Purification and Characterization of β-Glucosidase from Bacteroides JY-6, a Human Intestinal Bacterium

Abstract

A β-glucosidase (EC 3.2.1.21.) was purified 2500-fold from Bacteroides JY-6, an intestinal anaerobic bacterium of human. The specific activity of the homogeneously purified enzyme was 210 μmol/min/mg protein. The enzyme (Mr 75 kDa) was an monomer whose pI and optimal pH values were 4.6 and 5.5-6, respectively. The best substrates were p-nitrophenyl β-D-glucopyranoside and natural β-bound glucosides, such as prunin and poncirenin. Puerarin, which is a C-glycoside, was weakly effective. However, cellobiose, α-bound glycosides and rhamnoglucosides were not effective. The apparent K_ms for prunin and p-nitrophenyl-β-D-glucopyranoside were determined to be 0.08 and 0.19 mM, respectively. The enzyme was strongly inhibited by p-chloromercuriphenylsulfonic acid and reaction products such as p-nitrophenol and glucose.