Life depends on the realization of innumerable chemical reactions that take place inside and outside cells (for example, in organ cavities).
On the other hand, all these reactions depend for their realization on the existence of a certain enzyme. Enzymes are protein group substances and act as catalysts for chemical reactions.
Catalyst is a substance that accelerates the speed of occurrence of a certain chemical reaction.
Many enzymes have, in addition to the protein portion itself, consisting of an amino acid sequence, a non-protein portion.
The protein part is the apoenzyme and the non-protein part is the cofactor. When the cofactor is an organic molecule, it is called a coenzyme. The mechanism of action of the enzyme begins when it binds to the reagent, better known as substrate. an unstable enzyme-substrate complex is formed that soon crumbles, releasing the reaction products to the enzyme, which remains intact even though it participated in the reaction.
But for a chemical reaction to occur between two organic substances that are in the same solution, a certain amount of energy, usually in the form of heat, must be provided that favors the encounter and collision between them. Energy is also needed to break existing chemical bonds between the atoms of each substance, thus favoring the occurrence of other chemical bonds and the synthesis of a new substance from the initial two.
This starting energy, which gives a "push" for a chemical reaction to take place, is called the activation energy and has a certain value.
The enzyme causes a decrease in the activation energy required for a chemical reaction to occur and this facilitates the occurrence of the reaction.
The key-lock mechanism
In catalysis of a chemical reaction, enzymes interact with substrates, temporarily forming the so-called enzyme-substrate complex with them. In the formation of the secondary and tertiary structures of an enzyme (do not forget that the enzymes are proteins), certain locations in the molecule eventually appear that will serve to accommodate one or more substrates, just as a key lodges in the lock.
These docking sites are called active sites and are on the enzyme surface. By tapping into the active sites, the substrates are close together and can react more easily.
As soon as the chemical reaction with the substrates occurs, the enzyme-substrate complex is broken down. The products are released and the enzyme again attracts new substrates for the formation of other complexes.
Remember if!! An enzyme is not consumed during the chemical reaction it catalyzes.