Heterogeneous electron transfer kinetics biology

Nevertheless, voltammetric techniques have long been applied to the study of direct electron transfer processes of biological molecules. Such early voltammetric studies revealed a high degree of electrochemical irreversibility in the direct heterogeneous electron transfer reactions between electrodes and biological molecules. The irreversible nature of direct electron transfer observed in these early studies precluded the accurate and precise characterization of the electron transfer stoichiometry and thermodynamics of biological molecules. The models alluded to above were often used to account for the irreversible electron transfer kinetics observed in these studies. 

The OTTLE method is very useful for slow electron transfer kinetics such as those of biological redox processes, in which a mediator is frequently used in an indirect coulometric titration [6, 36] and metal complexes with slow heterogeneous kinetics. An example of the latter is a copper complex in which the Cu(II/I) couple very often shows a broad quasi-reversible wave due to slow heterogeneous kinetics. In this case, spectroelectrochemistry is a useful method for obtaining accurate E° values [37]. 

Heterogeneous electron reactions at liquid liquid interfaces occur in many chemical and biological systems. The interfaces between two immiscible solutions in water-nitrobenzene and water 1,2-dichloroethane are broadly used for modeling studies of kinetics of electron transfer between redox couples present in both media. The basic scheme of such a reaction is... 

In the last two decades, studies on the kinetics of electron transfer (ET) processes have made considerable progress in many chemical and biological fields. Of special interest to us is that the dynamical properties of solvents have remarkable influences on the ET processes that occur either heterogeneously at the electrode or homogeneously in the solution. The theoretical and experimental details of the dynamical solvent effects on ET processes have been reviewed in the literature [6], The following is an outline of the important role of dynamical solvent properties in ET processes. 

This book aims to provide a coherent, extensive view of the current situation in the field of chemical kinetics. Starting from the basic theoretical and experimental background, it gradually moves into specific areas such as fast reactions, heterogeneous and homogeneous catalysis, enzyme-catalysed reactions and photochemistry. It also focusses on important current problems such as electron-transfer reactions, which have implications at the chemical as well as biological levels. The cohesion between all these chemical processes is facilitated by a simple, user-friendly model that is able to correlate the kinetic data with the structural and the energetic parameters. 

SECM is a powerful tool for studying structures and heterogeneous processes on the micrometer and nanometer scale [8], It can probe electron, ion, and molecule transfers, and other reactions at solid-liquid, liquid-liquid, and liquid-air interfaces [9]. This versatility allows for the investigation of a wide variety of processes, from metal corrosion to adsorption to membrane transport, as discussed below. Other physicochemical applications of this method include measurements of fast homogeneous kinetics in solution and electrocatalytic processes, and characterization of redox processes in biological cells. 

---