Anion Binding to Mitochondrial Cytochromes c Studied through Electrochemistry

• DOI: 10.1111/j.1432-1033.1996.0208t.x
• Publication Date: 2004-07-23T09:46:52Z
• Authors: Gianantonio Batti...; Marco Borsari; Daniela Dallari; Isabella Lancellotti; Marco Sola
• Keywords: Affinities; Surface charge; Stoichiometry; Static electricity

The redox potential of horse and bovine heart cytochromes c determined through cyclic voltammetry is exploited to probe for anion–protein interactions, using a Debye–Hückel‐based model. In parallel, protein charge neutralization resulting from specific anion binding allows monitoring surface‐charge/ E o relationships. This approach shows that number anions, most which are biological relevance, namely Cl ‐ , HPO 2‐ 4 HCO 3 NO SO ClO citrate 3‐ oxalate bind specifically the surface, often in sequential manner as result presence multiple sites with different affinities. stoichiometries various anions toward given cytochrome general different. Chloride phosphate appear greater extent both proteins compared other anions. Differences specificity two cytochromes, although highly sequence‐related, observed few data discussed comparatively terms electrostatic geometric properties by reference proposed location amino acid composition sites, when available. Specific this large set bearing charges effect on due net positive surface charge(s) be monitored. 1 H NMR indeed indicates absence significant salt‐induced structural perturbations, hence above change predominantly origin. A systematic study relationships unprecedented. Values 15–25 mV (extrapolated at zero ionic strength) obtained decrease one charge, same order magnitude previous estimates either mutation or chemical modification lysines. effects anion‐induced persist also relatively high strength add related shielding whole surrounding atmosphere: dependence rate electron transfer between partners could involve changes driving force.