(b) : Secondary structure of proteins is mainly of two types.
(i) α-helix: This structure is formed when the chain of α-amino acid coils as a right handed screw (called ahelix) because of the formation of hydrogen bonds between amide groups of the same peptide chain.
(ii) β-plated sheet : In this structure the chains are held together by a very large number of hydrogen bonds between C = O and NH of different chains.