Comparative homology modeling-inspired protein engineering for improvement of catalytic activity of Mugil cephalus epoxide hydrolase.

The epoxide hydrolase (EH) of a marine fish, Mugil cephalus, was engineered to improve the catalytic activity based on comparative homology modeling. The 3-D crystal structure of the EH from Aspergillus niger was used as a template. A triple point mutant, F193Y for spatial orientation of the nucleophile (D199), W200L for removing electron density overlap between W200 and Y348, and E378D for good charge relay in the active site, was developed. The initial hydrolysis rate, the reaction time to reach 98 %ee, and yield were enhanced up to 35-fold, 26-fold and 32%, respectively, by homology modeling-inspired site-directed mutagenesis of M. cephalus EH.