What facilitates the formation of hydrogen bonds in beta turns?

The formation of hydrogen bonds in beta turns is primarily facilitated by the interaction between the carbonyl oxygen of one amino acid and the amine hydrogen of another amino acid that is typically three to four residues away in the sequence. This specific interaction is crucial because it lends the beta turn its characteristic structure, allowing the polypeptide chain to reverse its direction, which is essential for the compact and folded nature of many proteins.

Beta turns are a type of secondary structure that connects strands in antiparallel beta sheets and occur commonly in the turns of protein structures. The presence of hydrogen bonds in these turns contributes significantly to the stability of the protein’s overall conformation. It allows for tight turns in the backbone of the protein, which is often necessary for the intricate 3D structures that proteins adopt.

The other options do not describe the primary mechanism responsible for hydrogen bonding in beta turns, hence their role in facilitating these structures is limited compared to the carbonyl-amine interactions.