How can a cell be hydrolyzed

Hunger R

Private practice, Lürlibadstrasse 80, 7000 Chur, Switzerland

"Ultimately, in all life processes, it is only a very specific chemical reaction that provides the necessary energy, and that is the hydrolysis of adenosine triphosphate (ATP)." (1)

ATP cannot be saved. It breaks down in the cytosol into ADP and PO4 and releases -30.5 kJ / mol. At pH 7.0 it is in a strongly charged form. It carries approximately four negative charges. It forms stable complexes with divalent ions. In the cell it is mainly present as an Mg2 + complex. One of its most important functions is the transfer of a phosphate group from ATP to a substrate (ATPases, protein synthesis, etc.) The concentration in the cytosol remains constant at approx. 3 - 4 mmol / l, the Mg concentration at approx. 2 - 3 mmol / l. Mg turns the unstable ATP into the stable MgATP complex.

“More than 90% of the 70 kg of ATP that every person produces every day is provided by the mitochondria. They take up the ADP and the phosphate, which accrues during the hydrolysis of ATP, and regenerate from them ATP, which is transported back into the cytosol ”(1). The ATP is constantly hydrolyzed and re-synthesized. 50 g of ATP are regenerated on average every minute, around 1000 times a day. In the Zytsol, Mg transports the stable MgATP complex to its place of action.

As a positive effector of phosphofructokinase, ADP regulates the rate of glycolysis. MgATP reduces the breakdown of ATP into ADP and PO4. High levels of ATP and low levels of ADP slow down glycolysis. The consumption of glucose, which can be deposited as glycogen or fat in the cell, is reduced, or extracellularly, the build-up of glucose in the blood can lead to insulin resistance. The hydrolysis of the MgATP in the ATPases, during protein synthesis, etc. causes the ADP in the cytosol to increase through the transfer of PO4 from the ATP to its substrate and replaces the ADP from the reduced MgATP decay. During physical work, the ADP concentration in the muscle cells continues to rise and intensively activates the phosphofructokinase so that the glycolysis can burn enough glucose and prevent backlogs.

References: 1) Joachim Rassow in Biochemie, 3rd edition 2012. Thieme

2) physiology. Speckmann, Hescheler, Köhling. 6th edition 2013, Urban & Fischer