PMR conformational studies of Pd(II) complexes with Ala-Tyr and d-Leu-Tyr depeptides

Abstract

PMR studies of Pd(II) complexes with Ala-Tyr and D-Leu-Tyr revealed the essential role of metal ion in inducing the dipeptide conformation in solution. In a complex with tridentate coordination of dipeptide (pH 3–10) the most stable conformer of a tyrosine residue is that with the aromatic ring in gauche position to carboxyl and amide groups. At high pH a dipeptide is a bidentate ligand (NH 2, N −), the tyrosine residue changes its conformation drastically, and the most stable conformer is that with the aromatic ring in trans position to the carboxyl group. It was found that the C-terminal amino acid does not have any considerable influence on the conformation of an N-terminal amino acid in both kinds of complexes with palladium(II). Increasing the temperature up to 370 K has only a minor effect on the conformer population in solution.