Hepatic microsomal epoxide hydrase. Chemical evidence for a single polypeptide chain.
Highly purified hepatic microsomal epoxide hydrase, which had been purified in the presence of proteolytic enzyme inhibitors, was subjected to carboxypeptidase Y digestion, automated Edman degradation, and carbohydrate analysis. Carboxypeptidase Y digestion resulted in the near stoichiometric release of leucine, the COOH-terminal amino acid. Automated Edman degradation permitted the identification of the first 20 amino acid residues of epoxide hydrase. Methionine was identified as the NH2-terminal residue. The NH2-terminal region of epoxide hydrase is similar in hydrophobicity to the NH2-terminal precursor segments of several secretory proteins and the NH2-terminal regions of several microsomal cytochromes P-450. Carbohydrate analyses of the enzyme revealed the presence of 0.5 to 1.0 mol of mannose/50,000 g of protein. These results provide evidence for the presence of a single polypeptide chain in our purified enzyme preparations and suggest that there may be only one enzymic form of epoxide hydrase in microsomes from phenobarbital-treated rats.
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002268:Carboxypeptidases; D004851:Epoxide Hydrolases; D008862:Microsomes, Liver / Q000201:enzymology*; D010446:Peptide Fragments / Q000032:analysis; D051381:Rats
D000596:Amino Acids; D010446:Peptide Fragments; D004851:Epoxide Hydrolases; D002268:Carboxypeptidases