Biomolecules Question 11
11. The two polypeptides of human insulin are linked together by
[2016]
(a) hydrogen bonds
(b) phosphodiester bond
(c) covalent bond
(d) disulphide bridges
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Answer : d
Hints & Solutions
(d) Insulin is a hormone consisting of 2 polypeptide chains. Each chain is composed of a specific sequence of amino acid residues connected by peptide bonds. In humans, chain A has 21 amino acids, and chain $B$ has 30 . Post translational modifications result in the connection of these two chains by disulfide bridges.
Cysteine residues on A7 and B7, as well as A20 to B19 are covalently connected by disulfide bridges.
