Microcalorimetric study of the inhibition of butyrylcholinesterase by sodium arsenite and zinc chloride: use of a fractal kinetic model

Abstract : The inhibition of horse serum butyrylcholinesterase (EC 3.1.1.8) by sodium arsenite (NaAsO 2 ) and zinc chloride (ZnCl 2 ) was studied at 37 ◦ C in a TRIS buffer, pH 7.5, with a flow microcalorimeter operating in the mixing mode. The dose-response curves were analyzed with the Hill equation, as deduced from the "fractal kinetic" model of Savageau by considering an exponential distribution of reaction rate constants. The C 50 values were in the millimolar range and zinc chloride was a better inhibitor than sodium arsenite. This was confirmed by the values of the apparent rate constants. The Hill exponent, interpreted as a fractional reaction order, was also higher for zinc chloride. According to the statistical interpretation, the heterogeneity of binding reactions was slightly higher for Zn, in agreement with a speciation study which showed the existence of several Zn species in solution, with the free Zn 2+ ion accounting for about 10% of the total.
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https://hal-unilim.archives-ouvertes.fr/hal-00932223
Contributeur : Jean-Claude Bollinger <>
Soumis le : jeudi 16 janvier 2014 - 15:13:56
Dernière modification le : vendredi 25 octobre 2019 - 01:58:09

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Jean Debord, Jean-Claude Bollinger, François Bordas, Michel Harel, Thierry Dantoine. Microcalorimetric study of the inhibition of butyrylcholinesterase by sodium arsenite and zinc chloride: use of a fractal kinetic model. Thermochimica Acta, Elsevier, 2013, 561, pp.49-53. ⟨10.1016/j.tca.2013.03.027⟩. ⟨hal-00932223⟩

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