Biotransformation pathway and kinetics of the hydrolysis of the 3-O-and 20-O-multi-glucosides of PPD-type ginsenosides by ginsenosidase type I

Abstract

Ginsenosidase type I from Aspergillus niger g.48 can hydrolyze the 3-O- and 20-O-multi-glycosides of PPD-type ginsenosides. The enzyme molecular weight is approximately 74 kDa. When hydrolyzing the glycosides of Rb1, Rb3, Rb2 and Rc, the structures of which only differ in their terminal 20-O-glycosides, ginsenosidase type I hydrolyzes both the 3-O- and 20-O-glycosides of Rbl and Rb3 using two pathways, but the enzyme first hydrolyzes the 3-O-glucosides of Rb2 and Rc using one pathway. One pathway of Rbl hydrolyzes the 20-O-Glc of Rb1 to Rd -> F2 -> C-K; another pathway hydrolyzes the 3-O-Glc of Rb1 to Gyp17 -> Gyp75 -> C-K. Two hydrolysis pathways are used to hydrolyze the 20-O-Xyl and the 3-O-Glc of Rb3. According to the enzyme reaction parameters K-m, V-max and V-0 at a 10 mM substrate concentration, the enzyme hydrolysis velocity values decrease in the following order: the 20-O-Xyl of Rb3 -> Rd> the 20-O-Glc of Rb1 -> Rd> the 3-O-Gic of Rc> the 3-O-Glc of Rb2> the 3-O-Glc of Rd> the 3-O-Glc of Rb3 -> C-Mx1> the 3-O-Glc of Rb1 -> Gyp17> the 3-O-Glc of F2> the 3-O-Glc of 20(S)-Rg3.