EN
Acetylcholinesterase (AChE) sequentially extracted from mature specimens of Hymenolepis diminuta was shown to be a globular protein, the monomeric form of which (Ga₁) had molecular mass of 66 kDa as determined by SDS-PAGE. Amphiphilic character of the enzyme was revealed by Triton X-l14 phase partitioning. The cestode AChE preferred acetylthiocholine over propionyl- and butyrylthiocholine as substrate, split N-acetyl-ß-methylthiocholine and myristoylcholine but did not hydrolyze ß-carbonaphthoxycholine, a substrate for butyrylcholinesterases. It was sensitive to 10⁻⁵ M physostigmine and 10⁻⁵ M BW284C51 but not to 10⁻³ M iso-OMPA. No butyrylcholinesterase activity was detected in extracts from the parasite.