Enzymes are proteins that act as catalysts in biochemical reactions in the body, accelerating the conversion of one molecule (the substrate) into another (the product). Enzymes play a vital role in a wide range of physiological processes in the human body, including digestion, metabolism, and DNA replication. There are many different types of enzymes, but they can generally be classified into six main categories based on their function.
In addition, enzymes can also be classified based on their location within the body. For example, digestive enzyme types are produced by the pancreas and small intestine and help break down food in the digestive tract. Enzymes involved in DNA replication and repair are found in the nucleus of cells, while enzymes involved in energy production are found in the mitochondria.
Hydrolases
These enzymes catalyze the hydrolysis of various biomolecules, including proteins, carbohydrates, and lipids. Examples include proteases, which break down proteins into amino acids, and lipases, which break down lipids into fatty acids and glycerol. Hydrolases are a kind of digestive enzyme that is essential in human survival.
Transferases
These enzymes catalyze the transfer of functional groups (such as a phosphate group or a methyl group) from one molecule to another. Examples include kinases, which transfer phosphate groups from ATP to other molecules, and methyltransferases, which transfer methyl groups from one molecule to another.
Oxidoreductases
These enzymes catalyze oxidation-reduction reactions, in which electrons are transferred from one molecule to another. Examples include dehydrogenases, which catalyze the removal of hydrogen atoms from molecules, and oxidases, which catalyze the transfer of electrons from one molecule to another. While humans can increase their defenses against free radicals that oxidize cells using antioxidants, it is the enzymes that really do the heavy lifting in the body.
Isomerases
These enzymes catalyze the rearrangement of atoms within a molecule, converting one isomer into another. Examples include epimerizes, which convert one sugar epimer into another, and cis-trans isomerases, which catalyze the conversion of geometric isomers. Isomerases play a critical role in various physiological processes in the human body, including metabolism, DNA replication, and protein synthesis.
One of the most well-known examples of isomerases in the human body is the enzyme triosephosphate isomerase (TPI), which catalyzes the interconversion of dihydroxyacetone phosphate and glyceraldehyde-3-phosphate during the glycolytic pathway. This is an essential step in the process of energy production, as it allows for the conversion of glucose into ATP, the energy currency of the body.
Ligases
These enzymes catalyze the formation of covalent bonds between two molecules, using energy from ATP or another nucleotide. Examples include DNA ligases, which join together two DNA strands, and ATP synthases, which catalyze the formation of ATP from ADP and inorganic phosphate.
Lyases
These enzymes catalyze the cleavage of C-C, C-O, or C-N bonds, often without the use of water. Examples include decarboxylases, which catalyze the removal of a carboxyl group from a molecule, and aldolases, which catalyze the cleavage of a carbon-carbon bond in aldol reactions. People with lyases deficiencies struggle to regulate their blood sugar – experiencing hypoglycemic attacks. Lyases deficiencies are, thankfully, relatively rare.
