The pumping of H+ ions (protons) from the matrix of the mitochondrion through its inner membrane and into the intermembrane space. The energy from NADH is used to transport these protons, and the result is a proton-motive force that drives the synthesis of ATP. The inner mitochondrial membrane is impermeable to protons, but permeable to water, oxygen, and carbon dioxide molecules. However, the protons trapped in the intermembrane space can pass through the proton channel in each ATP synthase (q.v.) embedded in the membrane. The reentry of the protons into the matrix supplies the energy to convert ADP to ATP. See adenosine phosphate, chemiosmotic theory, cytochrome system, electron transport chain, nicotine-adenine dinucleotide (NAD).
Subjects: Genetics and Genomics.