Acetylcholinesterases

Acetylcholinesterases (AChEs) are a group of enzymes that break down the neurotransmitter acetylcholine. This breakdown is crucial for the proper functioning of the nervous system. Acetylcholine is a vital chemical messenger involved in muscle contraction, learning, and memory. Once acetylcholine has transmitted its signal across a synapse, AChE rapidly hydrolyzes it into choline and acetic acid, terminating the signal and allowing the synapse to reset for subsequent signaling.

There are several types of acetylcholinesterases, with the most prominent being true acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). While both enzymes can hydrolyze acetylcholine, they have different substrate specificities and distribution within the body. True AChE is primarily found in cholinergic synapses, the junctions where acetylcholine is released. BChE, on the other hand, has a broader distribution, found in plasma, liver, and other tissues, and can also break down other esters, such as butyrylcholine.

Inhibitors of acetylcholinesterase are a significant class of compounds with various applications. Some are used therapeutically to treat conditions like Alzheimer's disease and myasthenia gravis, where increasing acetylcholine levels can improve cognitive function or muscle strength. Conversely, certain pesticides and nerve agents function by irreversibly inhibiting AChE, leading to a buildup of acetylcholine and potentially fatal overstimulation of the nervous system. The study of acetylcholinesterases is fundamental to understanding neurobiology and developing targeted pharmacological interventions.