<P> The binding change mechanism involves the active site of a β subunit's cycling between three states . In the "loose" state, ADP and phosphate enter the active site; in the adjacent diagram, this is shown in pink . The enzyme then undergoes a change in shape and forces these molecules together, with the active site in the resulting "tight" state (shown in red) binding the newly produced ATP molecule with very high affinity . Finally, the active site cycles back to the open state (orange), releasing ATP and binding more ADP and phosphate, ready for the next cycle of ATP production . </P> <P> Like other enzymes, the activity of F F ATP synthase is reversible . Large - enough quantities of ATP cause it to create a transmembrane proton gradient, this is used by fermenting bacteria that do not have an electron transport chain, but rather hydrolyze ATP to make a proton gradient, which they use to drive flagella and the transport of nutrients into the cell . </P> <P> In respiring bacteria under physiological conditions, ATP synthase, in general, runs in the opposite direction, creating ATP while using the proton motive force created by the electron transport chain as a source of energy . The overall process of creating energy in this fashion is termed oxidative phosphorylation . The same process takes place in the mitochondria, where ATP synthase is located in the inner mitochondrial membrane and the F - part projects into mitochondrial matrix . The consumption of ATP by ATP - synthase pumps proton cations into the matrix . </P> <P> The evolution of ATP synthase is thought to have been modular whereby two functionally independent subunits became associated and gained new functionality . This association appears to have occurred early in evolutionary history, because essentially the same structure and activity of ATP synthase enzymes are present in all kingdoms of life . The F - ATP synthase displays high functional and mechanistic similarity to the V - ATPase . However, whereas the F - ATP synthase generates ATP by utilising a proton gradient, the V - ATPase generates a proton gradient at the expense of ATP, generating pH values of as low as 1 . </P>

Where does atp synthase get the energy to make atp