RT Journal Article
SR Electronic
T1 EXPRESSION, PURIFICATION, AND CHARACTERIZATION OF MOUSE CYP2D22
JF Drug Metabolism and Disposition
JO Drug Metab Dispos
FD American Society for Pharmacology and Experimental Therapeutics
SP 1167
OP 1174
DO 10.1124/dmd.105.008870
VO 34
IS 7
A1 Yu, Ai-Ming
A1 Haining, Robert L.
YR 2006
UL http://dmd.aspetjournals.org/content/34/7/1167.abstract
AB Metabolism of the prototype human CYP2D6 substrates debrisoquine and bufuralol proceeds at a much slower rate in mice; therefore, the mouse has been proposed as an animal model for the human CYP2D6 genetic deficiency. To interpret the molecular mechanism of this deficiency, a cDNA belonging to the CYP2D gene subfamily (Cyp2d22) has been cloned and sequenced from a mouse mammary tumor-derived cell line. In the current study, Cyp2d22 enzyme was overexpressed and purified from insect cells using a baculovirus-mediated system. The activity of this purified enzyme was directly compared with purified human CYP2D6 toward codeine, dextromethorphan, and methadone as substrates. Purified Cyp2d22 was found to catalyze the O-demethylation of dextromethorphan with significantly higher Km values (250 μM) than that (4.2 μM) exhibited by purified human CYP2D6. The Km for dextromethorphan N-demethylation by Cyp2d22 was found to be 418 μM, much lower than that observed with human CYP2D6 and near the Km for dextromethorphan N-demethylation catalyzed by CYP3A4. CYP2D6 catalyzed codeine O-demethylation, whereas Cyp2d22 and CYP3A4 mediated codeine N-demethylation. Furthermore, methadone, a known CYP3A4 substrate and CYP2D6 inhibitor, was N-demethylated by Cyp2d22 with a Km of 517 μM and Vmax of 4.9 pmol/pmol/min. Quinidine and ketoconazole, potent inhibitors to CYP2D6 and CYP3A4, respectively, did not show strong inhibition toward Cyp2d22-mediated dextromethorphan O- or N-demethylation. These results suggest that mouse Cyp2d22 has its own substrate specificity beyond CYP2D6-like-deficient activity. The American Society for Pharmacology and Experimental Therapeutics