Redox proteins and enzymes containing iron-sulfur clusters continue to emerge as key elements of cellular metabolism. Proteins and clusters of enormous complexity continue to succumb to experimental definition, such as nitrogenase and hydrogenase enzymes. Simpler systems, including iron-sulfur clusters of the general formula FexSy(SCys) z, have long been subject to fundamental research, including the theoretical modeling of cluster redox potential in variable protein environments. In this review, we explore results obtained on these systems, which are only relatively simple. If the efforts reviewed continue to flourish, they can form the foundation for methods and basic physical principles relevant to the most complex systems.
Keywords: Iron-sulfur, Ferredoxin, Rubredoxin, Redox, Protein dielectric, Effective dielectric, nitrogenase, atmospheric nitrogen, anionic mass, cysteine ligands.