Cytochrome gold electrode

Mayer D, Ataka K, Heberle J, Offenhaeusser A. 2005. Scanning probe microscopic studies of the oriented attachment and membrane reconstitution of cytochrome c oxidase to a gold electrode. Langmuir 21 8580-8583. 

Figure 3.89 Cyclic voltammograms of 500 pm cytochrome c at a gold electrode modified by (a) 2-mercaptopyridine, (b> 2-mercaptosuccinic acid, 4,4 -dithiobis(butanoic acid), (d) 4-mercaploaniline. pH 7.0 phosphate buffer +0.1 M NaC104. Scan rale 50mVs . From Allen...

Figure 3.96 The effect of increasing time of exposure (as indicated) of a gold electrode once-modified with SSBipy to thiophenol on the cyclic voltammetry of horse heart cytochrome t (0.4mM). 20 mM sodium phosphate/0.1 M NaCI04 pH 7.0. Scan rate 20mVs l. From Hill...

J.C. Cooper, G. Thompson, and C.J. McNeil, Direct electron transfer between immobilized cytochrome c and gold electrodes. Mol. Cryst. Liq. Cryst. 235, 127-132(1993). 

K.D. Gleria, H.A.O. Hill, V.J. Lowe, and D.J. Page, Direct electrochemistry of horse-heart cytochrome c at amino acid-modified gold electrodes. J. Electroanal. Chem. 213, 333-338 (1986). 

FIGURE 17.3 Scheme of the detection principle of antioxidant activity using a cytochrome c functionalized gold electrode. A0I is the antioxidant under investigation. (From [213], with permission.)... 

H. Allen, O. Hill, N.I. Hunt, and A.M. Bond, The transient nature of the diffusion controlled component of the electrochemistry of cytochrome c at bare gold electrodes an explanation based on a self-blocking mechanism. J. Electroanal. Chem. 436, 17-25 (1997). 

Y. Sato and F. Mizutani, Electrochemical responses of cytochrome c on gold electrodes modified with nucleic acid base derivatives - electrochemical and quartz crystal microbalance studies. Electrochim. Acta 45, 2869-2875 (2000). 

Z.Q. Feng, S. Imabayashi, T. Kakiuchi, and K. Niki, Electroreflectance spectroscopic study of the electron transfer rate of cytochrome c electrostatically immobilized on the w-carboxyl alkanethiol monolayer modified gold electrode. J. Electroanal. Chem. 394, 149-154 (1995). 

Y.H. Wu and S.S. Hu, The fabrication of a colloidal gold-carbon nanotubes composite film on a gold electrode and its application for the determination of cytochrome c. Colloid Surface B 41, 299-304 (2005). 

C. Hinnen, R. Parsons, and K. Niki, Electrochemical and spectroreflectance studies of the adsorbed horse heart cytochrome c and cytochrome c3 from D. vulgaris, miyazaki strain, at gold electrode. J. Electroanal. Chem. 147, 329-337 (1983). 

The pioneering works of Hill and Eddows have opened the way to realize fast and efficient electron transfer of enzymes at the electrode surface. They modified a gold electrode with 4,4 -bipyrydyl, an electron promoter, not a mediator since it does not take part in electron transfer in the potential region of interest, to accomplish rapid electron transfer of cytochrome [1], Their work has triggered intensive investigation of electron transfer of enzymes using modified electrodes [2]. 

Figure 3 shows the cyclic voltammograms of cytochrome c recorded in aqueous solution either when the protein is adsorbed (or immobilized) on the electrode (Sn02) surface (a), or when it diffuses to a gold electrode pretreated by adsorption of 4,4 -bipyridyl (b). 

Figure 4 (a) Typical cyclic voltammogram of cytochrome c recorded at a gold electrode... 

Within the promoter there can be subtle structural differences that influence the polar interaction with the protein. For example, Figure 5 illustrates the cyclic voltammograms of cytochrome c obtained at a gold electrode modified with isomers of pyridine-carboxylaldehyde-thiosemi-carbazone (PATS). 

Recently, an inorganic promoter as [Ru(CN)5(Spy)]4 (Spy = 4-thio-pyridine) adsorbed on a gold electrode surface also proved to be very effective in the direct electrochemistry of cytochrome c the tetraanion not... 

Figure 5 Cyclic voltammograms of cytochrome c recorded at gold electrodes modified with different isomers of PATS...

Let us pass to other cytochromes. Cytochrome f (or cytochrome C552) (FW = 15 000), the crystal structure of which is known,11 is an electron carrier present in the photosynthetic chain and also possesses a positive overall charge. It exhibits a reversible Fe(III)/Fe(II) reduction at a gold electrode modified with 4,4/-dithiopyridine,12 Figure 10. 

Figure 10 Cyclic voltammograms at a modified gold electrode (see text) of (a) cytochrome c (b) cytochrome f. Aqueous solution buffered at pH 7.3...

Figure 11 Cyclic voltammogram of cytochrome b5 recorded at a gold electrode pretreated with Cys-Lys-Cys. Aqueous solution at pH 7.0 (KCl 0.1 mol dm 3). Scan rate 0.005 Vs 1...

Before leaving our discussion of cytochromes, it is instructive to examine the voltammetric response of cytochrome c at a gold electrode modified by hydroxoalkanethiol carbon chains of variable length, Figure 14.28... 

Cyclic voltammograms recorded in an aqueous solution of cytochrome c (pH 7.1) at gold electrodes modified by (a) 3-hydroxo-l-propanthiol (b) 11-hydroxo-l-undecanthiol. Scan rate 0.5 V s . T = 0°C... 

Electrochemistry of disulfide unit present in cytochrome c (cyt c) molecules on gold electrodes has also been reported [169]. Disulfide unit in cytochrome c is strongly adsorbed on Au electrodes and this slows down the electron-transfer rate to the heme group. More recently, Krylov et al. [170] have immobilized cytochrome c by self-assembling on the surface-modified Au electrodes. CV was applied to study how denaturation and renaturation of cytochrome c depend on the solution composition. 

The above approach was also used to measure the ET kinetics between ferricyanide and cytochrome c (immobilized on a SAM supported by a gold electrode), as well as the tunneling ET rate constant between the protein and the underlying gold electrode [119]. The value of the measured bimolecular and... 

Fig. 14.37. Speculative cartoon of cytochrome adsorbed c on a COOH-termi-nated self-assembled monolayer on gold. A crys-talline region for HS(CH2)15COOH SAM is depicted. Alkanethiol molecules are represented as end-capped cylinders with a COOH terminus (black) and a thiolate (gray) attachment to the gold electrode. Polypeptide line diagrams of cytochrome c molecule are shown in an electrostatically favored orientation. For clarity, the heme group has been blackened. (Reprinted from Bowden, "Wiring Mother Nature, Interface 6(4) 40-45, Fig. 2, 1997. Reproduced by permission of the Electrochemical Society, Inc.)...

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