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{{protein
 
{{protein
 
| Name = acetylcholinesterase (Yt blood group)
 
| Name = acetylcholinesterase (Yt blood group)
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| LocusSupplementaryData = -26.2
 
| LocusSupplementaryData = -26.2
 
}}
 
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In [[neurochemistry]], '''Acetylcholinesterase''' or '''cholinesterase''' is an enzyme which [[catalyst|catalyzes]] the [[hydrolysis]] of the [[neurotransmitter]] [[acetylcholine]] into [[choline]] and [[acetic acid]], a reaction necessary to allow a [[cholinergic neuron]] to return to its resting state after activation.
{{Boxbottom}}
 
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In [[biochemistry]], '''cholinesterase''' is a term which refers to one of the two [[enzyme]]s:
 
  +
==Types==
  +
There are two types:
 
*'''Acetylcholinesterase''' ({{EC number|3.1.1.7}}) (AChE), also known as ''[[red blood cell|RBC]] cholinesterase'', ''erythrocyte cholinesterase'', or (most formally) ''acetylcholine acetylhydrolase'', found primarily in the [[blood]] and [[neural]] [[synapse]]s
 
*'''Acetylcholinesterase''' ({{EC number|3.1.1.7}}) (AChE), also known as ''[[red blood cell|RBC]] cholinesterase'', ''erythrocyte cholinesterase'', or (most formally) ''acetylcholine acetylhydrolase'', found primarily in the [[blood]] and [[neural]] [[synapse]]s
 
*'''Pseudocholinesterase''' ({{EC number|3.1.1.8}}) (BChE or BuChE), also known as ''plasma cholinesterase'', ''butyrylcholinesterase'', or (most formally) ''acylcholine acylhydrolase'', found primarily in the [[liver]]
 
*'''Pseudocholinesterase''' ({{EC number|3.1.1.8}}) (BChE or BuChE), also known as ''plasma cholinesterase'', ''butyrylcholinesterase'', or (most formally) ''acylcholine acylhydrolase'', found primarily in the [[liver]]
   
 
The difference between the two types of cholinesterase has to do with their respective preferences for [[substrate (biochemistry)|substrate]]s: the former hydrolyses acetylcholine more quickly; the latter hydrolyses [[butyrylcholine]] more quickly.
Both of these compounds [[catalyst|catalyze]] the [[hydrolysis]] of the [[neurotransmitter]] [[acetylcholine]] into [[choline]] and [[acetic acid]],
 
a reaction necessary to allow a [[cholinergic]] neuron to return to its resting state after activation.
 
   
  +
==History==
The difference between the two types of cholinesterase has to do with their respective preferences for [[substrate (biochemistry)|substrate]]s: the former hydrolyses acetylcholine more quickly; the latter hydrolyses [[butyrylcholine]] less quickly. In 1968, Walo Leuzinger ''et al'' successfully purified and cristalyzed the enzyme from electric eels at Columbia University, NY. The 3D structure of acetylcholinesterase was first determined in 1991 by Sussman ''et al'' using protein from the Pacific electric ray.
 
  +
In 1968, Walo Leuzinger ''et al'' successfully purified and crystallized the enzyme from [[electric eel]]s at Columbia University, NY. <ref>* Leuzinger W, Baker AL. ''Acetylcholinesterase, i. Large-scale purification, homogeneity, and amino acid analysis''. Proc Natl Acad Sci U S A. 1967 Feb; 57(2): 446-451. PMCID: 335526</ref><ref>Leuzinger W, Baker A L, Cauvin E. Acetylcholinesterase, II. ''Crystallization, Absorption Spectra, Isoionic Point.'' Proc Natl Acad Sci U S A, Vol. 59, No. 2 (Feb. 15, 1968), pp. 620-623. PMCID: 224717 </ref>
   
 
The 3D structure of acetylcholinesterase was first determined in 1991 by [[Joel Sussman]] ''et al'' using protein from the [[Pacific electric ray]].<ref>Sussman JL, Harel M, Frolow F, Oefner C, Goldman A, Toker L, Silman I. ''Atomic structure of acetylcholinesterase from Torpedo californica: a prototypic acetylcholine-binding protein.'' Science 1991;253:872-9. PMID 1678899.</ref>
An absence or mutation of the pseudocholinesterase enzyme leads to a medical condition known simply as [[pseudocholinesterase deficiency]]. This is a silent condition that only manifests itself when people who have the deficiency receive the muscle relaxants succinylcholine or mivacurium during a surgery.
 
  +
  +
==Clinical significance==
 
An absence or mutation of the pseudocholinesterase enzyme leads to a medical condition known simply as [[pseudocholinesterase deficiency]]. This is a silent condition that only manifests itself when people who have the deficiency receive the muscle relaxants [[succinylcholine]] or [[mivacurium]] during a surgery.
  +
  +
Elevation of plasma pseudocholinesterase was observed in 90.5% cases of acute myocardial infarction.<ref>Textbook of Medical Biochemistry, MN Chatterjea & Rana Shinde, 6th Ed, 2005 (Pg 565)</ref>
  +
  +
Acetylcholinesterase is tested in early pregnancy. A sample of amniotic fluid is removed by [[amniocentesis]]. The presence of AChE in the amniotic fluid can confirm a [[neural tube defect]], a common type of birth defect.[http://www.fbr.org/psl/psl-tests.html]
   
 
==Cholinesterase inhibitors==
 
==Cholinesterase inhibitors==
A [[cholinesterase inhibitor]] (or "anticholinesterase") suppresses the action of the enzyme. Because of its essential function, chemicals that interfere with the action of cholinesterase are potent [[neurotoxin]]s, causing excessive salivation and eye watering in low doses, followed by muscle spasms and ultimately death (examples are snake venom, sarin and VX).
+
A [[cholinesterase inhibitor]] (or "anticholinesterase") suppresses the action of the enzyme. Because of its essential function, chemicals that interfere with the action of cholinesterase are potent [[neurotoxin]]s, causing excessive salivation and eye watering in low doses, followed by muscle spasms and ultimately death (examples are some [[snake venoms]], and the nerve gases [[sarin]] and [[VX (nerve agent)|VX]]). One counteracting medication is [[pralidoxime]].
   
One of the most common classes of acetylcholinesterase inhibitors are phosphorus-based compounds which are designed to bind to the active site of the [[enzyme]]. The structural requirements are a [[phosphorus]] atom bearing two [[lipophilic]] groups, a leaving group (such as a [[halide]] or [[thiocyanate]]) and a [[Polymer|terminal]] [[oxygen]]. The entry on [[Lawesson's reagent]] has some details on one sub-class of the phosphorus-based compounds.
+
Among the most common acetylcholinesterase inhibitors are phosphorus-based compounds which are designed to bind to the active site of the [[enzyme]]. The structural requirements are a [[phosphorus]] atom bearing two [[lipophilic]] groups, a leaving group (such as a [[halide]] or [[thiocyanate]]) and a [[Polymer|terminal]] [[oxygen]]. The entry on [[Lawesson's reagent]] has some details on one sub-class of the phosphorus-based compounds.
   
Outside of [[biochemical warfare]], anticholinesterases are also used in [[anesthesia]] or in the treatment of [[myasthenia gravis]], [[glaucoma]] and [[Alzheimer's disease]]. Also such compounds are used for killing insects in a range of products including sheep dip. In addition to acute poisoning as described above, a semi-acute poisoning characterized by strong mental disturbances can occur.
+
Outside of [[biochemical warfare]], anticholinesterases are also used in [[anesthesia]] or in the treatment of [[myasthenia gravis]], [[glaucoma]] and [[Alzheimer's disease]]. Also, such compounds are used for killing [[insects]] in a range of products including [[sheep dip]], [[organophosphate]] pesticides, and [[carbamate]] pesticides. In addition to acute poisoning as described above, a semi-acute poisoning characterized by strong mental disturbances can occur. Also, prolonged exposure can cause [[birth defects]].
   
==See also==
 
   
 
==Additional images==
==References & Bibliography==
 
  +
<gallery>
==Key texts==
 
  +
Image:ACh.png|[[Acetylcholine]]
===Books===
 
  +
Image:Choline-skeletal.png|[[Choline]]
===Papers===
 
  +
Image:Acetic-acid-2D-skeletal.svg|[[Acetic acid]]
* Sussman J.L., Harel M., Frolow F., Oefner C., Goldman A., Toker L., Silman I. (1991). Atomic structure of acetylcholinesterase from Torpedo californica: a prototypic acetylcholine-binding protein. ''Science'', 253:872-9. PMID 1678899.
 
  +
Image:Butyrylcholine.png|[[Butyrylcholine]]
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</gallery>
  +
 
==See also==
  +
*[[Cholinergic blocking drugs]]
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*[[Cholinesterase inhibitors]]
   
  +
==Reference==
==Additional material==
 
  +
<references/>
===Books===
 
===Papers===
 
   
 
==External links==
 
==External links==
*[http://www.weizmann.ac.il/sb/faculty_pages/Sussman/movies.html Movies] showing the structure of acetylcholinesterase and intereactions with various inhibitors.
+
*[http://www.weizmann.ac.il/sb/faculty_pages/Sussman/movies.html Movies at weizmann.ac.il] showing the structure of acetylcholinesterase and interactions with various inhibitors.
  +
* {{PDB Molecule of the Month|pdb54_1}}
*[http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb54_1.html Acetylcholinesterase: Molecule of the Month on PDB]
 
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* {{MeshName|Acetylcholinesterase}}
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* {{MeshName|Pseudocholinesterase}}
   
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{{Esterases}}
[[Category:EC 3.1.1]]
 
   
 
[[Category:Esterases]]
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[[Category:Neurotransmitters]]
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[[Category:Peripheral membrane proteins]]
   
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<!--
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[[de:Cholinesterase]]
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[[fr:Cholinestérase]]
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[[it:Acetilcolinesterasi]]
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[[nl:Acetylcholinesterase]]
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[[ja:コリンエステラーゼ]]
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[[pl:Cholinoesteraza]]
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[[tr:Asetilkolinesteraz]]
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-->
 
{{enWP|Cholinesterase}}
 
{{enWP|Cholinesterase}}

Latest revision as of 08:31, 6 December 2008

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acetylcholinesterase (Yt blood group)
Symbol(s): ACHE YT
Locus: 7 q22
EC number 3.1.1.7
EntrezGene 43
OMIM 100740
RefSeq NM_015831
UniProt P22303
butyrylcholinesterase
Symbol(s): BCHE CHE1
Locus: 3 q26.1 -26.2
EC number 3.1.1.8
EntrezGene 590
OMIM 177400
RefSeq NM_000055
UniProt P06276

In neurochemistry, Acetylcholinesterase or cholinesterase is an enzyme which catalyzes the hydrolysis of the neurotransmitter acetylcholine into choline and acetic acid, a reaction necessary to allow a cholinergic neuron to return to its resting state after activation.

Types

There are two types:

  • Acetylcholinesterase (EC 3.1.1.7) (AChE), also known as RBC cholinesterase, erythrocyte cholinesterase, or (most formally) acetylcholine acetylhydrolase, found primarily in the blood and neural synapses
  • Pseudocholinesterase (EC 3.1.1.8) (BChE or BuChE), also known as plasma cholinesterase, butyrylcholinesterase, or (most formally) acylcholine acylhydrolase, found primarily in the liver

The difference between the two types of cholinesterase has to do with their respective preferences for substrates: the former hydrolyses acetylcholine more quickly; the latter hydrolyses butyrylcholine more quickly.

History

In 1968, Walo Leuzinger et al successfully purified and crystallized the enzyme from electric eels at Columbia University, NY. [1][2]

The 3D structure of acetylcholinesterase was first determined in 1991 by Joel Sussman et al using protein from the Pacific electric ray.[3]

Clinical significance

An absence or mutation of the pseudocholinesterase enzyme leads to a medical condition known simply as pseudocholinesterase deficiency. This is a silent condition that only manifests itself when people who have the deficiency receive the muscle relaxants succinylcholine or mivacurium during a surgery.

Elevation of plasma pseudocholinesterase was observed in 90.5% cases of acute myocardial infarction.[4]

Acetylcholinesterase is tested in early pregnancy. A sample of amniotic fluid is removed by amniocentesis. The presence of AChE in the amniotic fluid can confirm a neural tube defect, a common type of birth defect.[1]

Cholinesterase inhibitors

A cholinesterase inhibitor (or "anticholinesterase") suppresses the action of the enzyme. Because of its essential function, chemicals that interfere with the action of cholinesterase are potent neurotoxins, causing excessive salivation and eye watering in low doses, followed by muscle spasms and ultimately death (examples are some snake venoms, and the nerve gases sarin and VX). One counteracting medication is pralidoxime.

Among the most common acetylcholinesterase inhibitors are phosphorus-based compounds which are designed to bind to the active site of the enzyme. The structural requirements are a phosphorus atom bearing two lipophilic groups, a leaving group (such as a halide or thiocyanate) and a terminal oxygen. The entry on Lawesson's reagent has some details on one sub-class of the phosphorus-based compounds.

Outside of biochemical warfare, anticholinesterases are also used in anesthesia or in the treatment of myasthenia gravis, glaucoma and Alzheimer's disease. Also, such compounds are used for killing insects in a range of products including sheep dip, organophosphate pesticides, and carbamate pesticides. In addition to acute poisoning as described above, a semi-acute poisoning characterized by strong mental disturbances can occur. Also, prolonged exposure can cause birth defects.


Additional images

See also

Reference

  1. * Leuzinger W, Baker AL. Acetylcholinesterase, i. Large-scale purification, homogeneity, and amino acid analysis. Proc Natl Acad Sci U S A. 1967 Feb; 57(2): 446-451. PMCID: 335526
  2. Leuzinger W, Baker A L, Cauvin E. Acetylcholinesterase, II. Crystallization, Absorption Spectra, Isoionic Point. Proc Natl Acad Sci U S A, Vol. 59, No. 2 (Feb. 15, 1968), pp. 620-623. PMCID: 224717
  3. Sussman JL, Harel M, Frolow F, Oefner C, Goldman A, Toker L, Silman I. Atomic structure of acetylcholinesterase from Torpedo californica: a prototypic acetylcholine-binding protein. Science 1991;253:872-9. PMID 1678899.
  4. Textbook of Medical Biochemistry, MN Chatterjea & Rana Shinde, 6th Ed, 2005 (Pg 565)

External links


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