H-1-NMR, C-13-NMR, AND CD-113-NMR STUDY OF THE CD(II) COMPLEX OF A BLOCKED PEPTIDE, Z-CYS-ALA-PRO-HIS-OME, IN ORGANIC-SOLVENTS

The Cd(II) complex of a peptide, Z-Cys-Ala-Pro-His-OMe was prepared an d characterized by absorption, CD, H-1-, C-13-, and Cd-113-nmr and nuc lear Overhauser effect spectroscopy (NOESY) spectra to show the coordi nation of cysteine thiolate and histidine imizazole to Cd(II) ion. The NOESY spectra in dimethyl formamide showed that the cysteine residue 1 vas in proximity to the histidine residue. These results reveal the chelation of Z-Cys-Ala-Pro-His-OMe to Cd(II) ion in solution. Temperat ure-dependent dissociation equilibrium of histidine imidazole in solut ion was observed in this complex. Structural features of the chelating peptide are discussed. (C) 1995 John Wiley & Sons, Inc.