Stabilization of secondary structure elements by specific combinations of hydrophilic and hydrophobic amino acid residues is more important for proteins encoded by GC-poor genes

► Propensity scale for secondary structure of pentapeptides has been created. ► AT-pressure increases usage of helix-like pentapeptides in helix. ► GC-pressure increases usage of sheet-like pentapeptides in helix. ► GC-pressure increases usage of sheet-like pentapeptides in coil. ► Alanine preferably enters helix in sheet-like pentapeptides.