Enzymes are proteins (except for ribozyme) that act as biological catalysts converting ‘substrates’ into different molecular products. Almost all metabolic processes in human cells need enzyme catalysis. The citric acid cycle also known as the Krebs cycle, for example, is a metabolic pathway in the mitochondria of our cells. The pathway involves at least eight enzymes our body produces in a series of reactions to create and release chemical energy in the form of ATP.
Enzymes are often imagined as specific keys that fit into and open specific locks.
This specificity of fit is “achieved by binding pockets with complementary shape, charge and hydrophilic/hydrophobic characteristics to the substrates. Enzymes can therefore distinguish between very similar substrate molecules.”
Some enzymes, however, are more ‘broadly’ specific acting on a range of substrates. There is also a feature called ‘induced fit’ where enzymes may change shape to accommodate a substrate.
Enzymes are usually named according to the reaction they carry out: the suffix - ase is often combined with the name of the enzyme such as lactase that cleaves lactose, lipase breaks down lipids. Proteases produced in the stomach and pancreas, break down proteins into amino acids.
Enzymes that are produced by plants or through fermentation, for example, may have therapeutic effects for humans. A surprising study published in 2022 “examined the effect of the enzyme nattokinase on the S protein of SARS-CoV-2.” Study authors concluded that nattokinase, produced by Bacillus subtilis var. natto, had “a degradative effect on the S protein substrate.”