Protein ligand interactions .7. Halogenated pyridinium salts as inhibitors of acetylcholinesterase from Electrophorus electricus

The interaction of halo-quaternary pyridinium hydrochloride salts on acetyl cholinesterase (AChE, E.C. 3.1.1.7) has been investigated. Kinetic analysis has shown that they reflect a non-competitive inhibition with K-i values in the range 8-13 mu M and 5-34 mu M for chloro- and bromo-substituted salts respectively. Spectrophotometry was used to study the binding of the ligands with the enzyme and Scatchard analysis used to calculate the respective dissociation constants (Kd) and the number of binding sites. The substitution position of the halogen on the pyridine ring also influenced the binding capacity and the K-i values.