TABLE 1

Enzyme kinetic parameters of 2-oxo-clopidogrel formation from clopidogrel

The assays were performed by using the microsomes baculovirus/insect cells expressing human P450 (Supersomes). Km and Vmax values were expressed as mean ± S.E. of parameter estimate. CLint, expressed P450 and fmP450 (contribution ratio of each P450) values were scaled to eqs. 2 and 3 under Materials and Methods to determine contribution.

Incubation TimeKVmaxVmax/KmEnzyme Abundances*CLint, expressed P450fmP450 %
minμMpmol/pmol P450/minμl/pmol P450/minpmol P450/mg proteinμl/mg protein/min
CYP1A211.58 ± 1.352.27 ± 0.461.445274.935.8
CYP2B612.08 ± 0.737.66 ± 0.693.681140.519.4
CYP2C1911.12 ± 0.257.52 ± 0.366.711493.944.9
  • * The abundances of CYP1A2, CYP2B6, and CYP2C19 were obtained from the reported data in Rowland Yeo et al. (2004).