Peptide [alpha]/[3.sub.10]-helix dimorphism in the crystal state

An example of a solvent-driven [alpha]/[3.sub.10]-helix dimorphismis described for a peptide molecule in the crystalline state. The studies have shown that the interconversion between [alpha]- and [3.sub.10]-helices might be allowed even in peptides composed by [C.sup.[alpha]]-tetrasubstituted [alpha]-amino acids and has provided clues for understanding the interactions of 1,1,1,3,3,3-hexafluoropropan-2-ol (HFIP) with helical peptides.