Improvement of the thermostability and enzymatic activity of cholesterol oxidase by site-directed mutagenesis.

Site-directed mutagenesis was applied to enhance the thermostability and enzymatic activity of cholesterol oxidase (ChOx) isolated from Brevibacterium sp. Three amino acid residues (Q153E, F128L, and S143H) located near the FAD-binding site of the enzyme were substituted based on structural analysis. The specific activity of the two-sites mutant Q153E/F128L increased by 11.6% and the relative activity increased by 47% when grown for 2 h at 50 °C. This mutant is a potential industrial strain for producing ChOx.