GATE 2024 CY – Question 23
Among the following metalloproteins, the pair(s) of non-heme proteins is (are)
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Correct answer: (B) Hemocyanin and Carboxypeptidase; (C) Hemerythrin and Carbonic anhydrase
Explanation
**Heme proteins** contain an iron-porphyrin (heme) group. **Non-heme proteins** have metal ions bound to amino acid side chains.
- **Hemoglobin and myoglobin:** both contain heme. ✗
- **Hemocyanin** (copper, oxygen carrier in molluscs and arthropods) **and carboxypeptidase** (zinc enzyme): both non-heme. ✓
- **Hemerythrin** (non-heme di-iron oxygen carrier) **and carbonic anhydrase** (zinc enzyme): both non-heme. ✓
- **Cytochrome P-450** (heme iron) **and hemocyanin:** P-450 is a heme protein, so this pair is not both non-heme. ✗
Answer **B and C**.