“Ultimately a distinct chemical reaction delivers the energy for every life process: the hydrolysis of adenosintriphosphate (ATP)” (1).
It is not possible to store ATP. It immediately decays into ADP and PO4 in the cytosol and releases 30.5 KJ/mol energy. At a pH 7.0 ATP is highly loaded. It contains almost 4 negative charges. With two negative ions it forms stable complexes. In a cell ATP is mainly found as Mg2+ complexes. One of its main function is the transmission of a phosphate group from ATP to a substrate (ATPases, proteinsynthesis etc.). The concentration in the cytosol remains constant at about 3-4 mmol/l, the Mg concentration at about 2-3 mmol/l. Mg forms out of the instable ATP the stable MgATP complex.
“More than 90% of the 70kg ATP which are produced every day by a human being are formed in the mitochondria. They incorporate the ADP and phosphate which is produced by the hydrolyses and form ATP which is transported back to the cytosol” (1). The ATP is permanently hydrolyzed and newly synthesized. On average every minute 50 g of ATP are regenerated, about 1000 times per day. In the cytosol Mg transports the stable MgATP complex to the site of action.
ADP regulates as a positive effector of the phosphofructokinase the velocity of the glycolysis. MgATP reduces the degradation of ATP in ADP and PO4. High concentrations of ATP and low concentrations of ADP inhibit the glycolysis. The consumption of glucose is reduced. Less glucose may be transformed in glycogen or fat in the cells or extracellularly the accumulation of glucose in the blood may lead to insulin resistance. The hydrolysis of MgATP by the ATPases, by the synthesis of proteins etc. leads by transmission of PO4 from ATP to its substrate to an increase of ADP in the cytosol and replaces the ADP out of the reduced decay of MgATP. At exercise ADP further increases in the muscle cells and activates intensively the phosphofructokinase, so that the glycolysis may use enough glucose preventing an accumulation .
2) Physiologie. Speckmann, Hescheler, Köhling. 6. edition 2013, Urban&Fischer