Effects of pH, ionic composition of the medium and temperature on the redox properties of electron carrier metalloproteins studied through voltammetric techniques. Cytochromes c as an example

A review with 71 refs. The redox properties of cytochromes c are remarkably sensitive to pH, ionic strength, ionic compn. of the medium and temp. The effect of increasing concns. of a variety of anions on the redox potential of mitochondrial and bacterial species measured through voltammetric techniques indicate the presence of specific sites of interaction on the protein surface. Proton uptake and release and specific anion binding alter the protein charge and their effect on E° allow information to be obtained on electrostatic effects on the redox properties of the heme. The temp. dependence of the redox potential of cytochrome c changes with pH. At alk. pH values a T-induced structural change occurs above 40°