Mixed inhibition

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Mixed inhibition refers to a combination of two different types of reversible enzyme inhibition – competitive inhibition and uncompetitive inhibition. The term 'mixed' is used when the inhibitor can bind to either the free enzyme or the enzyme-substrate complex. In mixed inhibition, the inhibitor binds to a site different from the active site where the substrate binds. Mixed inhibition results in a decrease in the apparent affinity of the enzyme for the substrate () and a decrease in the apparent maximum enzyme reaction rate ().^[1]

Mathematically, mixed inhibition occurs when the factors α and α’ (introduced into the Michaelis-Menten equation to account for competitive and uncompetitive inhibition, respectively) are both greater than 1.

In the special case where α = α’, noncompetitive inhibition occurs, in which case is reduced but K_m is unaffected. This is very unusual in practice^[1]

[edit] References

v • d • e Pharmacology: enzyme inhibition Class Competitive inhibition - Uncompetitive inhibition - Non-competitive inhibition - Suicide inhibition - Mixed inhibition Substrate Oxidoreductase (EC 1): Aromatase inhibitors - Lipoxygenase inhibitor - Monoamine oxidase inhibitors Transferase (EC 2): Integrase inhibitor - Kinase inhibitors - Reverse transcriptase inhibitors Hydrolase (EC 3): Acetylcholinesterase inhibitors - Phosphodiesterase inhibitors - Protease inhibitors (ACE inhibitor, Trypsin inhibitor) Lyase (EC 4): Carbonic anhydrase inhibitors