v = Vmax[S] / (Km + [S])
The Michaelis-Menten equation v = Vmax[S]/(Km+[S]) describes enzyme-catalyzed reaction rates. Vmax = maximum velocity at saturating substrate. Km = substrate concentration at half-Vmax, reflecting enzyme-substrate affinity. Competitive inhibitors bind the active site, increasing apparent Km without changing Vmax. Non-competitive inhibitors bind elsewhere, decreasing apparent Vmax without changing Km. Uncompetitive inhibitors bind only the ES complex, decreasing both. The Lineweaver-Burk plot (1/v vs 1/[S]) linearizes the equation: y-intercept = 1/Vmax, x-intercept = -1/Km. Many drugs are enzyme inhibitors: statins inhibit HMG-CoA reductase, ACE inhibitors block angiotensin-converting enzyme.