How frequently do α-helices turn according to the structure's characteristics?

The α-helix is a common structural motif in proteins characterized by a right-handed spiral conformation. In this structure, each turn of the helix typically encompasses approximately 3.6 amino acid residues. This specific arrangement promotes hydrogen bonding between the carbonyl oxygen of one residue and the amide hydrogen of another residue located four residues further along the chain, which stabilizes the helical structure.

The helical turn provides a compact and efficient folding pattern that is essential for the stability and function of many proteins. The tight packing of residues within this turn is crucial for the overall three-dimensional structure of protein molecules. Thus, the correct answer signifies the predictive nature of α-helical structures in biochemistry, highlighting their periodic nature based on amino acid composition and molecular interactions.