The kinetic parameters for enzyme reactions containing 0–40 μM lysoPC 18:0 (stearoyl), and 15 nM group IA sPLA2 (see Fig. 3). Vehicle = no lysoPC. As the concentration of lysoPC increases Vmax is reduced. This result, along with the consistent reduction in Km, demonstrated that the inhibition was uncompetitive. The Ki value was calculated for 40 μM lysoPC only and from reactions with substrates above 15 μM (n.c. = not calculated). R2 = fit to Michaelis-Menten function. No inhibition was found after addition of 40 μM lysoPC 10:0 (decanoyl) to the reactions containing 30 μM substrate when compared to vehicle controls reacted at the same time.