Potentials of Coupling Membranes

According to Papa, the mechanism which links the redox enzymes with the ATPase complex is the proton flow. Each of these complexes is linked with the other complexes through the proton flow. In terms of thermodynamics the functioning of the primary proton pump results in an electrochemical potential gradient across the membrane, which includes the concentration and electric terms  

Since both terms on the right-hand side are vectors, A/Zh too is a vector motive force. In Mitchell s theory it is the membrane which is the essential condition for the vector nature of the flow. ApH refers to the bulk of the aqueous phases in contact with the membrane. 

Another remarkable property of primary proton pumps is that all the redox reactions take place with the participation of the compounds in which both proton and electron participate in the reaction simultaneously. The simplest and best known type of such a redox system is quinone/hydroquinone. So all the redox systems, despite their different potentials, have a common ingredient— protons. 

The next important postulate of Mitchell s theory concerns the consumers of the energy produced by primary pumps and presupposes the presence in the organella membranes of secondary proton pumps which use the transmembrane proton flow for ATP synthesis and a number of other processes. Essential to this theory is the 

Drachev et using a filter impregnated with lipids, were able to observe generation of a potential in liposomes with an inserted cytochromoxidase. But the absolute value of the transmembrane potential is calculated from an extremely complicated equivalent scheme. 

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