Impact of aza-substitutions on the preference of helix handedness for β-peptide oligomers: a DFT study

We studied the helix preference of the heterochiral pentamers of cis-2-aminocyclohexanecarboxylic acid (c-ACHC) and cis-2-aminocyclopentanecarboxylic acid (c-ACPC) with alternating backbone configurations by replacing C(β)-aza- or C(α)-aza-peptide residues using DFT methods in solution. The helix-handedness preferences of two pentamers were strongly affected by the replacement positions (i.e., chiralities) but not depending on the solvent polarity.