Harnessing the flexibility of peptidic scaffolds to control their copper(II) coordination properties

摘要

Two decapeptides, C-Asp (cyclic) and O-Asp (linear), containing three His and one Asp have been synthesized.Potentiometric studies in aqueous solution revealed the formation of a major species, [CuHL]2+, at 1:1 Cu2+:peptideratio and in the pH range 5.0–7.5. A detailed spectroscopic study, including UV-Vis, CD, EPR and NMR, showedthat the [CuHL]2+ species is very similar for both peptides and that Cu2+ is coordinated by the amino acid sidechain functionalities . Nonetheless, as a result of the cyclization, different behaviours were observed as revealed byCD and NMR data. Namely, a more rigid structure and slower Cu2+ exchange rate for [CuH(C-Asp)]2+ comparedto [CuH(O-Asp)]2+.