Electron acceptors, artificial, table

Uncouplers and Energy-linked Processes 1025 Table 18-5 Some Artificial Electron Acceptors... 

The development by Chance of a dual wavelength spectrophotometer permitted easy observation of the state of oxidation or reduction of a given carrier within mitochondria.60 This technique, together with the study of specific inhibitors (some of which are indicated in Fig. 18-5 and Table 18-4), allowed some electron transport sequences to be assigned. For example, blockage with rotenone and amytal prevented reduction of the cytochrome system by NADH but allowed reduction by succinate and by other substrates having their own flavoprotein components in the chain. Artificial electron acceptors, some of which are shown in Table 18-5,... 

APS-reductase does not occur in Rhodospirillaceae, Ectothiorhodospiraceae, and was not found in two species of the Chromatiaceae (see Tables I-IV). In Chromatium vinosum. APS-reductase activity is very high at the end of the exponential growth phase (48). and in Thiocapsa roseopersidna the spedfic activity of this enzyme increases, when sulfide is completely consumed by the cells (U. Fischer, unpublished). Normally, ferriqranide is used as an artificial electron acceptor for the enzyme, but Ulbricht (25) could show for Chromatium grarile that the cell s own c-type cytochrome could replace ferricyanide as electron acceptor. 

Among artificial electron acceptors only ferricyanide is rapidly reduced by complex I dichloroindophenol and methylene blue are poorly effective. As seen in Table II, preparations of complex I are also capable of reducing cytochrome c at a slow rate. This reaction is completely sensitive to inhibition by rotenone or antimycin A and probably results from the presence of traces of complex III in complex I preparations. 

While there is quite a variety of substances that can act as SECM mediators and that are artificial electron acceptors for GOx (Table 1), the extension to different redox enzymes is not straightforward, although examples have been reported. 

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