Enzymes Definition 

What are the enzymes and the functions?

Enzymes are the central drivers of biochemical metabolic processes in organisms — without enzymes, there is no life. From digestion to the energy metabolism of the cells, from information transfer to the copying of genetic information, all these processes are controlled by enzymes.

The special thing: Enzymes work very specifically — a single enzyme usually catalyzes only one single reaction and it only converts a very specific molecule, the so-called substrate. This makes enzymes special biological tools. There is a huge variety of enzymes with different abilities. For almost every biochemical reaction, nature’s toolbox contains its own biocatalysts. The building, degrading or rebuilding molecules, these are the core functions of enzymes. Their names end characteristically with “-ase”, i.e. cellulase, lipase or protease.

Enzymes enable and accelerate almost all biochemical reactions in the body. These reactions include the most diverse metabolic processes as well as the "discarding" (transcribing) and doubling (replicating) of genetic information.

In such reactions, enzymes temporarily bind to the substance to be converted (substrate) so that it can be broken down or otherwise altered. The enzymes themselves remain unchanged. However, they ensure that the energy required for the reaction (activation energy) is reduced. Actually, most chemical processes in cells require such high activation energy that they cannot or can only be carried out very slowly at the prevailing ambient temperature (internal body temperature of approx. 37 degrees Celsius). By lowering the activation energy, enzymes make such reactions possible in the first place or accelerate them sufficiently.

Enzymes can be divided into six main groups, depending on the type of chemical reaction they catalyze. These classes of enzymes (and some of their subgroups) are:

1. oxidoreductases: They catalyze reactions in which electrons are transferred (redox reactions); e.g. dehydrogenases, oxidases, reductases, catalases
2. Transferases: They catalyze reactions in which entire functional groups (such as phosphate groups) are transferred from one molecule to another; e.g. transaminases, kinases, DNA polymerases
3. Hydrolases: They catalyze reactions in which a chemical bond is either formed when water escapes or is split when water is added; e.g. peptidases, phosphatases, proteases
4. Lyases: They catalyze reactions in which chemical bonds are split or formed without energy consumption; e.g. aldolase
5. Isomerases: They are responsible for rearranging the binding relationships within a molecule; e.g. racemases, topoisomerases
6. Ligases (synthetases): They catalyze reactions in which two molecules are joined together with energy consumption; e.g. carboxylases