This applet demonstrates uncompetitive inhibition of an enzyme acting on a single substrate. Click on the Start button to plot reaction velocity (V) against substrate concentration (S) [left hand graph panel] and to show the corresponding Eadie-Hofstee plots (V/[S] versus V) [right graph panel].

Apparent V_maxs are equal to the intercepts on the V/[S] axis divided by the negative of the slopes of the regression lines in the right graph panel. Apparent K_ms are equal to the negative of the slopes of the regression lines in the right graph panel. The curves drawn through the data points in the left graph panel are obtained by substituting apparent V_maxs and corresponding apparent K_ms in the Michaelis-Menten equation:

Colors refer to different inhibitor concentrations (I0 = 0 mM --- BLACK; I1 = 0.1 mM --- RED; I2 = 0.2 mM --- BLUE; I3 = 0.5 mM --- MAGENTA).

Note that with the default values of [S] and V provided, both the apparent V_max and the apparent K_m values decrease as [I] increases. This shows that the inhibitor, I, is an "uncompetitive" inhibitor. This type of inhibition is distinguished from "noncompetitive" inhibition, which alters only apparent V_max, and from "competitive" inhibition which alters only apparent K_m.