Estimation of inhibitory organophosphates with purified pig liver carboxylesterase

Autor(en): Heymann, E
Stichwörter: Biochemistry & Molecular Biology; ESTERASE; kinetics of suicide inhibition; Pharmacology & Pharmacy; pig liver carboxylesterase; quantitation of organophosphate inhibitors; quantitation of suicide enzyme inhibitors; Toxicology
Erscheinungsdatum: 1999
Volumen: 119
Startseite: 577
Seitenende: 586
Organophosphates that inhibit acetylcholineesterase normally also inhibit pig liver carboxylesterase irreversibly. Since this liver esterase is well characterized and easily accessible in large amounts, we propose the use of this enzyme for the quantitation of low concentrations of such organophosphates. The principle of two estimation methods is described. Both methods involve the addition of an unknown amount of organophosphate to an assay mixture bf purified esterase, buffer and a low affinity esterase substrate. In the first of these methods the inhibitor concentration is calculated from the esterase activities before and after the addition of the inhibitor. In the second method, the amounts of inhibitor or of enzyme are changed in several assays, until equimolar conditions can be detected from the observed reaction kinetics. The theoretical background of these methods is discussed and practical examples for the estimation of paraoxon (order of 0.1 nmoles) are given. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.
3th International Meeting on Esterases Reacting with Organophosphorus Compounds, INTER UNVI CTR, DUBROVNIK, CROATIA, APR 15-18, 1998
ISSN: 00092797
DOI: 10.1016/S0009-2797(99)00072-1

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