Purification and enzymatic characterization of secretory glycoside hydrolase family 3 (GH3) aryl β-glucosidases screened from Aspergillus oryzae genome

摘要: By a global search of the genome database Aspergillus oryzae, we found 23 genes encoding putative β-glucosidases, among which 10 with signal peptide belonging to glycoside hydrolase family 3 (GH3) were overexpressed in A. oryzae using improved glaA gene promoter. Consequently, crude enzyme preparations from three strains, each harboring AO090038000223 (bglA), AO090103000127 (bglF), and AO090003001511 (bglJ), showed substrate preference toward p-nitrophenyl-β-d-glucopyranoside (pNPGlc) thus purified homogeneity enzymatically characterized. All enzymes (BglA, BglF, BglJ) preferentially hydrolyzed aryl β-glycosides, including pNPGlc, rather than cellobiose, these proven be β-glucosidases. Although specific activity BglF all substrates tested was significantly low, BglA BglJ appreciably high activities pNPGlc arbutin. The kinetic parameters for suggested that both had relatively higher hydrolytic fungal β-glucosidases reported. thermal pH stabilities those BglJ, particularly stable wide range (pH 4.5-10). In contrast, most heat- alkaline-labile Furthermore, more tolerant ethanol BglJ; as result, it much isoflavone glycosides presence BglJ. This study mining novel exhibiting microbial sequences is great use production beneficial compounds such aglycones.