Final answer:
The Poly-proline type II helix is a left-handed secondary structure in proteins, differing from the right-handed α-helix and the β-pleated sheet which has hydrogen bonds in parallel or antiparallel chain configurations.
Step-by-step explanation:
The Poly-proline type II helix is a distinct type of secondary structure found in proteins. This helix is characterized by its left-handed configuration, in contrast to the right-handed α-helix. The question pertains to the type of helix that the poly-proline type II adopts, and the correct answer is B) Left-handed helix.
For reference, the α-helix is a common secondary structure in proteins where the polypeptide chain forms a right-handed coil stabilized by hydrogen bonds between every fourth amino acid, causing 3.6 amino acid residues per turn. In contrast, in the β-pleated sheet, sections of the polypeptide chain also come together side-by-side, either in a parallel or antiparallel configuration, and are held together by hydrogen bonds between carbonyl and amino groups of the backbone.