A carbohydrate is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 and thus with the empirical formula Cm(H2O)n, which does not mean the H has covalent bonds with O. However, not all carbohydrates conform to this precise stoichiometric definition, nor are all chemicals that do conform to this definition automatically classified as carbohydrates.
A disaccharide is the sugar formed when two monosaccharides are joined by glycosidic linkage. Like monosaccharides, disaccharides are simple sugars soluble in water. Three common examples are sucrose, lactose, and maltose.
Chitobioses are a group of related disaccharides of β-1,4-linked glucosamine units. The term chitobiose is sometimes used to refer to different members of the group, depending on the method by which it was first isolated, resulting in some ambiguity as to which chemical compound the name is referring to.
Heparan sulfate (HS) is a linear polysaccharide found in all animal tissues. It occurs as a proteoglycan in which two or three HS chains are attached in close proximity to cell surface or extracellular matrix proteins. In this form, HS binds to a variety of protein ligands, including Wnt, and regulates a wide range of biological activities, including developmental processes, angiogenesis, blood coagulation, abolishing detachment activity by GrB, and tumour metastasis. HS has also been shown to serve as cellular receptor for a number of viruses, including the respiratory syncytial virus. One study suggests that cellular heparan sulfate has a role in SARS-CoV-2 Infection, particularly when the virus attaches with ACE2.
Vibrio alginolyticus is a Gram-negative marine bacterium. It is medically important since it causes otitis and wound infection. It is also present in the bodies of animals such as pufferfish, where it is responsible for the production of the potent neurotoxin, tetrodotoxin.
Galactosyltransferase is a type of glycosyltransferase which catalyzes the transfer of galactose. An example is B-N-acetylglucosaminyl-glycopeptide b-1,4-galactosyltransferase.
The enzyme chondroitin B lyase catalyzes the following process:
The enzyme chondroitin-sulfate-ABC exolyase catalyzes the following process:
Pectate lyase is an enzyme involved in the maceration and soft rotting of plant tissue. Pectate lyase is responsible for the eliminative cleavage of pectate, yielding oligosaccharides with 4-deoxy-α-D-mann-4-enuronosyl groups at their non-reducing ends. The protein is maximally expressed late in pollen development. It has been suggested that the pollen expression of pectate lyase genes might relate to a requirement for pectin degradation during pollen tube growth.
The enzyme protein-glucosylgalactosylhydroxylysine glucosidase (EC 3.2.1.107) catalyzes the following chemical reaction:
Oligosaccharides and polysaccharides are an important class of polymeric carbohydrates found in virtually all living entities. Their structural features make their nomenclature challenging and their roles in living systems make their nomenclature important.
(N-acetylneuraminyl)-galactosylglucosylceramide N-acetylgalactosaminyltransferase is an enzyme with systematic name UDP-N-acetyl-D-galactosamine:1-O-(O- - -O-beta-D-galactopyranosyl- -beta-D-glucopyranosyl)-ceramide 4-beta-N-acetyl-D-galactosaminyltransferase. This enzyme catalyses the following chemical reaction
Nigerose phosphorylase is an enzyme with systematic name 3-O-alpha-D-glucopyranosyl-D-glucopyranose:phosphate beta-D-glucosyltransferase. This enzyme catalyses the following chemical reaction
N,N'-diacetylchitobiose phosphorylase is an enzyme with the systematic name N,N'-diacetylchitobiose:phosphate N-acetyl-D-glucosaminyltransferase. This enzyme was found in the genus Vibrio initially but has now been found to be taken up by Escherichia coli as well as many other bacteria. One study shows that Escherichia coli can replicate on a medium that is just composed of GlcNAc a product of phosphorylation of N,N'-diacetylchitobiose as the sole source of carbon. Because E. coli can go on this medium, the enzyme is present. The enzyme has also been found in multiple eukaryotic cells as well, especially in eukaryotes that make chitin and break chitin down. It is believed that N,N'-diacetylchitobiose phosphorylase is an integral part of the phosphoenolpyruvate:glucose phosphotransferase system (PTS). It is assumed that it is involved with Enzyme Complex II of the PTS and is involved with the synthesis of chitin. The enzyme is specific for N,N'-diacetylchitobiose.
Unsaturated rhamnogalacturonyl hydrolase (EC 3.2.1.172, YteR, YesR) is an enzyme with systematic name 2-O-(4-deoxy-beta-L-threo-hex-4-enopyranuronosyl)-alpha-L-rhamnopyranose hydrolase. This enzyme catalyses the following chemical reaction
Gellan tetrasaccharide unsaturated glucuronyl hydrolase (EC 3.2.1.179, UGL, unsaturated glucuronyl hydrolase) is an enzyme with systematic name beta-D-4-deoxy-Delta4-GlcAp-(1->4)-beta-D-Glcp-(1->4)-alpha-L-Rhap-(1->3)-beta-D-Glcp beta-D-4-deoxy-Delta4-GlcAp hydrolase. This enzyme catalyses the following chemical reaction
Unsaturated chondroitin disaccharide hydrolase (EC 3.2.1.180, UGL, unsaturated glucuronyl hydrolase) is an enzyme with systematic name beta-D-4-deoxy-Delta4-GlcAp-(1->3)-beta-D-GalNAc6S hydrolase. This enzyme catalyses the following chemical reaction
N-acetyl-1-D-myo-inositol-2-amino-2-deoxy-alpha-D-glucopyranoside deacetylase (EC 3.5.1.103, MshB) is an enzyme with systematic name 1-(2-acetamido-2-deoxy-alpha-D-glucopyranosyl)-1D-myo-inositol acetylhydrolase. This enzyme catalyses the following chemical reaction
Rhamnogalacturonan exolyase is an enzyme with systematic name α-L-rhamnopyranosyl-(1→4)-α-D-galactopyranosyluronate exolyase. This enzyme catalyses the following chemical reaction
N-acetyl-β-d-glucosaminidase(EC 3.2.1.30; EC 3.2.1.52) is a mesophilic hydrolase that specifically hydrolyzes N-acetyl-glucosides. The enzyme is found across a wide variety of marine and terrestrial creatures with the primary function of breaking down oligosaccharides in the presence of water. One of the primary functions of the enzyme is to target and hydrolyze oligosaccharides containing chitin. In this chitinase function, the enzyme contributes to the ability of many organisms to break down chitin-containing molecules and subsequently digest or re-uptake environmental chitin, carbon, or nitrogen. The enzyme's crystal structure varies slightly across organisms, but is characterized by three or four domains with one active site. Across proteins, the active site entails an α-β barrel with either an arginine or tryptophan residues in the barrel pocket to bind incoming substrate.
