ATPsyntese

ATPsyntese, commonly known as ATP synthase, is a membrane-associated enzyme complex that catalyzes the formation of ATP from adenosine diphosphate (ADP) and inorganic phosphate (Pi) using energy from a proton or sodium motive force across a biological membrane. The overall reaction is ADP + Pi → ATP, supplying the cell with the primary energy currency used in numerous cellular processes.

Location and structure: In eukaryotes, ATPsyntese resides in the inner mitochondrial membrane; in chloroplasts, it is in the thylakoid membrane; in many bacteria, it is embedded in the plasma membrane. The enzyme typically consists of two coupled sectors: F0, a membrane-embedded proton channel, and F1, a peripheral catalytic domain. The flow of ions through F0 drives rotation of a central rotor, transmitting torque to the F1 unit where conformational changes in the catalytic subunits promote ATP synthesis. The complex operates as a rotary motor driven by the electrochemical gradient across the membrane.

Mechanism: Protons (or sodium ions in some organisms) move down their gradient, causing the rotor to turn. This mechanical energy is converted into chemical energy at the catalytic sites of F1, regenerating ATP from ADP and Pi. The process is reversible; under certain conditions, ATP hydrolysis can power proton pumping to maintain the gradient.

Diversity and significance: Some bacteria use a sodium motive force instead of a proton motive force. The stoichiometry of ATP production varies with the c-subunit count, but typically a small number of ATP molecules are produced per full rotation. ATPsyntese is a proven antibiotic target in some pathogens (for example, bedaquiline inhibits mycobacterial ATP synthase).

History: The rotary mechanism of ATPsyntese was established through decades of research and was recognized with Nobel Prize–level attention in 1997.