Melibiase | |||||||||
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![]() crystal structure of rice alpha-galactosidase | |||||||||
Identifiers | |||||||||
Symbol | Melibiase | ||||||||
Pfam | PF02065 | ||||||||
Pfam clan | CL0058 | ||||||||
InterPro | IPR000111 | ||||||||
SCOP2 | 1ktc / SCOPe / SUPFAM | ||||||||
CAZy | GH27 | ||||||||
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In molecular biology, glycoside hydrolase family 27 is a family of glycoside hydrolases.
Glycoside 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 >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 27 together with family 31 and the family 36 alpha-galactosidases form the glycosyl hydrolase clan GH-D, a superfamily of alpha-galactosidases, alpha-N-acetylgalactosaminidases, and isomaltodextranases which are likely to share a common catalytic mechanism and structural topology.
Alpha-galactosidase ( EC 3.2.1.22) (melibiase) [8] catalyzes the hydrolysis of melibiose into galactose and glucose. In man, the deficiency of this enzyme is the cause of Fabry's disease (X-linked sphingolipidosis). Alpha-galactosidase is present in a variety of organisms. There is a considerable degree of similarity in the sequence of alpha-galactosidase from various eukaryotic species. Escherichia coli alpha-galactosidase (gene melA), which requires NAD and magnesium as cofactors, is not structurally related to the eukaryotic enzymes; by contrast, an Escherichia coli plasmid encoded alpha-galactosidase (gene rafA P16551) [9] contains a region of about 50 amino acids which is similar to a domain of the eukaryotic alpha-galactosidases. Alpha-N-acetylgalactosaminidase ( EC 3.2.1.49) [10] catalyzes the hydrolysis of terminal non-reducing N-acetyl-D-galactosamine residues in N-acetyl-alpha-D- galactosaminides. In man, the deficiency of this enzyme is the cause of Schindler and Kanzaki diseases. The sequence of this enzyme is highly related to that of the eukaryotic alpha-galactosidases.
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