Purification and characterization of a novel ginsenoside-hydrolyzing β-D-glucosidase from the China white jade snail (Achatina fulica)

A beta-D-glucosidase, with broad regiospecific activity and designated as G H, was purified to homogeneity from the acetone power of viscera of the China white jade snail (Achatina fulica). G II consisted of two identical subunits (110 kDa) with a native molecular mass of 220 kDa. G II was stable over a wide pH range (4-10 at 30 degrees C for 24 h) and at a relatively high temperature (50 degrees C for 8 h). Moreover, it can cleave both beta-(1 -> 2)-glucosidic linkage at 3-C and beta-(1 -> 6)-glucosidic linkage at 20-C of ginsenosides and can hydrolyze ginsenosides Rb-1, Rb-2, Rb-3 and Rc into their active metabolites, compound K, compound Y, Mx, and Mc, respectively. The optimal activity against p-nitrophenyl-beta-D-glucopyranoside (pNPG) was at 50 degrees C and pH 5.0. Under the same condition, the K-m for pNPG was 0.224 mM with a Y-max of 0.203 mmol nitrophenol min(-1) mg(-1). Of the substrates tested, G II specifically hydrolyzed the beta-D-glucosides involving aryl-beta-glucosides, alkyl-beta-glucosides, and beta-linked disaccharides (i.e. sophorose, gentiobiose, and cellobiose). These findings make the novel enzyme potentially useful in biotransformation processes as well as in the modification of multiple ginsenosides. (c) 2006 Elsevier Inc. All rights reserved.