The hydrolyses of p-nitrophenyl α- and β-galactosides and p-nitrophenyl α- and β-glucosides by an α-galactosidase from Aspergillus fumigatis, an α-glucosidase from germinated barley, and almond β-glucosidase, which also has β-galactosidase activity, have been examined in the presence of glycerol, erythritol, d-threitol, ribitol, xylitol, d-arabitol and dl-butan-1,2,4-triol. The α-galactosidase was best inhibited by d-threitol, while the α-glucosidase was best inhibited by erythritol. Both inhibitions were competitive. The inhibitory character of these compounds may be attributed to their similarity in structure with the glycon of the substrate between C-3, C-4, C-5, and C-6. The β-glucosidase was best inhibited by erythritol, demonstrating a similarity of action between α- and β-glucosidases. However, the best inhibitor of β-galactosidase was erythritol. This observation confirmed the view that in almond emulsin, the glucosidase and galactosidase activities are found in the same enzyme.
ASJC Scopus subject areas
- Molecular Biology