| Melibiase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
 crystal structure of rice alpha-galactosidase | |||||||||
| Identifiers | |||||||||
| Symbol | Melibiase | ||||||||
| Pfam | PF02065 | ||||||||
| Pfam clan | CL0058 | ||||||||
| InterPro | IPR000111 | ||||||||
| SCOP2 | 1ktc / SCOPe / SUPFAM | ||||||||
| CAZy | GH36 | ||||||||
| |||||||||
| Raffinose_syn | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| Symbol | Raffinose_syn | ||||||||
| Pfam | PF05691 | ||||||||
| Pfam clan | CL0058 | ||||||||
| InterPro | IPR008811 | ||||||||
| CAZy | GH36 | ||||||||
| |||||||||
In molecular biology, glycoside hydrolase family 36 is a family of glycoside hydrolases.
Contents
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 36 together with family 31 and family 27 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.
This family also includes raffinose synthase proteins, also known as seed inhibition (Sip1) proteins. Raffinose (O-alpha- D-galactopyranosyl- (1-->6)- O-alpha- D-glucopyranosyl-(1<-->2)- O-beta- D-fructofuranoside) is a widespread oligosaccharide in plant seeds and other tissues. Raffinose synthase EC 2.4.1.82 is the key enzyme that channels sucrose into the raffinose oligosaccharide pathway. [11]
Glycoside hydrolase family 36 also includes enzymes with α-N-acetylgalactosaminidase EC 3.2.1.49 and stachyose synthase EC 2.4.1.67 activities.
Glycoside hydrolase family 36 can be subdivided into 11 families, GH36A to GH36K. [12]
