This enzyme belongs to glycosidase family-27, with a retaining mechanism. Alpha-galactosidases can be classified into glycosidase family-4, 27, 36, 57, 97 and 110 (see [9]). Alpha-galactosidases from eukaryotes are generally classified into glycosidase family-27, whereas prokaryotic alpha-galactosidases are mostly classified into glycosidase family-36 (see [9]). This enzyme is homologous to alpha-N-acetylgalactosaminidase (EC 3.2.1.49; D00665 in EzCatDB) and a counterpart enzyme from fungi (EC 3.2.1.22; D00863), which is specific for galactomannan. According to the literature [5], [6] and [10], the reaction proceeds as follows: (0) Considering the conservation and relative location of active-site residues, Arg227 (of 1r46) modulates the activity of Asp231, whilst Tyr134 modulates the activity of Asp170. (1) Asp231 (of 1r46) acts as a general acid to protonate the leaving group. This protonation may form an oxocarbenium-ion like transition-state. Asp92 may stabilize the transition-state through hydrogen bond with O4 atom of alpha-galactoside substrate. (2) Meanwhile, Asp170 makes a nucleophilic attack on the C1 atom of alpha-D-galactoside at the non-reducing end, forming a covalent intermediate with an inverted configuration at C1. (SN1-like reaction) (3) Asp231 acts as a general base to deprotonate a water molecule, to activate it. (4) The activated water makes a nucleophilic attack on the C1 atom of the covalent intermediate, releasing the alpha-D-galactose product.
Glycosphingolipid biosynthesis - globoseries
X-RAY CRYSTALLOGRAPHY (1.5 ANGSTROMS) OF 56-417 IN COMPLEX WITH D-GALACTOSE.
Crystal structure of rice alpha-galactosidase complexed with D-galactose.
X-RAY CRYSTALLOGRAPHY (3.45 ANGSTROMS) OF 32-422 IN COMPLEX WITH PRODUCT, HOMODIMERIZATION, GLYCOSYLATION AT ASN-139; ASN-192 AND ASN-215.
The molecular defect leading to Fabry disease: structure of human alpha-galactosidase.
X-RAY CRYSTALLOGRAPHY (1.54 ANGSTROMS) OF 28-441.
Crystal structure of alpha-galactosidase from Trichoderma reesei and its complex with galactose: implications for catalytic mechanism.
¿-Galactosidases and their applications in biotransformations.
Effects of pH and iminosugar pharmacological chaperones on lysosomal glycosidase structure and stability.
The tetramer structure of the glycoside hydrolase family 27 alpha-galactosidase I from Umbelopsis vinacea.
Catalytic mechanism of human alpha-galactosidase.
Identification of Asp-130 as the catalytic nucleophile in the main alpha-galactosidase from Phanerochaete chrysosporium, a family 27 glycosyl hydrolase.
The synthesis, testing and use of 5-fluoro-alpha-D-galactosyl fluoride to trap an intermediate on green coffee bean alpha-galactosidase and identify the catalytic nucleophile.
The 1.9 A structure of alpha-N-acetylgalactosaminidase: molecular basis of glycosidase deficiency diseases.