Amphiphile dependency of the monomeric and dimeric forms of acetylcholinesterase from human erythrocyte membrane.
Human erythrocyte membrane-bound acetylcholinesterase was converted to a monomeric species by treatment of ghosts with 2-mercaptoethanol and iodoacetic acid. After solubilization with Triton X-100, the reduced and alkylated enzyme was partially purified by affinity chromatography and separated from residual dimeric enzyme by sucrose density gradient centrifugation in a zonal rotor. Monomeric and dimeric acetylcholinesterase showed full enzymatic activity in presence of Triton X-100 whereas in the absence of detergent, activity was decreased to approx. 20% and 15%, respectively. Preformed egg phosphatidylcholine vesicles fully sustained activity of the monomeric species whereas the dimer was only 80% active. The results suggest that a dimeric structure is not required for manifestation of amphiphile dependency of membrane-bound acetylcholinesterase from human erythrocytes. Furthermore, monomeric enzyme appears to be more easily inserted into phospholipid bilayers than the dimeric species.
D000110:Acetylcholinesterase / Q000097:blood* / Q000378:metabolism; D003902:Detergents; D004910:Erythrocyte Membrane / Q000201:enzymology*; D006801:Humans; D046911:Macromolecular Substances; D012995:Solubility; D013329:Structure-Activity Relationship
D003902:Detergents; D046911:Macromolecular Substances; D000110:Acetylcholinesterase