LIASAS: FUNCTIONS AND TYPES - BIOLOGY - 2024

Lyases are enzymes that are involved in cutting or adding groups in a chemical compound. The principle of this reaction is based on the cutting of CC, CO or CN bonds. Consequently, new double bonds or ring structures are formed (Mahdi and Kelly, 2001).

On the other hand, lyases participate in cellular processes such as the citric acid cycle and in organic synthesis, such as the production of cyanohydrins.

Three-dimensional structure of polygalacturonic acid lyase (pectate lyase). By Jawahar Swaminathan and MSD staff at the European Institute of Bioinformatics, from Wikimedia Commons.

These proteins are different from other enzymes in that they have certain special details. In one sense of the reaction they act on two substrates, while in the opposite direction they affect only one substrate.

In fact, its effect causes the elimination of a molecule, which produces a structure with a double bond or the appearance of a new ring. In particular, the enzyme polygalacturonic acid lyase (pectate lyase), which breaks down pectin and gives rise to single units of galacturonic acid, rhamnose and dextrin. Furthermore, it is present in some phytopathogenic fungi and bacteria.

Lyase functions

Lyases are an interesting group of enzymes, which have many roles in the life of our planet. Thus, they are protagonists of important processes for the life of organisms.

That is, the lack of these proteins induces the death of beings. In short, the knowledge of these proteins is fun and shocking. On the other hand, it teaches the complexity of the processes that surround us.

In addition, their functions vary depending on the type of lyase. Consequently, there is a wide variety of enzymes with lyase activity. In such a way that they are capable of making cuts in the bonds of highly variable molecules.

On the other hand, let's see some examples of these proteins and the functions they carry out:

Phospholipase C

It provides this organism with the ability to modify the digestive system of some insects. Consequently, it favors its rapid multiplication throughout the animal's body.

Carbonic anhydrase

Converts carbon dioxide to bicarbonate and protons. In the presence of water, it is related to the maintenance of the acid-base balance in the blood and tissues, as well as the rapid elimination of carbon dioxide from these.

However, this enzyme in plants increases the concentration of carbon dioxide in the chloroplast, which increases the carboxylation of the enzyme rubisco.

Reaction catalyzed by carbonic anhydrase. By GarcíaGerry, from Wikimedia Commons.

Enolase

Converts 2-phosphoglycerate to phosphoenolpyruvate in glycolysis. As well as, it can perform the reverse reaction in gluconeogenesis. Obviously, it seeks to synthesize glucose when there is a deficit of this sugar in the cells.

In addition to these classic functions, enolase is present in the axons of nerve cells. It is also a marker of neuronal damage and other damage to the nervous system.

Carboxylase

As a result of its action, it removes the carboxyl groups from pyruvic acid. Consequently, it converts it to ethanol and carbon dioxide.

In yeast, it destroys the CO2 in the cells and produces ethanol. This compound works as an antibiotic.

Phospholipase C

It is located in the membranes of trypanosomes and a great variety of bacteria. It generates the cut of GPI proteins present in these membranes. In fact, it has been detected in Trypanosoma brucei.

PEPCK

It is involved in gluconeogenesis, converts oxaloacetate to phosphoenolpyruvate and carbon dioxide. On the other hand, in animals it allows liver or kidney cells to form glucose from other metabolites.

Aldolasse

It exerts its action in glycolysis; cuts fructose-1,6-BF into two trioses, DHAP and glyceraldehyde 3-phosphate. Therefore, this enzyme located in the cytosol of most organisms plays an important role in the extraction of energy from sugars.

On the other hand, the evaluation of blood (or serum) aldolase is a tool that allows to determine the damaged structures in organs such as the liver, muscle, kidney or heart.

Alkylmercury lyase

It exerts its action on a substrate of alkyl-mercury and hydrogen ions, to produce an alkane and mercury ions.

Its fundamental biological role is to participate in toxic elimination mechanisms, because it converts organic mercury compounds into agents that are not harmful.

Oxalomalate lyase

In particular, it transforms 3-oxomalate into two products: oxoacetate and glyoxylate.

It works in the Krebs cycle, so that fungi, protists and plants form sugars from acetates taken from the medium.

Types of lyases

Within the group of lyases there are several subclasses:

Carbon-carbon lyases

These enzymes cut carbon-carbon bonds. They are classified into the following types:

• Carboxy-lyases: that add or remove COOH. In particular, they remove groups of amino acids, of the type alpha-keto-acids and beta-keto-acids.
• CHO-liases: condenses aldol groups in the reverse direction.
• Oxo acid lyases: cut acid 3-ROH or reverse reactions.

Liasas c arbono-o xigen

These enzymes break CO bonds. They are between them:

1) Hydroliases, which remove water. As they are, carbonate or citrate de-hydratase, fumarate hydratase, among other proteins.

2) Liases, which remove alcohol from sugars. Heparin lyase, pectate lyase, glucuronan lyase, as well as many other enzymes are found (Albersheim 1962, Courtois 1997).

3) Liases that exert their action on phosphate substrates and remove phosphate.

Carbon-nitrogen lyases

Obviously, they are enzymes that cut carbon-nitrogen bonds. They are divided into:

1) Ammonium lyases, which break carbon-nitrogen bonds and form NH3. Whose action is on aspartate, threonine or histidine.

2) In addition, there are lyases that cut CN bonds in amides or amidines. For example, adenylosuccinate lyase.

3) Amino-lyases, cuts carbon-nitrogen bonds in amine groups. In such a way that, strict sidine synthase, deacetyl ipecoside synthase, are in this group of enzymes.

Carbon-sulfur lyases

They are enzymes that cut carbon-sulfur bonds. For example, cysteine ​​lyase, lactoylglutathione lyase, or methionine γ-lyase.

Carbon-halide lyases

First, this subclass was originally established on the basis of the enzyme for removing hydrochloric acid (HCl) from 1,1,1-trichloro-2,2-bis-ethane (DDT).

Phosphorous-oxygen lyases

Phospholipase C is in this category of lyases.

Carbon-phosphorus lyases

In particular, they exert their action on carbon-phosphorus bonds.

References

1. Mahdi, JG, Kelly, DR, 2001. Lyases. In: Rehm, H.-J., Reed, G. (Eds.), Biotechnology Set. Wiley – VCH Verlag GmbH, Weinheim, Germany, pp. 41-171.
2. Palomeque P., Martínez M., Valdivia E. and Maqueda M. (1985). Preliminary studies of the entomotoxic effect of Bacillus laterosporus against Ocnogyna baetica larvae in Jaén. Bull Serv. Plagues, 11: 147-154.
3. Lafrance-Vanasse, J.; Lefebvre, M.; Di Lello, P.; Sygusch, J.; Omichinski, JG (2008). Crystal Structures of the Organomercurial Lyase MerB in Its Free and Mercury-bound Forms insights into the mechanism of methylmercury degradation. JBC, 284 (2): 938-944.
4. Kondrashov, Fyodor A; Koonin, Eugene V; Morgunov, Igor G; Finogenova, Tatiana V; Kondrashova, Marie N. (2006). Evolution of glyoxilate cycle enzymes in Metazoa: evidence of multiple horizontal transfer events and pseudogene formation. Biology Direct, 1:31.
5. Albersheim, P. and Killias, U. (1962). Studies relating to the purification and properties of pectin transeliminase. Arch. Biochem. Biophys. 97: 107-115.
6. Courtois B, Courtois J (1997). Identification of glucuronan lyase from a mutant strain of Rhizobium meliloti. Int. J. Biol. Macromol. 21 (1-2): 3-9.