We explain what enzymes are and their structure. Also, how these proteins are classified and how they act.
What are enzymes?
Enzymes are a set of proteins responsible for catalyzing (firing, accelerating, modifying, slowing down and even stopping) various chemical reactions, provided they are thermodynamically possible. This means that are regulatory substances in the body of living beings, usually by decreasing the initial energy required to start the reaction.
Enzymes are essential for life and catalyze about 4,000 known chemical reactions, as long as the pH, temperature or chemical concentration conditions are stable, since enzymes, being proteins, can also become denatured and lose their effectiveness.
The first enzyme was discovered at mid 19th century by Anselme Payen and Jean-Francois Persoz, although the experiments around fermentation by Louis Pasteur had already intuited the presence of some organic “accelerating” substance in these processes, which at the time were considered purely chemical.
Enzymes today are widely known and in fact used by various human industries (food, chemicals, agriculture, oil, etc.), in addition to being an indispensable part of the components that maintain the internal balance of our body, accelerating necessary reactions (such as those that supply energy), activating and deactivating others selectively (as hormones do) and a motley etcetera.
Structure of enzymes
Most enzymes they are made up of globular proteins of highly variable size: from monomers of 62 amino acids, to huge chains of around 2500. However, only a few of them are directly involved in the catalysis of the reaction, known as active center.
The sequence in which all these amino acids are assembled determines the three-dimensional structure of the enzyme, which also dictates its specific functioning. Sometimes this structure also has sites to attract cofactors, that is, other substances whose intervention is necessary to produce the desired effect.
Enzymes are highly specific, that is, they do not react with anything or take part in any reaction. They have a very specific and precise biochemical task, which they carry out with a very low percentage of errors.
Classification of enzymes
Enzymes are classified based on the specific reaction they catalyze, as follows:
- Oxidoreductases. They catalyze oxidation-reduction reactions, that is, the transfer of electrons or hydrogen atoms from one substrate to another. Examples of these are the enzymes dehydrogenase and c oxidase.
- Transferases. They catalyze the transfer of a specific chemical group other than hydrogen, from one substrate to another. An example of this is the enzyme glucokinase.
- Hydrolases. They deal with hydrolysis reactions (breakdown of organic molecules by water molecules). For example, lactase.
- Liasas. Enzymes that catalyze the breaking or welding of substrates. For example, acetate decarboxylase.
- Isomerases. They catalyze the interconversion of isomers, that is, they convert a molecule into its three-dimensional geometric variant.
- Garters. These enzymes catalyze specific substrate binding reactions through the simultaneous hydrolysis of triphosphate nucleotides (such as ATP or GTP). For example, the enzyme private carboxylase.
How do enzymes work?
Enzymes can operate in different ways, although always reducing the activation energy of a chemical reaction, that is, the amount of energy needed to start it. These different modes are:
- Ambient. The activation energy is reduced by creating a favorable environment for the reaction to take place, for example, by modifying the chemical properties of the substrate through reactions with its own amino acid layer.
- Facilitate the transition. The transition energy is reduced without modifying the substrate, that is, creating an environment with optimal charges for the reaction to take place.
- Give an alternative route. In this case, the enzymes react with the substrate to generate an ES (Enzyme / Substrate) complex that “skips steps” in the ordinary path of the reaction, reducing the time necessary for it to occur.
- Increase the temperature. Within certain parameters, the action of the enzyme can be accelerated by an increase in caloric energy levels, given by parallel exothermic reactions.