What stabilizes antiparallel β-sheets in protein structure?

Antiparallel β-sheets are stabilized primarily by hydrogen bonds that occur between the backbone constituents of the polypeptide chains. In an antiparallel arrangement, the strands run in opposite directions, which allows for optimal alignment of the hydrogen bonds formed between the carbonyl oxygen of one amino acid and the amide hydrogen of another amino acid located on an adjacent strand. This specific configuration creates strong hydrogen bonding interactions that are crucial for the stability of the β-sheet structure.

While hydrophobic interactions, ionic bonds, and van der Waals forces can contribute to overall protein stability and folding, they do not provide the same direct stabilization mechanism for antifparallel β-sheets as hydrogen bonds do. In this case, it is the precise interaction of the polar groups in the backbone that governs the formation and stability of these vital structural elements within proteins.