TABLE 1

Enzymatic kinetic parameters of the thiolactone metabolite produced from prasugrel using recombinant RKIP and hCE2

Enzymatic kinetic parameters are expressed as mean ± S.E. of parameter estimate. The formation of thiolactone metabolite from prasugrel in the recombinant hCE2 indicated a non–straight line in the Eadie-Hofstee plot, suggesting involvement of the substrate inhibition kinetic properties. Therefore, the data were fitted to eq. 3 to calculate the K_m and V_max values. S (μM) is the substrate concentration, K_m (μM) is the Michaelis-Menten constant, V_max (pmol/min/μg protein) is the maximal reaction rate, and Ki is the inhibition constant for the substrate. Km and Vmax for the recombinant RKIP were calculated by using WinNonlin professional based on a pharmacodynamic compiled model (model no.101).