The synthesis of ATP from ADP and Pi is an _____ reaction

For the fist time the mitochondrial process of oxidative phosphorylation has been studied by determining the extent and initial rates of electron flow, H+ translocation, O2 uptake and ATP synthesis under close to in vivo concentrations of oxygen. The following novel results were obtained. 1) The real rates of O2 uptake and ATP synthesis are orders of magnitude higher than those observed under state-3 metabolic conditions. 2) The phosphorylative process of ATP synthesis is neither kinetically nor thermodynamically related to the respiratory process of H+ ejection. 3) The ATP/O stoichiometry is not constant but varies depending on all, the redox potential (), the degree of reduction of the membrane and the relative concentrations of O2, ADP, and protein. 4) The free energy of electron flow is not only used for the enzymatic binding and release of substrates and products but fundamentally for the actual synthesis of ATP from ADP and Pi. 5) The concentration of ADP that produces half-maximal responses of ATP synthesis () is not constant but varies depending on both and O2 concentration. 6) The process of ATP synthesis exhibits strong positive catalytic cooperativity with a Hill coefficient, of ~3.0. It is concluded that the most important factor in determining the extent and rates of ATP synthesis is not the level of ADP or the proton gradient but the concentration of O2 and the state of reduction and/or protonation of the membrane.

The synthesis of ATP from ADP and Pi by mitochondria

 2. Brand MD. The stoichiometry of proton pumping and ATP synthesis in mitochondria.  1994;16:20-4

ADP and Pi binding, (2) ATP synthesis, ..

. The medium was that described under Experimental Procedures. The experiment was initiated by adding 400 nmols of ADP and 6.3 nmols of ATP (as contaminant of ADP) to an free from RLM and succinate. After 1.5 min of incubation, 1.0 mg of RLM protein was added to initiate the hydrolysis of the 6.3 nmols of ATP that proceed without the uptake O2 until a seemingly endless state of equilibrium was attained. This period of equilibrium was only interrupted when either succinate (10 Mm) was added to initiate the simultaneous processes of O2 uptake and ATP synthesis or the concentration of O2 was near zero.

that synthesizes ATP from ADP and Pi

In the next steps of glycolysis, the phosphate on the 3-position of the 3-phosphoglycerate is transferred to the hydroxyl residue at position 2. Removal of the elements of water from 2-phosphoglycerate results in the formation of an enolic phosphate compound, phospho(enol)pyruvate (PEP). The free energy of hydrolysis of PEP to form the enol form of pyruvate and Pi is on the order of —4 kcal/mol. In aqueous solution, however, the enol form of pyruvate is very unstable. Thus, the hydrolysis of PEP to form pyruvate is a very exergonic reaction. The AG0 for this reaction is —14.7 kcal/mol, which corresponds to an equilibrium constant of 6.4 x 1010. PEP is thus an excellent phosphoryl donor and the formation of pyruvate is coupled to ATP synthesis. Since two molecules of pyruvate are formed per glucose catabolized, two ATP are formed. Thus the net yield of ATP is two per glucose oxidized to pyruvate.

CATABOLIC METABOLISM: THE SYNTHESIS OF ATP …

The hydrolysis of acyl phosphates, such as that of position 1 of 1,3-bisphosphoglycerate, is characterized by strongly negative AG0 values. That for 1,3-bisphos-phoglycerate is approximately —10 kcal/mol, which is significantly more negative than the AG0 for the hydrolysis of ATP to ADP and Pi. Thus, the transfer of the acyl phosphate from 1,3-bisphosphoglycerate to ADP to form 3-phosphoglycerate and ATP is a spontaneous reaction. Since two sugar acid bisphosphates are formed per glucose metabolized, the two ATP invested in the beginning of the pathway have been recovered.

Atp Synthesis | Adenosine Triphosphate | Citric Acid Cycle

Thus, ATP binding, not hydrolysis, is accompanied by a large free-energy change, and this binding energy is used to establish the pathway both kinetically and thermodynamically by driving the rapid dissociation of dynein from the microtubule.",}

ATP can be hydrolyzed to ADP and Pi by the ..

The oxidation of NADH and FADH2 by molecular oxygen is coupled in mitochondria to the endergonic synthesis of ATP from ADP and Pi. For many years the nature of the common intermediate between electron transport and ATP synthesis was elusive. Peter Mitchell, who received a Nobel Prize in chemistry in 1978 for his extraordinary insights, suggested that this common intermediate was the proton electrochemical potential. He proposed in the early 1960s that electron transport through the mitochondrial chain is obligatorily linked to the movement of protons across the inner membrane of the mitochondrion. In this way, part of the energy liberated by oxidative electron transfer is conserved in the form of the proton electrochemical potential. This potential, A^H+, is the sum of contributions from the activity gradient and that of the electrical gradient: