In biochemistry, cholinesterase is a term which refers to one of the two enzymes (EC 3.1.1.7):

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

Both of these compounds 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.

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.

An absence or mutation of the pseudochlinesterase 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 anaestetic agent succinylcholine during a surgery.

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 snake venom, sarin and VX).

Outside of biochemical warfare, anticholinesterases are used are also used in anesthesia or in the treatment of myasthenia gravis, glaucoma and Alzheimer's disease.

External link

• Acetylcholinesterase: Molecule of the Month on PDB