Spectrophotometric Determination of the Ionization Constants for the Oximes – Cholinesterases Reactivators at Different Temperatures

  • T.V. Schäfer State Scientific Research and Test Institute of the Military Medicine, 4 Lesoparkovaya str., Saint-Petersburg, 195043 Russia
  • A.A. Tyaptin State Scientific Research and Test Institute of the Military Medicine, 4 Lesoparkovaya str., Saint-Petersburg, 195043 Russia
  • T.B. Pechurina State Scientific Research and Test Institute of the Military Medicine, 4 Lesoparkovaya str., Saint-Petersburg, 195043 Russia
Keywords: temperature effect; ionization constants; protolytic dissotiation; absorbtion spectra; oximes


The goal of study was the determination of the ionization constants for the oximes – cholinesterases reactivators in aqueous solutions at different temperatures. The wavelengths of absorption maxima of the protonated and deprotonated oxime groups, the molar extinction coefficients of the various oximes species, and the ionization constants for the oxime cholinesterases reactivators (isonitrosin, pralidoxime, dipyroxime, toxogonin, methoxime, carboxime and asoxime) were obtained using spectrophotometric data (wavelength 190 to 450 nm) in solutions (pH 5 – 12) at 20°C, 25°C and 37°C. The proportion of nucleophilic forms involved in the oxime-induced reactivation of phosphorylated cholinesterases was shown to be is positively dependent on the incubation medium pH value and temperature. A hypothesis that the temperature affects the oximes ability to reactivate phosphorylated cholinesterases has been proposed.


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