Purification And Characterization Of Ginsenoside Rb3 Xylosidase

The ginsenosides Rb3 of the Panax notoginseng’s stem leaf accounts for more than 20%of the total saponins,and it has a lower utilization because the 20th carbon is connected with xylose and there is no xylosidase enzyme to hydrolysis xylose.The main content of this paper was to screen out a absidia that could produce the xylosidase enzyme that can hydrolysis the xylose of the ginsenosides Rb3.The crude enzyme was isolated and purified.And the enzymatic properties and kinetic constants of the purified enzyme were studied.First,the Absidia sp.P848r strains that can produce xylosidase enzyme were screened out,and its fermentation conditions were optimized.The best fermentation conditions were:adding0.4 mL bacteria in the bran without inducer leaching liquid medium and culturing 96 hours.Next,the crude enzyme was isolated and purified by DEAE-Cellulose DE52 anion chromatography.The purity was identified by SDS-PAGE electrophoresis,and a single band was obtained.The molecular weight of the enzyme protein was about 66.7 kDa.The enzymatic properties were studied and the results showed that the optimum reaction conditions pH value of ginsenoside Rb3 xylosyl hydrolase was 3.0,which was relatively stable in the range of pH 2.2⁸.0.The optimum temperature was 40℃,which was better stability in the range of 20℃⁶0℃;Metal ion K⁺,Na⁺,Mg²⁺,Mn²⁺,Ca²⁺ions had no obvious effects on enzyme reaction,and Zn²⁺,Pb²⁺,Ni²⁺had inhibitory effects on enzyme reaction.The results of the reaction kinetics showed that the K_m value was 65.63 mmol/L,and V_max was 2.03 mmol/（h·L）.In conclusion,the study on the catalytic properties of the curde enzymes found that it could hydrolysis the rich ginsenoside Rb3 of the Panax notoginseng’s stem leaf.And the ginsenoside Rb3 were hydrolysised to ginsenoside F2 and C-K.And the purified enzyme can hydrolyzes the pNP-β-D-xyloside.