Protein voltammetry direct

The utility of direct protein voltammetry is enhanced when the molecules... 

Au nanoparticle (AuNP) electrodes prepared through various other deposition strategies have been extensively used for protein voltammetry and in electrochemical biosensing applica-tions. ° ° Electrodes with layers of HRP-modified AuNPs (prepared through covalent modification, self-assembly, or layer-by-layer techniques) have been shown to exhibit electrocatalytic activity toward the reduction of H2O2 through direct electron transfer between electrode and enzyme redox... 

The use of direct electrochemical methods (cyclic voltammetry Pig. 17) has enabled us to measure the thermodynamic parameters of isolated water-soluble fragments of the Rieske proteins of various bci complexes (Table XII)). (55, 92). The values determined for the standard reaction entropy, AS°, for both the mitochondrial and the bacterial Rieske fragments are similar to values obtained for water-soluble cytochromes they are more negative than values measured for other electron transfer proteins (93). Large negative values of AS° have been correlated with a less exposed metal site (93). However, this is opposite to what is observed in Rieske proteins, since the cluster appears to be less exposed in Rieske-type ferredoxins that show less negative values of AS° (see Section V,B). 

The large size of redox enzymes means that diffusion to an electrode surface will be prohibitively slow, and, for enzyme in solution, an electrochemical response is usually only observed if small, soluble electron transfer mediator molecules are added. In this chapter, discussion is limited to examples in which the enzyme of interest is attached to the electrode surface. Electrochemical experiments on enzymes can be very simple, involving direct adsorption of the protein onto a carbon or modified metal surface from dilute solution. Protein film voltammetry, a method in which a film of enzyme in direct... 

Heering HA, Wiertz FGM, Dekker C, de Vries S. 2004. Direct immobilization of native yeast Iso-1 cytochrome c on bare gold Fast electron relay to redox enzymes and zeptomole protein-film voltammetry. J Am Chem Soc 126 11103-11112. 

The first reports on direct electrochemistry of a redox active protein were published in 1977 by Hill [49] and Kuwana [50], They independently reported that cytochrome c (cyt c) exhibited virtually reversible electrochemistry on gold and tin doped indium oxide (ITO) electrodes as revealed by cyclic voltammetry, respectively. Unlike using specific promoters to realize direct electrochemistry of protein in the earlier studies, recently a novel approach that only employed specific modifications of the electrode surface without promoters was developed. From then on, achieving reversible, direct electron transfer between redox proteins and electrodes without using any mediators and promoters had made great accomplishments. 

In this chapter, we review the recent progress in the development of different metal oxide nanoparticles with various shapes and size for fabrication of biosensors. The development of metal oxide nanomaterials surface film for direct electron exchange between electrodes and redox enzymes and proteins will be summarizing. The electrochemical properties, stability and biocatalytic activity of the proposed biosensors will be discussed. The biocompatibility of the metal oxide nanomaterials for enzymes and biomolecules will be evaluated. We will briefly describe some techniques for the investigation of proteins and enzymes when adsorbed to the electrode surfaces. Cyclic voltammetry, impedance spectroscopy, UV-visible spectroscopy and surface imaging techniques were used for surface characterization and bioactivity measuring. 

Electroanalyhcal techniques (also in combination with other techniques, e.g., ophcal techniques such as photometry and Raman spectrometry) can be employed to inveshgate many functional aspects of proteins and enzymes in particular. It is possible to study the biocatalytic process with respect to the chemistry of the active site, the interfacial and intramolecular ET, slow enzyme achva-tors or inhibitors, the pH dependence, the transport of tlie substrate, and even more parameters. For example, slow scan voltammetry can be used to determine the relation of ET rates or of protonation and ligand binding. In contrast, fast scan voltammetry allows the determination of rates of interfacial ET. In addition, it is also possible to investigate chemical reactions that are coupled to the ET process, such as protonation. The use of direct ET for mechanistic studies of redox enzymes was recently reviewed by Leger and Bertrand [27]. Mathemahcal models help to elucidate the impact of different variables on the enhre current signal [27, 75, 76]. 

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