inhibition

[in″hĭ-bish´un]

1. arrest or restraint of a process.

2. in psychoanalysis, the conscious or unconscious restraining of an impulse or desire. adj., adj inhib´itory.

competitive inhibition inhibition of enzyme activity by an inhibitor (a substrate analogue) that competes with the substrate for binding sites on the enzymes.

contact inhibition inhibition of cell division and cell motility in normal animal cells when in close contact with each other.

noncompetitive inhibition inhibition of enzyme activity by substances that combine with the enzyme at a site other than that utilized by the substrate.

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.

Synonym(s): selective inhibition

Farlex Partner Medical Dictionary © Farlex 2012

com·pet·i·tive in·hi·bi·tion

(kŏm-pet'i-tiv in'hi-bish'ŭn)

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.
Synonym(s): selective inhibition.

Medical Dictionary for the Health Professions and Nursing © Farlex 2012

competitive inhibition

a form of enzyme control in which an inhibitor molecule very similar in structure to the normal SUBSTRATE of an enzyme becomes reversibly bound to the ACTIVE SITE, thus reducing the quantity of enzyme available. However, if excess substrate is present the inhibitor can be forced out by the substrate molecule which takes its place and the reaction proceeds. Compare NONCOMPETITIVE INHIBITION.

Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005

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References in periodicals archive

Firstly, the interaction between phenol and chlorophenols (2-cp and 4-cp) could be regarded as competitive inhibition as the models revealed.

Cometabolic transformation of 2-chlorophenol and 4-chlorophenol in the presence of phenol by Pseudomonas putida

In evaluating the results of these studies, it appeared that most of the decrease in P sorption due to OM addition can be accounted for by considering the amount of P mineralised from the added OM, and not through competitive inhibition of P sorption by DOC compounds.

Competitive sorption reactions between phosphorus and organic matter in soil: a review

The results of two-tailed t-tests for the kinetics study revealed [V.sub.max] values that were not significantly different (P > 0.05) but [K.sub.m] values for the reactions that were significantly different (P < 0.05) (Figure 5; Table 2).This is indicative of competitive inhibition between sucrose and sucralose for binding to invertase, with sucrose having the higher binding affinity, which is why the inhibitory affect is concentration-based.

Metabolic effects of sucralose on environmental bacteria

This indicated a competitive inhibition in both the initial and the steady-state stages of the inhibited reaction.

Kinetics and mechanism study of competitive inhibition of Jack-Bean urease by Baicalin

In other words, because nondepolarizing agents act by competitive inhibition, their effect is dose related: larger doses overcome the effects of acetylcholine and block more receptors.

Neuromuscular blocking agents: mechanism of action, hazards, and USE in mechanical ventilation

You consider the possibility that medical treatment aimed at increasing dopamine in affected areas of the brain may be lowering serotonin by competitive inhibition.

Urinary neurotransmitters: testing to optimize treatment based upon a clinical diagnosis

In this case where both phenol and 4-cp share the same key enzymes, competitive inhibition exists and cometabolic transformation of 4-cp is strongly affected by the presence of phenol.

Enhanced cometabolic transformation of 4-chlorophenol in the presence of phenol by granular activated carbon adsorption

In serious cases, calcium gluconate, which acts as a substrate against competitive inhibition of calcium by the ciguatoxin, is typically recommended.

That summer seafood platter can have side of serious toxin

The inhibition constant [K.sub.i] (0.6%) showed a competitive inhibition (Figure 6A).

Differential effects of glyphosate and Roundup on human placental cells and aromatase

However, because 3-DA prevents Hcy production through competitive inhibition of the enzyme S-adenosyl-homocysteine hydrolase (SAHH), 3-DA interferes with popular assays of tHcy that are enzyme-conversion immunoassays based on SAHH (1, 2, 4).

3-deazaadenosine, a stabilizer of whole-blood homocysteine content, does not interfere with the single-enzyme homocysteine assay while totally inhibiting the enzyme conversion homocysteine immunoassay

Importantly, prebiotics inhibit pathogenic colonization in the gut by competitive inhibition. Some of the recognized prebiotics are fructo-oligosaccharides, lactulose, and trans-oligosaccharides.

ELISA tests for IgG/IgM gut flora immunity

A competitive inhibition anti-PA IgG ELISA was also developed to enhance diagnostic specificity to 100%.

Specific, sensitive, and quantitative enzyme-linked immunosorbent assay for human immunoglobulin G antibodies to anthrax toxin protective antigen. (Bioterrorism-Related Anthrax)