Final answer:
ATP synthase couples the proton motive force to ATP synthesis in the mitochondrial membrane, driven by the flow of protons across the membrane.
Step-by-step explanation:
The enzyme that couples the proton motive force to ATP synthesis in the inner mitochondrial membrane is called ATP synthase. It is a complex protein that functions like a turbine, using the flow of protons (H+ ions) across the inner mitochondrial membrane through chemiosmosis to drive the synthesis of ATP from ADP and inorganic phosphate (Pi). As protons move through ATP synthase, they trigger rotation within the enzyme, promoting the conversion of ADP and Pi into ATP, a process known as oxidative phosphorylation.