Properties of enzymes hydrating epoxides in human epidermis and liver

1. Cytosolic and microsomal epoxide hydrolyzing enzymes of human skin and liver were compared and found to be different. 2. Epidermal and hepatic cytosolic epoxide hydrolases were different in terms of substrate selectivity, pI, inhibitor sensitivity and affinity chromatographic properties. 3. Microsomal epoxide hydrolases had the same pIs but different substrate selectivities. 4. Cytosolic epoxide hydrolase from adults had higher specific activity than that from neonates or cultured epidermis, but lower activity than adult hepatic enzymes. 5. The sizes of cytosolic epoxide hydrolase from epidermis and liver were similar and lower than that from cultured fibroblasts. 6. Cytosolic epoxide hydrolase from all sources shared similar antigenic determinants.