the catalytic triad or the 'oxyanion hole' but only [5] . Decamethonium Binding sites of Torpedo californica acetylcholinesterase ( EC 3.1.1.7 ) with the bisquaternary ligand decamethonium (DME, 1acl ). DME is oriented along the ; one quaternary group is apposed to the indole moiety of (catalytic anionic site, CAS) and