Abstract
Rb1-hydrolyzing β-glucosidase from Aspergillus niger KCCM 11239 was studied to develop a bioconversion process for minor ginsenosides. The specific activity of the purified enzyme was 46.5 times greater than that of the crude enzyme. The molecular weight of the native enzyme was estimated to be approximately 123 kDa. The optimal pH of the purified enzyme was pH 4.0, and the enzyme proved highly stable over a pH range of 5.0–10.0. The optimal temperature was 70 °C, and the enzyme became unstable at temperatures above 60 °C. The enzyme was inhibited by Cu2+, Mg2+, Co2+, and acetic acid (10 mM). In the specificity tests, the enzyme was found to be active against ginsenoside Rb1, but showed very low levels of activity against Rb2, Rc, Rd, Re, and Rg1. The enzyme hydrolyzed the 20-C,β-(1→6)-glucoside of ginsenoside Rb1 to generate ginsenoside Rd and Rg3, and hydrolyzed 3-C,β-(1→2)-glucoside to generate F2. The properties of the enzyme indicate that it could be a useful tool in biotransformation applications in the ginseng industry, as well as in the development of novel drug compounds.
Highlights
Introduction β-Glucosidases (β-D-glucoside glucohydrolase, EC 3.2.1.21) are a heterogeneous group of enzymes that are capable of cleaving the β-glucosidic linkages of aryl and alkyl β-glucosides, β-linked oligoglucosides, and several other oligosaccharides, with the release of glucose, generally in the β configuration [1,2]
A maximum β-glucosidase activity of cultivation medium was obtained after 16 days
The β-glucosidase from A. niger KCCM 11239 differs from those of other β-glucosidases generated by A. niger reported far, which were 46, 110, and 240 kDa [16,17,18]
Summary
Changes in dry cell weight (DCW) and the β-glucosidase activity of A. niger KCCM 11239 on PDB medium at 30 °C were assessed under aerobic conditions. The formation of extracellular β-glucosidase activity is growth-associated, ending when the stationary phase of growth is reached. A maximum β-glucosidase activity of cultivation medium was obtained after 16 days (specific activity, 9.9 U/mg). The enzymatic activities were not changed during. The culture supernatants were collected and employed as the source of enzyme purification. ■, dry cell weight (DCW); ▲, β-glucosidase activity (U/mL) KCCM 11239. ■, dry cell weight (DCW); ▲, β-glucosidase activity (U/mL)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
