Heterogeneity of Rat Brain Acetylcholinesterase: A Study by Gel Filtration and Gradient Centrifugation

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Abstract
According to their solubilization properties, 2 classes of acetylcholinesterases (AChE) can be detected in the adult brain: a soluble species (easily solubilized without detergent), and a membrane-bound species (solubilized only in the presence of detergent). The latter was homogeneous by gel filtration (Stokes radius 8.05 .+-. 0.35 nm) and sucrose gradient centrifugation (9.75 .+-. 0.2 S) in the presence of Triton X-100. The soluble AChE gives 3 stable species in the presence of the same detergent with Stokes radii and sedimentation constants of 10.9 .+-. 0.5 nm and 16 .+-. 2 S; 6.75 .+-. 0.30 nm and 10.7 .+-. 0.4 S; 5.37 .+-. 0.35 nm and 4.37 .+-. 0.1 S. Co-chromatography and co-sedimentation or the reduction and alkylation of disulfide bridges show that all the soluble species are different from the membrane-bound AChE. The possibility that soluble and membrane-bound AChE are completely different molecules is discussed.