Hydration of cis- and trans-epoxymethyl stearates by the cytosolic epoxide hydrase of mouse liver.

Man is exposed to epoxides of fatty acids from a number of sources, yet their degradative metabolism is not well understood. In mouse liver the 100,000 g supernatant or the cytosolic fraction is the most active fraction in hydrating $\text{cis}$- and $\text{trans}$-epoxymethyl stearates with the oxirane ring opening in a $\text{trans}$ manner to give the corresponding $\text{threo}$ and $\text{erythro}$ diols, respectively. Hydration was also observed in the microsomal, nuclei and cell debris, and mitochondrial fractions in decreasing order of specific activity.