Table 2

Kinetic parameter estimates for demethylation of (S)-naproxen by the CYP2C9 variants

KmVmaxCLintR2
μM pmol/min/pmol P450 μl/min/pmol P450
CYP2C9*12-a 89.1 ± 66.01.39 ± 0.440.002  ± 0.00020.990
CYP2C9*32-b 2-c 2-c 0.0003  ± 0.000010.990
CYP2C9*52-b 2-c 2-c 0.0005  ± 0.000010.998
CYP2C9 F114L2-b 2-c 2-c 0.002  ± 0.00010.997

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

  • 2-a  Fitted to the two-binding site model (model 3) so that Km andVmax represent kinetics at binding site 1 and CLint represents kinetics at binding site 2.

  • 2-b  Fitted to linear function (model 2), where CLint is the turnover rate for that particular isoform.

  • 2-c  Not applicable since linear kinetics observed. CLint calculated as slope of the line.