A new class of peptide chelating agents towards copper(II) ions

Potentiometric and spectroscopic data including CD and EPR results as well as theoretical calculations have shown that the insertion of the tetrazole ring [-psi (CN4)-] in the tetraalanine sequence leads to a very effective peptide chelating agent towards Cu(II) ions. The [-psi (CN4)-] moiety induces a specific peptide conformation which favours the formation of one or two stable chelating rings stabilising a bent structure, with the coordination of 1N-type in Cut or 3N-type in both CuH-1L and CuH-2L species. It is worth noting that the Cu(II)-N-tetr bond does not undergo the hydrolysis process even at high pH although the N-tetr donor is weakly basic.