Helix–helix interfaces and ligand binding

Helix–helix parallel interfaces can be characterized by certain combinations of amino acids, which repeatedly occur at core positions a and d (leucine zipper nomenclature) in homologous and nonhomologous proteins and influence interhelical angles. Applied for the prediction of interhelical angles in glutathione S-transferase, intracellular chloride channel and annexin molecules from various sources, correct results were achieved in 58 out of 62 proteins. Interhelical angles are found to correlate with the conformation of the glutathione S-transferase ligands glutathione, s-hexylglutathione, glutathione sulfonic acid, and glutathione-s-dinitrobenzene.

► Helix–helix interfaces are characterized by combinations of amino acids at positions a and d.
► Amino acids at core positions influence interhelical angles.
► Glutathione S-transferase interhelical angles can be predicted from amino acids at core positions.
► Interhelical angles are found to correlate with the conformation of the GST ligands.