• Citer

Electrochemical square scheme analysis of macromolecule - electroactive ligand interactions, and its application to DNA binding

par De Rache, Aurore ;Buess Herman, Claudine ;Doneux, Thomas
Référence Journal of electroanalytical chemistry, 745, page (44-55)
Publication Publié, 2015

Article révisé par les pairs

• Accès en ligne
• Détails
• Contenu
• Statistiques

Résumé :

The physico-chemical characteristics of electroactive ligand–macromolecules interactions, such as the association constant or the binding stoichiometry, can be determined by voltammetric titration experiments. The interpretation of the electrochemical behaviour is however not straightforward, because: (i) a single macromolecule can contain various binding sites for a given ligand, so multiple complexes (1:1, 2:1, 3:1, . . .) should be considered; (ii) the free (unbound) and bound ligands have very different diffusion coefficients; (iii) the association/dissociation kinetics can have a significant impact on the voltammetric response. This contribution provides a theoretical framework for the analysis of such titration experiments, in the limiting cases of very fast (‘‘dynamic equilibrium’’) and very slow (‘‘static equilibrium’’) association/dissociation kinetics. Using a statistical site binding model (‘‘Scatchard binding’’) and introducing a conditional association constant, the problem can be treated with a simple electrochemical square scheme. The theoretical treatment is explicitly solved for popular voltammetric methods, but is sufficiently general to be adapted to voltammetries not considered here. Employing voltammetric methods displaying peak-shaped voltammograms, the ‘‘dynamic equilibrium’’ versus ‘‘static equilibrium’’ situations are readily diagnosed by the occurrence of an ‘‘isogalvanic point’’ in the latter case. The tools developed in the theoretical section are used to analyse experimental titration experiments performed on the [Ru(NH3)6]3+–DNA system. Two different DNA sequences are studied, and the results show that these sequences have distinct binding stoichiometries and association/dissociation kinetics with [Ru(NH3)6]3+.2015 Elsevier B.V. All rights reserved.