Cytosolic epoxide hydrolase from liver of control and clofibrate-treated mice. Structural comparison by HPLC peptide mapping.

Cytosolic epoxide hydrolases purified from livers of control and clofibrate-induced male C57B1/6 mice were compared. The proteins were reduced, alkylated and cleaved with trypsin and chymotrypsin. The digests were analyzed by HPLC and no qualitative differences were observed in the peptide mapping profiles of the two types of epoxide hydrolase preparation. The amino acid compositions and N-terminal residues of selected tryptic peptides also gave identical results for the control and clofibrate-induced mice. Both intact proteins have alpha-amino-blocked N-termini. The two enzyme forms are concluded to have highly similar, if not identical, primary structures.