Classification according to enzyme structure
Almost all enzymes are proteins and can be classified according to the length of the protein chain: In addition, there are individual protein chains that contain several enzyme activities, these are called multifunctional enzymes.
- Monomeric enzymes consisting of only one protein chain
- Oligomeric enzymes consisting of several protein chains (monomers)
- Multienzyme chainsSeveral enzymes that cooperate and regulate each other. These enzyme chains catalyze the successive steps in the metabolism of the cell.
Classification by cofactors
A further classification is the classification after consideration of the cofactors. Cofactors, coenzymes and co-substrates are names for different classifications of substances that influence biochemical reactions through their interaction with enzymes. Organic molecules and also ions (mostly metal ions) are considered.
The pure protein enzymes consist exclusively of proteins and the active center is formed only by amino acid residues and the peptide backbone. Amino acids are a class of organic compounds with at least one carboxy group (-COOH) and one amino group (-NH2). Holoenzymes consist of a protein part, the apoenzyme, and a cofactor, a low-molecular molecule (no protein).
Both together are important for the function of the enzyme. CoenzymesOrganic molecules as cofactors are called coenzymes. If they are covalently bound to the apoenzyme, they are called prosthetic groups or co-substrate.
A prosthetic group is a non-protein component that is firmly (usually covalently) bound to a protein and has a catalytic effect. Cosubstrates are the names of various classifications of substances that influence biochemical reactions through their interaction with enzymes. As biocatalysts, molecules that accelerate reactions in organisms, enzymes accelerate biochemical reactions. They reduce the activation energy that must be overcome in order for the substance to be converted.
