Illustration of the secondary structure of human butyrylcholinesterase (BChE). BChE, also called serum cholinesterase, is similar to the enzyme acetylcholinesterase (AChE) in that it catalyses the neurotransmitter (nerve signalling molecule) acetylcholine, producing choline and acetic acid. This allows the nerves that use acetylcholine (cholinergic neurons) to rest after passing on signals. Both AChE and BChE also catalyse the synthetic chemical butyrylcholine in a similar way to acetylcholine. AChE and BChE differ in that AChE, found in the blood and nerve synapses, catalyses acetylcholine more readily. BChE instead prefers butyrylcholine and is found in the liver.