Inhibition of electric eel acetylcholinesterase by triarylmethane dyes.
The effects of three cationic triarylmethane dyes--pararosaniline (PR), malachite green (MG), methyl green (MetG)--on electric eel AChE (eAChE) activity were tested at 25 degrees C, in 100 mM MOPS buffer (pH 8) containing 0.125 mM 5-5-dithio-bis(2-nitrobenzoic acid), 20-120 microM acetylthiocholine and 0-20 microM dye. All three dyes caused reversible, linear- or hyperbolic-mixed inhibition of esteratic activity. The respective inhibitory parameters for PR, MG and MetG were K(i)=8.4+/-0.67, 1.9+/-0.51 and 0.27+/-0.017 microM; alpha (competitive coefficient)=5.8+/-2.0, 4.8+/-1.8 and 2.7+/-0.32; beta (noncompetitive coefficient)=0, 0 and 0.20+/-0.011. The data were consistent with ligand binding at the peripheral site and a remote effect on substrate binding and turnover.
Kuçukkilinç
Tuba Tuylu
TT
Department of Biochemistry, Faculty of Pharmacy, Hacettepe University, Ankara, Turkey. ttuylu@hacettepe.edu
Ozer
Inci
I
D000110:Acetylcholinesterase / Q000187:drug effects*; D000818:Animals; D002800:Cholinesterase Inhibitors / Q000494:pharmacology*; D004396:Coloring Agents / Q000494:pharmacology*; D014101:Torpedo
D002800:Cholinesterase Inhibitors; D004396:Coloring Agents; D000110:Acetylcholinesterase