We explain what ATP is, what it is for and how this molecule is produced. In addition, what is the ATP cycle and oxidative phosphorylation.
What is the ATP?
In biochemistry, the acronym ATP designates the adenosine triphosphate or adenosine triphosphate, an organic molecule of the nucleotide type, essential for obtaining energy. Chemistry. ATP is the main source of energy for most of the cellular processes and functions of the human body and other living things.
The name of ATP comes from the molecular composition of this coenzyme, from a nitrogen base (known as adenine) linked to the carbon atom of a pentose sugar molecule (also Called ribose) and in turn with three phosphate ions bonded in another carbon atom. All this is summarized in the molecular formula of C10H16N5O13P3 .
The ATP molecule was discovered by the German biochemist Karl Lohmann in 1929, and its functioning and importance in the different energy transfer processes of the recent cell were recorded. In 1941, thanks to the studies of the German-American biochemist Fritz Albert Lipmann.
See also: Metabolism.
What is the purpose of ATP?
The ATP is a useful molecule to momentarily contain the chemical energy released during the metabolic processes of food breakdown, and release it again when necessary to boost the various biological processes of the body, such as cell transport, promote reactions that consume energy or even to carry out mechanical actions of the body, such as walking.
It must be said that ATP does not serve to store chemical energy, as is the case with glucoses or fat; It serves as a transport to the cellular regions where it is needed . Thus, when an energy injection is required, ATP is generated and disposed of as needed, since it is very soluble in water, through the process known as hydrolysis, and when dissolved it releases a large amount of energy in the form of phosphates and other useful molecules.
How is ATP produced?
ATP is synthesized through cellular respiration, specifically through the Krebs cycle, which is carried out in the mitochondria of the cell. For this, chemical energy stored in glucose, proteins and fats is released, through an oxidation process that releases CO2 and energy in the form of ATP. Each of these nutrients from the individual's diet has different metabolic pathways, but they converge on a common metabolite: acetyl-CoA, which starts the Krebs Cycle and allows the process of obtaining chemical energy to converge, since all The cells consume their energy in the form of ATP.
As said before, ATP cannot be stored in its natural state, but as part of more complex compounds, such as glycogen (where glucose is obtained and oxidation of this, in turn, ATP) in animals or Starch in plants. Similarly, it can be stored in the form of animal fat, through the synthesis of fatty acids.
The ATP Cycle involves various stages of chemical transformation, the most important being known as the Krebs Cycle (also the Citric Acid Cycle or the Tricarboxylic Acid Cycle). It is a fundamental process that occurs in the matrix of cellular mitochondria, and that consists of a succession of chemical reactions that aims to release the chemical energy contained in Acetyl-CoA obtained from the processing of the different nutritional nutrients of being alive, as well as obtaining precursors of other amino acids necessary for other biochemical reactions.
This cycle is part of a much larger process that is the oxidation of carbohydrates, lipids and proteins, being its intermediate stage: after the formation of Acetyl-CoA with the carbons of these organic compounds, and prior to oxidative phosphorylation where the "ATP" is assembled by an enzyme called ATP synthetase.
The Krebs Cycle operates thanks to 8 different enzymes that completely oxidize Acetyl-CoA and release two different molecules from each oxidized molecule: CO2 (carbon dioxide) and H2O (water). This occurs when the Acetyl-CoA is removed from carbon atoms that come together with oxaloacetate to form citrate or citric acid (with six carbons), which in turn undergoes a series of transformations that will successively cause isocitrate, ketoglutarate, succinyl-CoA, succinate, fumarate, malate and oxaloacetate again, producing on the way the material from which various ATP molecules will then be obtained.
This is the last stage of the nutrient utilization circuit (catabolism) that results in the production of ATP. It occurs in the cells and is the closure of cellular respiration, after glycolysis and the Krebs cycle. In this, about 38 ATP glucose are obtained for each glucose molecule, thanks to the NADH and FADH2 molecules that were charged during the Krebs cycle and can donate electrons.
This process operates on the basis of two opposing reactions : one that releases energy and another that uses that energy released to produce ATP molecules, thanks to the intervention of ATP synthetase, the enzyme responsible for building energy molecules, adding protons and a phosphate molecule to an ADP molecule (adenosine diphosphate), to obtain water and ATP.
Importance of ATP
ATP is a fundamental molecule for the vital processes of living organisms, as a transmitter of chemical energy for the synthesis of complex and fundamental macromolecules, such as those of DNA, RNA or for the synthesis of proteins that occurs within the cell. That is, the ATP provides a load of energy necessary for certain reactions that take place in the body.
This is explained because it has energy-rich bonds, which can be dissolved in water by the following reaction:
ATP + H2O = ADP (Adenos n Diphosphate) + P + Energy
ATP is key for the transport of macromolecules through the plasma membrane (exocytosis and cellular endocytosis) and also for the synaptic communication between neurons., so that its continuous synthesis is essential, from the glucose obtained from food. Such is its importance for life, that the intake of some toxic elements that inhibit ATP processes, such as arsenic or cyanide, is lethal and causes death in a fulminating way.