Segments of many polypeptides fold spontaneously into alpha helices or beta pleated sheets. Which interaction primarily stabilizes these secondary structures?

Core Concept

Alpha helices and beta sheets are stabilized primarily by hydrogen bonds between backbone carbonyl oxygens and amide hydrogens. These interactions involve the peptide backbone rather than direct side-chain hydrogen bonding, although amino acid sequence still influences whether a particular region favors a helix, sheet, turn, or another conformation.