The comparison of the structures of haemoglobin and myoglobin shows that they have
The comparison of the structures of haemoglobin and myoglobin shows that they have
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Correct Answer: Option A
Explanation
Haemoglobin (tetramer, MW ~64 kDa per subunit) and myoglobin (monomer, MW ~17 kDa) are both members of the globin protein superfamily. Primary structure comparison: Human haemoglobin-chain and myoglobin share only ~25–30% amino acid sequence identity — DIFFERENT primary structures. 3D structure comparison: Despite divergent sequences, both fold into the characteristic globin fold: 8-helices (designated A–H) with interconnecting loops, a central hydrophobic core, and a haem (iron-protoporphyrin IX) binding pocket. The fold is conserved by function (oxygen binding). This is an outstanding example of structural convergence/conservation despite sequence divergence — different primary structures but similar tertiary (globin fold) structures.