Cholinesterase enzyme. Molecular model of the secondary structure of butyrylcholinesterase (BChE), showing alpha helices (blue) and beta sheets (red and yellow). 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 catalyses 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.