Cholinesterase
The enzyme cholinesterase (EC 3.1.1.8, choline esterase; systematic name acylcholine acylhydrolase) catalyses the hydrolysis of choline-based esters:
- an acylcholine + H2O = choline + a carboxylate
| acetylcholinesterase (Yt blood group) | |||||||
|---|---|---|---|---|---|---|---|
Diagram of Pacific electric ray acetylcholinesterase. From PDB: 1EA5. | |||||||
| Identifiers | |||||||
| Symbol | ACHE | ||||||
| Alt. symbols | YT | ||||||
| NCBI gene | 43 | ||||||
| HGNC | 108 | ||||||
| OMIM | 100740 | ||||||
| RefSeq | NM_015831 | ||||||
| UniProt | P22303 | ||||||
| Other data | |||||||
| EC number | 3.1.1.7 | ||||||
| Locus | Chr. 7 q22 | ||||||
| |||||||
| butyrylcholinesterase | |||||||
|---|---|---|---|---|---|---|---|
Cartoon diagram of human butyrylcholinesterase. From PDB: 1P0I. | |||||||
| Identifiers | |||||||
| Symbol | BCHE | ||||||
| Alt. symbols | CHE1, CHE2, E1 | ||||||
| NCBI gene | 590 | ||||||
| HGNC | 983 | ||||||
| OMIM | 177400 | ||||||
| RefSeq | NM_000055 | ||||||
| UniProt | P06276 | ||||||
| Other data | |||||||
| EC number | 3.1.1.8 | ||||||
| Locus | Chr. 3 q26.1-26.2 | ||||||
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Several of these serve as neurotransmitters. Thus, it is either of two enzymes that catalyze the hydrolysis of these cholinergic neurotransmitters, such as breaking acetylcholine into choline and acetic acid. These reactions are necessary to allow a cholinergic neuron to return to its resting state after activation. For example, in muscle contraction, acetylcholine at a neuromuscular junction triggers a contraction; but for the muscle to relax afterward, rather than remaining locked in a tense state, the acetylcholine must be broken down by a choline esterase. The main type for that purpose is acetylcholinesterase (also called choline esterase I or erythrocyte cholinesterase); it is found mainly in chemical synapses and red blood cell membranes. The other type is butyrylcholinesterase (also called choline esterase II or plasma cholinesterase); it is found mainly in the blood plasma.