Inhibition of acetylcholine esterase and choline esterase by benzethonium chloride and avoidance of the benzethonium chloride carry-over inhibitory effect.
It has been shown that benzethonium chloride produces linear mixed-type inhibition of choline esterase and acetylcholine esterase. These enzymes also show-reagent-carry-over inhibition if the enzyme activities are measured in plastic cuvettes in which previously protein has been determined by the alkaline benzethonium chloride method. Choline esterase is about 10-fold more sensitive to benzethonium chloride than acetylcholine esterase. With acetylthiocholine as substrate Michaelis-Menten constants for choline esterase and acetylcholine esterase are 85 mumol/l and 102 mumol/l, respectively. Carry-over inhibitory effect of benzethonium chloride can be avoided by washing the cuvettes, after protein determination by the benzethonium chloride method, with 5 ml/l Triton X-100, 5 ml/l Tween 20 or 10 g/l sodium dodecyl sulphate. The latter has a disadvantage in that it precipitates out at low temperatures. The dry slide method (Johnson & Johnson) for serum choline esterase is free of the inhibitory effect until the concentration of benzethonium chloride in the sample reaches about 200 mumol/l.
Zaman
Z
Z
Department of Clinical Chemistry, University Hospitals Leuven, Belgium. zahur.zaman@uz.kuleuven.ac.be
Speeleveld
E
E
Sneyers
L
L
Desmet
K
K
D000110:Acetylcholinesterase / Q000187:drug effects* / Q000378:metabolism; D001558:Benzethonium / Q000009:adverse effects / Q000494:pharmacology*; D002092:Butyrylthiocholine / Q000378:metabolism; D002800:Cholinesterase Inhibitors / Q000009:adverse effects / Q000494:pharmacology*; D002802:Cholinesterases / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D007202:Indicators and Reagents / Q000009:adverse effects; D007700:Kinetics; D013379:Substrate Specificity
D002800:Cholinesterase Inhibitors; D007202:Indicators and Reagents; D001558:Benzethonium; D002092:Butyrylthiocholine; D000110:Acetylcholinesterase; D002802:Cholinesterases