Metal Ions as Enzyme Cofactors — NEET Biology
✅ Asked in NEET 2024The cofactor of the enzyme carboxypeptidase is:
The cofactor of the enzyme carboxypeptidase is:
Answer & NCERT explanation
Correct answer: C — Zinc
Carboxypeptidase is a zinc-containing metalloenzyme that requires zinc as its cofactor for proper functioning. Zinc acts as the cofactor that helps in the catalytic activity of this enzyme which cleaves peptide bonds. Flavin, niacin, and haem are cofactors for different enzymes.
Read more NCERT concept on the PYQ
A number of enzymes require metal ions for their activity which form coordination bonds with side chains at the active site and at the same time form one or more coordination bonds with the substrate, e.g., zinc is a cofactor for the proteolytic enzyme carboxypeptidase.
NTA tests your understanding that certain enzymes require metal ions (like zinc) as cofactors to function. These metal ions form coordination bonds with the enzyme's active site and with the substrate molecule itself, enabling catalysis. Students often mistake cofactors for coenzymes (which are organic) or forget that metal ions directly participate in substrate binding and catalysis. Remember: zinc in carboxypeptidase is a classic example—it's not just present in the enzyme but actively coordinates with both the protein structure and the substrate to facilitate protein digestion. This concept appears frequently because it bridges enzyme structure, metal chemistry, and biochemical function.
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