Rapid method for evaluation of cholinesterase inhibitors

Abstract

The fluorescence intensity of reversible inhibitor ethidium bromide fluorophore complex with equine blood butyryl cholinesterase decreases in the presence of inhibitor (tacrine) not fluorescing in the visible spectrum. An express method for tacrine evaluation is developed.

Biosensors as tools of environmental monitoring for organophosphorus nerve agents

“…The appearance of a new fluorescence band was detected within 10 s after the addition of the enzyme to a solution of ethidium bromide; in this case, the measured fluorescence intensity remained stable for more than 30 min [36]. Obviously, the new fluorescence bands were caused by the formation of a complex of ethidium bromide with the above enzymes because the solutions of cholinesterases do not fluo resce in a range of 500-700 nm.…”

“…The dependence of the fluorescence intensity of ethidium bromide (0.6 μM) at λ ~ 550 nm on the activity of enzyme (х) was linear in the test range of enzyme activity (0.5-2.0 U/mL) [36]: Under the action of the organophosphorus insecti cide paraoxon, the fluorescence intensity I fl of the ethidium bromide-BChE system decreased in 10-15 s. The dependence of the fluorescence intensity of the ethidium bromide-BChE system on the concentra tion of paraoxon (х) was linear in the test range of con centrations, and it can be presented in the following form [37]: Based on the complex of the ethidium bromide (the active center phosphorylation activator of cholinest erase) with horse BChE, a fluorescence optical bio sensor was developed for the monitoring of ambient air for organophosphorus insecticides and OPWAs, which is characterized a high speed of response [37]. The active constituent of the biosensor was the complex of ethidium bromide with horse BChE immobilized by a sol-gel method.…”

“…The ChE phosphorylation activator ethidium bro mide (Scheme 3) has the following advantages over well known activators [36]:…”

“…Chemical structure of ethidium bromide. addition of BChE preliminarily inhibited by 100% with the strong organophosphorus inhibitor paraoxon to the solution of ethidium bromide [36].…”

“…Absorption spectra of ethidium bromide and its com plex with horse BChE: (1) (7.5 µM) and (2) the complex of ethidium bromide with horse BChE (0.50 U/mL)[36].…”