query: subclass_of arabinosyltransferase
supports: In molecular biology , an arabinosyltransferase is a transferase enzyme acting upon arabinose . This enzyme is involved in polymerisation of arabinogalactan ( an essential component of the mycobacterial cell wall ) . Mycobacterially , the more precise term is arabinofuranosyltransferase , since the arabinose residues occur only in a furanose form . This enzyme has important clinical applications as it is believed to be the target of the antimycobacterial drug Ethambutol . Carbon (from "coal") is a chemical element with symbol C and atomic number 6. It is nonmetallic and tetravalentmaking four electrons available to form covalent chemical bonds. Three isotopes occur naturally, C and C being stable, while C is a radioactive isotope, decaying with a half-life of about 5,730 years. Carbon is one of the few elements known since antiquity. Monosaccharides (from Greek "monos": single, "sacchar": sugar), also called simple sugars, are the most basic units of carbohydrates. They are fundamental units of carbohydrates and cannot be further hydrolyzed to simpler compounds. The general formula is . They are the simplest form of sugar and are usually colorless, water-soluble, and crystalline solids. Some monosaccharides have a sweet taste. Examples of monosaccharides include glucose (dextrose), fructose (levulose) and galactose. Monosaccharides are the building blocks of disaccharides (such as sucrose and lactose) and polysaccharides (such as cellulose and starch). Further, each carbon atom that supports a hydroxyl group (so, all of the carbons except for the primary and terminal carbon) is chiral, giving rise to a number of isomeric forms, all with the same chemical formula. For instance, galactose and glucose are both aldohexoses, but have different physical structures and chemical properties. Enzymes are macromolecular biological catalysts. Enzymes accelerate, or catalyze, chemical reactions. The molecules at the beginning of the process upon which enzymes may act are called substrates and the enzyme converts these into different molecules, called products. Almost all metabolic processes in the cell need enzymes in order to occur at rates fast enough to sustain life. The set of enzymes made in a cell determines which metabolic pathways occur in that cell. The study of enzymes is called "enzymology". Gum arabic, also known as acacia gum, is a natural gum consisting of the hardened sap of various species of the acacia tree. Originally, gum arabic was collected from "Acacia nilotica" which was called the "Gum arabic tree"; in the present day, gum arabic is predominantly collected from two related species, namely "Acacia senegal" and "Vachellia (Acacia) seyal". Producers harvest the gum commercially from wild trees, mostly in Sudan (80%) and throughout the Sahel, from Senegal to Somaliathough it is historically cultivated in Arabia and West Asia. A transferase is any one of a class of enzymes that enact the transfer of specific functional groups (e.g. a methyl or glycosyl group) from one molecule (called the donor) to another (called the acceptor). They are involved in hundreds of different biochemical pathways throughout biology, and are integral to some of lifes most important processes. In organic chemistry, functional groups are specific groups (moieties) of atoms or bonds within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction(s) regardless of the size of the molecule it is a part of. However, its relative reactivity can be modified by other functional groups nearby. The atoms of functional groups are linked to each other and to the rest of the molecule by covalent bonds. Any subgroup of atoms of a compound also may be called a radical, and if a covalent bond is broken homolytically, the resulting fragment radicals are referred as free radicals. Functional groups can also be charged, e.g. in carboxylate salts (-COO), which turns the molecule into a polyatomic ion or a complex ion. Arabinose is an aldopentose  a monosaccharide containing five carbon atoms, and including an aldehyde (CHO) functional group. An aldehyde or alkanal is an organic compound containing a functional group with the structure CHO, consisting of a carbonyl center (a carbon double-bonded to oxygen) with the carbon atom also bonded to hydrogen and to an R group, which is any generic alkyl or side chain. The groupwithout Ris the aldehyde group, also known as the formyl group. Aldehydes are common in organic chemistry. Many fragrances are aldehydes.
  Structure and bonding.
  Aldehydes feature an sp-hybridized, planar carbon center that is connected by a double bond to oxygen and a single bond to hydrogen. The CH bond is not ordinarily acidic. Because of resonance stabilization of the conjugate base, an -hydrogen in an aldehyde (not shown in the picture above) is far more acidic, with a p"K" near 15, compared to the acidity of a typical alkane (pKa about 50). This acidification is attributed to (i) the electron-withdrawing quality of the formyl center and (ii) the fact that the conjugate base, an enolate anion, delocalizes its negative charge. Related to (i), the aldehyde group is somewhat polar. A glycosyl group is a univalent free radical or substituent structure obtained by removing the hemiacetal hydroxyl group from the cyclic form of a monosaccharide and, by extension, of a lower oligosaccharide.
  Glycosyl also reacts with inorganic acids, such as phosphoric acid, forming an ester such as glucose 1-phosphate. In biochemistry, a metabolic pathway is a linked series of chemical reactions occurring within a cell. The reactants, products, and intermediates of an enzymatic reaction are known as metabolites, which are modified by a sequence of chemical reactions catalyzed by enzymes. In a metabolic pathway, the product of one enzyme acts as the substrate for the next. These enzymes often require dietary minerals, vitamins, and other cofactors to function. An atom is the smallest constituent unit of ordinary matter that has the properties of a chemical element. Every solid, liquid, gas, and plasma is composed of neutral or ionized atoms. Atoms are very small; typical sizes are around 100 picometers (a ten-billionth of a meter, in the short scale). Galactose ("galacto-" + "-ose", "milk sugar"), sometimes abbreviated Gal, is a monosaccharide sugar that is less sweet than glucose and fructose. It is a C-4 epimer of glucose. Biopolymers are polymers produced by living organisms; in other words, they are polymeric biomolecules. Since they are polymers, biopolymers contain monomeric units that are covalently bonded to form larger structures. There are three main classes of biopolymers, classified according to the monomeric units used and the structure of the biopolymer formed: polynucleotides (RNA and DNA), which are long polymers composed of 13 or more nucleotide monomers; polypeptides, which are short polymers of amino acids; and polysaccharides, which are often linear bonded polymeric carbohydrate structures.
  Cellulose is the most common organic compound and biopolymer on Earth. About 33 percent of all plant matter is cellulose. The cellulose content of cotton is 90 percent, for wood is 50 percent. Arabinogalactan is a biopolymer consisting of arabinose and galactose monosaccharides. Two classes of arabinogalactans are found in nature: plant arabinogalactan and microbial arabinogalactan. In plants, it is a major component of many gums, including gum arabic and gum ghatti. It is often found attached to proteins, and the resulting arabinogalactan protein (AGP) functions as both an intercellular signaling molecule and a glue to seal plant wounds. Arabinogalactan protein (AGPs).
  Arabinogalactan protein is a broad term applied to diverse class of cell surface glycoproteins present in plant cell walls. It is heavily glycosylated, with only 2-10% comprising the protein region.The protein family has been earlier reported to contain O-linked glycans, whereas recent efforts employing mass spectrometry have revealed the presence of N-linked glycans as well within this protein family isolated from elongating cotton fiber cells. A molecule is an electrically neutral group of two or more atoms held together by chemical bonds. Molecules are distinguished from ions by their lack of electrical charge. However, in quantum physics, organic chemistry, and biochemistry, the term "molecule" is often used less strictly, also being applied to polyatomic ions.
candidates: acid aldehyde anion atom biochemistry biology biopolymer building c carbon cell charge chemical formula class coal constituent covalent bond day element enzyme family feature fiber functional group gas general glue greek group gum hydrogen ion isotope metabolic pathway milk molecule monosaccharide natural number order organic chemistry pathways physics plant process product protein radical rates scale sequence signaling molecule single species structure term transfer transferase
answer: protein