Affinity chromatography of triton-solubilized brain acetylcholinesterase

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 mumoles 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 degrees C was also investigated. The addition of MgCl2 to the purified enzyme prevented the rapid loss of enzyme activity.

Residual anionic properties of a covalently substituted controlled-pore glass, glyceryl-CPG

A commercial controlled-pore glass medium for exclusion chromatography which is substituted with glycerol to eliminate non-specific adsorption (Glyceryl-CPG) was examined. Experiments on the elution of acetylcholinesterase and ganglioside micelles at varied ionic strength and pH showed that a slight anionic character still persisted on the glass matrix. At ionic strengths above 0.1, this had no effect on the elution of proteins. The material was found to have no tendency to adsorb proteins and other compounds, and was judged an excellent medium for exclusion chromatography. As a support for affinity chromatography, Glyceryl-CPG could be activated by periodate to form a virtually neutral matrix-ligand system.

The effect of some amine oxides and disulphide compounds on the activity of acetylcholinesterase

Three amine oxides, two aliphatic and one aromatic, and 2,2'-dithiodipyridine were found to be weak reversible inhibitors of acetylcholinesterase. 5,5'-Dithiobis-(2-nitro-benzoic acid) had no effect on the enzyme under the conditions of the Ellman spectrophotometric assay.