Szucs proteins

Both ellipsometry and cyclic voltammetry were used by Szucs etal to investigate both the adsorption and the mediated and unmediated electron-transfer processes of cytochrome c on gold. The adsorption of cytochrome c was studied by ellipsometry on gold electrodes that had not been treated with surface modifiers. The measurements were carried out at 400 mV (vs. NHE), which was approximately equivalent to the open-circuit potential of the system in the absence of protein in the electrolyte. An irreversibly adsorbed layer formed that completely covered the electrode. They found the value of the calculated thickness of the adsorbed layer on bare gold to be about half that expected if cytochrome c has been in its native form, which suggested that significant unfolding occurred upon adsorption. 

Szucs et alP studied both the adsorption and the mediated and unmediated electron transfer from cytochrome c on a gold electrode using ellipsometry and cyclic voltammetry. They found that the protein formed an irreversibly adsorbed layer that completely covered the electrode. The adsorbed cytochrome c was able to mediate the reduction of cytochrome c in solution via electron transfer through the unfolded protein layer. They did not observe oxidation of cytochrome c in the potassium phosphate... 

Szucs et al found that the structural change upon adsorption on bare gold caused a change in the redox potential of cytochrome c from 260 to -150 mV. Since the reduction of bulk proteins was also changed to this lower potential, the authors concluded that the protein in solution could be reduced only when the adsorbed protein was already reduced. Thus, the adsorbed layer on bare gold acted as an immobilized mediator for electron transfer between the underlying metal and cytochrome c in solution, but only for the reduction process. Because this adsorbed mediator had a redox potential that is lower than the redox potential of the native... 

Szucs, J. and R.E. Gyurcsanyi. 2012. Towards protein assays on paper platforms with potentiometric... 

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