Axial ligand and polipeptide matrix effects on the reduction thermodynamics of cytochrome c

Insight into the mechanisms of reduction potential modulation in ET metalloproteins can be gained from the factorization of the corresponding enthalpic and entropic components, measured through variable temperature cyclic voltammetry experiments. We have compared the reduction thermodynamics forcytochrome c derivatives in which the axial methionine has been replaced by different ligands (ammonia, imidazole, 2-methyl-imidazole, azide and cyanide) and those for the adducts formed by microperoxidase-11 with the same ligands,plus N-acetylmethionine, glycine and phenyalanine.