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- Electron transfer biochemistry: metal reductase activity of triheme cytochrome C3Publication . Calçada, Eduardo Paulo de Oliveira Lopes; Louro, Ricardo Saraiva Loureiro de Oliveira; Correia, Ilídio Joaquim SobreiraAnaerobic microorganisms isolated from sediments such as Desulfuromonas acetoxidans displays a remarkably versatile respiratory mechanism. These microorganisms are Gramnegative, strictly anaerobic bacteria, capable of adapting their metabolism to a wide range of electron acceptors, like toxic elements and insoluble metals. From the large variety of cytochromes from these microorganisms, cytochrome c7 is the most abundant, being a small (9kDa) protein that contains three c‐type hemes with bis‐hystidinyl axial coordination. This protein participates in the reduction of metals. It presents a similar three‐dimensional fold as well a conserved arrangement of the three hemes analogous to the tetraheme cytochrome c3 from sulfate reducing bacteria. However it presents different thermodynamic and kinetic properties. Understanding the molecular mechanisms of the electron transfer in the respiratory chain became a major challenge. It was demonstrated that electrostatic environment of cytochrome c7 is the major factor that controls the binding site of redox partners in electron transfer reactions. Detailed knowledge of the behaviour of this protein in the respiratory electron transfer chain will provide the basis for optimization of applications of Desulfuromonas acetoxidans in bioremediation and also in the development of microbial fuel cell technology.