Final answer:
The poly-proline type II helix in proteins is primarily stabilized by peptide bonds. The option (C) is correct.
Step-by-step explanation:
The poly-proline type II helix in proteins is primarily stabilized by peptide bonds.
The poly-proline type II helix is a secondary structure that occurs when a polypeptide chain folds into a left-handed helical structure. It is found in proteins containing proline residues. In this helix, the backbone of the polypeptide chain forms the helical structure, and the peptide bonds stabilize the helix by providing hydrogen bonding between neighboring residues.
While other forces like van der Waals forces and hydrogen bonds also play a role in stabilizing protein structures, the specific stabilization of the poly-proline type II helix is mainly attributed to the peptide bonds formed in the backbone of the polypeptide chain. Therefore, option (C) is correct.