Modulation of the free energy of reduction in Metalloproteins

The ulytimate determinants of the reduction potential in redox metalloproteins are the enthalpy changes due to coordintaion features and the electrostatics at the site, including the polarity effects exerted by the bulk solvent. The latter follows Coulomb's law unless additional enthalpic terms, due to bond breaking/formation processes associated with structural changes, are present. Entropy changes due to reduction-induced changes in protein flexibility may be minor contributors