ferricytochrome c at 275 mM; (b) ferrocytochrome c at 310 M. Solution is pH 7.0 Tris/cacodylic acid buffer.

As the importance of preparing clean protein solutions became increasingly evident in work on cytochrome c, similar purification efforts with myoglobin also had a big effect on improving the heterogeneous electron transfer kinetics in work done by Bertha C.King [55]. As mentioned earlier, Taniguchi’s group later quantified the relationship between the hydrophilicity of an electrode surface with the heterogeneous electron transfer rate constant for myoglobin [47]. The direct electron transfer reaction of myoglobin at a number of solid electrodes now falls in the quasi-reversible heterogeneous electron transfer kinetic regime.