RT Journal Article
SR Electronic
T1 Characterization of Cytochrome P450 2D6.1 (CYP2D6.1), CYP2D6.2, and CYP2D6.17 Activities toward Model CYP2D6 Substrates Dextromethorphan, Bufuralol, and Debrisoquine
JF Drug Metabolism and Disposition
JO Drug Metab Dispos
FD American Society for Pharmacology and Experimental Therapeutics
SP 595
OP 601
DO 10.1124/dmd.30.5.595
VO 30
IS 5
A1 Kenda A. Marcucci
A1 Robin E. Pearce
A1 Charles Crespi
A1 Dorothy T. Steimel
A1 J. Steven Leeder
A1 Andrea Gaedigk
YR 2002
UL http://dmd.aspetjournals.org/content/30/5/595.abstract
AB Over 50 allelic variants of cytochrome P450 2D6 (CYP2D6) encoding fully functional, reduced-activity, or nonfunctional proteins have been described. Compared with Caucasians, studies in black populations demonstrate a tendency toward slower CYP2D6 activity, attributed in part to the presence of a variant allele associated with reduced activity, the CYP2D6*17 allele. To investigate the kinetic characteristics of this variant protein, expression constructs coding for CYP2D6.1, CYP2D6.2, and CYP2D6.17 gene products were prepared and transfected into mammalian COS-7 and insect (Trichoplusia ni) cells for expression. Microsomal fractions containing the expressed proteins were used to determine the kinetic parameters Km,Vmax, and intrinsic clearance (Clint) for the model substrates dextromethorphan, bufuralol, and debrisoquine. Relative to the wild-type CYP2D6.1 protein expressed in COS-7 cells, CYP2D6.17 exhibited a 2-fold higherKm and a 50% reduction inVmax using dextromethorphan as the substrate. In contrast, no appreciable change in bufuralolKm was observed with CYP2D6.17 whereasVmax was decreased by 50%. When expressed in the baculovirus expression system, CYP2D6.17 exhibited a 6-fold increase in Km but no change inVmax with dextromethorphan as the substrate, a 2-fold higher Km and 50% reduction inVmax with bufuralol, and a 3-fold increase in Km and no change inVmax with debrisoquine relative to CYP2D6.1. These data indicate that CYP2D6.17 exhibits reduced metabolic activity toward all three commonly used CYP2D6 substrates, although specific effects on substrate affinity and turnover demonstrate some substrate dependence. The American Society for Pharmacology and Experimental Therapeutics