Binding of the asymmetric forms of acetylcholinesterase to heparin

The interaction between acetylcholinesterase (EC 3.1.1.7) and heparin, a sulphated glycosaminoglycan, was studied by affinity chromatography. A specific binding of the asymmetric acetylcholinesterase to an agarose gel containing covalently bound heparin was demonstrated. This interaction required an intact collagenous tail, shown by the fact that the binding is abolished by pretreatment with collagenase. The globular forms did not bind to the column. Both total and intracellular asymmetric acetylcholinesterase forms isolated from the endplate region of the rat diaphragm muscle showed higher affinity for the heparin than did the enzyme from the non-endplate region. The binding to the resin was destabilized with 0.55 M-NaCl, and, among the various glycosaminoglycans tested, only heparin was able to displace the acetylcholinesterase bound to the column. Our results added further support to the concept that the asymmetric acetylcholinesterase forms are immobilized on the synaptic basal lamina via interactions with heparin-like molecules, probably related to heparan sulphate proteoglycans.