Inactivation of acetylcholinesterase by various fluorophores.
The inhibition of recombinant mouse acetylcholinesterase (rMAChE) and electric eel acetylcholinesterase (EEAChE) by seven, structurally different chromophore-based (dansyl, pyrene, dabsyl, diethylamino- and methoxycoumarin, Lissamine rhodamine B, and Texas Red) propargyl carboxamides or sulfonamides was studied. Diethylaminocoumarin, Lissamine, and Texas Red amides inhibited rMAChE with IC50 values of 1.00 microM, 0.05 microM, and 0.70 microM, respectively. Lissamine and Texas Red amides inhibited EEAChE with IC50 values of 3.57 and 10.4 microM, respectively. The other chromophore amides did not inhibit either AChE. The surprising inhibitory potency of Lissamine was examined in further detail against EEAChE and revealed a mixed-type inhibition with Ki = 11.7 microM (competitive) and Ki' = 24.9 microM (noncompetitive), suggesting that Lissamine binds to free enzyme and enzyme-substrate complex.
Guo
Lilu
L
Department of Biomedical and Pharmaceutical Sciences, Center for Structural and Functional Neuroscience, The University of Montana, Missoula, MT 59812, USA. lilu.guo@ateristech.com
Suarez
Alirica I
AI
Thompson
Charles M
CM
D000110:Acetylcholinesterase / Q000187:drug effects*; D000818:Animals; D002800:Cholinesterase Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D031541:Fluorescence Resonance Energy Transfer; D005456:Fluorescent Dyes / Q000737:chemistry / Q000494:pharmacology*; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D021241:Spectrometry, Mass, Electrospray Ionization
D002800:Cholinesterase Inhibitors; D005456:Fluorescent Dyes; D000110:Acetylcholinesterase