Classification Of Enzymes | Nomenclature Of Enzymes

Enzymes are proteins that speed up chemical reactions in our bodies. They play a vital role in digestion, metabolism, and other bodily functions. They are essential for life because they speed up the rate at which cells break down food into energy. Enzymes also play a role in our immune system and digestion.

Classification Of Enzymes

Enzymes are sometimes considered under two broad categories :

(a)  Intracellular Enzymes

Enzymes that work within cells are called intracellular enzymes. These enzymes play a role in many cellular processes, including metabolism, cell signaling, and gene expression.

(b)  Extracellular Enzymes

These enzymes are active outside the cell; Enzymes can be found both inside and outside of cells, with digestive enzymes being one type that is active outside of cells.

Nomenclature Of Enzymes

Enzymes were given names by their discoverers early on in an arbitrary way. For example, pepsin, trypsin, and chymotrypsin are just a few examples of enzymes where the name doesn’t describe the function or the nature of the substrate.

Suffixes were added to the substrate in some cases for naming purposes. lipase is an enzyme that acts on lipids; nuclease on nucleic acids; lactase on lactose. These are known as trivial names of enzymes which, however, don’t give complete information about the enzyme reaction (type of reaction, cofactor requirement, etc.)

In 1961, the International Union of Biochemistry (IUB) established the Enzyme Commission to study existing enzymes and come up with a system of classification and nomenclature. This system has been in place since 1964, with enzymes being divided into six major classes. Each class represents the general type of reaction that enzymes can cause.

Oxidoreductases:

Oxidoreductases are enzymes that help with the transfer of electrons between two molecules. This usually results in one molecule being oxidized (losing electrons) and the other being reduced (gaining electrons).

Transferases:

Transferases are enzymes that specialize in moving functional groups from one molecule to another. This chemical reaction is important in many biological processes, such as metabolism and signal transduction.

Hydrolases:

Hydrolases are enzymes that break down molecules by adding water to them. This helps to change the shape or structure of the molecule, making it easier for the body to absorb and use it.

Lyases:

Lyases are enzymes that have a special job- removal or addition of water, ammonia, CO2, and more. These enzymes play an important role in many biochemical processes.

Isomerases:

Isomerases are enzymes that catalyze the structural rearrangement of isomers. Isomers are molecules with the same molecular formula but different spatial arrangements of their atoms.

Ligases:

Enzymes known as ligases catalyze the joining of two molecules together using ATP energy. The International Union of Biochemistry has a system for naming these enzymes based on the substrates used and the type of reaction catalyzed, but these names are not widely used because they are complicated and difficult to remember. Therefore, most people use the more simple, trivial names for these enzymes instead.