ATP synthase

ATP synthase is a membrane protein complex that uses energy from a proton gradient to join ADP and inorganic phosphate into ATP. Its rotary mechanism couples proton flow through the membrane to chemical bond formation.

Chemiosmosis: Chemiosmosis is the use of an ion gradient across a membrane to drive cellular work. ATP synthase converts the proton gradient's stored energy into ATP.
Adenosine triphosphate: Adenosine triphosphate is a nucleotide that cells use to transfer energy and phosphate groups. ATP synthase produces this molecule from ADP and inorganic phosphate.
Oxidative phosphorylation: Oxidative phosphorylation uses energy from electron transfer to create a proton gradient that drives ATP production. Mitochondrial ATP synthase completes this process by using the gradient to make ATP.
Endosymbiotic theory: Endosymbiotic theory explains mitochondria and chloroplasts as descendants of bacteria incorporated into ancestral eukaryotic cells. Their ATP synthases retain similarities to bacterial enzymes, reflecting organelle ancestry.
Substrate-level phosphorylation: Substrate-level phosphorylation forms ATP by direct phosphate transfer from a metabolic intermediate to ADP. Unlike ATP synthase, it does not depend on a membrane proton gradient.
Proton-motive force: The proton-motive force is the combined electrical and chemical potential energy of a proton gradient across a membrane. It supplies the energy that drives proton passage through the enzyme.
Adenosine diphosphate: Adenosine diphosphate is a nucleotide formed when ATP loses a phosphate group. It is one of the two substrates joined to make ATP.
Mitochondrion: A mitochondrion is a eukaryotic cell organelle where oxidative phosphorylation produces much of the cell's ATP. Its inner membrane houses ATP synthase and the respiratory proton gradient.
Peter D. Mitchell: Peter D. Mitchell was a British biochemist who proposed the chemiosmotic theory of energy coupling. His theory explained how proton gradients power ATP synthase.
ATPase: An ATPase is an enzyme that hydrolyzes ATP to ADP and phosphate, often coupling that reaction to cellular work. ATP synthase can run in reverse as an ATP-hydrolyzing ion pump.

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