Hydrolysis represents the splitting of a chemical compound into smaller molecules with the inclusion of water. Hydrolysis plays a major role both in the inorganic field and in biology. In living organisms, hydrolytic cleavage occurs under the influence of enzymes.
What is hydrolysis?
Hydrolysis represents a cleavage of a chemical compound into smaller molecules with the inclusion of water. In living organisms, hydrolytic cleavage occurs under the influence of enzymes. In hydrolysis, chemical compounds are split into smaller molecules by absorbing water. This is true in both the inorganic and biological realms. In this process, one partial molecule combines with the hydroxyl group (OH group) and another partial molecule combines with the hydrogen ion (H+). To obtain neutral molecules, the electron of the hydroxyl group formally migrates to the proton. These reactions usually do not occur in one step. In simple reactions, only a few steps are necessary, while complicated conversions always involve a catalyst, which remains unchanged after all reaction steps have been completed. In biology, hydrolysis often involves the breakdown of highly polymeric or compounded compounds. The three most important nutrients carbohydrates (polysaccharides), fats or proteins are hydrolytically degraded. In living systems, the reactions always take place in the presence of enzymes. The enzymes represent catalysts, which are available again unchanged after the hydrolytic cleavage and are ready for the next reaction. The reversal of hydrolysis yields water and is called condensation.
Function and task
Hydrolyses are among the fundamental reactions in biological systems. They ensure that large biomolecules are constantly converted into monomers for use either in building endogenous substances or, through their degradation, in supplying energy to the body. Hydrolysis therefore plays a central role in the body. For example, after food intake, the important nutrients carbohydrates, fats and proteins are broken down into their individual components by hydrolysis. In the case of carbohydrates, for example, the breakdown of polysaccharides into the monomers glucose takes place with water absorption. Fats represent glycerol esterified with fatty acids. Hydrolytic cleavage produces the individual fatty acids and glycerol. Proteins are chains of peptidically linked amino acids that are hydrolytically cleaved into individual amino acids during digestion. Enzymes are involved in all hydrolytic reactions in the body. Enzymes are proteins that catalytically support the reactions. After hydrolysis, the enzymes are present unchanged. Hydrolysis does not only occur during food digestion. Hydrolysis and condensation reactions take place constantly in the body as part of the overall metabolism. Enzymes that catalyze hydrolysis are called hydrolases. The hydrolases can in turn be divided into peptidases, esterases or glycosidases. Among other things, peptidases degrade proteins to form individual amino acids. Esterases, on the other hand, can degrade fats into fatty acids and glycerol. In this case, they are lipases. Glycosidases break down glycosidic compounds. These are either polysaccharides, in which several sugar molecules are glycosidically linked, or compounds that have a glycosidic bond between a sugar moiety and a non-sugar moiety. Therefore, glycosidases include amylase, which converts starch to glucose. Other hydrolases include phosphatases and nucleases. The phosphatases hydrolytically cleave phosphate groups. A good example of this reaction is the conversion of ATP (adenosine triphosphate) to ADP (adenosine diphosphate). Overall, hydrolyses always proceed with the release of energy. This is particularly clear in the reaction of ATP to ADP. This is because this conversion provides the energy previously stored in ATP for other biochemical reactions, heat generation or mechanical movements. Nucleases are responsible for the complete degradation of nucleic acids. These are again divided into the ribonucleases and deoxyribonucleases. Both groups of enzymes hydrolytically cleave the phosphodiester bonds in the nucleic acid molecule to form the individual nucleotides.
Diseases and disorders
Because hydrolysis reactions are constantly occurring in the human body, a wide variety of diseases are also possible in this context.Digestion and many intermediate reactions in metabolism represent hydrolysis reactions. There are special enzymes for each reaction step. However, enzymes are proteins whose function can also be restricted by genetic changes. The failure or deficiency of any individual enzyme can have fatal consequences for health. Enzymes must sometimes be present in large quantities, so that an entire organ is necessary for their secretion. This is true for the digestive enzymes of the pancreas, among others. The pancreas produces mainly lipases and peptidases. It is largely responsible for digesting the food pulp coming from the stomach. Fats and proteins are broken down into their individual components. The body absorbs the amino acids, fatty acids, glycerol and glucose formed via the small intestine. In diseases of the pancreas, massive digestive complaints occur with diarrhea, flatulence and severe abdominal pain. Due to the lack of breakdown of fats, fatty stools may occur. In the acute form of pancreatitis, even self-digestion of the pancreas with a fatal outcome is possible. Due to various causes, the free outflow of digestive juices into the small intestine may be disturbed. They accumulate in the pancreas and dissolve it completely. In the chronic forms of pancreatitis, there is also a constant partial dissolution. Another example of a disease concerning hydrolytic processes is represented by mitochondriopathies. Due to disturbances in ATP synthesis, the energy-supplying reactions of ATP to ADP can only take place to a limited extent. The mitochondriopathies manifest themselves in chronic fatigue and weakness, among other symptoms.
