Heparin-acetylcholinesterase interaction: Specific detachment of class I-A forms and binding of class I and II-A...

This study describes the specificity, time-course and characteristics of the solubilization of class I-A forms of AChE by heparin, from the endplate regions of rat diaphragm muscle. Heparin fractions which differed in size charge, anticoagulant activity and capacity to bind type I collagen, were probed in their ability to extract AChE. No differences were found among all the fractions tested. Affinity chromatography on heparin-agarose of class I- and class II-A forms of esterase showed that both classes were able to bind to the column with the same relative affinity. Our results establish the use of heparin, as a solubilizing agent for the class I-A. The existence of a heparin-binding domain in class I- and class II-A forms of AChE, opens the possibility, that heparan sulfate proteoglycans could be involved in the anchorage of both types of esterase to synaptic regions. Finally, our results suggest that class I and class II-A do not correspond to intrinsically distinct molecules, but rather to identical molecules engaged in different interactions in the tissue.