| Xyloglucan endo-transglycosylase C terminal domain | |||||||||
|---|---|---|---|---|---|---|---|---|---|
 xyloglucan endotransglycosylase native structure. | |||||||||
| Identifiers | |||||||||
| Symbol | XET_C | ||||||||
| Pfam | PF06955 | ||||||||
| InterPro | IPR010713 | ||||||||
| SCOP2 | 1un1 / SCOPe / SUPFAM | ||||||||
| |||||||||
In molecular biology, the xyloglucan endo-transglycosylase (XET) is an enzyme that is involved in the metabolism of xyloglucan, which is a component of plant cell walls. This enzyme is part of glycoside hydrolase family 16.
Xyloglucan endo-transglycosylase (XET) is thought to be highly important during seed germination, fruit ripening, and rapid wall expansion. [1]
Xyloglucan is the predominant hemicellulose in the primary cell walls of most dicotyledons. With cellulose, it forms a network that strengthens the cell wall. XET catalyses the splitting of xyloglucan chains and the linking of the newly generated reducing end to the non-reducing end of another xyloglucan chain, thereby loosening the cell wall. [2]
Biochemistry or biological chemistry, is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology and metabolism. Over the last decades of the 20th century, biochemistry has become successful at explaining living processes through these three disciplines. Almost all areas of the life sciences are being uncovered and developed through biochemical methodology and research. Biochemistry focuses on understanding the chemical basis which allows biological molecules to give rise to the processes that occur within living cells and between cells, in turn relating greatly to the understanding of tissues and organs, as well as organism structure and function. Biochemistry is closely related to molecular biology, which is the study of the molecular mechanisms of biological phenomena.
A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mechanism. Cell walls are absent in animals but are present in most other eukaryotes including algae, fungi and plants and in most prokaryotes. A major function is to act as pressure vessels, preventing over-expansion of the cell when water enters.
A hemicellulose is one of a number of heteropolymers, such as arabinoxylans, present along with cellulose in almost all terrestrial plant cell walls. While cellulose is crystalline, strong, and resistant to hydrolysis, hemicelluloses have random, amorphous structure with little strength. They are easily hydrolyzed by dilute acid or base as well as a myriad of hemicellulase enzymes.
Metabolism is the set of life-sustaining chemical reactions in organisms. The three main purposes of metabolism are: the conversion of the energy in food to energy available to run cellular processes; the conversion of food to building blocks for proteins, lipids, nucleic acids, and some carbohydrates; and the elimination of metabolic wastes. These enzyme-catalyzed reactions allow organisms to grow and reproduce, maintain their structures, and respond to their environments. The word metabolism can also refer to the sum of all chemical reactions that occur in living organisms, including digestion and the transportation of substances into and between different cells, in which case the above described set of reactions within the cells is called intermediary metabolism.
Cytochromes P450 (CYPs) are a superfamily of enzymes containing heme as a cofactor that functions as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are important for the clearance of various compounds, as well as for hormone synthesis and breakdown. In 1963, Estabrook, Cooper, and Rosenthal described the role of CYP as a catalyst in steroid hormone synthesis and drug metabolism. In plants, these proteins are important for the biosynthesis of defensive compounds, fatty acids, and hormones.
Nicotinamide adenine dinucleotide phosphate, abbreviated NADP+ or, in older notation, TPN (triphosphopyridine nucleotide), is a cofactor used in anabolic reactions, such as the Calvin cycle and lipid and nucleic acid syntheses, which require NADPH as a reducing agent ('hydrogen source'). It is used by all forms of cellular life.
A branched-chain amino acid (BCAA) is an amino acid having an aliphatic side-chain with a branch. Among the proteinogenic amino acids, there are three BCAAs: leucine, isoleucine, and valine. Non-proteinogenic BCAAs include 2-aminoisobutyric acid.
XET may refer to:
1,4-alpha-glucan-branching enzyme, also known as brancher enzyme or glycogen-branching enzyme is an enzyme that in humans is encoded by the GBE1 gene.
Beta-glucosidase is an enzyme that catalyzes the hydrolysis of the glycosidic bonds to terminal non-reducing residues in beta-D-glucosides and oligosaccharides, with release of glucose.
Cholesterol side-chain cleavage enzyme is commonly referred to as P450scc, where "scc" is an acronym for side-chain cleavage. P450scc is a mitochondrial enzyme that catalyzes conversion of cholesterol to pregnenolone. This is the first reaction in the process of steroidogenesis in all mammalian tissues that specialize in the production of various steroid hormones.
Xyloglucan is a hemicellulose that occurs in the primary cell wall of all vascular plants; however, all enzymes responsible for xyloglucan metabolism are found in Charophyceae algae. In many dicotyledonous plants, it is the most abundant hemicellulose in the primary cell wall. Xyloglucan binds to the surface of cellulose microfibrils and may link them together. It is the substrate of xyloglucan endotransglycosylase, which cuts and ligates xyloglucans, as a means of integrating new xyloglucans into the cell wall. It is also thought to be the substrate of alpha-expansin, which promotes cell wall enlargement.
Propionyl-CoA is a coenzyme A derivative of propionic acid. It is composed of a 24 total carbon chain and its production and metabolic fate depend on which organism it is present in. Several different pathways can lead to its production, such as through the catabolism of specific amino acids or the oxidation of odd-chain fatty acids. It later can be broken down by propionyl-CoA carboxylase or through the methylcitrate cycle. In different organisms, however, propionyl-CoA can be sequestered into controlled regions, to alleviate its potential toxicity through accumulation. Genetic deficiencies regarding the production and breakdown of propionyl-CoA also have great clinical and human significance.
Branched-chain amino acid aminotransferase (BCAT), also known as branched-chain amino acid transaminase, is an aminotransferase enzyme (EC 2.6.1.42) which acts upon branched-chain amino acids (BCAAs). It is encoded by the BCAT2 gene in humans. The BCAT enzyme catalyzes the conversion of BCAAs and α-ketoglutarate into branched chain α-keto acids and glutamate.
The plant cell wall is made up of hydrated polymetric material, allowing it to have viscoelastic properties. The primary cell wall of a plant consists of cellulose fibers, hemicellulose, and xyloglucans. This load bearing network is also surrounded by pectins and glycoproteins.
In enzymology, a xyloglucan:xyloglucosyl transferase (EC 2.4.1.207) is an enzyme that catalyzes the chemical reaction in which a beta-(1,4) bond in the backbone of a xyloglucan in broken; the xyloglucanyl segment is then transferred to the O4 of the non-reducing terminal glucose residue of either xyloglucan or an oligosaccharide thereof.
A 2-oxoisovalerate dehydrogenase subunit alpha, mitochondrial is an enzyme that in humans is encoded by the BCKDHA gene.
Polygalacturonase, also known as pectin depolymerase, PG, pectolase, pectin hydrolase, and poly-alpha-1,4-galacturonide glycanohydrolase, is an enzyme that hydrolyzes the alpha-1,4 glycosidic bonds between galacturonic acid residues. Polygalacturonan, whose major component is galacturonic acid, is a significant carbohydrate component of the pectin network that comprises plant cell walls. Therefore, the activity of the endogenous plant PGs works to soften and sweeten fruit during the ripening process. Similarly, phytopathogens use PGs as a means to weaken the pectin network, so that digestive enzymes can be excreted into the plant host to acquire nutrients.
Glucanases are enzymes that break down large polysaccharides via hydrolysis. The product of the hydrolysis reaction is called a glucan, a linear polysaccharide made of up to 1200 glucose monomers, held together with glycosidic bonds. Glucans are abundant in the endosperm cell walls of cereals such as barley, rye, sorghum, rice, and wheat. Glucanases are also referred to as lichenases, hydrolases, glycosidases, glycosyl hydrolases, and/or laminarinases. Many types of glucanases share similar amino acid sequences but vastly different substrates. Of the known endo-glucanases, 1,3-1,4-β-glucanase is considered the most active.
Alpha-D-xyloside xylohydrolase is an enzyme. This enzyme catalyses the following chemical reaction