Equine cytochrome P450 2C92: cDNA cloning, expression and initial characterization

H. K. DiMaio Knych, C. DeStefano Shields, A. R. Buckpitt, S. D. Stanley

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


Substantial gaps exist in our knowledge of the metabolic clearance of therapeutic agents in horses. Accordingly, a cytochrome P450 monooxygenase in the 2C family was cloned from an equine liver, sequenced and expressed in a baculovirus expression system. Catalytic activities of the recombinant protein were measured with a number of substrates. The protein, assigned CYP2C92, displayed optimal catalytic activity with diclofenac using molar ratios of CYP2C92 to NADPH CYP450 reductase of 1:18. Addition of cytochrome b5 to diclofenac incubations had no significant effect on metabolic turnover. CYP2C92 catalyzed diclofenac metabolism was 20-fold slower than the human counterpart, CYP2C9. CYP2C92 demonstrated comparable tolbutamide and (S)-warfarin hydroxylase activity compared to CYP2C9, upon addition of b5 to the reactions. The results of this study demonstrate substantial interspecies differences in metabolism of substrates by CYP2C orthologues in the horse and human and support the need to fully characterize this enzyme system in equids.

Original languageEnglish (US)
Pages (from-to)49-55
Number of pages7
JournalArchives of Biochemistry and Biophysics
Issue number1
StatePublished - May 1 2009
Externally publishedYes


  • CYP2C
  • CYP450
  • Diclofenac
  • Horse
  • Mephenytoin
  • Phase I metabolism
  • Tolbutamide
  • Warfarin

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology


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