An insect juvenile hormone-specific epoxide hydrolase is related to vertebrate microsomal epoxide hydrolases

We describe the first cDNA sequence encoding a juvenile hormone-specific epoxide hydrolase from an insect. A full-length cDNA clone revealed a 462-amino-acid open reading frame encoding an amino acid sequence with 44% identity and 64% similarity to human microsomal epoxide hydrolase. All residues in the catalytic triad (residues Asp(227)-His(428)-Asp(350) in the M. sexta protein) were present, as was the conserved Trp(154) corresponding to the oxyanion hole. The surprising similarity of insect juvenile hormone epoxide hydrolase to vertebrate microsomal epoxide hydrolases, coupled with the ancient lineage of the epoxide hydrolases and haloalkane dehalogenases, suggests that this catabolic enzyme evolved from an original ubiquitous detoxication function to a more recent role in hormonal regulation. (C) 1996 Academic Press, Inc.