TY - JOUR T1 - Expression and Characterization of Dog Cytochrome P450 2A13 and 2A25 in Baculovirus Infected Insect Cells JF - Drug Metabolism and Disposition JO - Drug Metab Dispos DO - 10.1124/dmd.110.033068 SP - dmd.110.033068 AU - Diansong Zhou AU - Alban J. Linnenbach AU - Ruifeng Liu AU - Rick A. Luzietti AU - Jennifer J. Harris AU - Catherine L. Booth-Genthe AU - Scott W. Grimm Y1 - 2010/01/01 UR - http://dmd.aspetjournals.org/content/early/2010/04/09/dmd.110.033068.abstract N2 - Dog CYP2A13 and CYP2A25 were co-expressed with dog NADPH-cytochrome P450 reductase (OR) in baculovirus infected-Sf9 insect cells. CYP2A13 effectively catalyzed 7-ethoxycoumarin (7EC) deethylation and coumarin hydroxylation with apparent Km values of 4.8 and 2.1 μM, respectively, similar to those observed using dog liver microsomes (7.5 and 0.75 μM, respectively). CYP2A25 exhibited much lower affinity towards 7EC, with apparent Km value of 150 μM, indicating CYP2A13 plays a more significant role in the metabolism of these CYP2A substrates. Similar to the dog CYP1A2 enzyme, CYP2A13 efficiently catalyzed phenacetin deethylation with a Km value of 3.9 μM, suggesting phenacetin is not a selective probe for dog CYP1A2 activity. Both dog CYP2A13 and CYP2A25 exhibited little or no catalytic activity towards other common CYP probe substrates including bupropion, amodiaquine, diclofenac, S-mephenytoin, bufuralol, dextromethorphan, midazolam and testosterone. These results provided additional information about the selectivity of these commonly used probe substrates.The American Society for Pharmacology and Experimental Therapeutics ER -