Ginsenoside Glycosidases From Panax Ginseng

In order to hydrolyze the ginsenosides specifically, the ginsenoside- -glucosidase and the ginsenoside- -arabinofuranase are purified, characterized, and ginsenoside Rg3 and Re are hydrolyzed by the enzymes as well. It shows the possibility of hydrolyzing ginsenosides specifically. The ginsenoside-p-glucosidase and the ginsenoside-a-arabinofuranase from ginseng root are purified to one spot in PAGE by buffer extraction, (NH4)2SO4 precipitation and ion exchange chromatography.The ginsenoside-p-glucosidase hydrolyzes the ginsenoside Rg3 sugar moiety to ginsenoside Rh2. The optimal temperature is 55-60 , and the optimal pH is 5.0. Ca2+ ion has the positive effect, while Cu2+ has the negative effect on it. Its molecular weight is about 59 kDa in SDS polyacrylamide gel electrophoresis. The N-end sequence of ginsenoside-p-glucosidase is SLDANYVPKYVTLPL, which has no homology with the p-glucosidases whose protein sequence are known. The hydrolysis of ginsenoside-p-glucosidase is different from the original exocellulase such as -glucosidase (ECS.2.1.21). In addition, the Michaelis-Menten model of ginsenoside- -glucosidase is built.The ginsenoside-a-arabinofuranase hydrolyzes the ginsenoside Re to ginsenoside Rd. The optimal temperature is 50 , and the optimal pH is 5.0. Cu2+ inhibites the enzyme activity. Its molecular weight is about 86 kDa in SDS polyacrylamide gel electrophoresis.In hydrolyzing ginsenoside Rg3 to Rh2 by the saponin glycosidases, the conversion rate is 60% in the condition of substrate Rg310mg/ml, pH5.0, 55 , 24h. After butanol extraction and separation on the silica gel column, the purity of the product Rh2 is about 90% and the yield is 32%. The ginsenoside-p-glucosidase can hydrolyze both 20(S)- Rg3 and 20(R)- Rg3 to form 20(S)- ginsenoside Rh2, i. e. 3-O-(p-glucopyranosyl)-dammar-24-en-3p, 12P, 20(S)-triol and 20(R)- ginsenoside Rh2, i. e. 3-O-(p-glucopyranosyl)-dammar-24-en-3p, 12p, 20(S)-triol respectively, according to the data of the 'HNMR, 13CNMR and MS. The reaction rate of 20(S)-Rg3 and 20(R)- Rgs is nearly the same.In hydrolyzing ginsenoside Re to Rd by the ginsenoside-cc-arabinofuranase, the conversion rate is 60% in the condition of substrate Re 30mg/ml, pH5.0, 50 , 24h. After butanol extraction and separation on the silica gel column, the purity of the product Rd is about 90% and the yield is 34%. The product from Re is 20(S)-Rd, i. e. 3-O-(p-glucopyranosyl-(1 - 2)-p-lucopyranosyl)-20-O-(p-glucopyranosyl)- dammar 24-en-3p, 12(3, 20(S)-triol according to the data of the 'HNMR, 13CNMR and MS.All this proves the possibility of transforming ginsenosides into the rare ginsenosides. It also lays a foundation on studying glycosidase especially saponin glycosidase further.