Amphiphilic properties of acetylcholinesterase monomers in mouse plasma

Mouse plasma acetylcholinesterase (AChE) tetramers (G 4) and dimers (G 2) were retained by edrophonium-Sepharose, whereas AChE monomers (G 1), and G 4, G 2 and G 1 butyrylcholinesterase (BuChE) forms were not. Plasma G 4 or G 1 AChE did not differ in their affinity for edrophonium. G 1 AChE, and G 1 and G 2 BuChE were retained in octyl-Sepharose, while G 4 and G 2 AChE, and G 4 BuChE eluted freely. The amphiphilic behaviour of G 1 AChE remained unmodified after incubation with trypsin. The electrophoretic mobility of the AChE monomers varied with the detergent added to the samples. The results show that mouse plasma G 1 AChE possesses hydrophobic regions, which prevent its binding to the affinity matrix, and afford its interaction with octyl-Sepharose. The hydrophobic regions in G 1 AChE probably provide conformational stability to disulfide-linked subunits in hydrophilic dimers.