Metalloproteins electron transfer processes

Because the enthalpies and entropies of metalloprotein electron transfer processes are influenced by changes in protein conformation and solvation, as well as by other structural and medium effects (5, 165, 166), comparison of these parameters over a range of HiPIPs differing by single-point mutations affords considerable insight into the factors underlying cluster redox chemistry. 

The aim in solution studies on metalloprotein is to be able to say more about intermolecular electron transfer processes, first of all by studying outer-sphere reactions with simple inorganic complexes as redox partners. With the information (and experience) gained it is then possible to turn to protein-protein reactions, where each reactant has its own complexities... 

In-situ tunneling through metalloproteins as a three-center multiphonon electron transfer process... 

These intramolecular electron transfer processes provide an opportunity to examine electron transfer within the protein environment. Addition of a reduc-tant, such as aniline, results in efficient reaction of the Ru(III) with the reduc-tant to form Ru(II), which leaves the heme iron in the reduced state. If a redox active metalloprotein is present in the solution, electron transfer between the reduced heme and the added protein can be observed. Production of reduced heme iron and removal of the Ru(III) intermediate can be accomplished within a few hundred nanoseconds, which allows the study of extremely rapid interprotein electron transfer reactions. 

MOLECULAR INTERACTIONS BETWEEN METALLOPROTEINS INVOLVED IN ELECTRON TRANSFER PROCESSES TETRAHEME CYTOCHROME Cj AND FLAVODOXIN. NMR AND MOLECULAR MODELING STUDIES... 

Molecular interactions between metalloproteins involved in electron transfer processes tetraheme cytochrome C3 and flavodoxin. NMR and molecular modeling studies... 

Fritsch-Faules and Faulkner have examined data published on electron transfer processes in metalloprotein systems to test the predictions of their analysis. Original data were obtained from laser flash photolysis and pulse radiolysis measurements. Typical values of A = 3.06 X 10 s and k = 0.105 mm were used. The value of ro chosen... 

Structural studies on electron transfer metalloproteins provide an important origin for discussion of the electron transfer processes themselves.The reduction potentials of a number of cytochromes c, cyt c copper blue proteins plastocyanin, Pc azurin, Az stellacyanin, St and HiPIP, or high potential iron protein, from Chromatium vinosum have been determined using spectro-... 

Redox reactions usually lead, however, to a marked change in the species, as reactions 4-6 indicate. Important reactions involve the oxidation of organic and metalloprotein substrates (reactions 5 and 6) by oxidizing complex ions. Here the substrate often has ligand properties, and the first step in the overall process appears to be complex formation between the metal and substrate species. Redox reactions will often then be phenomenologically associated with substitution. After complex formation, the redox reaction can occur in a variety of ways, of which a direct intramolecular electron transfer within the adduct is the most obvious. 

Highly optimized ET reactions are essential for the operation of these biochemical machines. Much of the research on biological electron transfer aims to define the electronic and structural factors that regulate the rates and efficiencies of these essential transformations. This chapter will focus on studies of ET through proteins, particularly metalloproteins. ET processes involving DNA molecules have been the subject of extensive research as well, but this work is beyond the scope of this chapter. 

Sumi, H. (1998) V-I characteristics of STM processes as a probe detecting vibronic interactions at a redox state in large molecular adsorbates such as electron-transfer metalloproteins. Journal of Physical Chemistry E, 102, 1833-1844. 

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