Question

The helical structure of a protein is stabilized by:
A.Peptide bond
B.Dipeptide bond
C.Hydrogen bonds
D.Van Der Waals forces

Answer 1

Hint: Folded structure that forms within a polypeptide due to interactions between atoms of the backbone is known as secondary structure. $\alpha $ helix and the $\beta $ pleated sheet are the most common types of secondary structures.

Complete step by step answer:
The secondary structures are $\alpha $ helix and the $\beta $ pleated sheet. Both of these structures are held in shape by hydrogen bonds, which form between the carbonyl of one amino acid and the amino group of another. $\beta $ pleated sheet is supercoiled coils in which 2-3 helices coil around each to form a stable structure. Although, alpha helix is the most common and the most stable secondary structure of the protein.
 The helical structure of proteins or the alpha helix is the secondary structure of proteins and it is stabilized by hydrogen bonds. In helical structure, the carbonyl oxygen atoms in ${\text{C = O}}$ points in one direction, towards the amide hydrogen atoms in ${\text{N - H}}$ groups, 4 residues away. These groups together form a hydrogen bond, one of the main forces of secondary structure stabilization in proteins. Hydrogen bonds are shown by dashed lines.

Therefore, we can conclude that the correct answer to this question is option C.

Note:
 Make sure you remember the positioning of hydrogen bonds in the protein structures. The telephone cord shape of the $\alpha $ helix is held in place by hydrogen bonds between every ${\text{N - H}}$ group and the oxygen of a ${\text{C = O}}$ group in the next turn of the helix, interacting with four amino acids down the chain. The typical helix is about 11 amino acids long.