Question

Write a note on the formation of α-helix.

Answer 1

1. In the α-helix substructure, the amino acids are arranged in a right-handed helical (spiral) structure and are stabilized by the hydrogen bond between the carbonyl oxygen one amino acid (n^th residue) with amino hydrogen of the fifth residue (n + 4^th residue).

2. The side chains of the residues protrude outside of the helix. Each turn of an α-helix contains about 3.6 residues and is about 5.4 Å long.

3. The amino acid proline produces a line in the helical structure and is often called a helical breaker due to its rigid cyclic structure.

4. Many fibrous proteins such as α-Keratin in hair, nails, wool, skin, and myosin in muscles have α-helix structure. The stretching property of human hair is due to the helical structure of α-keratin in hair.

5. Structure of α-helix

                 Secondary structure of proteins