title: On the homogeneity of 11-S acetylcholinesterase.
abstract: 11-S acetylcholinesterase (acetylcholine hydrolase, EC 3.1.1.7) purified by affinity chromatography of trypsin-digested homogenates was shown to be contaminated with three other active forms of enzyme. The initial purification used an affinity column of the inhibitor, N-methylacridinium ion. Chromatography of the "affinity-pure" sample on hydroxyapatite resulted in two peaks of acetylcholinesterase activity. One peak contained only a form sedimenting at 11-S (approx. 85% of the recovered activity). The other peak consisted of a 9.5-S form, in addition to 14-S and 18-S forms. The 9.5-S form (approx. 7% of the activity) co-electrophoresed with 11-S in 6% polyacrylamide gels and co-sedimented with the same form in sucrose density gradients containing 0.1 M NaCl. The purified 11-S enzyme was shown to be homogeneous by sucrose density gradient centrifugation and electrophoresis. These results indicate that 11-S acetylcholinesterase may be unsuitable for some characterization studies due to undetected contamination by the 9.5-S form.
mesh_terms: D000110:Acetylcholinesterase / Q000302:isolation & purification*; D000166:Acridines; D000818:Animals; D002846:Chromatography, Affinity; D004593:Electrophorus; D008970:Molecular Weight; D011487:Protein Conformation
chemical_list: D000166:Acridines; C028189:N-methylacridine; D000110:Acetylcholinesterase