ATP generation

This mechanism was first described as the chemiosmotic theory of ATP generation, or the Mitchell hypothesis. 

As protons pass through a channel in the ATP synthase complex, ADP and P, are joined to form ATP. 

ATP synthesized in the mitochondria is translocated to the cytoplasm by a cotransporter that simultaneously brings ADP into the mitochondria. 

The ATP yield from glucose metabolism via oxidative phosphorylation is approximately 34—36 ATP molecules per glucose molecule (Table 7-1). 

The calculated ATP yield is somewhat variable because glycolytic electrons transferred by the glycerol phosphate shuttle bypass complex I of the electron transport chain. 

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Engelhardt s experiments in 1930 led to the notion that ATP is synthesized as the result of electron transport, and, by 1940, Severo Ochoa had carried out a measurement of the P/O ratio, the number of molecules of ATP generated per atom of oxygen consumed in the electron transport chain. Because two electrons are transferred down the chain per oxygen atom reduced, the P/O ratio also reflects the ratio of ATPs synthesized per pair of electrons consumed. After many tedious and careful measurements, scientists decided that the P/O ratio was 3 for NADH oxidation and 2 for succinate (that is, [FADHg]) oxidation. Electron flow and ATP synthesis are very tightly coupled in the sense that, in normal mitochondria, neither occurs without the other. 

Assuming that the concentrations of ATP, ADP, and P in chloroplasts are 3 mM, 0.1 mM, and 10 mM, respectively, what is the AG for ATP synthesis under these conditions Photosynthetic electron transport establishes the proton-motive force driving photophosphorylation. What redox potential difference is necessary to achieve ATP synthesis under the foregoing conditions, assuming an electron pair is transferred per molecule of ATP generated ... 

In dass 2 (ATP generating), the rate of metabolite production, and oxidation state, are inversely related to the growth effidency. 

The lower than expected yields can be explained by the nature of methane oxidation to methanol in these bacteria. This reaction, catalysed by methane mono-oxygenase, is a net consumer of reducing equivalents (NADH), which would otherwise be directed to ATP generation and biosynthesis. In simple terms the oxidation of methane to methanol consumes energy, lowering the yield. 

In Erythrocytes, the First Site in Glycolysis for ATP Generation May Be Bypassed... 

Sophisticated isotope experiments were also performed using H2180 (Mildred Cohn) and 32P, and various exchange reactions identified between ATP, ADP, and Pr Analysis of the mode of action of two inhibitors was also relevant. Dinitrophenol (DNP) uncoupled the association between oxidation and ATP generation (Lardy and Elvejhem, 1945 Loomis and Lipmann, 1948). Oligomycin inhibited reaction (ii) above, blocking the terminal phosphorylation to give ATP, but not apparently the formation of A C. 

Once an enzyme-catalysed reaction has occurred the product is released and its engagement with the next enzyme in the sequence is a somewhat random event. Only rarely is the product from one reaction passed directly onto the next enzyme in the sequence. In such cases, enzymes which catalyse consecutive reactions, are physically associated or aggregated with each other to form what is called a multi enzyme complex (MEC). An example of this arrangement is evident in the biosynthesis of saturated fatty acids (described in Section 6.30). Another example of an organized arrangement is one in which the individual enzyme proteins are bound to membrane, as for example with the ATP-generating mitochondrial electron transfer chain (ETC) mechanism. Intermediate substrates (or electrons in the case of the ETC) are passed directly from one immobilized protein to the next in sequence. 

Dopson M, Lindstrom EB, Hallberg KB. 2002. ATP generation dnring rednced inorganic snlfnr componnd oxidation by Acidithiobacillns caldns is exclnsively dne jto electron transport phosphorylation. ExtremophUes 6 123-9. 

Mitochondria are subcellular organelles that are energy-generating machines. The electron transport chain is key to ATP generation in mitochondria. 

The faster the run, the greater the contribution from anaerobic glycolysis for ATP generation. 

For calculation of rate of ATP generation from glucose, assuming complete oxidation of glucose, multiply rate of glucose utilisation by 30. 

Figure 2.8 The ATP/ADP cycle. The major ATP-generating process from fuel oxidation is oxidative phosphorylation driven by electron transport in the mitochondria. In muscle, the major energy-requiring process is physical activity. The phosphate ion is omitted from the figure for the sake of simplicity.

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