You’ve probably heard something out there about the well-known enzymes, haven’t you? Our organism, to be alive, depends on a series of chemical reactions that occur inside cells and also outside them (in organ cavities, for example). As the temperature of our body is approximately 36oC and the pH close to neutrality (7.0), the environment is not favorable to the development of all these reactions. 

The transformation of proteins into amino acids, for example, is a process where a “breakage” of proteins occurs, and can be performed in laboratories that wish to obtain amino acids in their free form. The difference is that to be able to break the bonds outside the human body, in laboratories it is necessary to subject proteins to boiling processes in acid or basic medium.

Ribozymes: molecules that have a catalyst role

Enzymes are substances of the protein group and act as catalysts for chemical reactions. All enzymes are proteins, but not all proteins are enzymes. It is also important to highlight that some RNA molecules, known as ribozymes, act as enzymes, besides having a catalyst role.

What are catalysts?

Catalysts are substances with the ability to accelerate chemical reactions without participating in them as reagents. That is: they participate in the reaction, increase their speed, but are recovered unchanged at the end of it. The principle of catalyst is to decrease the activation energy. That is, the enzyme binds to a substrate molecule in a specific region called the binding site.

This region is a fitting that presents one side surrounded by chains of amino acids that help bind the substrate, and the other side of this chain acts on catalysis. Enzymatic reactions are very important in food and occur not only in fresh food, but also during its processing and storage. The aroma of onion, for example, is due to the action of alinase, an enzyme that acts on the compounds that contain sulfur present in that food.

How is the nomenclature of enzymes done?

Among the various ways that can be found to perform the nomenclature of enzymes, we can mention 3 most used exampl
es. First, by the classic or recommended name. In this type of nomenclature, it is usually named by adding the termination -ase to the name of the substrate on which the enzyme acts.

For example: the enzyme amylase, it acts on the hydrolysis reaction of starch in glucose molecules. Secondly, we can use the usual name, i.e.: use names consecrated by use, such as trypsin and pepsin. Thirdly, we use the systematic name: this is the most complex form applied to the nomenclature, where we usually use three parts: the name of the substrate, the type of catalyzed reaction and the suffix -ase.

How are enzymes classified?

First, we can classify the enzymes according to the channeled chemical reaction. In this sense, they can be divided into six groups according to the catalization.

Characteristic groups of enzymes

According to the characteristics involved in catalysing, we can classify the groups of enzymes into:


Oxide-reutases: that we can be represented by oxidation-reduction reactions or electron transfer. It is more common to find Dehydrogenenases and Oxidases, for example.

Transferases: groups of enzymes responsible for the transfer of functional groups such as amine, phosphate, acile and carboxy, such as Kinases and Transaminases, for example.

Isomerases: group involving interconversion reactions between optical or geometric isomers, such as Epimerases, for example.

Liases: groups responsible for the breaking reactions of covalent bonds, in addition to the removal of water, ammonia and carbon dioxide molecules, such as Dehydraratses and Decarboxyses.

Hydrolases: group responsible for covalent bond hydrolysis reactions, and peptidases can be cited, for example.

Main types of enzymes

As we have seen, depending on the reaction, the function of an enzyme can change. With this, we can find various types of enzymes that have a differentiated role in the body. Among the main types of enzymes, we can mention:

Catalase: responsible, mainly for the decomposition of hydrogen peroxide.

Lipase: this, in turn, fulfills the role of facilitating lipid digestion.

Trypsin: its main function is to take care of proteins that have not gone through the digestion process.

Protease: Its main function is to act on protein reactions.

Urease: responsible for the degradation of urea.

Enzymes that cause darkening in food

Fruits and vegetables that contain phenolic compounds in their composition, when cut and exposed to air, suffer darkening caused by the enzyme polyphenoloxidase (PPO). What this enzyme does is oxidize the phenols to orthoquinones. These latter compounds polymerize easily forming dark compounds, melanins. These enzyme darkening reactions can be more easily observed in light-colored vegetables such as bananas, potatoes and apples, for example.

References

BiologyNet: Enzymes.
Stoodi: Enzymes
.- Scientific knowledgeR7: Enzymes.



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