Epoxide hydrolase regiospecificity

Farin EM, Omiecinski CJ. 1993. Regiospecific expression of cytochrome P-450s and microsomal epoxide hydrolase in human brain tissue. J Toxicol Environ Health 40 317-335. 

The term dihydrodiol is widely used in reference to vicinal dihydroxydihydro-derivatives of aromatic hydrocarbons. Although most known and potential benzene oxide or substituted benzene oxide metabolites tend to be quite unstable, a recent study has described the isolation of a relatively stable arene oxide metabolite of 2,2, 5,5 -tetrachlorobiphenyl. Perhaps because of the generally high susceptibility of benzene oxide 1 and many substituted benzene oxides to isomerize to phenols, relatively little has been reported on the kinetics and regiospecificity of their microsomal epoxide hydrolase (EC 3.3.2.3) catalyzed trans hydration to dihydro-... 

Recently, the characterization of NcsF2, one of two epoxide hydrolases encoded by the NCS gene cluster, which catalyzed regiospecific addition of H2O to C-2 of both R)- and (5)-styrene oxides to afford (/ )- and (5)-1-phenyl-1,2-ethanediols, respectively, was reported, supporting its proposed role in 301 biosynthesis [329]. 

Enzymic hydrolysis of the racemic mixture of fl-D-ribo-spoxide (68) and its L-enantiomer (69) using microsomal epoxide hydrolase ( MEH ) was found to be enantioselective, but not regiospecific. Thus the D-epoxide gave the D-arabino- and D xylo-diols (70) and (71) in an 88 12 ratio (Scheme 14), while the L-epoxide (69) remained unreacted In reviewing earlier work on... 

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