Kinetics of inhibition of A/Tokyo/3/67 influenza virus neuraminidase by compound 3. (A) Double reciprocal plot showing competitive inhibition of the reaction by compound 3 final concentrations of 0 (●), 35 (○), 70 (▪), 140 (□), 210 (⧫), and 280 (◊) μM. (B) Replot of the slopes from panel A against inhibitor concentration to determine the Ki value of 59 μM from the abscissa intercept.