Isolation and characterization of two β-d-glucosidases from bifidobacterium breve 203

Two β-D-glucosidases were purified to homogeneity from Bifidobacterium breve 203: One (β-D-glucosidase I; molecular weight, 96,000) showed reactivity toward β-nitrophenyl O-NP) β-D-fucoside, 74% of that to p-NP β-D-glucoside, and the other β-D-glucosidase II; molecular weight, 450,000) did not. They also differed in their thermal and pH stabilities. Laminaribiose, cellobiose and gentiobiose were hydrolyzed by β-D-glucosidase I, with 53%, 34% and 3% of the reactivity inthe case ofp-NP β-D-glucoside, and by β -D-glucosidase II, with 53%, 6% and 107% of the reactivity. The reaction of β-D-glucosidase I with p-NP β-D-fucoside was enhanced by the addition of glucose and other monosaccharides to the reaction mixture, whereas that with p-NP β-D-glucoside was notaffected. The activity of β-D-glucosidase II with p-NP β-D-glucoside was inhibited by glucose.