Enzyme kinetics of ginsenosidase type IV hydrolyzing 6-O-multi-glycosides of protopanaxatriol type ginsenosides

In this work, the kinetics of ginsenosidase type IV hydrolyzing the 6- O -multi-glycosides of protopanaxatriol type ginsenosides (PPT) from Aspergillus sp.39g strain were investigated. The enzyme molecular weight was about 56 kDa. The enzyme hydrolyzes the 6- O -α- l -(1 → 2)-rhamnoside of ginsenoside Re and 6- O -β- d -(1 → 2)-xyloside of R1 into Rg1, and subsequently hydrolyzes 6- O -β- d -glucoside of Rg1 into F1. The enzyme hydrolyzes 6- O -α- l -(1 → 2)-rhamnoside of Rg2 and 6- O -β- d -(1 → 2)-glucoside of Rf into Rh1, and subsequently hydrolyzes 6- O -β- d -glucoside of Rh1 into its aglycone. The enzyme K m and V max for Re were 22.2 mM, and 7.94 mM/h; the K m and V max for R1 were 7.06 mM and 1.61 mM/h; the enzyme transformation velocity ( V 0 ) at 5 mM substrate was 1.46 mM/h for Re, and 0.67 mM/h for R1. Therefore, the enzyme hydrolysis on the Re rhamnoside was faster than that on R1 xyloside. The enzyme V 0 on Rg1 was 0.05 mM/h that indicated the enzyme hardly hydrolyzed the 6- O -β- d -glucoside of Rg1. The enzyme kinetic parameters of Rg2 and Rf were 5.74 and 9.43 mM for K m ; 2.70 and 2.84 mM/h for V max ; 1.26 and 0.98 mM/h for V 0 at 5 mM substrate, respectively. Thus the enzyme hydrolysis on Rg2 rhamnoside was faster than that on the glucoside of Rf.