JEE Main 2021 · 17 March · morning · Single correct · +4 / −1
With respect to drug-enzyme interaction, identify the wrong statement.
- (a) Allosteric inhibitor changes the enzyme's active site
- (b) Allosteric inhibitor competes with the enzyme's active site
- (c) Competitive inhibitor binds to the enzyme's active site
- (d) Non-Competitive inhibitor binds to the allosteric site
Answer and solution
Answer (b) Allosteric inhibitor competes with the enzyme's active site
Solution
Chemistry ma’am · 3 steps
Ask where each inhibitor sits: the active site itself, or a different site that reshapes it.
- Competitive inhibitor. It looks like the substrate and binds at the active site itself. The inhibitor and the substrate compete for the same spot, so (c) is correct.
- Allosteric inhibitor. It binds at a different site, called the allosteric site. This changes the shape of the active site, so the substrate can no longer fit. That makes (a) correct, and since this is how non-competitive inhibition works, (d) is correct too.
Statement Where the inhibitor binds Verdict (a) Allosteric changes the active site allosteric site, reshapes the active site correct (b) Allosteric competes for the active site allosteric site, not the active site wrong (c) Competitive binds the active site active site correct (d) Non-competitive binds the allosteric site allosteric site correct - So. An allosteric inhibitor never occupies the active site, so it does not compete with the substrate there. Statement (b) is the wrong one.
The idea to keep. Competition happens only at the active site. An inhibitor that binds anywhere else is non-competitive or allosteric: it changes the active site's shape instead of blocking it.
Answer from the NTA final answer key. Solution by PrepWiser.