Effect of the Peptidic Scaffold in Copper(II) Coordination and the Redox Properties of Short Histidine-Containing Peptides


A linear decapeptide containing three His and one Asp residues and a β-turn-inducing dProPro unit was synthesised. A detailed potentiometric, mass spectrometric and spectroscopic study showed that at a 1:1 ratio of CCu /Cpeptide this peptide formed a major [CuH(OdPro Asp)](2+) species (pH range 5.5-7.0), in which the Cu(2+) ion was bound to the His and Asp residues in square-planar or square-pyramidal geometries. The stability constant corrected for protonated species (log K* CuH(O dPro-Asp)=9.33) is almost equal to the value obtained for the parent [CuH(OAsp)](2+) species (log K*CuH(O-Asp) =9.28), but lower than that obtained for the cyclic [CuH(CAsp)](2+) complex (log K*CuH(C-Asp) =10.79) previously published. Thus, the replacement of the ProGly unit by the stronger β-turn-inducing dProPro unit did not generate a more stable copper(II) species, although the OdPro Asp peptide was structured in solution, as shown by circular dichroism (CD) spectroscopy. Interestingly, the calculated value of Keff showed that this peptide behaved similarly to the OAsp or CAsp counterparts, depending on the pH value. The cyclic voltammetry data indicated that the most easily reducible species were [CuH(OAsp)](2+) (E'(0) =262 mV versus a normal hydrogen electrode (NHE)) and [CuH(OdPro Asp)](2+) (E'(0) =294 mV versus NHE) complexes, the peptidic scaffolds of which are open. A lower value was obtained for [CuH(CAsp)](2+) (E'(0) =24 mV versus NHE). A different degree of non-reversibility was observed for the three copper(II) complexes; this could reflect a different degree of flexibility in their respective peptidic scaffolds.


Ana Fragoso, Tiago Carvalho, Pierre Rousselot-Pailley, Margarida M. Correia dos Santos, Rita Delgado, Olga Iranzo

our authors

Share this project:

Related Publications

We use cookies for marketing activities and to offer you a better experience. By clicking “Accept Cookies” you agree with our cookie policy. Read about how we use cookies by clicking "Privacy and Cookie Policy".