A single-stranded amphipathic alpha-helix in aqueous solution: design, structural characterization, and its application for determining alpha-helical propensities of amino acids.

In order to investigate the positional effect of a-helical propensities of amino acids in an amphipathic α-helix, an amphipathic α-helical model peptide (Ac-Glu-Ala-Glu-Lys-Ala-Ala-Lys-Glu- Ala-Glu-Lys-Ala-Ala-Lys-Glu-Ala-Glu-Lys-amide) was designed and characterized by circular dichroism and 2D-NMR spectroscopies. This peptide contains 65% α-helical structure in solution, and its monomeric molecular weight in aqueous solution was determined by size-exclusion chromatography. The independence of a-helical structure and stability on peptide concentration demonstrates that helix formation of this peptide is a monomolecular process