title: Conversion of acetylcholinesterase hydrophilic tetramers into amphiphilic dimers and monomers.
abstract: Exposure of purified hydrophilic tetramers of acetylcholinesterase (AChE) from fetal bovine serum to various guanidinium chloride (Gdn) concentrations led to inactive tetramers (2 M Gdn) and dimers (6 M Gdn). The native tetramers were almost fully monomerized by reduction, a minor fraction of the released monomers remaining active. Sedimentation analysis and hydrophobic chromatography showed that the modified tetramers, dimers and monomers had amphiphilic properties. Intrinsic fluorescence spectra and binding of the amphiphilic probe, 1-anilino-8-naphthalene sulfonate (ANS), revealed that AchE subunit in the modified tetramers were in a 'molten globule' structure, the dimers in a denatured stated, and the inactive monomers in a 'native-like' structure. These data show that AChE subunits possess a flexible conformation, which may be important for generating a full set of molecular forms. In addition, the behavior of the active monomers with amphiphiles may explain the interactions of type II AChE forms with membranes.
authors.affiliation: Departamento de Bioquímica y Biología Molecular A, Edificio de Veterinaria, Universidad de Murcia, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Flores-Flores
authors.forename: A
authors.initials: A
authors.lastname: Martinez-Martinez
authors.forename: E
authors.initials: E
authors.lastname: Muñoz-Delgado
authors.forename: C J
authors.initials: CJ
authors.lastname: Vidal
mesh_terms: D000110:Acetylcholinesterase / Q000097:blood / Q000737:chemistry* / Q000302:isolation & purification; D000817:Anilino Naphthalenesulfonates; D000818:Animals; D002417:Cattle; D002499:Centrifugation, Density Gradient; D002846:Chromatography, Affinity; D004591:Electrophoresis, Polyacrylamide Gel; D005456:Fluorescent Dyes; D019791:Guanidine; D006146:Guanidines; D007531:Isoflurophate / Q000378:metabolism; D046911:Macromolecular Substances; D008970:Molecular Weight; D017830:Octoxynol; D011485:Protein Binding; D011487:Protein Conformation; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet
chemical_list: D000817:Anilino Naphthalenesulfonates; D005456:Fluorescent Dyes; D006146:Guanidines; D046911:Macromolecular Substances; D007531:Isoflurophate; C027132:1-anilino-8-naphthalenesulfonate; D017830:Octoxynol; D000110:Acetylcholinesterase; D019791:Guanidine