Table 3

Kinetic parameter estimates for 5′-hydroxylation of piroxicam by the CYP2C9 variants

KmVmaxCLint3-cKiR2
μM pmol/min/pmol P450 μl/min/pmol P450 μM
CYP2C9*13-a 30.5  ± 2.60.181  ± 0.0050.00591277  ± 1460.996
CYP2C9*33-a 29.5  ± 17.10.007  ± 0.0020.0002396  ± 2300.866
CYP2C9*53-b 202  ± 34.40.043  ± 0.0030.00020.986
CYP2C9 F114L3-a 94.9  ± 18.00.447  ± 0.0050.0047570  ± 1250.984

Values are the parameter estimates ± S.E. of the estimate.

  • 3-a  Data sets were best fit to a substrate inhibition model (model 4).

  • 3-b  Fitted to standard Michaelis-Menten equation (model 1).

  • 3-c  CLint calculated as the ratio of Vmax/Km, a measure of the efficiency of the enzyme.