title: Enzymatic biotransformation of ginsenoside Rb1 to compound K by recombinant β-glucosidase from Microbacterium esteraromaticum.
abstract: We cloned and characterized a β-glucosidase (bgp3) gene from Microbacterium esteraromaticum isolated from ginseng field. The bgp3 gene consists of 2,271 bp encoding 756 amino acids which have homology to the glycosyl hydrolase family 3 protein domain. The molecular mass of purified Bgp3 was 80 kDa, as determined by SDS-PAGE. The enzyme (Bgp3) catalyzed the conversion of ginsenoside Rb1 to the more pharmacologically active minor ginsenoside Rd and compound K. The Bgp3 hydrolyzed the outer glucose moiety attached to the C-20 position of ginsenoside Rb1, followed by hydrolysis of the inner glucose moiety attached to the C-3 position. Using 0.1 mg mL(-1) enzyme in 20 mM sodium phosphate buffer at 40 °C and pH 7.0, 1.0 mg mL(-1) ginsenoside Rb1 was transformed into 0.46 mg mL(-1) compound K within 60 min with a corresponding molar conversion yield of 77%. Bgp3 hydrolyzed the ginsenoside Rb1 along the following pathway: Rb1 → Rd → compound K.
authors.affiliation: Department of Oriental Medicinal Material & Processing, College of Life Science, Kyung Hee University, Yongin, Korea. linhuk@hotmail.com
authors.forename: Lin-Hu
authors.initials: LH
authors.lastname: Quan
authors.forename: Jin-Woo
authors.initials: JW
authors.lastname: Min
authors.forename: Yan
authors.initials: Y
authors.lastname: Jin
authors.forename: Chao
authors.initials: C
authors.lastname: Wang
authors.forename: Yeon-Ju
authors.initials: YJ
authors.lastname: Kim
authors.forename: Deok-Chun
authors.initials: DC
authors.lastname: Yang
mesh_terms: D000192:Actinomycetales / Q000201:enzymology* / Q000235:genetics; D015870:Gene Expression; D036145:Ginsenosides / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D013379:Substrate Specificity; D001617:beta-Glucosidase / Q000235:genetics / Q000378:metabolism*
chemical_list: D036145:Ginsenosides; D011994:Recombinant Proteins; D001617:beta-Glucosidase; C442759:ginsenoside Rb1; C112772:ginsenoside compound K