Purification and characterization of a novel and unique ginsenoside Rg(1)-hydrolyzing beta-D-Glucosidase from Penicillium sclerotiorum

In this paper, a novel and unique ginsenoside Rg(1)-hydrolyzing beta-D-Glucosidase from Penicillium sclerotiorum was isolated, characterized, and generally described. The beta-Glucosidase is an similar to 180 kDa glycoprotein with pI 6.5, and consists of four identical subunits of similar to 40 kDa. The beta-Glucosidase was active in a narrow pH range (4-5) and at relatively high temperature (60-70 degrees C). The optimal activity against p-nitrophenyl-beta-D-glucopyranoside (pNPG) was as follows: pH 4.5 and temperature 65 degrees C. Under these conditions, the K-m of the enzyme was 0.715 mM with a V-max of 0.243 mmol nitrophenol/min mg. Metal ions such as Ba2+, K+, Fe3+, and Co2+ significantly promoted the enzymatic activity, while Ca2+, Mg2+, and Ag+ inhibited its activity. Of the tested substrates, only ginsenoside Rg(1) could be specifically hydrolyzed by the beta-Glucosidase at the C6-glucoside to form the rare ginsenoside F-1. These properties were novel and different from those of other previously described glycosidases.