Organophosphorus inhibition and heat inactivation kinetics of particulate and soluble forms of peripheral nerve neuropathy target esterase
✍ Scribed by Barril, J. ;Tormo, N. ;Diaz-Alejo, N. ;Vilanova, E.
- Book ID
- 102876485
- Publisher
- John Wiley and Sons
- Year
- 1995
- Tongue
- English
- Weight
- 796 KB
- Volume
- 10
- Category
- Article
- ISSN
- 0887-2082
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✦ Synopsis
Neuropathy target esterase (NTE) is the proposed target site for the mechanism of initiation of the so-called organophosphorus-induced delayed polyneuropathy (OPIDP). NTE is operationally defined in this article as the phenylvalerate esterase activity which is resistant to inhibition by 40 pM paraoxon and sensitive to 250 p M mipafox. Soluble (S-NTE) and particulate (P-NTE) forms of NTE had first been identified in hen sciatic nerve [E. Vilanova, J. Barril, V. Carrera, and M. C. Pellin (1990). J. Neurochem., 55, 1258-12651. P-NTE and S-NTE showed different sensitivities to the inhibition by several organophosphorus compounds over a range of inhibitor concentrations for a 30 or 120 minute fixed inhibition time at 37°C. S-NTE was less sensitive to the inhibition by 0,O'-diisopropyl phosphorofluoridate (DFP), hexyl 2,5-dichlorophenyl phosphoramidate (H-DCP), and mipafox than P-NTE and brain NTE, while the opposite was true for 0,s-dimethyl phosphoroamidothioate (methamidophos). For each of the four inhibitors assayed, S-NTE showed two components of different sensitivity according to the inhibition curves fitted with exponential models. However, the inhibition of P-NTE by mipafox, DFP, and HDCP did not show the presence of a considerable proportion of a second component. The kinetics of heat inactivation showed that P-NTE inactivated faster and to a greater extent than S-NTE. It is concluded that (1) sciatic nerve S-NTE is more different from brain NTE than P-NTE; (2) P-NTE and S-NTE have different sensitivities to the inhibition by the studied organophosphorous compounds;
(3) the inhibition curves suggest that S-NTE has two different enzymatic components while these are not so evident for P-NTE.