title: Purification and characterization of a ginsenoside Rb(1)-hydrolyzing β-glucosidase from Aspergillus niger KCCM 11239.
abstract: Rb(1)-hydrolyzing β-glucosidase from Aspergillus niger KCCM 11239 was studied to develop a bioconversion process for minor ginsenosides. The specific activity of the purified enzyme was 46.5 times greater than that of the crude enzyme. The molecular weight of the native enzyme was estimated to be approximately 123 kDa. The optimal pH of the purified enzyme was pH 4.0, and the enzyme proved highly stable over a pH range of 5.0-10.0. The optimal temperature was 70 °C, and the enzyme became unstable at temperatures above 60 °C. The enzyme was inhibited by Cu(2+), Mg(2+), Co(2+), and acetic acid (10 mM). In the specificity tests, the enzyme was found to be active against ginsenoside Rb(1), but showed very low levels of activity against Rb(2), Rc, Rd, Re, and Rg(1). The enzyme hydrolyzed the 20-C,β-(1→6)-glucoside of ginsenoside Rb(1) to generate ginsenoside Rd and Rg(3), and hydrolyzed 3-C,β-(1→2)-glucoside to generate F(2). The properties of the enzyme indicate that it could be a useful tool in biotransformation applications in the ginseng industry, as well as in the development of novel drug compounds.
authors.affiliation: Division of Animal Life Science, Konkuk University, Seoul 143-701, Korea.
authors.forename: Kyung Hoon
authors.initials: KH
authors.lastname: Chang
authors.affiliation: Division of Animal Life Science, Konkuk University, Seoul 143-701, Korea.
authors.forename: Mi Na
authors.initials: MN
authors.lastname: Jo
authors.affiliation: Bio/Molecular Informatics Center, Konkuk University, Seoul 143-701, Korea.
authors.forename: Kee-Tae
authors.initials: KT
authors.lastname: Kim
authors.affiliation: Division of Animal Life Science, Konkuk University, Seoul 143-701, Korea.|Bio/Molecular Informatics Center, Konkuk University, Seoul 143-701, Korea.
authors.forename: Hyun-Dong
authors.initials: HD
authors.lastname: Paik
mesh_terms: D001234:Aspergillus niger / Q000201:enzymology*; D005656:Fungal Proteins / Q000737:chemistry* / Q000302:isolation & purification*; D036145:Ginsenosides / Q000737:chemistry*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D013379:Substrate Specificity; D001617:beta-Glucosidase / Q000737:chemistry* / Q000302:isolation & purification*
chemical_list: D005656:Fungal Proteins; D036145:Ginsenosides; C442759:ginsenoside Rb1; D001617:beta-Glucosidase
keywords: Aspergillus niger KCCM 11239; ginsenoside F2; ginsenoside Rb1; ginsenoside Rd; β-glucosidase