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Transient accumulation of elastic energy in proton translocating ATP synthase

1999; Wiley; Volume: 449; Issue: 1 Linguagem: Inglês

10.1016/s0014-5793(99)00386-5

1873-3468

Dmitry A. Cherepanov, Armen Y. Mulkidjanian, Wolfgang Junge,

Fuel Cells and Related Materials

ATP synthase is conceived as a rotatory engine with two reversible drives, the proton‐transporting membrane portion, F 0 , and the catalytic peripheral portion, F 1 . They are mounted on a central shaft (subunit γ) and held together by an eccentric bearing. It is established that the hydrolysis of three molecules of ATP in F 1 drives the shaft over a full circle in three steps of 120° each. Proton flow through F 0 probably generates a 12‐stepped rotation of the shaft so that four proton‐translocating steps of 30° each drive the synthesis of one molecule of ATP. We addressed the elasticity of the transmission between F 0 and F 1 in a model where the four smaller steps in F 0 load a torsional spring which is only released under liberation of ATP from F 1 . The kinetic model of an elastic ATP synthase described a wealth of published data on the synthesis/hydrolysis of ATP by F 0 F 1 and on proton conduction by F 0 as function of the pH and the protonmotive force. The p K values of the proton‐carrying group interacting with the acidic and basic sides of the membrane were estimated as 5.3–6.4 and 8.0–8.3, respectively.