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Results show that Chromatium vinosum hydrogenase, adsorbed at a pyrolytic graphite edgeplane electrode, exhibits high level of hydrogen oxidation activity which is limited by the rate of substrate diffusion as measured by protein film voltammetry.

A study was conducted to characterize a stable 8Fe Azotobacter vinelandii ferrodoxin I (AvFdI), a member of a class of proteins associated with aerobic organisms supporting one (3Fe-4S)(super +/0) cluster and one (4Fe-4S)(super 2+/+) cluster. Protein samples were anaerobically determined under Ar in a Vacuum Atmospheres glovebox. Results indicated that AvFDI supported 3Fe and 4Fe clusters with similar reduction potentials.

The kinetics and mechanism of redox-coupled, long-range proton transfer in an iron-sulfur protein, Azotobacter vinelandii Ferredoxin, was investigated using fast-scan protein-film voltammetry. Results conform to a model for stepwise electron and proton transfers. The system offers an intriguing functional model for redox-driven proton pumps, being both well-defined at the molecular level and amenable to detailed examination by film voltammetry.

Characterization of the novel 'hyper-reduced' form of protein-bound (3Fe-4S) clusters showed that its formation is reversible. It was also determined that in the weakly acidic/neutral region of pH, the cluster consumes a total of three protons for the overall three-proton reduction of (3Fe-4S)(super 1+). In the two-electron reduction of (3Fe-4S)(super 0) in a range of proteins, the product is surprisingly inert each time and the pH-dependent reduction potential is in the region of -700 mV vs SHE at pH 7.