Km and Vmax values for rat CYP2B1, 2C6, and 2C11

Recombinant enzymes (1 pmol of CYP2B1 and CYP2C11 or 0.5 pmol of CYP2C6) were incubated with various amounts of substrate (EFC for CYP2B1 and CYP2C6 or DBF for CYP2C11) and regenerating system in potassium phosphate buffer, pH 7.4, at 37°C for 30 min. Product formation in picomoles of product per picomoles of enzyme per minute was plotted at each concentration of substrate. Data were fitted to the Michaelis-Menten equation for a single enzyme model, and kinetic parameters were estimated by nonlinear regression. Values are means ± S.E.M. for a total of four measurements.

2B1EFC66.7 ± 7.67.1 ± 0.3
2C6EFC6.0 ± 0.920.2 ± 0.7
2C11DBF1.3 ± 0.10.52 ± 0.02