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Oxidative phosphorylation (UK / ɒ k ˈ s ɪ d. ə. t ɪ v /, US / ˈ ɑː k. s ɪ ˌ d eɪ. t ɪ v / [1]) or electron transport-linked phosphorylation or terminal oxidation is the metabolic pathway in which cells use enzymes to oxidize nutrients, thereby releasing chemical energy in order to produce adenosine triphosphate (ATP).
The citric acid cycle produces NADH and FADH2 through oxidation that will be reduced in oxidative phosphorylation to produce ATP. [ 2 ] [ 3 ] The cytosolic, intermembrane space , compartment has a higher aqueous:protein content of around 3.8 μL/mg protein relative to that occurring in mitochondrial matrix where such levels typically are near 0 ...
Phosphorylation of glucose and fructose 6-phosphate uses two ATP from the cytoplasm. Glycolysis pay-off phase 4 Substrate-level phosphorylation 2 NADH 3 or 5 Oxidative phosphorylation: Each NADH produces net 1.5 ATP (instead of usual 2.5) due to NADH transport over the mitochondrial membrane Oxidative decarboxylation of pyruvate 2 NADH 5
The glycerol phosphate shuttle was first characterized as a major route of mitochondrial hydride transport in the flight muscles of blow flies. [5] [6] It was initially believed that the system would be inactive in mammals due to the predominance of lactate dehydrogenase activity over glycerol-3-phosphate dehydrogenase 1 (GPD1) [5] [7] until high GPD1 and GPD2 activity were demonstrated in ...
Oxidative phosphorylation contributes the majority of the ATP produced, compared to glycolysis and the Krebs cycle. While the ATP count is glycolysis and the Krebs cycle is two ATP molecules, the electron transport chain contributes, at most, twenty-eight ATP molecules. A contributing factor is due to the energy potentials of NADH and FADH 2.
Coupling with oxidative phosphorylation is a key step for ATP production. However, in specific cases, uncoupling the two processes may be biologically useful. The uncoupling protein, thermogenin —present in the inner mitochondrial membrane of brown adipose tissue —provides for an alternative flow of protons back to the inner mitochondrial ...
ADP and phosphate are needed as precursors to synthesize ATP in the payoff reactions of the TCA cycle and oxidative phosphorylation mechanism. [4] During the payoff phase of glycolysis, the enzymes phosphoglycerate kinase and pyruvate kinase facilitate the addition of a phosphate group to ADP by way of substrate-level phosphorylation. [5]
In oxidative phosphorylation, the key control point is the reaction catalyzed by cytochrome c oxidase, which is regulated by the availability of its substrate – the reduced form of cytochrome c. The amount of reduced cytochrome c available is directly related to the amounts of other substrates: