Abstract: The genomic DNA extracted from Aspergillus niger 3.316 was used as template to amplify the β-glucosidase gene bgl by PCR to obtain a 2 080-bp amplicon. Bioinformatic analysis showed that the encoded protein was predicted to contain 860 amino acid residues with 4 major hydrophobic regions. Its secondary structures might contain 63.26% random coils, 20.58% α-helix, and 16.16% β-sheet. The protein consisted of (β/α)8 TIM barrel domain, (β/α)6 sandwich domain, and fibronectin Ⅲ-like domain. The active site and heat tolerance mechanism were predicted to be located in the active center of the enzyme. Its active sites might be Asp280 of (β/α)8 TIM barrel domain and Glu509 of (β/α)6 sandwich domain. The thermal stability of the glucosidase might be related to the presence of 211 amino acid residues in the hydrophobic region, 48 proline residues and α- helix.

Key words: β-glucosidase, active site, thermostability-associated structure, Aspergillus niger