Mag: A Cα-methylated, side-chain unsaturated α-amino acid. Introduction into model peptides and conformational preference

Article abstract of DOI:10.1016/S0040-4020(00)00274-X

By a chemo-enzymatic approach we synthesized the chiral, C(α)- methylated α-amino acid Mag, characterized by a side-chain C(γ)=C(δ) bond. We also prepared a series of model peptides containing Mag in combination with Aib and Ala. All of the peptides were fully characterized and their conformational preference was determined in solution by FT-IR absorption and ¹H NMR investigations. X-Ray diffraction analyses of L-Mag, a derivative and three peptides are also presented. We find that this C(α)-methylated α- amino acid is an excellent β-turn and 3₁₀-helix former. A peptide with two Mag residues one on top of the other after one complete turn of the 3₁₀- helix has been synthesized and characterized. 2000 Elsevier Science Ltd.