α-Galactosidase

Template:Use dmy dates Template:Cs1 config Template:Enzyme α-Galactosidase ( EC 3.2.1.22, α-GAL, α-GAL A; systematic name α-D-galactoside galactohydrolase) is a glycoside hydrolase enzyme that catalyses the following reaction:

Hydrolysis of terminal, non-reducing α-D-galactose residues in α-D-galactosides, including galactose oligosaccharides, galactomannans and galactolipids

It catalyzes many catabolic processes, including cleavage of glycoproteins, glycolipids, and polysaccharides.

The enzyme is encoded by the GLA gene.

Function

This enzyme is a homodimeric glycoprotein that hydrolyses the terminal α-galactosyl moieties from glycolipids and glycoproteins. It predominantly hydrolyzes ceramide trihexoside, and it can catalyze the hydrolysis of melibiose into galactose and glucose.

Reaction mechanism

File:Reaction mechanism for human α-GAL.png

A double displacement reaction mechanism of α-GAL's catalytic action.The ligand (black) when bound in the active site of the enzyme (blue). The two key amino acid residues in the active site are Asp-170 and Asp-231. First, Asp-170 performs a nucleophilic attack on the glycosidic bond to release the terminal α-galactose molecule from the ligand. Then, Asp-231 serves as an acid to remove a proton from water, making it more nucleophilic to attack the galactose-Asp complex and release α-galactose from the active site.

Applications

α-Galactosidase from Aspergillus niger is the active ingredient in Beano, a dietary supplement for bloating and flatulence.

Recombinant α-galactosidase made by baker's yeast is approved in Europe as a feed additive intended to make poultry food more digestible.

See also

• β-galactosidase
• Migalastat, a drug targeting α-galactosidase
• Classification of α-galactosidases (according to CAZy)

External links

• Template:MeshName
• Template:UCSC gene info

This article incorporates text from the United States National Library of Medicine, which is in the public domain.