Interactions between Ni2+ ions and tetrapeptides containing (Asp/Lys)HisGly(l/d)His sequence

A series of linear tetrapeptides containing two histidyl residues in positions 2 and 4 with different chirality: DHGH, DHG(d-His), KHGH, KHG(d-His), Ac-DHGH-NH2, Ac-DHG(d-His)-NH2, Ac-KHGH-NH2, and Ac-KHG(d-His)-NH2 were synthesized, characterized and their binding properties towards Ni2+ were investigated. To establish the stoichiometry and the stability of the resulting Ni2+ complexes, potentiometric titrations were carried out. The coordination mode of the complexes formed was investigated by performing extensive spectroscopic analyses (UV–Vis, CD) in strict correlation with the potentiometric results. The effects of the nature of the first amino acid (Lys versus Asp) and of the N-terminal amino group acetylation were determined. A careful comparison of the Ni2+ coordination abilities of the linear peptides provides a specific insight into the impact of the chirality of the C-terminal histidine residue (His4) on the metal binding properties.

A series of linear tetrapeptides containing two histidyl residues in position 2 and 4 were synthesized, characterized and their nickel (II) binding properties were investigated. The effects of the nature of the first amino acid (Lys versus Asp) and of the N-terminal amino group acetylation were determined. A careful comparison of the nickel (II) coordination abilities of the linear peptides provides a specific insight into the effects of histidine chirality on the metal binding properties.Figure optionsDownload as PowerPoint slide