competitive inhibitor


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com·pet·i·tive in·hi·bi·tion

blocking of the action of an enzyme by a compound that binds to the free enzyme, preventing the substrate from binding and thus preventing the enzyme from acting on that substrate. The competitive inhibitor is often a substrate analogue and binds at the active site; however, this is not an absolute requirement for competitive inhibition. Saturating concentrations of substrate can remove the inhibition. Compare: isostery.

competitive inhibitor

1. A chemical that binds to or blocks another reagent from participating in a reaction.
2. A medication, hormone, or other intercellular messenger that binds and blocks the cellular receptor or target enzyme of another agent. Drugs that act by competitive inhibition may treat or prevent disease by inactivating pathogenic enzymes or by blocking the effects of hormones or precursor molecules. For example, protease inhibitors interfere with production of human immunodeficiency virus (HIV) by binding and inactivating the protease enzyme; selective estrogen-receptor modulators limit the impact of estrogen by replacing this hormone on cells sensitive to its effects.
See also: inhibitor
References in periodicals archive ?
In summary, our demonstration that narezode decreases the incidence of oxalate formation, metabolic acidosis, and renal tubule damage when used to treat EG poisoning--plus the apparent lack of side effects in our patients- supports the addition of this competitive inhibitor to treatment regimens for EG poisoning.
MA as a competitive inhibitor prevents the binding of the substrate by binding reversibly the active site of CYP3A4 enzyme.
Perchlorate is a competitive inhibitor of the sodium iodide symporter (NIS), the thyroid cell-surface protein responsible for transporting iodide from the plasma into the thyroid.
The first property is that an uncompetitive inhibitor as a target conjugate is preferred over a competitive inhibitor because uncompetitive inhibitors are rare in nature and should be less susceptible to interferences from drugs and naturally occurring substances, which frequently are competitive inhibitors of enzymes.
Onvansertib is a highly-selective adenosine triphosphate competitive inhibitor of the serine/threonine polo-like-kinase 1 (PLK 1) enzyme, which is over-expressed in multiple hematologic and solid tumor cancers.
Dimethylaminoethanol (DMAE), a competitive inhibitor of choline transport, elicited dysmorphology beginning at the mid-blastula stage, with anomalies beginning progressively later as the concentration of DMAE was lowered.
In the previously reported study from our laboratory, the [IC.sub.50] for pure MPA increased from 13.7 to 132 nmol/L, whereas as expected, the [IC.sub.50] for xanthine monophosphate, a well-known, weaker binding competitive inhibitor of IMPDH, remained unchanged (mean [+ or -] SD, 713 [+ or -] 116 [micro]mol/L) as the concentration of human IMPDH was increased from 26 to 260 nmol/L.
PCM-075 is an oral, highly-selective adenosine triphosphate competitive inhibitor of the serine/threonine polo-like-kinase 1 (PLK 1).
These are comparable to the results of enzymatic kinetic study showing HM-1 was a competitive inhibitor of the formation of CYP3A4-catalyzed 6[beta]-hydroxyl testosterone.
It is thought that because of its similarity in ionic size to iodide, the perchlorate ion is a competitive inhibitor of iodide at the sodium iodide symporter (NIS), the plasma membrane protein that catalyzes the accumulation of iodide into thyroid cells (Wolff 1998).
Alpha methyl ornithine, a potent competitive inhibitor of ornithine decarboxylase blocks proliferation of rat hepatoma cells in culture.
PCM-075 is an oral highly-selective adenosine triphosphate competitive inhibitor of the serine/threonine polo-like-kinase 1 (PLK 1) enzyme, which is over-expressed in multiple hematologic and solid tumor cancers.

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