Inhibitor
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Template:Cleanup-date An inhibitor is a type of effector that decreases or prevents the rate of a chemical reaction. Inhibitors are sometimes called "negative catalysts".
Inhibitors are often used as medicines to decrease the rate of enzyme mediated reactions, but they can also act as poisons. Other examples include antioxidants and antipolymerization agents.
A corrosion inhibitor is added to antifreeze (coolant) used in engines, hydraulic fluids, boiler water, fuels, and many other industrial fluids.
Biochemical inhibitors
An enzyme inhibitor is a molecule that binds to an enzyme and decreases its rate of reaction. There are three kinds of these biochemical inhibitors.
- Competitive inhibitors have an affinity for the active site of an enzyme close to the affinity that the substrate of an enzyme has. The inhibitor binds to the active site of the enzyme, so its substrate cannot bind there, thus preventing the enzyme from either putting stress on the bonds of the substrate in a decomposition reaction, or from attaching one substrate to another in a synthesis reaction, depending on the function of the specific enzyme.
- Allosteric inhibitors bind to the allosteric site of an enzyme, a location on its structure separate from the active site that, when a molecule binds to it, can alter the shape of the enzyme. When an inhibitor binds to the allosteric site of an enzyme, it changes the conformation or three-dimensional shape of the enzyme so that the substrate does not fit in the active site.
- Irreversible inhibitors bind covalently to an enzyme so that they preclude its activity completely. Some poisons block vital enzymes this way.
In many organisms, inhibitors may act as part of a feedback mechanism. If an enzyme produces too much of one substance in the organism, that substance may act as an inhibitor for the enzyme that produces it, causing production of the substance to slow down or stop when there is sufficient amount.
See also
es:Inhibidor competitivo fr:Inhibiteur id:Inhibitor nl:Inhibitor pl:Inhibitor ru:Ингибитор sv:Inhibitor Template:Biochem-stub