Phosphorylation coupling

All the ATP comes from oxidative phosphorylation coupled to the metabolism of acetyl-CoA by the TCA cycle. No oxygen, no p oxidation. 

The biochemical classification of mitochondrial DNA is based on the five major steps of mitochondrial metabolism. These steps are illustrated in Figure 42-3 and divide mitochondrial diseases into five groups defects of mitochondrial transport, defects of substrate utilization, defects of the Krebs cycle, defects of the respiratory chain and defects of oxidation-phosphorylation coupling. 

Greenlund AC, Farrar MA, Viviano BL, Schreiber RD. Ligand induced interferon-gamma receptor tyrosine phosphorylation couples the receptor to its signal transduction system (p912). EMBO J 1994 13 1591-1600. 

All parasitic flatworms capable of anaerobic metabolism favour malate as the primary mitochondrial substrate and the oxidative decarboxylations of first malate and then pyruvate generate intramitochondrial reducing power in the form of NADH (Fig. 20.1). In contrast, the pathways used to reoxidize intramitochondrial NADH are quite diverse and depend on the stage or species of parasite under examination, but in all cases, redox balance is maintained and electron-transport associated ATP is generated by the NADH-reduction of fumarate to succinate. In the cestode, hi. diminuta, succinate and acetate are the major end products of anaerobic malate dismutation and are excreted in the predicted 2 1 ratio. In the trematode F. hepatica, succinate is then further decarboxylated to propionate with an additional substrate level phosphorylation coupled to the decarboxylation of methylmalonyl CoA. F. hepatica forms primarily propionate and acetate as end products, again in a ratio of 2 1 to maintain redox balance. 

Reduced oxidative phosphorylation coupled with increased glycolysis in ATP synthesis during die adaptation of fish to cold has been reported by other authors also (Eckbeig, 1962 Freed, 1965 Gubin et al., 1972 Ramaswama and Sushella, 1974 Wells, 1978 Bilyk, 1989). 

Allen, J.F., Bennett,J., Steinback, K.E. and Amtzen, C.J. 1981. Chloroplast protein phosphorylation couples plastoquinone redox changes to distribution of excitation energy between the two photosystems. Nature (Lond) 291.25-29. 

Reductive phosphorylation of p-benzoquinones (1, 1233). This reaction is generally improved by use of P(OCH,),/ClSi(CH,),. which provides p-hydroxyphenyl phosphates after methanolysis. Moreover, C-phosphorylation occurs to a minor extent with this modification. This reductive phosphorylation coupled with selective cleavage of the phosphoryl group with BrSi(CH,)3 (9, 74) provides a route to monoprotected hydroqui-nones from monosubstituted p-benzoquinones. 

The stoichiometry of protons translocated per ATP formed (H /ATP), the related ratio of protons transported into the thylakoid per electron flowing through the chain (H /e") and the resulting ratio ATP/2 e are still controversial. As the assimilation of CO2 requires 3 ATP and 2 NADPH per CO2 assimilated in the plants utilizing the Calvin cycle (the ATP requirement is 5 molecules/C02 in C4 plants), additional light quanta are necessary if the ratio ATP/NADPH (or ATP/2 e ) is lower than 1.5, to produce ATP in the amount needed. This could be provided by cyclic photophosphorylation or the phosphorylation coupled to the Meh-ler reaction (reoxidation by oxygen of the reduced acceptors of PS I). 

Lehninger AL. Phosphorylation coupled to oxidation of di-hydrodiphosphopyridine nucleotide. J. Biol. Chem. 1951 190 345-359. 

The net result of this reaction is the formation of two molecules of ATP per molecule of glucose. This formation of ATP is known as substrate-level phosphorylation to distinguish it from the oxidative phosphorylation coupled to electron transport that occurs in mitochondria (Chapter 14). In erythrocytes,... 

Recall that conversion of ADP to ATP occurs mostly by mitochondrial oxidative phosphorylation coupled to electron transport (Chapter 14). 

The extent of coupling between photophosphorylation and electron transport in chloroplasts is usually expressed by the ratio of ATP formed per pair of electrons transferred, written as ATP/Cj or P/Cj. This parameter expresses the amount of ATP formed divided by the number of pairs of electrons transferred through the electron-transfer chain. The P/ej ratio for phosphorylation coupled to the transfer of electrons from water to photosystem I can be computed by taking the HVe ratio of 2 (4 protons per electron-pair transferred) and the HVATP ratio of 3 (three protons required to flow through CFo F to produce one ATP), to obtain the P/c2 value of 1.33. 

Oxidative Phosphorylation Couples the Oxidation of Carbon Fuels to ATP Synthesis with a Proton Gradient... 

Dimethyl-2-chloro-2-oxo-l,3,2-dioxaphosphole (2). This new reagent for phosphorylative coupling of two different alcohols can be prepared from (1) in 82% overall yield as formulated. This new reagent undergoes displacement... 

One-flask phosphorylative coupling to unsymmetrical dialkyl phosphates... 

One-flask phosphorylative coupling to unsymmetrieal dialkyl phosphates (4). Ramirez and Marecek have developed a convenient method for the preparation of dialkylacetoinyl phosphates (3) without isolation of intermediates. The reagent is the p-nitrophenyl(l,2-dimethylethenylenedioxy)phosphate (2), prepared by the reaction of p-nitrophenol with (1). The reaction is carried out in CHjClj by dropwise addition of R OH and triethylamine (1 eq. of each) to... 

DR Sanadi, DM Gibson, P Ayengar, L Quellet. Evidence for a new intermediate in the phosphorylation coupled to a-ketoglutarate oxidation. Biochim Biophys Acta 13 146-148, 1954. 

Fig. 1 (A) Absorption change at 524 nm in a flash group in the absence (-ADP) and presence (+ADP) of phosphorylation. The solid lines represent the fitted curves. (B) Current-voltage relation calculated from the data in Fig. lA. Jp is calculated as the difference of the flux (+ADP) and the flux (-ADP). (C) Phosphorylation-coupled proton flux as a...

Amount of phosphorylation-coupled protons translocated through the membrane as a function of the amount of synthesized ATP. The slope of the curve gives the H /ATP ratio. 

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