Characterization of Recombinant beta-Glucosidase from Arthrobacter chlorophenolicus and Biotransformation of Ginsenosides Rb-1, Rb-2, Rc, and Rd

Abstract

The focus of this study was the cloning, expression, and characterization of recombinant ginsenoside hydrolyzing beta-glucosidase from Arthrobacter chlorophenolicus with an ultimate objective to more efficiently bio-transform ginsenosides. The gene bglAch, consisting of 1,260 bp (419 amino acid residues) was cloned and the recombinant enzyme, over-expressed in Escherichia coli BL21 (DE3), was characterized. The GST-fused BglAch was purified using GST.Bind agarose resin and characterized. Under optimal conditions (pH 6.0 and 37 degrees C) BglAch hydrolyzed the outer glucose and arabinopyranose moieties of ginsenosides Rb-1 and Rb-2 at the C20 position of the aglycone into ginsenoside Rd. This was followed by hydrolysis into F-2 of the outer glucose moiety of ginsenoside Rd at the C-3 position of the aglycone. Additionally, BglAch more slowly transformed Rc to F-2 via C-Mci (compared to hydrolysis of Rb-1 or Rb-2). These results indicate that the recombinant BglAch could be useful for the production of ginsenoside F-2 for use in the pharmaceutical and cosmetic industries.