α-Helical Propensities of Amino Acids in the Hydrophobic Face of an Amphipathic α- Helix

The α-helical propensity of the 20 amino acids was determined using as a test model, an amphipathic α--helical peptide that is small, monomeric and non-interacting. Amino acid substitutions were made at a "guest" site, centrally located in the non-polar face and surrounded by a uniform environment. The α--helical propensity scale generated using this model system is complete and represents the intrinsic a-helical propensity in the absence of intra- and interchain side-chain interactions.