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An inhibitor is a type of effector (biology) that decreases or prevents a chemical reaction. They are often 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.
Inhibitors and Enzymes
Inhibitors also affect enzymes, they are divided into three kinds:
Irreversible inhibitors which often react covalently with the enzyme molecule they permanently stop the enzyme working.
Competitive inhibitors compete with the substrate for the active site but do not react in it and stop it being used, a high concentration of substate stops this happening.
You can also get allosteric inhibitors which bind to another part of the enzyme and stop it working, this isn't permanent. The body often uses this as a feedback regulation in metabolic pathways with the product being the allosteric inhibitor which stops itself being produced when present in abundance.
Inhibitions in Behaviour
Inhibitions in behavior may have a positive connotation (behaving properly, responsibly) or a negative one (being shy, boring, not brave). They are reduced by common forms of intoxication like alcohol.
A special use of the term inhibition; meaning to prevent habitual reactions, is a principle of how Alexander Technique works.
See also:
receptor antagonist
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