776244-45-2Relevant academic research and scientific papers
The L-Proline Residue as a 'Break-point' in Metal - Peptide Systems
Pettit, Leslie D.,Steel, Ian,Formicka-Kozlowska, Grazyna,Tatarowski, Tomasz,Bataille, Michael
, p. 535 - 540 (2007/10/02)
Results are reported of a potentiometric and spectrophotometric study of the H+ and Cu2+ complexes of the tetrapeptides X-Gly-Gly-Gly, Gly-X-Gly-Gly, Gly-Gly-X-Gly, and Gly-Gly-Gly-X where X is the proline (Pro) and sarcosine (Sar) residue (Gly=glycine).All the tetrapeptides (HL) form the series of complexes , -1L>, -2L>, and -3L> (charges omitted).The ligands Gly-X-Gly-Gly also form the bis-complex, .When inserted in a peptide chain the Pro and Sar residues cannot co-ordinate to Cu2+ through their peptide nitrogens since they do not possess ionizable protons.In addition the Pro residue tends to force the peptide chain to form a 'β-turn' and so adopt a 'bent' conformation.These studies demonstrate the formation of a large chelate ring when tetrapeptides containing Pro (and , to a smaller extent, Sar) in the second or third positions co-ordinate to Cu2+.This ring spans the terminal residues of the peptide chain and locks the peptide into a 'bent' or 'horse-shoe' shaped conformation.Cu2+ could therefore play an important role in activating oligopeptides (e.g. neuropeptides) containing proline.
