Which of the following best describes the stability of an alpha helix?

The stability of an alpha helix is best described as being primarily due to intrachain hydrogen bonds. In an alpha helix structure, the main chain of the polypeptide forms a helical shape where each carbonyl oxygen atom (C=O) of one amino acid forms a hydrogen bond with the amide hydrogen (N-H) of another amino acid that is four residues earlier in the sequence. This pattern of hydrogen bonding is crucial because it helps to stabilize the helical structure, preventing it from unraveling and maintaining its shape.

In this conformation, the specific geometry of the hydrogen bonds contributes to the helix’s right-handed twist, allowing for the most efficient packing of the backbones while retaining essential functionality. While other types of interactions can influence protein stability, intrachain hydrogen bonds are pivotal in establishing and maintaining the alpha helical structure.