Lineweaver-Burk double reciprocal plots illustrating the kinetics of plasma sPLA2 activity in the presence of lysoPCs 16:0 and 18:0. Plots are from ex vivo experiments with plasma. More inhibition (larger differences in 1/V) was found with added lysoPCs (20 μM) as the substrate concentration was increased (smaller 1/[S]). LysoPC treatment also reduced Km (increase in the absolute value of the x intercept). These kinetic parameters were also calculated by nonlinear regression of Michaelis-Menten functions and confirm the uncompetitive character of the inhibition (Table 1).