A brief overview is give here . Amount of substrate. Control of activity. Multisubunit enzymes Homoallostery - cooperative substrate binding and activation. Heteroallostery - regulation by effector molecules, which can be positive or negative.
Allosteric effectors bind at a site different from the active site.
Reversible covalent modification is widely used to regulate enzyme activity. Phosphorylation of a Ser is a common reaction. Irreversible covalent modification . Many enzymes are made as inactive precursors - zymogens . Activation of the zymogen involves proteolytic removal a peptide from the amino terminal.