrix
438731
cycle ingest amino acids beyond what is necessary for the minimum daily requirements the ammonia that is produced will not be able to be converted to urea. These individuals can experience hyperammonemia or the buildup of a cycle intermediate. Most urea cycle disorders are associated with hyperammonemia, however argininemia and some forms of argininosuccinic aciduria do not present with elevated ammonia. Urea cycle The urea cycle (also known as the ornithine cycle) is a cycle of biochemical reactions that produces urea ((NH)CO) from ammonia (NH). This cycle occurs in ureotelic organisms. The urea cycle converts highly toxic ammonia to urea
Urea cycle
20380275
are a few different proposed mechanisms with which the nitrogen is transferred to the host plant. These pathways of nitrogen transfer are thought to be exclusively biotrophic, a significant amount of nitrogen may also be transferred necrotorphically but through a significantly different process.. In the first pathway the amino acids are transferred to the extraradical mycelium where the amino acids are broken down by the catabolic stage of the urea cycle. The primary amino acid synthesized and intra-fungally transferred is arginine, which is catabolized into ammonium.The ammonium is then shunted into the interfacial space between the peloton and the surrounding
Orchid mycorrhiza
16940344
in the absence of sulfur are able to produce and incorporate into protein tellurocysteine and telluromethionine. Hydroxyglycine, an amino acid with a hydroxyl side-chain, is highly unstable. In cells, especially autotrophs, several non-proteinogenic amino acids are found as metabolic intermediates. However, despite the catalytic flexibility of PLP-binding enzymes, many amino acids are synthesised as keto-acids ("e.g." 4-methyl-2-oxopentanoate to leucine) and aminated in the last step, thus keeping the number of non-proteinogenic amino acid intermediates fairly low. Ornithine and citrulline occur in the urea cycle, part of amino acid catabolism (see below). In addition to primary metabolism, several non-proteinogenic amino acids
Non-proteinogenic amino acids
278162
sole source of carbon, and genes involved in the cholesterol use pathway(s) have been validated as important during various stages of the infection lifecycle of "M. tuberculosis". Amino acids are either used to synthesize proteins and other biomolecules, or oxidized to urea and carbon dioxide as a source of energy. The oxidation pathway starts with the removal of the amino group by a transaminase. The amino group is fed into the urea cycle, leaving a deaminated carbon skeleton in the form of a keto acid. Several of these keto acids are intermediates in the citric acid cycle, for example the
Metabolism
1695230
glutamate. Then glutamate transfers the amino group to oxaloacetate. This transfer is so that the oxaloacetate can be converted to aspartate or other amino acids. Eventually, this product will also proceed into oxidative deamination to once again produce alpha-ketoglutarate, an alpha-keto acid that will undergo the TCA cycle, and ammonium, which will eventually undergo the urea cycle. Transaminases are enzymes that help catalyze the reactions that take place in transamination. They help catalyze the reaction at the point when the amino group is transferred from the original amino acid, like glutamate to alpha-ketoglutarate, and hold onto it to transfer it
Protein catabolism
9912959
Ketogenic amino acid A ketogenic amino acid is an amino acid that can be degraded directly into acetyl-CoA, which is the precursor of ketone bodies. This is in contrast to the glucogenic amino acids, which are converted into glucose. Ketogenic amino acids are unable to be converted to glucose as both carbon atoms in the ketone body are ultimately degraded to carbon dioxide in the citric acid cycle. In humans, two amino acids are exclusively ketogenic: In humans, five amino acids are both ketogenic and glucogenic: In humans, the remaining thirteen amino acids are exclusively glucogenic (i.e. are not ketogenic).
Ketogenic amino acid
9912958
Ketogenic amino acid A ketogenic amino acid is an amino acid that can be degraded directly into acetyl-CoA, which is the precursor of ketone bodies. This is in contrast to the glucogenic amino acids, which are converted into glucose. Ketogenic amino acids are unable to be converted to glucose as both carbon atoms in the ketone body are ultimately degraded to carbon dioxide in the citric acid cycle. In humans, two amino acids are exclusively ketogenic: In humans, five amino acids are both ketogenic and glucogenic: In humans, the remaining thirteen amino acids are exclusively glucogenic (i.e. are not ketogenic).
Ketogenic amino acid
1068808
and the body of it is gradually dissolved. This may occur by bacterial action (the bacteria being washed into the pitcher by rainfall) or by enzymes secreted by the plant itself. Furthermore, some pitcher plants contain mutualistic insect larvae, which feed on trapped prey, and whose excreta the plant absorbs. Whatever the mechanism of digestion, the prey items are converted into a solution of amino acids, peptides, phosphates, ammonium and urea, from which the plant obtains its mineral nutrition (particularly nitrogen and phosphorus). Like all carnivorous plants, they all grow in locations where the soil is too poor in minerals
Pitcher plant
13538467
the canaline-urea cycle (analogous to the ornithine-urea cycle) is formed. Every time a canavanine molecule runs through the canaline-urea cycle, the two terminal nitrogen atoms are released as urea. Urea is an important by-product of this reaction sequence because it makes ammonicial ammonia (urease-mediated) that is available to support intermediary nitrogen metabolism. -Canaline can be reductively cleaved to -homoserine, a non-protein amino acid of great importance in the formation of a host of essential amino acids. In this way, the third nitrogen atom of canavanine enters into the reactions of nitrogen metabolism of the plant. As homoserine, its carbon skeleton
Canaline
9027715
cannot synthesize. In addition, the amino acids arginine, cysteine, glycine, glutamine, histidine, proline, serine, and tyrosine are considered conditionally essential, meaning they are not normally required in the diet, but must be supplied exogenously to specific populations that do not synthesize it in adequate amounts. For example, enough arginine is synthesized by the urea cycle to meet the needs of an adult but perhaps not those of a growing child. Amino acids that must be obtained from the diet are called essential amino acids. Nonessential amino acids are produced in the body. The pathways for the synthesis of nonessential amino
Amino acid synthesis
12300148
body. Protein molecules contain nitrogen atoms in addition to carbon, oxygen, and hydrogen. The fundamental components of protein are nitrogen-containing amino acids. Essential amino acids cannot be made by the animal. Some of the amino acids are convertible (with the expenditure of energy) to glucose and can be used for energy production just as ordinary glucose. By breaking down existing protein, some glucose can be produced internally; the remaining amino acids are discarded, primarily as urea in urine. This occurs normally only during prolonged starvation. Other dietary substances found in plant foods (phytochemicals, polyphenols) are not identified as essential nutrients
Animal nutrition
12719
intermediates in the metabolic pathways for standard amino acids – for example, ornithine and citrulline occur in the urea cycle, part of amino acid catabolism (see below). A rare exception to the dominance of α-amino acids in biology is the β-amino acid beta alanine (3-aminopropanoic acid), which is used in plants and microorganisms in the synthesis of pantothenic acid (vitamin B), a component of coenzyme A. -isomers are uncommon in live organisms. For instance, gramicidin is a polypeptide made up from mixture of - and -amino acids. Other compounds containing -amino acid are tyrocidine and valinomycin. These compounds disrupt bacterial
Amino acid
8548572
Acid Score. Most proteins are decomposed to single amino acids by digestion in the gastro-intestinal tract. Digestion typically begins in the stomach when pepsinogen is converted to pepsin by the action of hydrochloric acid, and continued by trypsin and chymotrypsin in the small intestine. Before the absorption in the small intestine, most proteins are already reduced to single amino acid or peptides of several amino acids. Most peptides longer than four amino acids are not absorbed. Absorption into the intestinal absorptive cells is not the end. There, most of the peptides are broken into single amino acids. Absorption of the
Protein (nutrient)
1695222
directly recycled to form new proteins, converted into different amino acids, or can undergo amino acid catabolism to be converted to other compounds via the Krebs cycle. The primary reason for protein catabolism is so organisms can convert proteins into a form of energy that they can use or store. To reuse their proteins, bacteria or soil microorganisms break down their proteins through protein catabolism into their individual amino acids and are used to form bacterial proteins or oxidized for energy. To convert to energy, once the proteins are broken down, they are typically deaminated (removal of an amino group)
Protein catabolism
6462059
are necessary for the formation of leucine from 2-oxolsovalerate. Degradation of branched-chain amino acids involves the branched-chain alpha-keto acid dehydrogenase complex (BCKDH). A deficiency of this complex leads to a buildup of the branched-chain amino acids (leucine, isoleucine, and valine) and their toxic by-products in the blood and urine, giving the condition the name maple syrup urine disease. The BCKDH complex converts branched-chain amino acids into acyl-CoA derivatives, which after subsequent reactions are converted either into acetyl-CoA or succinyl-CoA that enter the citric acid cycle. Enzymes involved are branched chain aminotransferase and 3-methyl-2-oxobutanoate dehydrogenase. While most amino acids are oxidized
Branched-chain amino acid
935182
essential in the diet: they cannot be synthesized in the body. Protein molecules contain nitrogen atoms in addition to carbon, oxygen, and hydrogen. The fundamental components of protein are nitrogen-containing amino acids, some of which are essential in the sense that humans cannot make them internally. Some of the amino acids are convertible (with the expenditure of energy) to glucose and can be used for energy production just as ordinary glucose. By breaking down existing protein, some glucose can be produced internally; the remaining amino acids are discarded, primarily as urea in urine. This occurs naturally when atrophy takes place,
Human nutrition
2866704
converts propionyl-CoA to methylmalonyl-CoA. This is one step in the process of converting certain amino acids and fats into sugar for energy. Individuals with PA cannot perform this conversion because the enzyme propionyl-CoA carboxylase is nonfunctional. The essential amino acids valine, methionine, isoleucine, and threonine, as well as odd-chain fatty acids (hence the mnemonic "VOMIT"), are simply converted to propionyl-CoA, before the process stops, leading to a buildup of propionyl-CoA. Instead of being converted to methylmalonyl-CoA, propionyl-CoA is then converted into propionic acid, which builds up in the bloodstream. This in turn causes an accumulation of dangerous acids and toxins,
Propionic acidemia
318785
amino acids are obtained through the consumption of foods containing protein. Ingested proteins are then broken down into amino acids through digestion, which typically involves denaturation of the protein through exposure to acid and hydrolysis by enzymes called proteases. Some ingested amino acids are used for protein biosynthesis, while others are converted to glucose through gluconeogenesis, or fed into the citric acid cycle. This use of protein as a fuel is particularly important under starvation conditions as it allows the body's own proteins to be used to support life, particularly those found in muscle. In animals such as dogs and
Protein
2388248
pyruvic acid or other α-keto acids with ammonia in the presence of ferrous hydroxide or in the presence of ferrous sulfide and hydrogen sulfide generates alanine or other α-amino acids. Reaction of α-amino acids in aqueous solution with COS or with CO and HS generates a peptide cycle wherein dipeptides, tripeptides etc. are formed and subsequently degraded via N-terminal hydantoin moieties and N-terminal urea moieties and subsequent cleavage of the N-terminal amino acid unit. Proposed reaction mechanism for reduction of CO on FeS: Ying et al. (2007) have proved that direct transformation of mackinawite (FeS) to pyrite (FeS) on reaction
Iron–sulfur world hypothesis
918093
Ornithine Ornithine is a non-proteinogenic amino acid that plays a role in the urea cycle. Ornithine is abnormally accumulated in the body in ornithine transcarbamylase deficiency. The radical is ornithyl. -Ornithine is one of the products of the action of the enzyme arginase on -arginine, creating urea. Therefore, ornithine is a central part of the urea cycle, which allows for the disposal of excess nitrogen. Ornithine is recycled and, in a manner, is a catalyst. First, ammonia is converted into carbamoyl phosphate (). Ornithine is converted into a urea derivative at the δ (terminal) nitrogen by carbamoyl phosphate synthetase. Another
Ornithine
698278
reaction: This arrangement means that the root nodules are sources of nitrogen for peas and many legumes, making them relatively rich in plant proteins. All proteins contain nitrogenous amino acids. Nitrogen is therefore a necessary ingredient in the production of proteins. Hence, peas and many legumes are among the best sources of plant protein. When a pea plant dies in the field, for example following the harvest, all of its remaining nitrogen, incorporated into amino acids inside the remaining plant parts, is released back into the soil. In the soil, the amino acids are converted to nitrate (NO), making the
Pea
6366
containing bleach, as the resulting chemical reaction produces highly toxic fumes. Liquid ammonia is dangerous because it is hygroscopic and because it can freeze flesh. See Gas carrier#Health effects of specific cargoes carried on gas carriers for more information. The toxicity of ammonia solutions does not usually cause problems for humans and other mammals, as a specific mechanism exists to prevent its build-up in the bloodstream. Ammonia is converted to carbamoyl phosphate by the enzyme carbamoyl phosphate synthetase, and then enters the urea cycle to be either incorporated into amino acids or excreted in the urine. Fish and amphibians lack
Ammonia
18277480
Homocitrulline -Homocitrulline is an amino acid and a metabolite of ornithine in mammalian (including human) metabolism. The amino acid can be detected in larger amounts in the urine of individuals with urea cycle disorders. At present, it is thought that the depletion of the ornithine supply causes the accumulation of carbamyl-phosphate in the urea cycle which may be responsible for the enhanced synthesis of homocitrulline and homoarginine. Both amino acids can be detected in urine. Amino acid analysis allows for the quantitative analysis of these amino acid metabolites in biological fluids such as urine or blood. Homocitrulline is one methylene
Homocitrulline
3198711
of the carboxyl carbon (via ninhydrin) from amino acids recovered from soil that has been treated with a labeled substrate demonstrates assimilation of that substrate into microbial protein. This approach was successfully used to reveal that some ammonium oxidizing bacteria, also called nitrifying bacteria use urea as a carbon source in soil. A ninhydrin solution is commonly used by forensic investigators in the analysis of latent fingerprints on porous surfaces such as paper. Amino acid containing fingermarks, formed by minute sweat secretions which gather on the finger's unique ridges, are treated with the ninhydrin solution which turns the amino acid
Ninhydrin
8092530
of blood. In children, a BUN:Cr ratio of 30 or greater has a sensitivity of 68.8% and a specificity of 98% for upper gastrointestinal bleeding. A common assumption is that the ratio is elevated because of amino acid digestion, since blood (excluding water) consists largely of the protein hemoglobin and is broken down by digestive enzymes of the upper GI tract into amino acids, which are then reabsorbed in the GI tract and broken down into urea. However, elevated BUN:Cr ratios are not observed when other high protein loads (e.g., steak) are consumed. Renal hypoperfusion secondary to the blood lost
BUN-to-creatinine ratio
1695223
so that they can be processed into the Krebs/Citric Acid (TCA) Cycle. By proceeding into the Citric Acid Cycle, the original proteins will be converted into usable energy for the organism. There are also other processes to convert amino acids into usable molecules to enter the TCA cycle, such as transamination (transfer of amino group), decarboxylation (removal of carboxyl group), and dehydrogenation (removal of hydrogen). The proteins are digested in the intestines to produce the amino acids. The proteins are continuously being broken down and reformed, depending on the current needs that the body has. Proteins have different half-lives: some
Protein catabolism
5968021
protein aversion. Forced feeding of protein may lead to convulsions and coma. Mental development is normal if prolonged episode of hyperammonemia can be avoided. Some patients develop severe pulmonary and renal complications. High levels of plasma glutamine and glycine are observed. It has been associated with SLC7A7. In LPI, urinary excretion of cationic amino acids (ornithine, arginine and lysine) is increased and these amino acids are poorly absorbed from the intestine. Therefore, their plasma concentrations are low and their body pools become depleted. Deficiency of arginine and ornithine restricts the function of the urea cycle and leads to hyperammonemia after
Lysinuric protein intolerance
733741
involved in this biosynthesis include: Isoleucine is both a glucogenic and a ketogenic amino acid. After transamination with alpha-ketoglutarate the carbon skeleton can be converted into either succinyl CoA, and fed into the TCA cycle for oxidation or converted into oxaloacetate for gluconeogenesis (hence glucogenic). It can also be converted into acetyl CoA and fed into the TCA cycle by condensing with oxaloacetate to form citrate. In mammals Acetyl CoA cannot be converted back to carbohydrate but can be used in the synthesis of ketone bodies or fatty acids, hence ketogenic. Isoleucine, like other branched-chain amino acids, is associated with
Isoleucine
85531
de-aminated alanine into glucose, under the influence of high levels of glucagon and/or epinephrine in the blood. Here the addition of "oxaloacetate" to the mitochondrion does not have a net anaplerotic effect, as another citric acid cycle intermediate ("malate") is immediately removed from the mitochondrion to be converted into cytosolic oxaloacetate, which is ultimately converted into glucose, in a process that is almost the reverse of glycolysis. In protein catabolism, proteins are broken down by proteases into their constituent amino acids. Their carbon skeletons (i.e. the de-aminated amino acids) may either enter the citric acid cycle as intermediates (e.g. "alpha-ketoglutarate"
Citric acid cycle
438728
substrates, both of which are elevated when free amino acids are elevated. So Glu not only is a substrate for NAGS but also serves as an activator for the urea cycle. The remaining enzymes of the cycle are controlled by the concentrations of their substrates. Thus, inherited deficiencies in cycle enzymes other than do not result in significant decreases in urea production (if any cycle enzyme is entirely missing, death occurs shortly after birth). Rather, the deficient enzyme's substrate builds up, increasing the rate of the deficient reaction to normal. The anomalous substrate buildup is not without cost, however. The
Urea cycle
14254603
the cud, is chewed by the molars, grinding down the coarse vegetation to small particles. The cud is then swallowed again and further digested by specialized microorganisms in the rumen. These microbes are primarily responsible for decomposing cellulose and other carbohydrates into volatile fatty acids cattle use as their primary metabolic fuel. The microbes inside the rumen also synthesize amino acids from non-protein nitrogenous sources, such as urea and ammonia. As these microbes reproduce in the rumen, older generations die and their cells continue on through the digestive tract. These cells are then partially digested in the small intestines, allowing
Cattle
17245907
the nitrogen cycle and the sulfur cycle. Three different pathways can be involved in the nitrogen cycle: ammonification of amino acids, dissimilatory reduction of nitrate, and degradation of urea or uric acid. In sulfur cycle, bacteria follow the dissimilatory reduction of sulfate. The microbial urease catalyzes the hydrolysis of urea into ammonium and carbonate. One mole of urea is hydrolyzed intracellularly to 1 mol of ammonia and 1 mole of Carbamic acid (1), which spontaneously hydrolyzes to form an additional 1 mole of ammonia and carbonic acid (2). CO(NH) + HO ---> NHCOOH + NH (1) NHCOOH + HO --->
Microbiologically induced calcite precipitation
11246575
urea cycle and metabolism of amino groups, phenylalanine metabolism, tryptophan metabolism, cyanoamino acid metabolism, benzoate degradation via coa ligation, and styrene degradation. Amidases contain a conserved stretch of approximately 130 amino acids known as the AS sequence. They are widespread, being found in both prokaryotes and eukaryotes. AS enzymes catalyse the hydrolysis of amide bonds (CO-NH2), although the family has diverged widely with regard to substrate specificity and function. Nonetheless, these enzymes maintain a core alpha/beta/alpha structure, where the topologies of the N- and C-terminal halves are similar. AS enzymes characteristically have a highly conserved C-terminal region rich in serine
Amidase
16539057
urea cycle to convert enough of the ammonia into urea. Since transamination of proteins is a leading producer of ammonia, protein restriction may be recommended as a therapy to reduce the symptoms of the episode. THAN can also be treated by avoiding amino acids in TPN or total parenteral nutrition or by giving a high caloric diet to limit catabolism of the tissues and therefore to minimize the breakdown of endogenous protein. The most common treatments are dialysis (both peritoneal and hemodialysis), sodium benzoate, and arginine. Sodium Benzoate combines with glycine to be excreted in the form of hippuric acid.
Transient hyperammonemia of the newborn
2668356
Nisin Nisin is a polycyclic antibacterial peptide produced by the bacterium "Lactococcus lactis" that is used as a food preservative. It has 34 amino acid residues, including the uncommon amino acids lanthionine (Lan), methyllanthionine (MeLan), didehydroalanine (Dha), and didehydroaminobutyric acid (Dhb). These unusual amino acids are introduced by posttranslational modification of the precursor peptide. In these reactions a ribosomally synthesized 57-mer is converted to the final peptide. The unsaturated amino acids originate from serine and threonine, and the enzyme-catalysed addition of cysteine residues to the didehydro amino acids result in the multiple (5) thioether bridges. Subtilin and epidermin are related
Nisin
733705
plays an important role in the urea cycle. Racemic aspartic acid can be synthesized from diethyl sodium phthalimidomalonate, (CH(CO)NC(COEt)). The major disadvantage of the above technique is that equimolar amounts of each enantiomer are made. Using biotechnology it is now possible to use immobilised enzymes to create just one type of enantiomer owing to their stereospecificity. In plants and microorganisms, aspartate is the precursor to several amino acids, including four that are essential for humans: methionine, threonine, isoleucine, and lysine. The conversion of aspartate to these other amino acids begins with reduction of aspartate to its "semialdehyde", OCCH(NH)CHCHO. Asparagine is
Aspartic acid
7529549
Citrullination Citrullination or deimination is the conversion of the amino acid arginine in a protein into the amino acid citrulline. Citrulline is not one of the 20 standard amino acids encoded by DNA in the genetic code. Instead, it is the result of a post-translational modification. Citrullination is distinct from the formation of the free amino acid citrulline as part of the urea cycle or as a byproduct of enzymes of the nitric oxide synthase family. Enzymes called arginine deiminases (ADIs) catalyze the deimination of free arginine, while protein arginine deiminases or peptidylarginine deiminases (PADs) replace the primary ketimine group
Citrullination
20127599
and formula_9 are standard deviations for formula_6 and formula_7 Experimental Exchangeability was devised by Yampolsky and Stoltzfus. It is the measure of the mean effect of exchanging one amino acid into a different amino acid. It is based on analysis of experimental studies where 9671 amino acids replacements from different proteins, were compared for effect on protein activity. Amino acids can also be classified according to how many different amino acids they can be exchanged by through single nucleotide substitution. Some amino acids are more likely to be replaced. One of the factors that influences this tendency is physicochemical distance.
Amino acid replacement
8539043
must be taken to ensure the variable of interest is quantified by BV. Factors which affect BV can be grouped into properties of the protein source and properties of the species or individual consuming the protein. Three major properties of a protein source affect its BV: Amino acid composition is the principal effect. All proteins are made up of combinations of the 21 biological amino acids. Some of these can be synthesised or converted in the body, whereas others cannot and must be ingested in the diet. These are known as essential amino acids (EAAs), of which there are 9
Biological value
85536
cytosol. There it is cleaved by ATP citrate lyase into acetyl-CoA and oxaloacetate. The oxaloacetate is returned to mitochondrion as "malate" (and then converted back into "oxaloacetate" to transfer more "acetyl-CoA" out of the mitochondrion). The cytosolic acetyl-CoA is used for fatty acid synthesis and the production of cholesterol. Cholesterol can, in turn, be used to synthesize the steroid hormones, bile salts, and vitamin D. The carbon skeletons of many non-essential amino acids are made from citric acid cycle intermediates. To turn them into amino acids the alpha keto-acids formed from the citric acid cycle intermediates have to acquire their
Citric acid cycle
42879
the pathways, intermediates from other biochemical pathways are converted to the α-keto acid skeleton, and then an amino group is added, often via transamination. The amino acids may then be linked together to make a protein. A similar process is used to break down proteins. It is first hydrolyzed into its component amino acids. Free ammonia (NH), existing as the ammonium ion (NH) in blood, is toxic to life forms. A suitable method for excreting it must therefore exist. Different tactics have evolved in different animals, depending on the animals' needs. Unicellular organisms simply release the ammonia into the environment.
Biochemistry
278159
secrete these enzymes from specialized cells in their guts, including the stomach and pancreas, and salivary glands. The amino acids or sugars released by these extracellular enzymes are then pumped into cells by active transport proteins. Carbohydrate catabolism is the breakdown of carbohydrates into smaller units. Carbohydrates are usually taken into cells once they have been digested into monosaccharides. Once inside, the major route of breakdown is glycolysis, where sugars such as glucose and fructose are converted into pyruvate and some ATP is generated. Pyruvate is an intermediate in several metabolic pathways, but the majority is converted to acetyl-CoA through
Metabolism
12698
formula HNCHRCOOH in most cases, where R is an organic substituent known as a "side chain"); often the term "amino acid" is used to refer specifically to these. They include the 22 proteinogenic ("protein-building") amino acids, which combine into peptide chains ("polypeptides") to form the building-blocks of a vast array of proteins. These are all -stereoisomers ("left-handed" isomers), although a few -amino acids ("right-handed") occur in bacterial envelopes, as a neuromodulator (-serine), and in some antibiotics. Twenty of the proteinogenic amino acids are encoded directly by triplet codons in the genetic code and are known as "standard" amino acids. The
Amino acid
11581381
in tumor cells, all glycolytic intermediates above pyruvate kinase accumulate and are channelled into synthetic processes, which branch off from glycolytic intermediates such as nucleic acid-, phospholipid-, and amino acid synthesis. Nucleic acids, phospholipids, and amino acids are important cell building-blocks, which are greatly needed by highly proliferating cells, such as tumor cells. Due to the key position of pyruvate kinase within glycolysis, the tetramer:dimer ratio of PKM2 determines whether glucose carbons are converted to pyruvate and lactate under the production of energy (tetrameric form) or channelled into synthetic processes (dimeric form). In tumor cells, PKM2 is mainly in the
PKM2
1906428
ribosome molecules translate this code to a specific sequence of amino acids. The ribosome is a multi-subunit structure containing rRNA and proteins. It is the "factory" where amino acids are assembled into proteins. tRNAs are small noncoding RNA chains (75-90 nucleotides) that transport amino acids to the ribosome. tRNAs have a site for amino acid attachment, and a site called an anticodon. The anticodon is an RNA triplet complementary to the mRNA triplet that codes for their cargo amino acid. Aminoacyl tRNA synthetases (enzymes) catalyze the bonding between specific tRNAs and the amino acids that their anticodon sequences call for.
Translation (biology)
4984441
hexulose phosphate is converted into GAP and either pyruvate or dihydroxyacetone phosphate (DHAP). The pyruvate or DHAP is used towards biomass while the other 2 hexulose phosphate molecules and the molecule of GAP are used to regenerate the 3 molecules of ribulose-5-phosphate. Unlike the other assimilatory pathways, the serine cycle uses carboxylic acids and amino acids as intermediates instead of carbohydrates. First, 2 molecules of formaldehyde are added to 2 molecules of the amino acid glycine. This produces two molecules of the amino acid serine, the key intermediate of this pathway. These serine molecules eventually produce 2 molecules of 2-phosphoglycerate,
Methylotroph
18277485
impaired immune function, and progressively brittle bones that are prone to fracture and a lung disorder called pulmonary alveolar proteinosis may also develop. In addition, the accumulation of amino acids in the kidneys can cause end-stage renal disease (ESRD). In ESRD the kidneys are no longer able to filter fluids and waste products from the body effectively. Homocitrulline -Homocitrulline is an amino acid and a metabolite of ornithine in mammalian (including human) metabolism. The amino acid can be detected in larger amounts in the urine of individuals with urea cycle disorders. At present, it is thought that the depletion of
Homocitrulline
4872188
condition, when a high amount of carbohydrate is taken, it is rapidly absorbed in some cases where a part of the stomach is surgically removed, the excessive glucose appears in urine producing glucosuria. Blood is filtered by millions of nephrons, the functional units that comprise the kidneys. In each nephron, blood flows from the arteriole into the glomerulus, a tuft of leaky capillaries. The Bowman's capsule surrounds each glomerulus, and collects the filtrate that the glomerulus forms. The filtrate contains waste products (e.g. urea), electrolytes (e.g. sodium, potassium, chloride), amino acids, and glucose. The filtrate passes into the renal tubules
Glycosuria
2514387
Proteinogenic amino acid Proteinogenic amino acids are amino acids that are incorporated biosynthetically into proteins during translation. The word "proteinogenic" means "protein creating". Throughout known life, there are 22 genetically encoded (proteinogenic) amino acids, 20 in the standard genetic code and an additional 2 that can be incorporated by special translation mechanisms. In contrast, non-proteinogenic amino acids are amino acids that are either not incorporated into proteins (like GABA, -DOPA, or triiodothyronine), misincorporated in place of a genetically encoded amino acid, or not produced directly and in isolation by standard cellular machinery (like hydroxyproline). The latter often results from post-translational
Proteinogenic amino acid
2514378
Proteinogenic amino acid Proteinogenic amino acids are amino acids that are incorporated biosynthetically into proteins during translation. The word "proteinogenic" means "protein creating". Throughout known life, there are 22 genetically encoded (proteinogenic) amino acids, 20 in the standard genetic code and an additional 2 that can be incorporated by special translation mechanisms. In contrast, non-proteinogenic amino acids are amino acids that are either not incorporated into proteins (like GABA, -DOPA, or triiodothyronine), misincorporated in place of a genetically encoded amino acid, or not produced directly and in isolation by standard cellular machinery (like hydroxyproline). The latter often results from post-translational
Proteinogenic amino acid
11296501
magnesium binding site at amino acids 131 and 133, and a Flavin mononucleotide binding site at amino acids 188 and 195. As of late 2007, 14 structures have been solved for this class of enzymes, with PDB accession codes , , , , , , , , , , , , , and . Riboflavin kinase In enzymology, a riboflavin kinase () is an enzyme that catalyzes the chemical reaction Thus, the two substrates of this enzyme are ATP and riboflavin, whereas its two products are ADP and FMN. Riboflavin is converted into catalytically active cofactors (FAD and FMN) by
Riboflavin kinase
935195
are soluble in the digestive juices within the small intestine, where they are absorbed into the blood. Once absorbed, they cannot be stored in the body, so they are either metabolized as required or excreted in the urine. Proteins consist of amino acids in different proportions. The most important aspect and defining characteristic of protein from a nutritional standpoint is its amino acid composition. Amino acids which an animal cannot synthesize on its own from smaller molecules are deemed essential. The synthesis of some amino acids can be limited under special pathophysiological conditions, such as prematurity in the infant or
Human nutrition
12720
cell walls, particularly in Gram-positive bacteria. Only 837 -amino acids were found in Swiss-Prot database (187 million amino acids analysed). The 20 amino acids that are encoded directly by the codons of the universal genetic code are called "standard" or "canonical" amino acids. A modified form of methionine ("N"-formylmethionine) is often incorporated in place of methionine as the initial amino acid of proteins in bacteria, mitochondria and chloroplasts. Other amino acids are called "non-standard" or "non-canonical". Most of the non-standard amino acids are also non-proteinogenic (i.e. they cannot be incorporated into proteins during translation), but two of them are proteinogenic,
Amino acid
2060236
sources of plant protein. When a legume plant dies in the field, for example following the harvest, all of its remaining nitrogen, incorporated into amino acids inside the remaining plant parts, is released back into the soil. In the soil, the amino acids are converted to nitrate (NO), making the nitrogen available to other plants, thereby serving as fertilizer for future crops. In many traditional and organic farming practices, crop rotation involving legumes is common. By alternating between legumes and nonlegumes, sometimes planting nonlegumes two times in a row and then a legume, the field usually receives a sufficient amount
Legume
6651199
their substrates into products. "Bioactivation" may also refer to the process where inactive prodrugs are converted into their active metabolites, or the "toxication" of protoxins into actual toxins. An enzyme may be reversibly or irreversibly bioactivated. A major mechanism of irreversible bioactivation is where a piece of a protein is cut off by cleavage, producing an enzyme that will then stay active. A major mechanism of reversible bioactivation is where a cofactor binds to an enzyme, which then remains active while the cofactor is bound, and stops being active when the cofactor is removed. In protein synthesis, amino acids are
Activation
438723
salt, which is excreted in solid form. The entire process converts two amino groups, one from NH and one from Aspartate, and a carbon atom from HCO, to the relatively nontoxic excretion product urea at the cost of four "high-energy" phosphate bonds (3 ATP hydrolyzed to 2 ADP and one AMP). The conversion from ammonia to urea happens in five main steps. The first is needed for ammonia to enter the cycle and the following four are all a part of the cycle itself. To enter the cycle, ammonia is converted to carbamoyl phosphate. The urea cycle consists of four
Urea cycle
438724
enzymatic reactions: one mitochondrial and three cytosolic. 1 -ornithine2 carbamoyl phosphate3 -citrulline4 argininosuccinate5 fumarate6 -arginine7 urea -Asp -aspartateCPS-1 carbamoyl phosphate synthetase IOTC Ornithine transcarbamoylaseASS argininosuccinate synthetaseASL argininosuccinate lyaseARG1 arginase 1 Before the urea cycle begins ammonia is converted to carbamoyl phosphate. The reaction is catalyzed by carbamoyl phosphate synthetase I and requires the use of two ATP molecules. The carbamoyl phosphate then enters the urea cycle. 1) Carbamoyl phosphate is converted to citrulline. With catalysis by ornithine transcarbamoylase, the carbamoyl phosphate group is donated to ornithine and releases a phosphate group. 2) A condensation reaction occurs between the amino group
Urea cycle
11020099
represent sources of experimental bias. SILAC- Stable Isotope Labeling with Amino Acids in Cell Culture Stable isotope labeling with amino acids in cell culture (SILAC) is a method that involves metabolic incorporation of “heavy” C- or N-labeled amino acids into proteins followed by MS analysis. SILAC requires growing cells in specialized media supplemented with light or heavy forms of essential amino acids, lysine or arginine. One cell population is grown in media containing light amino acids while the experimental condition is grown in the presence of heavy amino acids. The heavy and light amino acids are incorporated into proteins through
Quantitative proteomics
18697587
Urea extraction crystallization The urea extraction crystallization is a process for separating linear paraffins (n-paraffins, n-alkanes) from hydrocarbon mixtures through the formation of urea-n-paraffin-clathrates. The process is primarily used to lower the pour point of petroleum products, by-products of the process are n-paraffins in high purity. The method may also applied for the separation of fatty acids and fatty alcohols. In addition to urea also thiourea is used in the process. In addition to the n-alkanes are also unbranched fatty acids with more than four carbon atoms, their esters and unbranched fatty alcohols can migrate into the channels of the
Urea extraction crystallization
16940335
but are added in place of a stop codon when a specific sequence is present, UGA codon and SECIS element for selenocysteine, UAG PYLIS downstream sequence for pyrrolysine. All other amino acids are termed "non-proteinogenic". There are various groups of amino acids: These groups overlap, but are not identical. All 22 proteinogenic amino acids are biosynthesised by organisms and some, but not all, of them also are abiotic (found in prebiotic experiments and meteorites). Some natural amino acids, such as norleucine, are misincorporated translationally into proteins due to infidelity of the protein-synthesis process. Many amino acids, such as ornithine, are
Non-proteinogenic amino acids
12300151
"essential" (an animal cannot produce them internally) and some are "non-essential" (the animal can produce them from other nitrogen-containing compounds). A diet that contains adequate amounts of amino acids (especially those that are essential) is particularly important in some situations: during early development and maturation, pregnancy, lactation, or injury (a burn, for instance). A few amino acids from protein can be converted into glucose and used for fuel through a process called gluconeogenesis; this is done in quantity only during starvation. Dietary minerals are the chemical elements required by living organisms, other than the four elements carbon, hydrogen, nitrogen, and
Animal nutrition
6327923
Nitrogen balance Nitrogen balance is a measure of nitrogen input minus nitrogen output. Nitrogen Balance = Nitrogen intake - Nitrogen loss Sources of nitrogen intake include meat, dairy, eggs, nuts and legumes, and grains and cereals. Examples of nitrogen losses include urine, feces, sweat, hair, and skin. Blood urea nitrogen can be used in estimating nitrogen balance, as can the urea concentration in urine. Nitrogen is a fundamental component of amino acids, which are the molecular building blocks of protein. Therefore, measuring nitrogen inputs and losses can be used to study protein metabolism. Positive nitrogen balance is associated with periods
Nitrogen balance
3363905
2010. Alberta was the first Canadian province to implement CF screening in 2007. Quebec, New Brunswick, Nova Scotia, Newfoundland and Prince Edward Island do not include CF in their screening programs. The United Kingdom as well as many European Union countries screen for CF as well. Switzerland is one of the latest countries to add CF to their newborn screening menu, doing so in January 2011. Disorders of the distal urea cycle, such as citrullinemia, argininosuccinic aciduria and argininemia are included in newborn screening programs in many jurisdictions that using tandem mass spectrometry to identify key amino acids. Proximal urea
Newborn screening
280667
of this compound to dimethylamine is responsible for the early odour in unfresh saltwater fish. In animals, free radical nitric oxide (derived from an amino acid), serves as an important regulatory molecule for circulation. Nitric oxide's rapid reaction with water in animals results in production of its metabolite nitrite. Animal metabolism of nitrogen in proteins, in general, results in excretion of urea, while animal metabolism of nucleic acids results in excretion of urea and uric acid. The characteristic odour of animal flesh decay is caused by the creation of long-chain, nitrogen-containing amines, such as putrescine and cadaverine, which are breakdown
Nitrogen
13259744
nucleotides must be sufficiently high [2]. Standard methods of sequence comparisons use a substitution matrix to accomplish this [4]. Similarities between amino acids or nucleotides are quantified in these substitution matrices. The substitution score (formula_1) of amino acids formula_2 and formula_3 can we written as follows: formula_4 where formula_5 denotes the probability of amino acid formula_2 mutating into amino acid formula_3 [2]. In a large set of sequence alignments, counting the number of amino acids as well as the number of aligned pairs formula_8 will allow you to derive the probabilities formula_5 and formula_10. Since protein sequences need to maintain
CS-BLAST
2227861
Imino acid In chemistry, an imino acid is any molecule that contains both imino (>C=NH) and carboxyl (-C(=O)-OH) functional groups. Imino acids are related to amino acids, which contain both amino (-NH) and carboxyl (-COOH) functional groups, differing in the bonding to the nitrogen. The D-amino acid oxidase enzymes are able to convert amino acids into imino acids. Also the direct biosynthetic precursor to the amino acid proline is the imino acid ("S")-Δ-pyrroline-5-carboxylate (P5C). Amino acids containing a secondary amine group (the only proteinogenic amino acid of this type is proline) are sometimes named imino acids, though this usage is
Imino acid
3592822
water solubility. Concentration as a food preservative is limited by the FDA in the U.S. to 0.1% by weight. Sodium benzoate is also allowed as an animal food additive at up to 0.1%, according to AFCO's official publication. Sodium benzoate has been replaced by potassium sorbate in the majority of soft drinks in the United Kingdom. Sodium benzoate is used as a treatment for urea cycle disorders due to its ability to bind amino acids. This leads to excretion of these amino acids and a decrease in ammonia levels. Recent research shows that sodium benzoate may be beneficial as an
Sodium benzoate
16940336
metabolic intermediates produced biosynthetically, but not incorporated translationally into proteins. Post-translational modification of amino-acid residues in proteins leads to the formation of many proteinaceous, but non-proteinogenic, amino acids. Other amino acids are solely found in abiotic mixes (e.g. α-methylnorvaline). Over 30 unnatural amino acids have been inserted translationally into protein in engineered systems, yet are not biosynthetic. In addition to the IUPAC numbering system to differentiate the various carbons in an organic molecule, by sequentially assigning a number to each carbon, including those forming a carboxylic group, the carbons along the side-chain of amino acids can also be labelled with
Non-proteinogenic amino acids
16940337
Greek letters, where the α-carbon is the central chiral carbon possessing a carboxyl group, a side chain and, in α-amino acids, an amino group – the carbon in carboxylic groups is not counted. (Consequently, the IUPAC names of many non-proteinogenic α-amino acids start with "2-amino-" and end in "-ic acid".) Most natural amino acids are α-amino acids in the L conformation, but some exceptions exist. Some non-α amino acids exist in organisms. In these structures, the amine group displaced further from the carboxylic acid end of the amino acid molecule. Thus a β amino acid has the amine group bonded
Non-proteinogenic amino acids
4759807
Stickland fermentation Stickland fermentation or The Stickland Reaction is the name for a chemical reaction that involves the coupled oxidation and reduction of amino acids to organic acids. The electron donor amino acid is oxidised to a volatile carboxylic acid one carbon atom shorter than the original amino acid. For example, alanine with a three carbon chain is converted to acetate with two carbons. The electron acceptor amino acid is reduced to a volatile carboxylic acid the same length as the original amino acid. For example, glycine with two carbons is converted to acetate. In this way, amino acid fermenting
Stickland fermentation
984981
ratio of the distance traveled by each protein to the length of the gel (Rf) one can make conclusions about the relative molecular weight of the proteins, where the length of the gel is determined by the distance traveled by a small molecule like a tracking dye. For nucleic acids, urea is the most commonly used denaturant. For proteins, sodium dodecyl sulfate (SDS) is an anionic detergent applied to protein samples to coat proteins in order to impart two negative charges (from every SDS molecule) to every two amino acids of the denatured protein. 2-Mercaptoethanol may also be used to
Polyacrylamide gel electrophoresis
918096
acids to stimulate GH release by athletes is not recommended." -Ornithine -aspartate (LOLA), a stable salt of ornithine and aspartic acid, has been used in the treatment of cirrhosis. Ornithine Ornithine is a non-proteinogenic amino acid that plays a role in the urea cycle. Ornithine is abnormally accumulated in the body in ornithine transcarbamylase deficiency. The radical is ornithyl. -Ornithine is one of the products of the action of the enzyme arginase on -arginine, creating urea. Therefore, ornithine is a central part of the urea cycle, which allows for the disposal of excess nitrogen. Ornithine is recycled and, in a
Ornithine
433175
a reasonable time-frame. Many animals (e.g., dogs) have a much more concentrated urine and it contains a higher urea amount than normal human urine; this can prove dangerous as a source of liquids for consumption in a life-threatening situation (such as in a desert). Urea can cause algal blooms to produce toxins, and its presence in the runoff from fertilized land may play a role in the increase of toxic blooms. The substance decomposes on heating above melting point, producing toxic gases, and reacts violently with strong oxidants, nitrites, inorganic chlorides, chlorites and perchlorates, causing fire and explosion. Amino acids
Urea
334932
of D-amino acids in nature. Cross-linking between amino acids in different linear amino sugar chains occurs with the help of the enzyme DD-transpeptidase and results in a 3-dimensional structure that is strong and rigid. The specific amino acid sequence and molecular structure vary with the bacterial species. The peptidoglycan monomers are synthesized in the cytosol and are then attached to a membrane carrier bactoprenol. Bactoprenol transports peptidoglycan monomers across the cell membrane where they are inserted into the existing peptidoglycan. In the first step of peptidoglycan synthesis, glutamine, which is an amino acid, donates an amino group to a sugar,
Peptidoglycan
75978
which the hydrogen of the hydroxyl (–OH) group is replaced with a metal cation. Thus, acetic acid found in vinegar reacts with sodium bicarbonate (baking soda) to form sodium acetate, carbon dioxide, and water: Carboxylic acids also react with alcohols to give esters. This process is widely used, e.g. in the production of polyesters. Likewise, carboxylic acids are converted into amides, but this conversion typically does not occur by direct reaction of the carboxylic acid and the amine. Instead esters are typical precursors to amides. The conversion of amino acids into peptides is a major biochemical process that requires ATP.
Carboxylic acid
292192
lacks one or more of the essential amino acids. It is possible with protein combinations of two incomplete protein sources (e.g., rice and beans) to make a complete protein source, and characteristic combinations are the basis of distinct cultural cooking traditions. However, complementary sources of protein do not need to be eaten at the same meal to be used together by the body. Excess amino acids from protein can be converted into glucose and used for fuel through a process called gluconeogenesis. Water is excreted from the body in multiple forms; including urine and feces, sweating, and by water vapour
Nutrition
16111956
of urea, discovering that amino acids (glycine and leucine) are intermediate links between protein and urea., With Bernhard Naunyn (1839–1925) he conducted important research involving the behavior of benzene-derived hydrocarbons in the body. Otto Schultzen Karl Ludwig Wilhelm Otto Schultzen (16 July 1837 – 7 December 1875) was a German physician born in Lissa. He studied medicine at the Universities of Königsberg and Berlin, earning his doctorate in 1862 with the thesis "Deinanition, accedit observatio et exploratio microscopica". Afterwards he was an assistant to Friedrich Theodor von Frerichs (1819–1885) at the medical clinic in Berlin. He gained his habilitation in
Otto Schultzen
11874926
metabolism of the amino acids serine, threonine and proline. Glycocyamine is formed in the mammalian organism primarily in the kidneys by transferring the guanidine group of L-arginine by the enzyme L-Arg:Gly-amidinotransferase (AGAT) to the amino acid glycine. From L-arginine, ornithine is thus produced, which is metabolized in the urea cycle by carbamoylation to citrulline. In a further step, glycocyamine is methylated to creatine with "S"-adenosyl methionine by the enzyme guanidinoacetate N-methyltransferase (GAMT). The creatine is released into the bloodstream. Guanidinoacetic acid was first prepared in 1861 by Adolph Strecker by reaction of cyanamide with glycine in aqueous solution: Glycine can
Glycocyamine