The energy-transducing membrane is topologically closed and has a low proton permeability

The energy-transducing membrane is topologically closed and has a low proton permeability 

In order to maintain a A/1h+ across a membrane, and to ensure that it is used for the synthesis of ATP and not dissipated by leakage, the membrane must be closed and not leaky to protons. From the rate at which a pH gradient across the membrane decayed, it was shown that the effective proton conductance of the mitochondrial inner membrane [8], bacterial plasma membrane [9], and chloroplast thylakoid membrane [10] have a value of only some 0.5 jttS2/cm, or a million-fold less than the aqueous phases on either side. 

The uncouplers which abolish the coupling of respiratory rate to ATP synthesis act as proton translocators, inducing net proton translocation across the membranes. In this way the proton circuit can be short-circuited , allowing the protons translocated by the generator of to cross back across the membrane without passing through the ATP synthase and producing ATP. The majority of the uncouplers are protonatable, lipophilic compounds with an extensive pi-orbital system which allows the electron of the anionic, de-protonated form to be delocalized [11]. This enhances the permeability of the anionic form in the hydrophobic membrane, and allows the proton translocators to permeate in both their neutral (protonated) and anionic (deprotonated) forms. In this way they can catalyze the net transport of protons 

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