Butyrylcholinesterase

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BCHE
Protein BCHE PDB 1p0i.png
Available structures
PDB Ortholog search: PDBe RCSB
Identifiers
Aliases BCHE, CHE1, CHE2, E1, butyrylcholinesterase
External IDs OMIM: 177400 MGI: 894278 HomoloGene: 20065 GeneCards: BCHE
Genetically Related Diseases
cardiovascular disease[1]
Targeted by Drug
bambuterol, physostigmine, pyridostigmine, rivastigmine, tacrine[2]
RNA expression pattern
PBB GE BCHE 205433 at tn.png
More reference expression data
Orthologs
Species Human Mouse
Entrez
Ensembl
UniProt
RefSeq (mRNA)

NM_000055

NM_009738

RefSeq (protein)

NP_000046.1

NP_033868.3

Location (UCSC) Chr 3: 165.77 – 165.84 Mb Chr 3: 73.64 – 73.71 Mb
PubMed search [3] [4]
Wikidata
View/Edit Human View/Edit Mouse

Butyrylcholinesterase (HGNC symbol BCHE), also known as BChE, BuChE, pseudocholinesterase, or plasma (cholin)esterase,[5] is a nonspecific cholinesterase enzyme that hydrolyses many different choline-based esters. In humans, it is made in the liver, found mainly in blood plasma, and encoded by the BCHE gene.[6]

It is very similar to the neuronal acetylcholinesterase, which is also known as RBC or erythrocyte cholinesterase.[5] The term "serum cholinesterase" is generally used in reference to a clinical test that reflects levels of both of these enzymes in the blood.[5] Assay of butyrylcholinesterase activity in plasma can be used as a liver function test as both hypercholinesterasemia and hypocholinesterasemia indicate pathological processes.

Butyrylcholine is a synthetic compound that does not occur in the body naturally. It is used as a tool to distinguish between acetylcholinesterase and butyrylcholinesterase.

Clinical significance[edit]

Pseudocholinesterase deficiency results in delayed metabolism of only a few compounds of clinical significance, including the following: succinylcholine, mivacurium, procaine, heroin, and cocaine. Of these, its most clinically important substrate is the depolarizing neuromuscular blocking agent, succinylcholine, which the pseudocholinesterase enzyme hydrolyzes to succinylmonocholine and then to succinic acid.

In individuals with normal plasma levels of normally functioning pseudocholinesterase enzyme, hydrolysis and inactivation of approximately 90-95% of an intravenous dose of succinylcholine occurs before it reaches the neuromuscular junction. The remaining 5-10% of the succinylcholine dose acts as an acetylcholine receptor agonist at the neuromuscular junction, causing prolonged depolarization of the postsynaptic junction of the motor-end plate. This depolarization initially triggers fasciculation of skeletal muscle. As a result of prolonged depolarization, endogenous acetylcholine released from the presynaptic membrane of the motor neuron does not produce any additional change in membrane potential after binding to its receptor on the myocyte. Flaccid paralysis of skeletal muscles develops within 1 minute. In normal subjects, skeletal muscle function returns to normal approximately 5 minutes after a single bolus injection of succinylcholine as it passively diffuses away from the neuromuscular junction. Pseudocholinesterase deficiency can result in higher levels of intact succinylcholine molecules reaching receptors in the neuromuscular junction, causing the duration of paralytic effect to continue for as long as 8 hours. This condition is recognized clinically when paralysis of the respiratory and other skeletal muscles fails to spontaneously resolve after succinylcholine is administered as an adjunctive paralytic agent during anesthesia procedures. In such cases respiratory assistance is required.[7]

In 2008, an experimental new drug was discovered for the potential treatment of cocaine abuse and overdose based on the pseudocholinesterase structure. It was shown to remove cocaine from the body 2000 times as fast as the natural form of BChE. Studies in rats have shown that the drug prevented convulsions and death when administered cocaine overdoses.[8] This enzyme also metabolizes succinylcholine which accounts for its rapid degradation in the liver and plasma. There may be genetic variability in the kinetics of this enzyme that can lead to prolonged muscle blockade and potentially dangerous respiratory depression that needs to be treated with assisted ventilation.

Mutant alleles at the BCHE locus are responsible for suxamethonium sensitivity. Homozygous persons sustain prolonged apnea after administration of the muscle relaxant suxamethonium in connection with surgical anesthesia. The activity of pseudocholinesterase in the serum is low and its substrate behavior is atypical. In the absence of the relaxant, the homozygote is at no known disadvantage.[9]

Finally, pseudocholinesterase metabolism of procaine results in formation of paraaminobenzoic acid (PABA). If the patient receiving procaine is on sulfonamide antibiotics such as bactrim the antibiotic effect will be antagonized by providing a new source of PABA to the microbe for subsequent synthesis of folic acid.

Prophylactic countermeasure against nerve gas[edit]

Butyrylcholinesterase is a prophylactic countermeasure against organophosphate nerve agents. It binds nerve agent in the bloodstream before it can exert effects in the nervous system. Because it is a biological scavenger (and universal target), it is currently the only therapeutic agent effective in providing complete stoichiometric protection against the entire spectrum of organophosphate nerve agents.[10]

Physiological role[edit]

It was recently indicated that butyrylcholinesterase could be a physiological ghrelin regulator.[11]

Interactive pathway map[edit]

Click on genes, proteins and metabolites below to link to respective articles. [§ 1]

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IrinotecanPathway_WP46359 go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article Go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article go to article Go to article go to article
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  1. ^ The interactive pathway map can be edited at WikiPathways: "IrinotecanPathway_WP46359". 

Inhibitors[edit]

Nomenclature[edit]

The nomenclatural variations of BCHE and of cholinesterases generally are discussed at Cholinesterase § Types and nomenclature.

See also[edit]

References[edit]

  1. ^ "Diseases that are genetically associated with BCHE view/edit references on wikidata". 
  2. ^ "Drugs that physically interact with Cholinesterase view/edit references on wikidata". 
  3. ^ "Human PubMed Reference:". 
  4. ^ "Mouse PubMed Reference:". 
  5. ^ a b c Jasmin L (2013-05-28). "Cholinesterase - blood". University of Maryland Medical Center. 
  6. ^ Allderdice PW, Gardner HA, Galutira D, Lockridge O, LaDu BN, McAlpine PJ (Oct 1991). "The cloned butyrylcholinesterase (BCHE) gene maps to a single chromosome site, 3q26". Genomics. 11 (2): 452–4. doi:10.1016/0888-7543(91)90154-7. PMID 1769657. 
  7. ^ "Pseudocholinesterase Deficiency". Medscape. WebMD LLC. 
  8. ^ Zheng F, Yang W, Ko MC, Liu J, Cho H, Gao D, Tong M, Tai HH, Woods JH, Zhan CG (Sep 2008). "Most efficient cocaine hydrolase designed by virtual screening of transition states". Journal of the American Chemical Society. 130 (36): 12148–55. doi:10.1021/ja803646t. PMC 2646118Freely accessible. PMID 18710224. Lay summaryScienceDaily. 
  9. ^ "Entrez Gene: BCHE butyrylcholinesterase". 
  10. ^ "Medical Identification and Treatment Systems(MITS)". Joint Program Executive Office for Chemical and Biological Defense. United States Army. 
  11. ^ Chen VP, Gao Y, Geng L, Parks RJ, Pang YP, Brimijoin S (Feb 2015). "Plasma butyrylcholinesterase regulates ghrelin to control aggression". Proceedings of the National Academy of Sciences of the United States of America. 112 (7): 2251–6. doi:10.1073/pnas.1421536112. PMID 25646463. 
  12. ^ Brus B, Košak U, Turk S, Pišlar A, Coquelle N, Kos J, Stojan J, Colletier JP, Gobec S (Oct 2014). "Discovery, biological evaluation, and crystal structure of a novel nanomolar selective butyrylcholinesterase inhibitor". Journal of Medicinal Chemistry. 57 (19): 8167–79. doi:10.1021/jm501195e. PMID 25226236. 

Further reading[edit]

External links[edit]