Rotational catalysis

The concept of rotational catalysis by ATP synthase is based on (a) P and 0 exchange rate data attesting to strong cooperativity with sequential participation of several catalytic sites (b) Pi and ATP 0-isotopomer distributions indicating that all catalytic sites exhibit identical catalysis and (c) that catalysis is strongly influenced by the y-subunit whose primary structure was not likely to account for spatially similar interactions with the /3-subunits . The model was found to be compatible with the 2.8 A resolution structure of bovine heart mitochondrial Fi-ATPase. ... 

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

Rotational Catalysis Is Key to the Binding-Change Mechanism for ATP Synthesis... 

On the basis of detailed kinetic and binding studies of the reactions catalyzed by F0Fi, Paul Boyer proposed a rotational catalysis mechanism in which the three active sites of F take turns catalyzing ATP synthesis... 

ATP synthase carries out rotational catalysis, in which the flow of protons through F0 causes each of three nucleotide-binding sites in Fi to cycle from (ADP + PJ-bound to ATP-bound to empty conformations. 

The mechanism of chloroplast ATP synthase is also believed to be essentially identical to that of its mitochondrial analog ADP and P, readily condense to form ATP on the enzyme surface, and the release of this enzyme-bound ATP requires a proton-motive force. Rotational catalysis sequentially engages each of the three JS subunits of the ATP synthase in ATP synthesis, ATP release, and ADP + Pj binding (Figs 19-24, 19-25). 

ATP synthase 704 FiATPase 708 rotational catalysis 711 P/O ratio 712 P/2e ratio 712 acceptor control 716 mass-action ratio 716 light-dependent reactions 723 light reactions 723 carbon-assimilation reactions 723 carbon-fixation reaction 723 thylakoid 724 stroma 724 exciton transfer 725 chlorophylls 725... 

Rotational catalysis 1021 Table 18-4 Some Well-Known Respiratory... 

Boekema, E.J., Ubbink-Kok, T., Lolkema.J. S., Brisson, A., and Konings, W. N. (1997). Visualization of a peripheral stalk in V-type ATPase Evidence for the stator structure essential to rotational catalysis. Proc. Natl Acad. Sci. USA 94, 14291-14293. 

Elucidation of the crystal structure of the bovine heart mitochondrial Fi-ATPase (Abraham et al., 1994, Gibbons et. al., 2000) focused attention on rotational catalysis in coupling ATP synthesis and hydrolysis with the proton translocation. Electron microscopy and X-ray structural analysis studies have shown that theFi(part of the enzyme is separated from the Fo by a narrow stalk of around 45 A. 

The World s Smallest Molecular Motor Rotational Catalysis... 

How much speculation was involved in your main achievements, the postulation of the binding change mechanism and the rotational catalysis of ATP production ... 

The rotational aspects remained more speculative and were presented that way in my pubheations. I only said that the rotational catalysis was the best way I could explain the present data. We also had some experiments that people did not pay much attention to but they added considerably to the evidence that there was rotational catalysis. It was enough for me to think that the speculation was likely to be correct, but it remained speculative until John Walker s results became available. On the other hand, I did say that alternate side participation, the second facet, had been adequately established. 

If I want to test myself to see how sure I am of something, I would say, Would I bet a granddaughter on it.> I would not bet a granddaughter on the rotational catalysis I have barely reached the stage to bet all the scientific support in this country on the validity of rotational catalysis, but not a granddaughter. 

Rotational Catalysis Is the Worlds Smallest Molecular Motor... 

Rotational catalysis. Boyer suggested that there... 

Adenosine triphosphate (ATP) is synthesized by rotational catalysis in the Fi domain of mitochondrial FoFi-ATPase. The domain Fq consists of one a, two b and a ring of 9—15 subunits c depending on the species. The subunits c form a ring, connected to the domain Fi via the subunit s and then y and two subunits b and 5. Water-soluble Fi domain has the subunits asPsybe. Catalytic nucleotide-binding sites are formed by each of three subunits p. The chirality (handedness) of the molecular complex is essential for its unidirectional rotation (Tsumuraya et al., 2009). 

Furthermore, rotational catalysis was proposed for the FO-ys-(aP)3-Fl complex [45]. This rotation might be electrically driven by the reversible ballistic proton mechanism, as follows. In ATP synthesis, each ADP-Pi loaded aP-site of the water exposed Fl head is bound in turn to the hydrophobic, topically bent, ys axis. This internal axis is inserted into the FO membrane component so as to form an effective channel for ballistic protons. The aP catalytic unit is comparable to a myosin head, while the biochemical role of the ys axis is quite similar to that of the actin filament in the enzymatic cycle (Scheme 2). Thus, in the direction of synthesis, the impact of a trans-membrane ballistic Fi+ within the hydrophobic catalytic region is proposed to drive three concomitant effects First, dehydration of the terminal phosphate bond results in ATP synthesis. Second, molecular recoil upon the FI+ impact dissociates the ys-aP complex. Third, the abrupt increase of electric charge at the hydrophobic site drives fast relative rotation at 120° towards hydrophobic ys interaction with the next, ADP-Pi loaded, aP-site. Simultaneous exchange of products and substrates, carried out at the other two, water exposed, aP sites, might electrically dictate ongoing rotation in the appropriate direction. 

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