Mammalian respiratory electron transfer chain

In the thermodynamically redox-stable resting state, CcOs all Cu ions are in the Cu state and all hemes are Fe . From this state, CcOs can be reduced by one to four electrons. One-electron reduced CcOs are aerobically stable with the electron delocalized over the Cua and heme a sites. The more reduced forms—mixed-valence (two-electron reduced), three-electron reduced, and fully (four-electron) reduced—bind O2 rapidly and reduce it to the redox level of oxide (—2 oxidation state) within <200 p-s [Wikstrom, 2004 Michel, 1999]. This rate is up to 100 times faster than the average rate of electron transfer through the mammalian respiratory chain under normal... 

The oxidation of fatty acids is catalyzed by the FAD-containing acyl coenzyme A dehydrogenases which transfer reducing equivalents to the mitochondrial respiratory chain via a flavin-containing electron transfer flavoprotein (ETF) and subsequently via an ETF dehydrogenase (an Fe/S flavoprotein In addition to the mammalian... 

In juvenile liver fluke and miracidia, a respiratory chain up to cytochrome c oxidase is active and all evidence obtained so far indicates that in F. hepatica at least this electron-transport chain is not different from the classical one present in mammalian mitochondria (Figs 20.1 and 20.2). In the aerobically functioning stages, electrons are transferred from NADH and succinate to ubiquinone via complex I and II of the respiratory chain, respectively. Subsequently, these electrons are transferred from the formed ubiquinol to oxygen via the complexes III and IV of the respiratory chain. 

Electron transport and oxidative phosphorylation represent the most complex membrane processes yet uncovered in living mammalian cells. The broad outlines of this pathway are not much in question. Thus, the oxidation of one molecule of NADH by the respiratory chain results in the formation of three molecules of ATP. Three complexes along this chain—NADH-Q reductase, QH2-cytochrome c reductase, and cytochrome c oxidase—contain the sites where energy is transduced and enabled to interact with the ATPase to generate ATP (Fig. 2). Abundant evidence exists, as well, for the transfer of energy among these three complexes without the involvement of ATP synthesis for instance in ion translocation by the mitochondrion (Emster, 1977). 

---