Figure 3.

Effect of alkyl chain length and sulfur oxidation state upon inhibitor potency for A) porcine esterase and B) fatty acid amide hydrolase, FAAH. IC₅₀ values were measured following either 5 or 15 min incubation of enzyme and inhibitor. Results are shown as the average ± standard deviation of 3 replicates (error bars are not viewable due to the logarithmic scale, average RSD = 5.4% for esterase and 8% for FAAH). Linear regression values (r²) for the FAAH curves for R = 6, 8, 10 and 12 carbons were: 5 min 0.94, 0.64, 0.46 and 0.41, respectively; 15 min 0.72, 0.45, 0.47 and 0.48, respectively. If an exponential fit was used, the 15 min values were: 0.99, 0.82, 0.69 and 0.62, respectively. The general inhibitor scaffolding is shown in the insert of graph B, with X being thioether, sulfoxide or sulfone as shown in Figure 1. The graph symbols are: Sulfone 5 min, Sulfone 15 min, Sulfoxide 5 min, Sulfoxide 15 min, Thioether 5 min, Thioether 15 min