ATP synthase mechanism

An advanced review of kinetic, structural, and biochemical evidence for the ATP synthase mechanism. 

Each of the three P sites probably, in turn, becomes the high-affinity site, consistent with an ATP synthase mechanism involving protein conformational changes. 

ATP-Synthase Mechanism a Rotating Carousel with Multiple Catalytic Sites... 

FIGURE 22.21 The mechanism of photophosphorylation. Photosynthetic electron transport establishes a proton gradient that is tapped by the CFiCFo ATP synthase to drive ATP synthesis. Critical to this mechanism is the fact that the membrane-bound components of light-induced electron transport and ATP synthesis are asymmetrical with respect to the thylakoid membrane so that vectorial discharge and uptake of ensue, generating the proton-motive force. 

The electrochemical potential difference is used to drive a membrane-located ATP synthase which in the presence of P + ADP forms ATP (Figure 12-8). Scattered over the surface of the inner membrane are the phos-phorylating complexes, ATP synthase, responsible for the production of ATP (Figure 12-1). These consist of several protein subunits, collectively known as F, which project into the matrix and which contain the phosphorylation mechanism (Figure 12-8). These sub-... 

Figure 12-9. Mechanism of ATP production by ATP synthase. The enzyme compiex consists of an Fq sub-compiex which is a diskof "C" protein subunits. Attached is a y-subunit in the form of a "bentaxie." Protons passing through the disk of "C" units cause it and the attached y-subunit to rotate. The y-subunit fits inside the F, subcompiex of three a- and three (3-sub-units, which are fixed to the membrane and do not rotate. ADP and P are taken up sequentiaiiy by the (3-subunits to form ATP, which is expeiied as the rotating y-subunit squeezes each (3-subunit in turn. Thus, three ATP moiecuies are generated per revoiution. For ciarity, not aii the subunits that have been identified are shown—eg, the "axie" aiso contains an e-subunit.

Senios AE, Nadanaciva S, Weher J. 2002. The molecular mechanism of ATP synthesis by FiFq-ATP synthase. Biochim Biophys Acta 1553 188. 

Figure 5.19 Binding-change mechanism for ATP synthase. Rotation of the y subunit inter-converts the three-(3 subunits. The subunit in the tight (T) form contains newly synthesized ATP that cannot be released. Rotation by 120° converts it to the open (O) form, from which ATP can be released, allowing it to bind ADP and P, to begin a new cycle. (From Berg et al., 2001. Reproduced with permission from W.H. Freeman and Co.)...

Campbell, P.N., Smith, A.D. and Peters, T.J. (2005) Biochemistry Illustrated Biochemistry and Molecular Biology in the Post-Genomic Era, 5th edition, Elsevier, London and Oxford, 242 pp. Capaldi, R. and Aggeler, R. (2002) Mechanism of FjF0-type ATP synthase, a biological rotary motor, TIBS, 27, 154-160. 

It shows a section through a bacterial cell (only one corner of the cell is shown). ATP synthase links the discharge of the transmembrane proton gradient to the formation of ATP, A simple mechanism (hydrogen cycling) B. a mechanism in which the membrane-bound electron-transfer proteins are proton pumps. 

Substances that functionally separate oxidation and phosphorylation from one another are referred to as uncouplers. They break down the proton gradient by allowing ions to pass from the intermembrane space back into the mitochondrial matrix without the involvement of ATP synthase. Uncoupling effects are produced by mechanical damage... 

Rotational catalysis by ATP synthase, BINDING CHANGE MECHANISM ROTATIONAL CORRELATION TIME CORRELATION FUNCTION ROTATIONAL DIFFUSION FLUORESCENCE... 

Keywords. ATP synthase. Oxidative phosphorylation. Binding change mechanism. Torsional mechanism. Molecular physiological engineering... 

The Molecular Mechanism of ATP Synthesis by F Fq-ATP Synthase A Scrutiny of the Major Possibilities 67... 

In a series of papers, we have proposed the torsional mechanism of energy transduction and ATP synthesis, the only unified and detailed molecular mechanism of ATP synthesis to date [16-20,56] which addresses the issues of ion translocation in Fq [16, 20, 56], ionmotive torque generation in Fq [16, 20, 56], torque transmission from Fq to Fj [17,18], energy storage in the enzyme [17], conformational changes in Fj [18], and the catalytic cycle of ATP synthesis [18, 19]. We have also studied the thermodynamic and kinetic aspects of ATP synthesis [19,20,41,42,56]. A kinetic scheme has been developed and mathematically analyzed to obtain a kinetic model relating the rate of ATP synthesis to pHjn and pH m in the Fq portion and the adenine nucleotide concentrations in the Fj portion of ATP synthase. Analysis of these kinetic models reveals a wealth of mechanistic details such as the absence of cooperativity in the Fj portion of ATP synthase, order of substrate binding and product release events, and kinetic inequivalence of ApH and Aip. 

Fig. 4. Schematic diagram of the ApH - Aip two mutually non-colinear half-channel model for torque generation by the Fq portion of ATP synthase forming a part of the torsional mechanism of energy transduction and ATP synthesis [16-20,56]...

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