Enzyme inhibitor effects on Michaelis-Menten curves

Steps:

• Without inhibitor: hyperbolic curve with baseline Km (x-intercept) and Vmax (y-max).
• Competitive inhibitor: increases Km (shifts curve right), Vmax unchanged.
• Non-competitive inhibitor: decreases Vmax (lowers asymptote), Km unchanged.
• Match graph lines: line 1 (highest Vmax, lowest Km) = no inhibitor; line 2 (same Vmax, higher Km) = competitive; line 3 (lower Vmax, same Km) = non-competitive.

Why A is correct:

• Matches standard kinetics: competitive alters Km via [I]/(1+[I]) factor in Michaelis-Menten equation; non-competitive reduces Vmax by binding non-active site.

Why the others are wrong:

• B: Swaps competitive and non-competitive, ignoring Km specificity.
• C: Misassigns no inhibitor to line 3, which has reduced Vmax.
• D: Reverses all, confusing Vmax depression with Km shift.

Final answer: A