|PROSITE documentation PDOC00443|
α-galactosidase (EC 18.104.22.168) (melibiase)  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). α-galactosidase is present in a variety of organisms. There is a considerable degree of similarity in the sequence of α-galactosidase from various eukaryotic species.
Escherichia coli α-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 α-galactosidase (gene rafA)  contains a region of about 50 amino acids which is similar to a domain of the eukaryotic α-galactosidases.
α-N-acetylgalactosaminidase (EC 22.214.171.124)  catalyzes the hydrolysis of terminal non-reducing N-acetyl-D-galactosamine residues in N-acetyl-α-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 α-galactosidases.
We selected, as a signature pattern for these enzymes, the N-terminal part of the conserved domain. The pattern contains two conserved aspartic acid residues which could be involved in the catalytic mechanism.Note:
December 2004 / Pattern and text revised.
PROSITE method (with tools and information) covered by this documentation:
|1||Authors||Dey P.M., Pridham J.B.C.|
|Title||Biochemistry of -galactosidases.|
|Source||Adv. Enzymol. 36:91-130(1972).|
|2||Authors||Aslanidis C., Schmid K., Schmitt R.|
|Title||Nucleotide sequences and operon structure of plasmid-borne genes mediating uptake and utilization of raffinose in Escherichia coli.|
|Source||J. Bacteriol. 171:6753-6763(1989).|
|3||Authors||Wang A.M., Bishop D.F., Desnick R.J.|
|Title||Human alpha-N-acetylgalactosaminidase-molecular cloning, nucleotide sequence, and expression of a full-length cDNA. Homology with human alpha-galactosidase A suggests evolution from a common ancestral gene.|
|Source||J. Biol. Chem. 265:21859-21866(1990).|
|Title||A classification of glycosyl hydrolases based on amino acid sequence similarities.|
|Source||Biochem. J. 280:309-316(1991).|