title: Anatoxin-a(s), an anticholinesterase from the cyanobacterium Anabaena flos-aquae NRC-525-17.
abstract: Anatoxin a(s) [antx-a(s)] given intraperitoneally to Sprague-Dawley rats at different doses (0.1-1.0 mg/kg) caused signs of severe cholinergic overstimulation. Assays of rat blood acetylcholinesterase (AChE) revealed a dose-dependent inhibition. The in vitro inhibition of electric eel acetylcholinesterase (AChE, E.C. 3.1.1.7) and horse serum butyrylcholinesterase (BUChE, E.C. 3.1.1.8) by antx-a(s) was time- and concentration-dependent. The inhibition of electric eel AChE follows first order kinetics, indicative of irreversible inhibition. The irreversibility of electric eel AChE inhibition was confirmed by a plot of Vmax versus total enzyme concentration [ET]. The kinetics of inhibition of cholinesterase by antx-a(s) supports the previous pharmacological findings that antx-a(s) is an anticholinesterase and that signs of intoxication by it are primarily due to cholinesterase inhibition.
mesh_terms: D000818:Animals; D001427:Bacterial Toxins; D001667:Binding, Competitive / Q000187:drug effects; D002091:Butyrylcholinesterase / Q000378:metabolism; D002800:Cholinesterase Inhibitors / Q000302:isolation & purification; D000458:Cyanobacteria / Q000201:enzymology*; D000087522:Cyanobacteria Toxins; D004593:Electrophorus; D006736:Horses; D007700:Kinetics; D008297:Male; D008387:Marine Toxins / Q000302:isolation & purification / Q000494:pharmacology*; D052998:Microcystins; D051381:Rats; D011919:Rats, Inbred Strains; D014326:Tropanes
chemical_list: D001427:Bacterial Toxins; D002800:Cholinesterase Inhibitors; D000087522:Cyanobacteria Toxins; D008387:Marine Toxins; D052998:Microcystins; D014326:Tropanes; C509783:anatoxin a; D002091:Butyrylcholinesterase