Hydration of an 18O epoxide by a cytosolic epoxide hydrolase from mouse liver

Abstract

Listen

Translate article

The mechanism of enzymatic epoxide hydration by a cytosolic or 100,000 g soluble mammalian liver enzyme (in contrast to the microsomal enzymes) was examined by monitoring 18O distribution following chemical and enzymatic hydrations of 16O or 18O epoxide labeled (±) 1-(4′-ethylphenoxy)-3, 7-dimethyl-6, 7-epoxyoctane. Acid catalyzed hydration of the 18O epoxide in 16O water, and hydration of the 16O epoxide in 18O water, indicated that attack by water was predominantly on the tertiary carbon (C-7). Enzymatic epoxide hydration led to attack predominantly on secondary carbon (C-6). These data are consistent with water attacking as a nucleophile in the enzymatic reaction.