Glycoproteins are proteins which contain oligosaccharide chains covalently attached to amino acid side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glycosylation. Secreted extracellular proteins are often glycosylated.
The terms glycans and polysaccharides are defined by IUPAC as synonyms meaning "compounds consisting of a large number of monosaccharides linked glycosidically". However, in practice the term glycan may also be used to refer to the carbohydrate portion of a glycoconjugate, such as a glycoprotein, glycolipid, or a proteoglycan, even if the carbohydrate is only an oligosaccharide. Glycans usually consist solely of O-glycosidic linkages of monosaccharides. For example, cellulose is a glycan composed of β-1,4-linked D-glucose, and chitin is a glycan composed of β-1,4-linked N-acetyl-D-glucosamine. Glycans can be homo- or heteropolymers of monosaccharide residues, and can be linear or branched.
N4-(beta-N-acetylglucosaminyl)-L-asparaginase (EC 3.5.1.26, aspartylglucosylamine deaspartylase, aspartylglucosylaminase, aspartylglucosaminidase, aspartylglycosylamine amidohydrolase, N-aspartyl-beta-glucosaminidase, glucosylamidase, beta-aspartylglucosylamine amidohydrolase, 4-N-(beta-N-acetyl-D-glucosaminyl)-L-asparagine amidohydrolase) is an enzyme with systematic name N4-(beta-N-acetyl-D-glucosaminyl)-L-asparagine amidohydrolase. This enzyme catalyses the following chemical reaction
The enzyme mannosyl-glycoprotein endo-β-N-acetylglucosaminidase (endoglycosidase H) (EC 3.2.1.96) has systematic name glycopeptide-D-mannosyl-N4-(N-acetyl-D-glucosaminyl)2-asparagine 1,4-N-acetyl-β-glucosaminohydrolase. It is a highly specific endoglycosidase which cleaves asparagine-linked mannose rich oligosaccharides, but not highly processed complex oligosaccharides from glycoproteins. It is used for research purposes to deglycosylate glycoproteins and to monitor intracellular protein trafficking through the secretory pathway.
In enzymology, a 3-galactosyl-N-acetylglucosaminide 4-alpha-L-fucosyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, a glycoprotein 2-beta-D-xylosyltransferase (EC 2.4.2.38) is an enzyme that catalyzes the chemical reaction
In enzymology, a glycoprotein 3-alpha-L-fucosyltransferase (EC 2.4.1.214) is an enzyme that catalyzes the chemical reaction
In enzymology, a glycoprotein 6-alpha-L-fucosyltransferase (EC 2.4.1.68) is an enzyme that catalyzes the chemical reaction
PNGase also known as N-glycanase 1 or peptide-N(4)-(N-acetyl-beta-glucosaminyl)asparagine amidase is an enzyme that in humans is encoded by the NGLY1 gene. PNGase is a de-N-glycosylating enzyme that removes N-linked or asparagine-linked glycans (N-glycans) from glycoproteins. More specifically, NGLY1 catalyzes the hydrolysis of the amide bond between the innermost N-acetylglucosamine (GlcNAc) and an Asn residue on an N-glycoprotein, generating a de-N-glycosylated protein, in which the N-glycoylated Asn residue is converted to asp, and a 1-amino-GlcNAc-containing free oligosaccharide. Ammonia is then spontaneously released from the 1-amino GlcNAc at physiological pH (<8), giving rise to a free oligosaccharide with an N,N’-diacetylchitobiose structure at the reducing end.
Glycopeptides are peptides that contain carbohydrate moieties (glycans) covalently attached to the side chains of the amino acid residues that constitute the peptide.
N-linked glycosylation, is the attachment of an oligosaccharide, a carbohydrate consisting of several sugar molecules, sometimes also referred to as glycan, to a nitrogen atom, in a process called N-glycosylation, studied in biochemistry. The resulting protein is called an N-linked glycan, or simply an N-glycan.
Beta-1,4-mannosyl-glycoprotein 4-beta-N-acetylglucosaminyltransferase is an enzyme with systematic name UDP-N-acetyl-D-glucosamine:beta-D-mannosyl-glycoprotein 4-beta-N-acetyl-D-glucosaminyltransferase. This enzyme catalyses the following chemical reaction
Alpha-1,3-mannosyl-glycoprotein 4-beta-N-acetylglucosaminyltransferase is an enzyme with systematic name UDP-N-acetyl-D-glucosamine:3-(2- -alpha-D-mannosyl)-glycoprotein 4-beta-N-acetyl-D-glucosaminyltransferase. This enzyme catalyses the following chemical reaction
Alpha-1,6-mannosyl-glycoprotein 4-beta-N-acetylglucosaminyltransferase is an enzyme with systematic name UDP-N-acetyl-D-glucosamine:2,6-bis(N-acetyl-beta-D-glucosaminyl)-alpha-D-mannosyl-glycoprotein 4-beta-N-acetyl-D-glucosaminyltransferase. This enzyme catalyses the following chemical reaction
Endo-α-N-acetylgalactosaminidase (EC 3.2.1.97, endo-α-acetylgalactosaminidase, endo-α-N-acetyl-D-galactosaminidase, mucinaminylserine mucinaminidase, D-galactosyl-3-(N-acetyl-α-D-galactosaminyl)-L-serine mucinaminohydrolase, endo-α-GalNAc-ase, D-galactosyl-N-acetyl-α-D-galactosamine D-galactosyl-N-acetyl-galactosaminohydrolase) is an enzyme with systematic name glycopeptide-D-galactosyl-N-acetyl-α-D-galactosamine D-galactosyl-N-acetyl-galactosaminohydrolase. This enzyme catalyses the following chemical reaction
Mannosyl-oligosaccharide glucosidase (MOGS) (EC 3.2.1.106, processing α-glucosidase I,Glc3Man9NAc2 oligosaccharide glucosidase, trimming glucosidase I, GCS1) is an enzyme with systematic name mannosyl-oligosaccharide glucohydrolase. MOGS is a transmembrane protein found in the membrane of the endoplasmic reticulum of eukaryotic cells. Biologically, it functions within the N-glycosylation pathway.
Neopullulanase is an enzyme of the alpha-amylase family with systematic name pullulan 4-D-glucanohydrolase (panose-forming). This enzyme principally catalyses the following chemical reaction by cleaving pullulan's alpha-1,4-glucosidic bonds:
Mannosylglycoprotein endo-beta-mannosidase is an enzyme. This enzyme catalyses the following chemical reaction:
Peptide:N-glycosidase F, commonly referred to as PNGase F, is an amidase of the peptide-N4-(N-acetyl-beta-glucosaminyl)asparagine amidase class. PNGase F works by cleaving between the innermost GlcNAc and asparagine residues of high mannose, hybrid, and complex oligosaccharides from N-linked glycoproteins and glycopeptides. This results in a deaminated protein or peptide and a free glycan.
Asparagine peptide lyase are one of the seven groups in which proteases, also termed proteolytic enzymes, peptidases, or proteinases, are classified according to their catalytic residue. The catalytic mechanism of the asparagine peptide lyases involves an asparagine residue acting as nucleophile to perform a nucleophilic elimination reaction, rather than hydrolysis, to catalyse the breaking of a peptide bond.
