Zhang_2020_Int.J.Biol.Macromol_164_2795

A novel epoxide hydrolase from Glycine max, designated GmEH3, was excavated based on the computer-aided analysis. Then, gmeh3, a GmEH3-encoding gene, was cloned and successfully expressed in E. coli Rosetta(DE3). Among the ten investigated rac-epoxides, GmEH3 possessed the highest and best complementary regioselectivities (regioselectivity coefficients, alpha(S) = 93.7% and beta(R) = 97.2%) in the asymmetric hydrolysis of rac-m-chlorostyrene oxide (5a), and the highest enantioselectivity (enantiomeric ratio, E = 55.6) towards rac-phenyl glycidyl ether (7a). The catalytic efficiency (k(cat)(S)/K(m)(S) = 2.50 mM(-1) s(-1)) of purified GmEH3 for (S)-5a was slightly higher than that (k(cat)(R)/K(m)(R) = 1.52 mM(-1) s(-1)) for (R)-5a, whereas the k(cat)/K(m) (5.16 mM(-1) s(-1)) for (S)-7a was much higher than that (0.09 mM(-1) s(-1)) for (R)-7a. Using 200 mg/mL wet cells of E. coli/gmeh3 as the biocatalyst, the scale-up enantioconvergent hydrolysis of 150 mM rac-5a at 25 degreesC for 1.5 h afforded (R)-5b with 90.2% ee(p) and 95.4% yield(p), while the kinetic resolution of 500 mM rac-7a for 2.5 h retained (R)-7a with over 99% ee(s) and 43.2% yield(s). Furthermore, the sources of high regiocomplementarity of GmEH3 for (S)- and (R)-5a as well as high enantioselectivity towards rac-7a were analyzed via molecular docking (MD) simulation.