Multiple molecular forms of acetylcholinesterase from human erythrocyte membranes. Interconversion and subunit...

Quantitative separation of eight multiple molecular forms of acetylcholinesterase isolated from human erythrocyte membranes was accomplished by sucrose density gradient centrifugation in a zonal rotor. Hydrodynamic properties of the four most abundant oligomers were investigated by analytical ultracentrifugation. The S20, w values obtained for these components ranged from 12.5 S to 19.0 S with corresponding molecular weights between 500 000 and 1 131 000. These oligomers are built up of 6-14 subunits. Analysis of each isolated homogenous form after storage for 6 months at 4 degrees C revealed interconversion into the original eight components. Upon addition of Triton X-100 the oligomers disaggregate to yield a single 7-S form, which reaggregates upon removal of the detergent. Such reaggregation can be prevented by chaotropic ions indicating that hydrophobic interactions are important in the formation of these oligomeric forms.