Feedback inhibition (end-product inhibition) in a multi-step metabolic pathway is typically mediated by:
Answer and explanation
Correct answer: D. The final pathway product binding allosterically to the first committed enzyme
- Step 1: Cells maintain homeostasis by preventing the over-accumulation of metabolic end products.
- Step 2: In feedback inhibition, the end product acts as an allosteric inhibitor that binds to a non-catalytic regulatory site on the first rate-limiting committed enzyme.
- Step 3: A classic example is the inhibition of threonine deaminase by L-isoleucine, which instantly arrests flux through the isoleucine biosynthetic pathway.
Answer
The final pathway product binding allosterically to the first committed enzyme.
Why not the others: Substrate binding competitively to terminal enzyme does not regulate pathway initiation; Covalent phosphorylation of all intermediates is energetically wasteful; Proteolytic degradation is an irreversible, slow process rather than rapid feedback.
Practise more Biomolecules and Enzymes.
Free questions with an explanation for every one, and full timed NEET UG mock tests.
More Biomolecules and Enzymes questions
- In competitive enzyme inhibition, how do the Michaelis constant () and the maximum velocity () change in the presence of the i…
- Which classic example illustrates competitive inhibition of an enzyme by a substrate analog?
- According to the B-DNA structural model described by Watson and Crick, what are the pitch of the helix and the distance between two successi…
- Which of the following nitrogenous bases is a double-ring purine derivative found in both DNA and RNA?
- Why does cellulose fail to give a blue color with iodine solution, whereas starch produces an intense blue complex?
- Lecithin, an essential component of the alveolar surfactant and cellular membranes, is classified chemically as a: