Question

Primary structure of polypeptide is stabilised or secondary structure of polypeptide is maintained by

• A. Hydrogen bonds
• B. Disulphide bonds
• C. Ionic bonds
• D. Hydrophobic interactions

Answer 1

Answer: (A)

Hydrogen bonds

The secondary structure of protein or the primary polypeptide is stabilized by the hydrogen bond.

Alpha helix structure of protein is a form of secondary structure of the protein. It is formed due to formation of hydrogen bonds between backbone amide and carbonyl groups. The hydrogen bonds are formed between N-H group of one amino residue with a C=O group of 4th amino acid from the amino acid bearing N-H group. Each turn of alpha helix contains 3.6 amino acid residue.

β-pleated secondary protein structure is formed by the parallel or anti parallel polypeptide chain linked together by H - bonds. It is stabilized by the hydrogen bonds formed between N-H and C=O of the adjacent polypeptide chains. The distance between the adjacent amino acids are 3.5 A${}^o$.

So, the correct answer is option A.