Stabilization of Cu(I) for binding and calorimetric measurements in aqueous solution

摘要

Conditions have been developed for the comproportionation reaction of Cu²⁺ and copper metal to prepare aqueous solutions of Cu⁺ that are stabilized from disproportionation by MeCN and other Cu⁺-stabilizing ligands. These solutions were then used in ITC measurements to quantify the thermodynamics of formation of a set of Cu⁺ complexes (Cu^I(MeCN)3⁺, Cu^IMe6Trien⁺, Cu^I(BCA)2³⁻, Cu^I(BCS)2³⁻), which have stabilities ranging over 15 orders of magnitude, for their use in binding and calorimetric measurements of Cu⁺ interaction with proteins and other biological macromolecules. These complexes were then used to determine the stability and thermodynamics of formation of a 1 : 1 complex of Cu⁺ with the biologically important tri-peptide glutathione, GSH. These results identify Me6Trien as an attractive Cu⁺-stabilizing ligand for calorimetric experiments, and suggest that caution should be used with MeCN to stabilize Cu⁺ due to its potential for participating in unquantifiable ternary interactions.