What structural feature do α-helices and β-sheets maximize to allow polypeptides to traverse the interior of a protein?

α-helices and β-sheets are secondary structures in proteins that are stabilized primarily by hydrogen bonding between the backbone amide and carbonyl groups of the polypeptide chain. In an α-helix, each carbonyl oxygen forms a hydrogen bond with the amide hydrogen of an amino acid that is four residues earlier in the sequence, resulting in a helical structure. In β-sheets, hydrogen bonds form between adjacent strands, where carbonyl oxygens and amide hydrogens in neighboring strands interact.

This hydrogen bonding is crucial because it provides the stability needed for these structures to assume a more compact form. By maximizing hydrogen bonds, both α-helices and β-sheets create a more rigid and organized structure that allows polypeptides to fold properly. This efficient packing mechanism minimizes exposure of hydrophobic regions to the aqueous environment, effectively allowing the interior of the protein to accommodate its hydrophobic core.

In summary, the primary structural feature that allows α-helices and β-sheets to traverse the interior of a protein is the maximization of hydrogen bonds, which provide stability and enhance the overall structural integrity of proteins.