Uncompetitive inhibitor

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Lineweaver-Burk plot of uncompetitive enzyme inhibition.

Uncompetitive inhibition takes place when an enzyme inhibitor binds only to the complex formed between the enzyme and the substrate (the E-S complex).

[edit] Mechanism

This reduction in the effective concentration of the E-S complex increases the enzyme's apparent affinity for the substrate through Le Chatelier's principle (K_m is lowered) and decreases the maximum enzyme activity (V_max), as it takes longer for the substrate or product to leave the active site. Uncompetitive inhibition works best when substrate concentration is high.

[edit] Equation

$\ 1/v=\frac{K_m}{V_{max}[S]}+\frac{1+[I]}{K_iV_{max}}$

The Lineweaver-Burk equation for an uncompetitive inhibitor produces a line parallel to the original enzyme-substrate plot, but with a higher y-intercept (due to the increase of $\ 1/V_{max}$ ).

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