Cloning and characterization of a recombinant α-glucosidase from Ensifer adhaerens NBRC 100388 and evaluation of its glucosyl transfer activity

Abstract

Abstract Terpene alcohol glycosides are useful compounds in industry. An α-glucosidase gene from a strain of Ensifer adhaerens NBRC 100388 showing transglucosylation activity toward alkylalcohols, which belongs to the glycosides hydrolase family 13, was cloned and expressed in Escherichia coli BL21 (DE3). The molecular mass of the purified recombinant α-glucosidase protein was estimated to be 60 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This α-glucosidase from E. adhaerens NBRC 100388 (EaG) was able to hydrolyze maltose, maltotriose, maltotetraose, maltulose, sucrose, trehalose, ethyl α-D-glucoside, and p-nitrophenyl D-glucoside (p-NPG). The enzyme activity increased in the presence of NH4+ and K+ ions but was inhibited by Cu+ and Zn2+. The enzyme exhibited optimal activity with maltose at a pH of 7.5 and a temperature of 45 °C. The transglucosylation activity was observed not only for nerol, a primary alcohol, but also for 6-gingerol, a secondary alcohol, and (−)-linalool, a tertiary alcohol. The enantioselectivity for the glucosyl transfer toward the acceptor of (±)-linalool was 21.5% ee for the (−)-isomer. Thus, purified EaG can be used in the synthesis of pharmaceuticals, chemicals, and fragrances owing to its ability to catalyze the transglucosylation of tertiary alcohols.