Types of Enzymes
There are six types of biochemical reactions that occur in the body, and the enzymes that cause these reactions are called accordingly:
Oxidoreductases: These enzymes catalyze oxidation and reduction processes, hence their name. Electrons in the form of hydride ions or hydrogen atoms are exchanged in these processes. These enzymes serve as hydrogen donors when a substrate is oxidized. Dehydrogenases and reductases are the names given to these enzymes. These enzymes are known as oxidases when the acceptor is oxygen.
Transferases are responsible for the transfer of functional groups from one molecule to another. For example, alanine aminotransferase shuffles the alphaamino group between alanine and aspartate, and so on. Some transferases, such as hexokinase in glycolysis, also transfer phosphate groups between ATP and other molecules, as well as sugar residues to produce disaccharides.
Hydrolases: These enzymes catalyze processes involving the hydrolysis process.
They add water to break single bonds. Because they break peptide connections in proteins, some hydrolases act as digestive enzymes. Hydrolases are transferases because they move the water molecule from one chemical to another. Glucose-6-phosphatase, for example, removes the phosphate group from glucose-6-phosphate, leaving only glucose and H3PO4.
Lyases: These enzymes catalyze processes in which functional groups are introduced to break double bonds in molecules or where functional groups are removed to generate double bonds. Pyruvate decarboxylase, for example, is a lyase that removes CO2 from pyruvate. Deaminases and dehydratases are two more examples.
Isomerases: These enzymes catalyze processes in which a functional group is transferred to a different place inside the same molecule, resulting in a molecule that is an isomer of the earlier molecule. To convert glucose 6-phosphate to fructose 6-phosphate, triosephosphate isomerase and phosphoglucose isomerase are used.
Ligases are enzymes that serve the opposite function of hydrolases. Ligases form bonds by eliminating the water component, whereas hydrolases break bonds by adding water. There are various subclasses of ligases that are involved in the production of ATP.