Enzyme Inhibition Kinetics of Novel Compounds

Inhibitions of the activities of AChE, BChE, MAO-A, and MAO-B by the 15 compounds were investigated at an inhibitor concentration of 10 µM. IC₅₀ values were also determined. The reference reversible inhibitors of AChE and BChE, MAO-A, and MAO-B used were tacrine (or donepezil), toloxatone and lazabemide, respectively, and the reference irreversible inhibitors of MAO-A and MAO-B used were clorgyline and pargyline, respectively. Kinetic parameters, inhibition types, and K_i values of PJ5 (for BChE), PJ13 and PJ15 (for AChE) were determined as the methods previously described^{43 (link)}. Enzyme kinetics were investigated at five different substrate concentrations, that is, at 0, ~ 1/2 × IC₅₀, IC₅₀, and 2 × IC₅₀ for each inhibitor. The inhibition types and K_i values were determined using Lineweaver–Burk Plots and secondary plots.