Enzyme Kinetics: Saturation & Inhibition

As substrate concentration [S] rises, reaction rate climbs then plateaus — every active site is busy (enzyme is saturated at V_max). Add an inhibitor to see how the curve changes. Rate v = V_max[S] / (K_m + [S]).

── no inhibitor ── current curve ● your [S]

Inhibitor:

V_max (apparent)100

K_m (apparent)20

at this [S], rate v0

% of V_max0%

substrate [S] 20

Try: switch to Competitive — K_m rises but V_max is unchanged (high [S] out-competes the inhibitor). Then Noncompetitive — V_max drops and no amount of [S] recovers it.