Two-Step Purification of a Novel β-Glucosidase with High Transglycosylation Activity and Another Hypothetical β-Glucosidase in Aspergillus oryzae HML366 and Enzymatic Characterization

摘要

Two novel β-glucosidases (BGHG1 and BGHG2) were purified from the enzyme extract of Aspergillus oryzae HML366 through nondenaturing gel electrophoresis and anionexchange chromatography. The molecular weights for BGHG1 and BGHG2 were 93 and 138 kDa, respectively. The amino acid sequences were determined by matrix-assisted laser desorption/ionization tandem time of flight. The Mascot and Blast analyses indicated that BGHG1 has the same sequence as the hypothetical protein XP_001816831 from A. oryzae RIB40. Sequence comparison suggested that both enzymes belong to the glycosyl hydrolase family 3. Results from thin layer chromatography and high performance liquid chromatography showed that BGHG2 has relatively high transglycosylation activity, and after preliminary optimization, it was able to convert glucose to produce 52.48 mg/ml gentiobiose. This is the first report of production of hypothetical protein XP_001816831 and β-glucosidase with high transglycosylation activity in A. oryzae. Results provide a valuable reference for potential applications in food industry, biomass power generating industry, and many others.