JEE Main levelSingle correct optionDifficulty 2 of 3bm097
Which statement about the alpha-helix is correct?
AIt is a left-handed coil in which only side chains form hydrogen bonds.
BIt is a right-handed coil in which each C=O is hydrogen bonded to an N-H four residues further along the same chain.
CIt is stabilised mainly by disulfide bridges between its turns.
DIt is held together by hydrogen bonds between two different polypeptide strands lying side by side.
Answer: B
The alpha-helix of proteins is right-handed with about 3.6 residues per turn; hydrogen bonds link C=O of residue n to N-H of residue n+4. Hydrogen bonding between adjacent strands is a feature of the beta-pleated sheet.