NS9283 is a noncompetitive inhibitor of AChE. NS9283 was applied at concentrations ranging from 1 to 9 μm. The AChE activity of mouse recombinant AChE was measured with ATC in the concentration range of 0.1 to 1.0 mm. The velocity of hydrolysis of ATC is expressed as V_norm defined as v/V_max (where v is the velocity in a given condition and V_max is the maximum velocity measured in the absence of inhibitor). The K_m measured in the absence of NS9283 was 0.10 ± 0.01 mm. NS9283 shows a noncompetitive inhibition profile. The K_i was evaluated (see Materials and Methods) as 11.2 ± 0.8 μm (three experiments).