PURIFICATION AND CHARACTERIZATION OF BETA-GLUCOSIDASE FROM BACTEROIDES JY-6, A HUMAN INTESTINAL BACTERIUM

A beta-glucosidase (EC 3.2.1.21.) was purified 2500-fold from Bacteroi des JY-6, an intestinal anaerobic bacterium of human. The specific act ivity of the homogeneously purified enzyme was 210 mu mol/min/mg prote in. The enzyme (Mr 75 kDa) was an monomer whose pI and optimal pH valu es were 4.6 and 5.5-6, respectively. The best substrates were p-nitrop henyl beta-D-glucopyranoside and natural beta-bound glucosides, such a s prunin and poncirenin. Puerarin, which is a C-glycoside, was weakly effective. However, cellobiose, a-bound glycosides and rhamnoglucoside s were not effective. The apparent K-ms for prunin and p-nitrophenyl-b eta-D-glucopyranoside were determined to be 0.08 and 0.19 mM, respecti vely. The enzyme was strongly inhibited by p-chloromercuriphenylsulfon ic acid and reaction products such as p-nitrophenol and glucose.