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Allosteric regulation of an enzyme. In the fields of biochemistry and pharmacology an allosteric regulator (or allosteric modulator) is a substance that binds to a site on an enzyme or receptor distinct from the active site, resulting in a conformational change that alters the protein's activity, either enhancing or inhibiting its function.
Competitive inhibition can be overcome by adding more substrate to the reaction, which increases the chances of the enzyme and substrate binding. As a result, competitive inhibition alters only the K m, leaving the V max the same. [3] This can be demonstrated using enzyme kinetics plots such as the Michaelis–Menten or the Lineweaver-Burk plot.
It is important to note that while all non-competitive inhibitors bind the enzyme at allosteric sites (i.e. locations other than its active site)—not all inhibitors that bind at allosteric sites are non-competitive inhibitors. [1] In fact, allosteric inhibitors may act as competitive, non-competitive, or uncompetitive inhibitors. [1]
The mechanisms of allosteric inhibition are varied and include changing the conformation (shape) of the enzyme such that it can no longer bind substrate (kinetically indistinguishable from competitive orthosteric inhibition) [10] or alternatively stabilise binding of substrate to the enzyme but lock the enzyme in a conformation which is no ...
Allosteric enzymes are enzymes that change their conformational ensemble upon binding of an effector (allosteric modulator) which results in an apparent change in binding affinity at a different ligand binding site. This "action at a distance" through binding of one ligand affecting the binding of another at a distinctly different site, is the ...
If the ability of the inhibitor to bind the enzyme is exactly the same whether or not the enzyme has already bound the substrate, it is known as a non-competitive inhibitor. [1] [2] Non-competitive inhibition is sometimes thought of as a special case of mixed inhibition. In mixed inhibition, the inhibitor binds to an allosteric site, i.e. a ...
This can be competitive inhibition, uncompetitive inhibition, non-competitive inhibition or partially competitive inhibition. If the molecule induces enzymes that are responsible for its own metabolism, this is called auto-induction (or auto-inhibition if there is inhibition). These processes are particular forms of gene expression regulation.
At normal concentrations, phosphate activates the enzyme by binding to its allosteric regulatory site. However, at high concentrations, phosphate is shown to have an inhibitory effect by competing with the substrate ribose 5-phosphate for binding at the active site. ADP is the key allosteric inhibitor of ribose-phosphate diphosphokinase.