Cholinesterase

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cholinesterase

[′kō·lə′nes·tə‚rās]
(biochemistry)
An enzyme found in blood and in various other tissues that catalyzes hydrolysis of choline esters, including acetylcholine. Abbreviated chE.

Cholinesterase

 

any of a group of enzymes of the hydrolase class that act as a catalyst in the hydrolysis of choline esters, according to the equation

(CH3)3N + CH2CH2OCOR + H2O → (CH3)3N+ CH2CH2OH + RCOOH

The cholinesterase of the greatest biological importance is that of the nervous system, acetylcholinesterase (ACE), which acts as a catalyst mainly for the hydrolysis of acetylcholine (R = CH3). Cholinesterases that hydrolyze predominately the esters of choline and other carboxylic acids, such as propionic and butyric acid, have retained the trivial name cholinesterase.

ACE catalyzes the hydrolysis of acetylcholine to acetic acid and choline. Acetylcholine, a highly active substance, is secreted in the synapses of the nervous system and takes part in the transmission of nerve impulses from one nerve cell to the next and from nerve cells to the appropriate organs, such as muscles and endocrine glands. It must be rapidly broken down, however, because accumulations of it block the transmission of nerve impulses and cause paralysis—that is, the loss of nerve functions. For this reason, substances that suppress ACE activity are highly toxic; such substances include organophosphate insecticides, physostigmine, and proserine.

An enzyme with properties similar to those of ACE is found in erythrocytes, but its biological function is not yet known. Less specific cholinesterases are found in blood serum and certain organs and tissues of animals. The most active ACE has been discovered in the electric organs of fish of the suborder Batoidea. Individual cholinesterases of high purity have been obtained from various organs and tissues.

All cholinesterases are proteins with molecular weights ranging from 70,000 to 1,000,000; they contain no coenzymes of low molecular weight. A very important role in the catalytic activity of cholinesterases is played by the amino acids serine, histidine, aspartic acid, and glutamic acid.

V. A. IAKOVLEV

References in periodicals archive ?
La genetica de la deficiencia de BChE fue precisada en 1957 y se dice que es una piedra angular en farmacogenetica /farmacogenomica (10, 11).
Para el estudio de los datos de actividad BChE se utilizo el programa estadistico Prism 6.
Amplification of the genes BCHE and SLC2A2 in 40% of squamous cell carcinoma of the lung.
A manera de conclusion, se enfatiza la importancia de promover como herramienta de diagnostico en la practica veterinaria, la medicion de BChE en animales intoxicados, asi como en salud publica promover la denuncia obligatoria y registro centralizado de la intoxicacion por plaguicidas en animales, para aportar a la fiscalizacion de la venta de estos productos y a la educacion a conciencia del riesgo de uso de los mismos en consideracion de la salvaguarda de la salud animal y humana como bien primario.
The hydrogen bonds formed with the amino acid residues at the catalytic site could be responsible for the potency of angustidine (2) as a BChE inhibitor.
BChE activity also followed the similar trend with a maximum inhibition up to 88.
A biochemical test from the 1950s for the phenotypic identification of BChE variants helped determine that the pharmacogenetic effect of BChE variants was familial (4-6).
It was suggested that in these two patients who died, BChE might not have been effective once neuromuscular involvement developed.
Since BChE is elevated in the brain of advanced AD patients, BNC may be most efficacious in severe and advanced AD patients, where butyrylcholinesterase levels are abnormally.
The BChE inhibition activity was performed according to the method described in literature [15] with slight modification.