Question

ncouplers interfere with what portion of the electron transport system? Which portion of the electron transport system will still be operational even in the presence of uncouplers? Explain, briefly. Give an example of a small-molecule uncoupler and a peptidic uncoupler.

Answer 1

Oxidative phosphorylation (includes glow of electrons through Electron transport chain) forms electron transport system used for generation of ATP.

• An uncoupler is an agent which inhibits ATP synthesis by oxidative phosphorylation as uncouplers dissociate phosphorylation reactions from those of electron transport chain i.e. Uncouplers inhibit ATP synthesis by oxidative phosphorylation but do not affect the ETC.
• 2,4 DNP (2,4 dinitrophenol) is an uncoupler which acts as H+ ionophore. It allows leakage of H+​​​​​ from inner mitochondrial membrane, therefore proton motive force is not generated and ATP synthase is unable to synthesize ATP
• Thermogenin is an example of uncoupling protein which disspates H+ gradient which is required for ATP synthesis by allowing flow of H+ from intermembrane space back to mitochondrial matrix.