Rapidly hydrolyzes acetylcholine and releases choline into the synapse (Probable). It can hydrolyze propionylcholine and butyrylthiocholine in vitro (Probable). acetylcholine + H2O = acetate + choline + H(+) Oligomer composed of disulfide-linked homodimers. May be secreted or membrane associated via a non-catalytic subunit. Detected at all stages. Found to be more abundant in larval stages than in embryos or adults. Belongs to the type-B carboxylesterase/lipase family.