Highly selective hydrolysis for the outer glucose at the C-20 position in ginsenosides by β-glucosidase from Thermus thermophilus and its application to the production of ginsenoside F2 from gypenoside XVII

β-Glucosidase from Thermus thermophilus has specific hydrolytic activity for the outer glucose at the C-20 position in protopanaxadiol-type ginsenosides without hydrolysis of the inner glucose. The hydrolytic activity of the enzyme for gypenoside XVII was optimal at pH 6.5 and 90 °C, with a half-life of 1 h with 3 g enzyme l−1 and 4 g gypenoside XVII l−1. Under the optimized conditions, the enzyme converted the substrate gypenoside XVII to ginsenoside F2 with a molar yield of 100 % and a productivity of 4 g l−1 h−1. The conversion yield and productivity of ginsenoside F2 are the highest reported thus far among enzymatic transformations.