title: Purification and characterization of a novel ginsenoside Rc-hydrolyzing β-glucosidase from Armillaria mellea mycelia.
abstract: Ginsenosides are the principal compounds responsible for the pharmacological effects and health benefits of Panax ginseng root. Among protopanaxadiol (PPD)-type ginsenosides, minor ginsenosides such as ginsenoside (G)-F2, G-Rh2, compound (C)-Mc1, C-Mc, C-O, C-Y, and C-K are known to be more pharmacologically active constituents than major ginsenosides such as G-Rb1, G-Rb2, G-Rc, and G-Rd. A novel ginsenoside Rc-hydrolyzing β-glucosidase (BG-1) from Armillaria mellea mycelia was purified as a single protein band with molecular weight of 121.5 kDa on SDS-PAGE and a specific activity of 17.9 U mg-1protein. BG-1 concurrently hydrolyzed α-(1 → 6)-arabinofuranosidic linkage at the C-20 site or outer β-(1 → 2)-glucosidic linkage at the C-3 site of G-Rc to produce G-Rd and C-Mc1, respectively. The enzyme also hydrolyzed outer and inner glucosidic linkages at the C-3 site of G-Rd to produce C-K via G-F2, and inner glucosidic linkage at the C-3 site of C-Mc1 to produce C-Mc. C-Mc was also slowly hydrolyzed α-(1 → 6)-arabinofuranosidic linkage at the C-20 site to produce C-K with reaction time prolongation. Finally, the pathways for formation of C-Mc and C-K from G-Rc by BG-1 were G-Rc → C-Mc1 → C-Mc and G-Rc → G-Rd → G-F2 → C-K, respectively. The optimum reaction conditions for C-Mc and C-K formation from G-Rc by BG-1 were pH 4.0-4.5, temperature 45-60 °C, and reaction time 72-96 h. This is the first report of efficient production of minor ginsenosides, C-Mc and C-K from G-Rc by β-glucosidase purified from A. mellea mycelia.
authors.affiliation: Department of Food Science and Technology, Chonbuk National University, Jeonju, 54896, Republic of Korea.
authors.forename: Jitendra
authors.initials: J
authors.lastname: Upadhyaya
authors.affiliation: Department of Food Science and Biotechnology, Chonbuk National University, Iksan, 54596, Republic of Korea.
authors.forename: Min-Sun
authors.initials: MS
authors.lastname: Yoon
authors.affiliation: Department of Food Science and Technology, Chonbuk National University, Jeonju, 54896, Republic of Korea.
authors.forename: Min-Ji
authors.initials: MJ
authors.lastname: Kim
authors.affiliation: Department of Food Science and Biotechnology, Chonbuk National University, Iksan, 54596, Republic of Korea.
authors.forename: Nam-Soo
authors.initials: NS
authors.lastname: Ryu
authors.affiliation: Agricultural Research and Extension Services, Iksan, 54591, Republic of Korea.
authors.forename: Young-Eun
authors.initials: YE
authors.lastname: Song
authors.affiliation: Department of Food Science and Technology, Chonbuk National University, Jeonju, 54896, Republic of Korea.
authors.forename: Young-Hoi
authors.initials: YH
authors.lastname: Kim
authors.affiliation: Department of Food Science and Technology, Chonbuk National University, Jeonju, 54896, Republic of Korea. kmyuko@jbnu.ac.kr.
authors.forename: Myung-Kon
authors.initials: MK
authors.lastname: Kim
keywords: Armillaria mellea; Enzymatic hydrolysis; Ginsenoside Rc; Minor ginsenosides; β-Glucosidase