Cobra venom acetylcholinesterase. Purification and molecular properties.
Acetylcholinesterase from cobra (Naja naja oxiana) venom has been purified by affinity chromatography to an homogeneous state, as ascertained by sodium dodecylsulfate/polyacrylamide gel electrophoresis and sedimentation analysis. The specific activity of the preparation was 5000 IU/mg with acetylcholine as substrate. Unlike acetylcholinesterases from insoluble cell structures, the native molecule of the cobra venom enzyme consists of a single polypeptide chain of molecular weight 67,000 +/- 2000. At high enzyme concentrations (greater than 0.2 mg/ml, greater than 1 microM) and ionic strength 0.1 M, it reversibly tends to form  higher-molecular-weight 7.1-S aggregates. Despite the apparent structural simplicity of the venom acetylcholinesterase, the disc electrophoresis and isoelectric focusing experiments revealed that the enzyme exists in a number of forms with a common molecular weight but with different isoelectric points. Neuraminidase treatment did not reduce the number of the forms.
D000110:Acetylcholinesterase / Q000302:isolation & purification*; D000818:Animals; D004546:Elapid Venoms; D046911:Macromolecular Substances; D008970:Molecular Weight; D012794:Sialic Acids / Q000032:analysis
D004546:Elapid Venoms; D046911:Macromolecular Substances; D012794:Sialic Acids; D000110:Acetylcholinesterase