Affinity chromatography of acetylcholinesterase : The use of amberlite cg-120 for dissociating the enzyme-inhibitor complex

Acetylcholinesterase from rat brain was solubilized with 1% (w/v) Triton X-100 and purified by affinity chromatography. Two different ligands were investigated. The most efficient purification was obtained when the enzyme was eluted from a column containing the acetylcholinesterase inhibitor N-methyl-3-aminopyridinium iodide covalently linked to Sepharose 2B. An initial recovery of 6% of the applied enzyme increased to 70% after treatment with Amberlite CG-120. The partially purified enzyme had a specific activity of 205 μmoles min−1 mg−1 and a purification of 162-fold with respect to the brain homogenate and 44-fold with respect to the Triton solubilized enzyme. The effect of metal cations on the stability of the partially purified enzyme during storage at − 20°C was also investigated. The addition of MgCl2 to the purified enzyme prevented the rapid loss of enzyme activity.