Category:Complex:ATP synthase

ATP Synthase (aka F_OF₁-ATP synthase or F-type ATPase) is one of the central enzymes in energy metabolism for most organisms. It is a membrane protein found in the inner membrane of mitochondria, the thylakoid membrane of chloroplasts, and the plasma membrane of bacteria. Structurally ATP synthase is composed of two portions: hydrophobic membrane-embedded F_O and hydrophilic F₁ that protrudes by approximately 10 nm from the membrane plane. Both portions are multisubunit complexes. In E. coli F_O is composed of subunits a, b and c in stoichiometry 1:2:10; F₁ consists of subunits alpha, beta, gamma, delta and epsilon in stoichiometry of 3:3:1:1:1.

In most organisms including E. coli ATP synthase uses energy stored in a proton electrochemical potential gradient to make ATP from ADP + P_i. In some other bacteria, e.g. Propionigenium modestum or Iliobacter tartaricus sodium ion gradient energy is used.

During ATP synthesis protons pass through F_O and cause rotation of a ring-shape oligomer of 10 c subunits relative to the peripheral ab₂-complex. This rotation is mechanically passed to subunits gamma and epsilon in F₁. The rotation of the latter relative to other F₁ subunits causes the co-ordinated binding and release of nucleotides and P_i and results in ATP synthesis.

"Proton translocation and ATP synthesis (or hydrolysis) are coupled by a unique mechanism, subunit rotation. Electrochemical energy contained in the proton gradient is converted into mechanical energy in form of subunit rotation, and back into chemical energy as ATP". ^[1]

References

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External Links

Animation of ATP Synthase