Multinuclear Silver(I)–Selenium Clusters Formation in Selenopeptides
Résumé
The reactions of ionic silver (Ag+) with arginine vasopressin (AVP), a nonapeptide hormone cyclized by two cysteine residues, and its diselenium analogue was explored by an integrated LC-MS, UV-vis, and DFT approach. The replacement of Cys by SeCys in AVP increased the reactivity of the peptide toward Ag+ ions under mildly reducing conditions, with the formation of a Se4Ag4 cluster provided by Ag(I)-mediated dimerization of diselenide AVP. Specific electronic absorption bands confirmed the formation of the Ag4peptide2 complex, supported by DFT calculations. These results provide the first ever evidence that Ag(I) ions bind a selenopeptide and prefer SeCys over Cys as binding sites, opening a perspective on the involvement of selenobiomolecules in the emerging cellular toxicity of silver.
