Question

Most common types of secondary structures of proteins are

• A. $\alpha$-helix and $\beta$-helix structures
• B. $\alpha$- helix and $\beta$- pleated sheet structures
• C. right and left hand twisted structures
• D. globular and fibrous structures

Answer 1

Answer: (B)

Due to regular folding of backbone of the peptide chain, two most common secondary structures of proteins are $\alpha$-helix and $\beta$-pleated structures. In $\alpha$-helix, all $H$-bonds are formed by twisting the chain into a right handed helix. In $\beta$-pleated, all peptide chains are stretched to maximum extension and then laid side by side and connected by hydrogen bonds.