Cadmium-113 and carbon-13 nuclear magnetic resonance spectrometry of cadmium peptide complexes.
The cadmium complexes of glycylglycine, glycylglycylglycine, glycyl-gamma-aminobutyric acid and beta-alanylglycine (beta-Ala-Gly) have been investigated by (113) Cd and (13)C nuclear magnetic resonance spectrometry. The minima observed in plots of the (113)Cd chemical shift vs. pH are consistent with cadmium binding first at the carboxylic site and then at the amino-group site. The chemical shift vs. pH profile for the beta-Ala-Gly system is different from that for the other peptides, and is interpreted as suggesting formation of a five-membered chelate between Cd(II) and glycyl residues at the N-terminal groups and not at the C-terminal groups. The data further indicate that the NH groups of the peptide linkages are probably not involved in complexation with cadmium. Finally, a reported pH-dependent (113)Cd resonance for parvalbumin has been reassigned.
Wang
S M
SM
Kent State Universtiy, Kent, Ohio 44242, USA.
Gilpin
R K
RK