标题：Purification and Characterization of Ginsenoside Ra-Hydrolyzing β-D-Xylosidase from Bifidobacterium breve K-110, a Human Intestinal Anaerobic Bacterium
摘要：β- D -Xylosidase (EC 3.2.1.37) has been purified from ginsenoside Ra-metabolizing Bifidobacterium breve K-110, which was isolated from human intestinal microflora. β- D -Xylosidase was purified to apparent homogeneity by a combination of ammonium sulfate precipitation, QAE-cellulose, butyl-toyopearl, hydroxyapatit and Q-Sepharose column chromatographies with the final specific activity of 51.8 μmol/min/mg. Molecular weight of β- D -xylosidase is 49 kDa by SDS-PAGE and gel filtration, which consisted of a single subunit. β- D -Xylosidase showed optimal activity at pH 5.0 and 37 °C. The purified enzyme was potently inhibited by PCMS. β- D -Xylosidase acted to the greatest extent on p -nitrophenyl-β- D -xylopyranoside, followed by ginsenoside Ra1 and ginsenoside Ra2. This enzyme hydrolyzed xylan to xylose, but did not act on p -nitrophenyl-β-glucopyranoside, p -nitrophenyl-β-galactopyranoside or p -nitrophenyl-β- D -fucopyranoside. These findings suggest that this is the first reported purification of ginsenoside-hydrolyzing β- D -xylosidase from an anaerobic Bifidobacterium sp.
关键词：Bifidobacterium breve K-110;ginsenoside Ra;β- D -xylosidase;purification
