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 p
eptide chelating agent towards Cu(II) ions. The [-psi (CN4)-] moiety induce
s 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 wort
h noting that the Cu(II)-N-tetr bond does not undergo the hydrolysis proces
s even at high pH although the N-tetr donor is weakly basic. (C) 2001 Elsev
ier Science Ltd. All rights reserved.