Glycoside hydrolasesEC 3.2.1. are a widespread group of enzymes that hydrolyse the glycosidic bond between two or more carbohydrates, or between a carbohydrate and a non-carbohydrate moiety. A classification system for glycoside hydrolases, based on sequence similarity, has led to the definition of >100 different families.[1][2][3] This classification is available on the CAZy web site,[4][5] and also discussed at CAZypedia, an online encyclopedia of carbohydrate active enzymes.[6][7]
Glycoside hydrolase family 20 CAZY GH_20 comprises enzymes with several known activities; beta-hexosaminidase (EC 3.2.1.52); lacto-N-biosidase (EC 3.2.1.140). Carbonyl oxygen of the C-2 acetamido group of the substrate acts as the catalytic nucleophile/base in this family of enzymes.
In the brain and other tissues, beta-hexosaminidase A degrades GM2 gangliosides; specifically, the enzyme hydrolyses terminal non-reducing N-acetyl-D-hexosamine residues in N-acetyl-beta-D-hexosaminides. There are 3 forms of beta-hexosaminidase: hexosaminidase A is a trimer, with one alpha, one beta-A and one beta-B chain; hexosaminidase B is a tetramer of two beta-A and two beta-B chains; and hexosaminidase S is a homodimer of alpha chains. The two beta chains are derived from the cleavage of a precursor. Mutations in the beta-chain lead to Sandhoff disease, a lysosomal storage disorder characterised by accumulation of GM2 ganglioside.[8]
ReferencesEdit
^Henrissat B, Callebaut I, Fabrega S, Lehn P, Mornon JP, Davies G (July 1995). "Conserved catalytic machinery and the prediction of a common fold for several families of glycosyl hydrolases". Proceedings of the National Academy of Sciences of the United States of America. 92 (15): 7090–4. Bibcode:1995PNAS...92.7090H. doi:10.1073/pnas.92.15.7090. PMC41477. PMID 7624375.
^Davies G, Henrissat B (September 1995). "Structures and mechanisms of glycosyl hydrolases". Structure. 3 (9): 853–9. doi:10.1016/S0969-2126(01)00220-9. PMID 8535779.
^Henrissat B, Bairoch A (June 1996). "Updating the sequence-based classification of glycosyl hydrolases". The Biochemical Journal. 316 (Pt 2): 695–6. doi:10.1042/bj3160695. PMC1217404. PMID 8687420.
^Lombard V, Golaconda Ramulu H, Drula E, Coutinho PM, Henrissat B (January 2014). "The carbohydrate-active enzymes database (CAZy) in 2013". Nucleic Acids Research. 42 (Database issue): D490–5. doi:10.1093/nar/gkt1178. PMC3965031. PMID 24270786.
^"Glycoside Hydrolase Family 20". CAZypedia.org. Retrieved 2018-03-06.
^CAZypedia Consortium (December 2018). "Ten years of CAZypedia: a living encyclopedia of carbohydrate-active enzymes" (PDF). Glycobiology. 28 (1): 3–8. doi:10.1093/glycob/cwx089. PMID 29040563.
^Bolhuis PA, Ponne NJ, Bikker H, Baas F, Vianney de Jong JM (September 1993). "Molecular basis of an adult form of Sandhoff disease: substitution of glutamine for arginine at position 505 of the beta-chain of beta-hexosaminidase results in a labile enzyme". Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease. 1182 (2): 142–6. doi:10.1016/0925-4439(93)90134-m. PMID 8357844.
This article incorporates text from the public domain Pfam and InterPro: IPR015883
glycoside, hydrolase, family, molecular, biology, glycoside, hydrolase, family, family, glycoside, hydrolases, glycosyl, hydrolase, family, catalytic, domainwildtype, streptomyces, plicatus, beta, hexosaminidase, complex, with, product, glcnac, identifierssymb. In molecular biology glycoside hydrolase family 20 is a family of glycoside hydrolases Glycosyl hydrolase family 20 catalytic domainwildtype streptomyces plicatus beta hexosaminidase in complex with product glcnac IdentifiersSymbolGlyco hydro 20PfamPF00728Pfam clanCL0058InterProIPR015883SCOP21qba SCOPe SUPFAMCAZyGH20CDDcd02742Available protein structures Pfam structures ECOD PDBRCSB PDB PDBe PDBjPDBsumstructure summaryGlycosyl hydrolase family 20 domain 2crystallographic structure of human beta hexosaminidase aIdentifiersSymbolGlyco hydro 20bPfamPF02838InterProIPR015882SCOP21qba SCOPe SUPFAMCAZyGH20Available protein structures Pfam structures ECOD PDBRCSB PDB PDBe PDBjPDBsumstructure summaryGlycoside hydrolases EC 3 2 1 are a widespread group of enzymes that hydrolyse the glycosidic bond between two or more carbohydrates or between a carbohydrate and a non carbohydrate moiety A classification system for glycoside hydrolases based on sequence similarity has led to the definition of gt 100 different families 1 2 3 This classification is available on the CAZy web site 4 5 and also discussed at CAZypedia an online encyclopedia of carbohydrate active enzymes 6 7 Glycoside hydrolase family 20 CAZY GH 20 comprises enzymes with several known activities beta hexosaminidase EC 3 2 1 52 lacto N biosidase EC 3 2 1 140 Carbonyl oxygen of the C 2 acetamido group of the substrate acts as the catalytic nucleophile base in this family of enzymes In the brain and other tissues beta hexosaminidase A degrades GM2 gangliosides specifically the enzyme hydrolyses terminal non reducing N acetyl D hexosamine residues in N acetyl beta D hexosaminides There are 3 forms of beta hexosaminidase hexosaminidase A is a trimer with one alpha one beta A and one beta B chain hexosaminidase B is a tetramer of two beta A and two beta B chains and hexosaminidase S is a homodimer of alpha chains The two beta chains are derived from the cleavage of a precursor Mutations in the beta chain lead to Sandhoff disease a lysosomal storage disorder characterised by accumulation of GM2 ganglioside 8 References Edit Henrissat B Callebaut I Fabrega S Lehn P Mornon JP Davies G July 1995 Conserved catalytic machinery and the prediction of a common fold for several families of glycosyl hydrolases Proceedings of the National Academy of Sciences of the United States of America 92 15 7090 4 Bibcode 1995PNAS 92 7090H doi 10 1073 pnas 92 15 7090 PMC 41477 PMID 7624375 Davies G Henrissat B September 1995 Structures and mechanisms of glycosyl hydrolases Structure 3 9 853 9 doi 10 1016 S0969 2126 01 00220 9 PMID 8535779 Henrissat B Bairoch A June 1996 Updating the sequence based classification of glycosyl hydrolases The Biochemical Journal 316 Pt 2 695 6 doi 10 1042 bj3160695 PMC 1217404 PMID 8687420 Home CAZy org Retrieved 2018 03 06 Lombard V Golaconda Ramulu H Drula E Coutinho PM Henrissat B January 2014 The carbohydrate active enzymes database CAZy in 2013 Nucleic Acids Research 42 Database issue D490 5 doi 10 1093 nar gkt1178 PMC 3965031 PMID 24270786 Glycoside Hydrolase Family 20 CAZypedia org Retrieved 2018 03 06 CAZypedia Consortium December 2018 Ten years of CAZypedia a living encyclopedia of carbohydrate active enzymes PDF Glycobiology 28 1 3 8 doi 10 1093 glycob cwx089 PMID 29040563 Bolhuis PA Ponne NJ Bikker H Baas F Vianney de Jong JM September 1993 Molecular basis of an adult form of Sandhoff disease substitution of glutamine for arginine at position 505 of the beta chain of beta hexosaminidase results in a labile enzyme Biochimica et Biophysica Acta BBA Molecular Basis of Disease 1182 2 142 6 doi 10 1016 0925 4439 93 90134 m PMID 8357844 This article incorporates text from the public domain Pfam and InterPro IPR015883 Portal nbsp Biology Retrieved from https en wikipedia org w index php title Glycoside hydrolase family 20 amp oldid 1169067007, wikipedia, wiki, book, books, library,
