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

Abstract

A β- d-glucosidase, with broad regiospecific activity and designated as G II, 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 °C for 24 h) and at a relatively high temperature (50 °C for 8 h). Moreover, it can cleave both β-(1 → 2)-glucosidic linkage at 3-C and β-(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-β- d-glucopyranoside ( pNPG) was at 50 °C and pH 5.0. Under the same condition, the K m for pNPG was 0.224 mM with a V max of 0.203 mmol nitrophenol min −1 mg −1. Of the substrates tested, G II specifically hydrolyzed the β- d-glucosides involving aryl-β-glucosides, alkyl-β-glucosides, and β-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.