What are the properties of allosteric enzymes


from Greek: ἄλλως (allos) - different and στερεός (stereós) - place
English: allostery, allosteric regulation

1 definition

Allostery is the property of many enzymes composed of several subunits to change their spatial structure under the influence of the active binding center. Proteins with this property are called allosteric proteins. The conversion of the conformations is called the allosteric effect or allosteric conversion.

2 effect

Allosteric conversion is brought about by allosteric effectors which, in the case of allosterically regulated enzymes, are not identical to the substrate.

The binding of the effectors does not take place in the active center and causes an activation or inactivation of the active center through conformational changes and thus an activation or inhibition of the enzymes, transport or regulation proteins.

The activation of a protein by an allosteric effector is called allosteric activation or a positive allosteric effect. The inhibition of an allosteric protein by an allosteric effector is referred to as allosteric inhibition or negative allosteric effect. The binding site of an allosteric protein for the effector molecule is called the allosteric center.

3 nomenclature

In some sources, the relationship described above is also referred to as "heteroallostery" and a "homoallostery" is differentiated from it. In homoallostery, the binding of a substrate in the active site facilitates the binding of a second substrate molecule. However, this mechanism is better described by the term cooperativity.

4 function

Allosteric effects allow the catalytic activities of enzymes, binding activities of transport proteins or regulatory proteins to be regulated by small molecules. Allosterically regulated proteins are numerous in the metabolism of the cell and play an important role there. Allosteric enzymes catalyze the first steps of a biosynthetic chain and are allosterically inhibited by the end product of the biosynthetic chain in question.