Redox thermodynamics of cytochrome c adsorbed on mercaptoundecanol monolayer electrodes

Thermodynamics and kinetics of the electron transfer process of spinach plastocyanin adsorbed on a modified gold electrode

“…As shown elsewhere, the enthalpic stabilization of the reduced state is due to the hydrophobic environment and the low solvent accessibility of the metal center; the negative value of DS 0 rc , which favors the oxidized state, is indeed typical of buried metal centers [35,46,48]. It is well-documented [1,22,23,46,49] that E°0 and the DS 0 rc and DH 0 rc values for freely diffusing proteins are influenced by the nature and concentration of the electrolyte(s) in solution. The data reported in Table 1 show that this is also the case for adsorbed pc, whose reduction thermodynamics turns out to be affected by the ionic strength of the solution in contact with the electrode surface.…”

“…Cytochrome c has been the most thoroughly investigated species in this respect: relatively fast electron transfer in nondenaturing conditions has been obtained recently for this species immobilized both covalently and electrostatically on bare or functionalized solid electrodes [1][2][3][4][5][6][7][8][9][10]16,[19][20][21][22][23][24][25][26]. Much less has been done for other ET proteins.…”

Thermodynamic and kinetic aspects of the electron transfer reaction of bovine cytochrome c immobilized on 4-mercaptopyridine and 11-mercapto-1-undecanoic acid films

“…MP interacts weakly with cyt c through H-bond networks involving the pyridine nitrogen and, possibly, water molecules. The same interaction should also occur for cyt c adsorbed on 11-mercapto-1-undecanol films (MU) [38] for which the E°0 value is 16 mV more positive than that on MP. This must be the result of the formation of different Hbond networks which are responsible for changes in the extent of the electrostatic interaction between the protein surface and the heme center.…”

“…The formal reduction potentials E°0 for cyt c were calculated from the average of the anodic and cathodic peak potentials. This is appropriate since a is found to be approximately 0.5 and E°0 is almost independent of the scan rate in the range 0.02-10 V s -1 [12,31,[38][39][40][41]. The experiments were performed at least two times and the reduction potentials were found to be reproducible within ±2 mV.…”

“…Reduction thermodynamics and surface coverage for bovine cyt c on different SAMs a : 4-mercaptopyridine (MP), 11-mercapto-1-undecanoic acid (MUA), 11-mercapto-1-undecanol (MU) kJ mol -1 , ±4 mV, ±5%, respectively b From Ref [38]. c Values determined for the freely diffusing protein in the same conditions (from Ref [38]…”