Enzyme Inhibition Kinetics

Steps:

• Recall competitive inhibitors bind active site, competing with substrate, increasing Km but Vmax unchanged.
• Recall non-competitive inhibitors bind allosteric site, reducing enzyme activity, decreasing Vmax but Km unchanged.
• Evaluate choices against these effects on Km and Vmax.
• Identify D matches standard kinetic impacts.

Why D is correct:

• In Michaelis-Menten kinetics, competitive inhibition raises Km (apparent affinity decreases) without affecting Vmax, while non-competitive lowers Vmax by reducing effective enzyme concentration.

Why the others are wrong:

• A: Reverses binding sites—competitive bind active site, non-competitive bind allosteric.
• B: Oversimplifies shapes; competitive mimic substrate for binding, but non-competitive shapes vary without mimicking.
• C: Inaccurate; competitive typically mimic substrate shape, non-competitive can have varied shapes for allosteric binding.

Final answer: D