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 (triggering, accelerating, modifying, slowing down and even stopping) various chemical reactions, whenever they are thermodynamically possible. This means that are regulatory substances in the body of living beings usually decreasing the initial energy required to start the reaction.
Enzymes are essential for life and catalyze around 4000 known chemical reactions as long as the pH, temperature or chemical concentration conditions are stable, since enzymes, being proteins, can also denature and lose their effectiveness.
The first enzyme was discovered mid 19th century by Anselme Payen and Jean-Francois Persoz, although Louis Pasteur's experiments on fermentation had already intuited the presence of some organic “accelerator” 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), selectively activating and deactivating others (as hormones do) and a variety of etcetera.
See also: Biomolecules
Structure of enzymes
Most enzymes are made up of globular proteins of very variable size: from monomers of 62 amino acids, to enormous chains of around 2500. However, only a few of them are those 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 intervene in any reaction. They have a very punctual 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, 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.
- Ligases. 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 decreasing the activation energy of a chemical reaction, that is, the amount of energy necessary to start it. These different modes are:
- Ambient The activation energy is reduced by creating a favorable environment for the reaction to occur, for example, by modifying the chemical properties of the substrate through reactions with its own layer of amino acids.
- Promote the transition The transition energy is reduced without modifying the substrate, that is, creating an environment with optimal charges for the reaction to occur.
- 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, enzyme action can be accelerated by an increase in heat energy levels, given through parallel exothermic reactions.
