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Substrate-level phosphorylation exemplified with the conversion of ADP to ATP. Substrate-level phosphorylation is a metabolism reaction that results in the production of ATP or GTP supported by the energy released from another high-energy bond that leads to phosphorylation of ADP or GDP to ATP or GTP (note that the reaction catalyzed by creatine kinase is not considered as "substrate-level ...
There are two steps in the pyruvate kinase reaction in glycolysis. First, PEP transfers a phosphate group to ADP, producing ATP and the enolate of pyruvate. Secondly, a proton must be added to the enolate of pyruvate to produce the functional form of pyruvate that the cell requires. [14]
Phosphoenolpyruvate (2-phosphoenolpyruvate, PEP) is the carboxylic acid derived from the enol of pyruvate and phosphate. It exists as an anion. PEP is an important intermediate in biochemistry. It has the highest-energy phosphate bond found (−61.9 kJ/mol) in organisms, and is involved in glycolysis and gluconeogenesis.
PEP (phosphoenol pyruvate) group translocation, also known as the phosphotransferase system or PTS, is a distinct method used by bacteria for sugar uptake where the source of energy is from phosphoenolpyruvate (PEP). It is known to be a multicomponent system that always involves enzymes of the plasma membrane and those in the cytoplasm.
The reaction is similar to the reaction catalysed by pyruvate kinase, which also converts pyruvate to PEP. [3] However, pyruvate kinase catalyses an irreversible reaction, and does not consume ATP. By contrast, PPDK catalyses a reversible reaction, and consumes 1 molecule of ATP for each molecule of pyruvate converted.
In enzymology, a pyruvate, water dikinase (EC 2.7.9.2) is an enzyme that catalyzes the chemical reaction. ATP + pyruvate + H 2 O AMP + phosphoenolpyruvate + phosphate. The 3 substrates of this enzyme are ATP, pyruvate, and H 2 O, whereas its 3 products are AMP, phosphoenolpyruvate, and phosphate.
ATP can also be produced by “substrate level phosphorylation” reactions (ADP phosphorylation by (1,3)-bisphosphoglycerate, phosphoenolpyruvate, phosphocreatine), by the succinate-CoA ligase and phosphoenolpyruvate carboxylkinase, and by adenylate kinase, an enzyme that maintains the three adenine nucleotides in equilibrium (+).
Phosphoenolpyruvate carboxykinase (EC 4.1.1.32, PEPCK) is an enzyme in the lyase family used in the metabolic pathway of gluconeogenesis. It converts oxaloacetate into phosphoenolpyruvate and carbon dioxide. [1] [2] [3] It is found in two forms, cytosolic and mitochondrial.