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Hydrolysis of the phosphate groups in ATP is especially exergonic, because the resulting inorganic phosphate molecular ion is greatly stabilized by multiple resonance structures, making the products (ADP and P i) lower in energy than the reactant (ATP). The high negative charge density associated with the three adjacent phosphate units of ATP ...
The chain of redox reactions driving the flow of electrons through the electron transport chain, from electron donors such as NADH to electron acceptors such as oxygen and hydrogen (protons), is an exergonic process – it releases energy, whereas the synthesis of ATP is an endergonic process, which requires an input of energy.
Notably, the final steps of ATP hydrolysis include the fast release of phosphate and the slow release of ADP. [43] [44] The release of a phosphate anion from bound ADP anion into water solution may be considered as an exergonic reaction because the phosphate anion has low molecular mass.
In chemical thermodynamics, an exergonic reaction is a chemical reaction where the change in the free energy is negative (there is a net release of free energy). [1] This indicates a spontaneous reaction if the system is closed and initial and final temperatures are the same.
The flow of electrons through the electron transport chain is an exergonic process. The energy from the redox reactions creates an electrochemical proton gradient that drives the synthesis of adenosine triphosphate (ATP). In aerobic respiration, the flow of electrons terminates with molecular oxygen as the final electron acceptor.
An example of a coupled reaction is the phosphorylation of fructose-6-phosphate to form the intermediate fructose-1,6-bisphosphate by the enzyme phosphofructokinase accompanied by the hydrolysis of ATP in the pathway of glycolysis. The resulting chemical reaction within the metabolic pathway is highly thermodynamically favorable and, as a ...
A notable occurrence of dephosphorylation is the conversion of ATP to ADP and inorganic phosphate. Dephosphorylation employs a type of hydrolytic enzyme, or hydrolase , which cleaves ester bonds. The prominent hydrolase subclass used in dephosphorylation is phosphatase , which removes phosphate groups by hydrolysing phosphoric acid monoesters ...
ATP hydrolysis may widen the periplasmic opening and push the substrate towards the outer leaflet of the lipid bilayer. Hydrolysis of the second ATP molecule and release of P i separates the NBDs followed by restoration of the resting state, opening the chamber towards the cytoplasm for another cycle. [41] [44] [52] [55] [81] [85]