JEE Main 2022 · 28 July · evening · Single correct · +4 / −1
Two statements in respect of drug-enzyme interaction are given below
Statement I : Action of an enzyme can be blocked only when an inhibitor blocks the active site of the enzyme.
Statement II : An inhibitor can form a strong covalent bond with the enzyme.
In the light of the above statements, choose the correct answer from the options given below
- (a) Both Statement I and Statement II are true
- (b) Both Statement I and Statement II are false
- (c) Statement I is true but Statement II is false
- (d) Statement I is false but Statement II is true
Answer and solution
Answer (d) Statement I is false but Statement II is true
Solution
Chemistry ma’am · 4 steps
The word only sinks Statement I: an inhibitor can also block an enzyme from outside its active site.
- Competitive inhibition. Some drugs look like the substrate and sit in the active site. The substrate cannot bind, so the enzyme stops working.
- Allosteric inhibition. Other drugs bind at an allosteric site, a different place on the enzyme. This changes the shape of the active site, so the substrate no longer fits. The enzyme is blocked without anything touching its active site, so Statement I is false.
- Strong covalent bond. If an inhibitor forms a strong covalent bond with the enzyme, it cannot be removed easily. The enzyme is blocked permanently, and the body has to make fresh enzyme. This does happen, so Statement II is true.
- So. Statement I is false and Statement II is true, which is option (d).
The idea to keep. An enzyme can be blocked at its active site or at an allosteric site. A strong covalent bond makes the block permanent. Watch for words like only in statement questions.
Answer from the NTA final answer key. Solution by PrepWiser.