Acetylcholinesterase from Apis mellifera head. Evidence for amphiphilic and hydrophilic forms characterized by Triton X-114 phase separation.
The polymorphism of bee acetylcholinesterase was studied by sucrose-gradient-sedimentation analysis and non-denaturing electrophoretic analysis of fresh extracts. Lubrol-containing extracts exhibited only one form, which sedimented at 5 S when analysed on high-salt Lubrol-containing gradients and 6 S when analysed on low-salt Lubrol-containing gradients. The 5 S/6 S form aggregated upon removal of the detergent when sedimented on detergent-free gradients and was recovered in the detergent phase after Triton X-114 phase separation. Thus the 5 S/6 S enzyme corresponds to an amphiphilic acetylcholinesterase form. In detergent-free extracts three forms, whose apparent sedimentation coefficients are 14 S, 11 S and 7 S, were observed when sedimentations were performed on detergent-free gradients. Sedimentation analyses on detergent-containing gradients showed only a 5 S peak in high-salt detergent-free extracts and a 6 S peak, with a shoulder at about 7 S, in low-salt detergent-free extracts. Electrophoretic analysis in the presence of detergent demonstrated that the 14 S and 11 S peaks corresponded to aggregates of the 5 S/6 S form, whereas the 7 S peak corresponded to a hydrophilic acetylcholinesterase form which was recovered in the aqueous phase following Triton X-114 phase separation. The 5 S/6 S amphiphilic form could be converted into a 7.1 S hydrophilic form by phosphatidylinositol-specific phospholipase C digestion.
Belzunces
L P
LP
I.N.R.A. Domaine Saint Paul, Laboratoire de Biochimie, Montfavet, France.
Toutant
J P
JP
Bounias
M
M
D000110:Acetylcholinesterase / Q000302:isolation & purification*; D000818:Animals; D001516:Bees / Q000201:enzymology*; D002462:Cell Membrane / Q000201:enzymology; D002499:Centrifugation, Density Gradient; D003902:Detergents; D004591:Electrophoresis, Polyacrylamide Gel; D006257:Head / Q000201:enzymology; D007527:Isoenzymes / Q000302:isolation & purification*; D008861:Microsomes / Q000201:enzymology; D017830:Octoxynol; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D054801:Phosphoinositide Phospholipase C; D010727:Phosphoric Diester Hydrolases; D011092:Polyethylene Glycols
D003902:Detergents; D007527:Isoenzymes; D011092:Polyethylene Glycols; D017830:Octoxynol; C010615:Nonidet P-40; D000110:Acetylcholinesterase; D010727:Phosphoric Diester Hydrolases; D054801:Phosphoinositide Phospholipase C; D043265:Phosphatidylinositol Diacylglycerol-Lyase