Chemiosmosis is the process that uses the proton gradient built up by the electron transport chain to make ATP. The idea was proposed by Peter Mitchell in 1961 and won him a Nobel Prize in 1978.
2. Protons accumulate there, so their concentration is higher than in the matrix. This forms an electrochemical gradient (a difference in both concentration and charge), a store of potential energy.
3. The inner membrane is impermeable to protons, except through channels in the enzyme ATP synthase.
4. Protons diffuse back into the matrix through ATP synthase. Their flow makes part of the enzyme rotate, which provides the energy to join ADP and inorganic phosphate:ADP + Pi → ATP Because this ATP production depends on the oxidation of reduced NAD and reduced FAD, it is called oxidative phosphorylation.The protons that return to the matrix combine with electrons and oxygen to form water, which helps keep the gradient steep.Uncouplers make the inner membrane leaky to protons, so protons flow back without passing through ATP synthase. Electron transport continues, but the energy is released as heat instead of being used to make ATP. Brown fat in newborn babies and hibernating mammals uses a natural uncoupling protein to generate heat.The same mechanism makes ATP in chloroplasts, where protons are pumped into the thylakoid space.
2. Protons accumulate there, so their concentration is higher than in the matrix. This forms an electrochemical gradient (a difference in both concentration and charge), a store of potential energy.
3. The inner membrane is impermeable to protons, except through channels in the enzyme ATP synthase.
4. Protons diffuse back into the matrix through ATP synthase. Their flow makes part of the enzyme rotate, which provides the energy to join ADP and inorganic phosphate: