Redox potential table

Many of the reactions of halogens can be considered as either oxidation or displacement reactions the redox potentials (Table 11.2) give a clear indication of their relative oxidising power in aqueous solution. Fluorine, chlorine and bromine have the ability to displace hydrogen from hydrocarbons, but in addition each halogen is able to displace other elements which are less electronegative than itself. Thus fluorine can displace all the other halogens from both ionic and covalent compounds, for example... 

Various methods have been used to determine the redox potentials (Table XI). Very commonly, EPR-monitored chemical redox titration is performed, which can be used to measure the redox potential not only in isolated complexes but also in membrane preparations. In general, there is good agreement between redox potentials determined in membranes, isolated complexes, or isolated Rieske proteins or fragments the only exception is the water-soluble Rieske fragment from spinach bef complex where differences of more than 50 mV have been observed by the same group but using different methods (31). 

The sequence of the carriers in the chain is shown in Figure 9.6. Each of the components of the chain reduces the next, in sequence, according to the redox potential (Table 9.3). The enzymes and their prosthetic groups are organised into complexes, which can be isolated by gentle disruption of the whole mitochondrion or its inner membrane. Ubiqui-... 

Since the geometries of all peptide complexes studied by Margerum and coworkers are presumed to be essentially the same, these workers were able to generate an empirical set of factors that affect the Cu(III/II) redox potentials for the peptide complexes, analogous to the empirical factors generated by Addison for Cu(II/I) redox potentials (Table 3). These empirical additivity effects for Cu(III/II)-peptide complexes are listed in Table 7 [201]. 

The type I copper sites function as electron transfer centers in the blue copper proteins and in multicopper enzymes, particularly oxidases (33). They are characterized by their intense blue color, their unusually small A values, and their very positive redox potentials (Table II). X-ray crystal structures of several blue copper proteins have been determined, notably plastocyanin (34), azurin (35), cucumber basic blue protein (36), and pseudoazurin (37). The active site structures show marked similarities but also distinct differences (Fig. 8). 

It is a major surprise (98) to find a bis(Met)heme with such a low redox potential (Table II) and a possible explanation for this is that the heme is located in a region of the protein with a relatively high local negative charge density arising from carboxylic acid groups. 

The arrangement of components of the electron transport chain was deduced experimentally. Since electrons pass only from electronegative systems to electropositive systems, the carriers react according to their standard redox potential (Table 14-2). Specific inhibitors and spectroscopic analysis of respiratory chain components are used to identify the reduced and oxidized forms and also aid in the determination of the sequence of carriers. 

Enrichment cultures have been tried repeatedly in the past to search for bacteria that can utilize reduced phosphorus compounds as electron donors in their dis-similatory metabolism. Both hypophosphite and phosphite could be excellent electron donors for a microbial energy metabolism because their oxidation releases electrons at very low redox potentials (Table 1). So far, only one bacterium has been isolated that can run its energy metabolism on the basis of phosphite oxidation to phosphate. 

Re2 Re2 ) and their redox potentials (Table 7.13) correlate linearly with the Hammett constant... 

Electron donors and acceptors differ in the efficiency with which they donate or accept electrons. Their ability to transfer electrons is expressed as the standard oxidation-reduction potential (or standard redox potential) denoted by which is a constant for a redox couple dependent upon temperature, pH and the concentration of the oxidized and reduced species. The measurement of the standard redox potential of redox couples has been by three methods a spectrophoto-metric method, a potentiometric method and electron spin resonance. By convention, standard redox potentials (Table 13.2) refer to reactions recorded as oxidant+ electron(s)- reductant. Electrons flow from couples of higher potential to those of lower potential in an attempt to equalize the two potentials, a phenomenon termed the electron motive force which is measured in volts (or millivolts). These data are not absolute values since measurements of free carriers differ from that of bound carriers, e.g. FeSg., exhibits an apparent E ... 

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