Α-Galactosidase

This article is about the enzyme. For the carbohydrate commonly called "alpha gal", see Galactose-alpha-1,3-galactose.

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:^[1]

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

α-galactosidase
α-Galactosidase tetramer, Mortierella vinacea
Identifiers
EC no.	3.2.1.22
CAS no.	9025-35-8
Databases
IntEnz	IntEnz view
BRENDA	BRENDA entry
ExPASy	NiceZyme view
KEGG	KEGG entry
MetaCyc	metabolic pathway
PRIAM	profile
PDB structures	RCSB PDB PDBe PDBsum
Gene Ontology	AmiGO / QuickGO
Search PMC articles PubMed articles NCBI proteins

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

The enzyme is encoded by the GLA gene.^[2]

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.^{[citation needed]}

Reaction mechanism

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.^[3][4][5]

Applications

α-Galactosidase from Aspergillus niger is the active ingredient in Beano, a dietary supplement for bloating and flatulence.^[6][7]

Recombinant α-Galactosidase made by baker's yeast is approved in Europe as a feed additive intended to make poultry food more digestible.^[8]

See also

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

References

1. Scriver CR, Sly WS, Childs B, ABeaudet AL, Valle D, Kinzler KW, et al. (15 December 2000). The Metabolic & Molecular Basis of Inherited Disease (8th ed.). McGraw-Hill. ISBN 978-0-07-913035-8.
2. Calhoun DH, Bishop DF, Bernstein HS, Quinn M, Hantzopoulos P, Desnick RJ (November 1985). "Fabry disease: isolation of a cDNA clone encoding human α-galactosidase A". Proceedings of the National Academy of Sciences of the United States of America. 82 (21): 7364–8. Bibcode:1985PNAS...82.7364C. doi:10.1073/pnas.82.21.7364. PMC 391345. PMID 2997789.
3. Koshland DE (1953). "Stereochemistry and the Mechanism of Enzymatic Reactions". Biological Reviews. 28 (4): 416–436. doi:10.1111/j.1469-185x.1953.tb01386.x. S2CID 86709302.
4. Brumer H, Sims PF, Sinnott ML (April 1999). "Lignocellulose degradation by Phanerochaete chrysosporium: purification and characterization of the main α-galactosidase". The Biochemical Journal. 339 (1): 43–53. doi:10.1042/bj3390043. PMC 1220126. PMID 10085226.
5. Vocadlo DJ, Davies GJ (October 2008). "Mechanistic insights into glycosidase chemistry". Current Opinion in Chemical Biology. 12 (5): 539–55. doi:10.1016/j.cbpa.2008.05.010. PMID 18558099.
6. Di Stefano M, Miceli E, Gotti S, Missanelli A, Mazzoccahi S, Corazza GR (January 2007). "The effect of oral alpha-galactosidase on intestinal gas production and gas-related symptoms". Dig. Dis. Sci. 52 (1): 78–83. doi:10.1007/s10620-006-9296-9. PMID 17151807. S2CID 35435660.
7. Ganiats TG, Norcross WA, Halverson AL, Burford PA, Palinkas LA (November 1994). "Does Beano prevent gas? A double-blind crossover study of oral alpha-galactosidase to treat dietary oligosaccharide intolerance". J Fam Pract. 39 (5): 441–5. PMID 7964541.
8. Bampidis V, Azimonti G, Bastos ML, Christensen H, Dusemund B, Durjava M, et al. (August 2023). "Assessment of the feed additive consisting of alpha-galactosidase produced by Saccharomyces cerevisiaeCBS 615.94 and endo-1,4-beta-glucanase produced by Aspergillus nigerCBS 120604 (Agal-Pro BL/BL-L®) for use in chickens for fattening, minor poultry species for fattening and chickens reared for laying for the renewal of its authorisation (Kerry Ingredients & Flavours Ltd.)". EFSA Journal. European Food Safety Authority. 21 (8): e08175. doi:10.2903/j.efsa.2023.8175. PMC 10424062. PMID 37583944.

External links

• alpha-Galactosidase at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
• Human GLA genome location and GLA gene details page in the UCSC Genome Browser.

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