Adducts with Acetyl- and Butyrylcholinesterase

In principle, organophosphate-inhibited BuChE in human plasma is a persistent (half-life 5-16 days) and relatively abundant (plasma concentration approximately 80 nM) source for biomonitoring of exposure to organophosphate anticholinesterases. Polhuijs et al. (44) developed a procedure for the analysis of phosphylated binding sites, for example, 

An alternative displacement method, reported by Nagao and coworkers (46,47), is based on a lengthy and more complex procedure. Sarin-bound acetylcholinesterase was solubilized from erythrocyte membranes, digested with trypsin (37 °C, 24 h), and the hydrolysis product isopropyl methylphos-phonic acid released by digestion with alkaline phosphatase (37 °C, 48 h). High molecular mass 

All three of the mass spectrometric methods described above were applied to casualties of terrorist attacks in Japan. It should be noted that in most cases the samples were collected within 24 h of the exposure, in contrast to cases of CW exposure to sulfur mustard. 

Application of the fluoride-reactivation method to serum samples of victims from the Tokyo subway attack, and of the Matsumoto incident, yielded, sarin concentrations in the range of 0.2-4.1ng/ml serum (44). Evidently, these casualties had been exposed to an organophosphate with the formula i-PrO(CH3)P(0)X, presumably with X = F (sarin). 

The hydrolytic displacement method was applied to four victims killed in the Tokyo subway attack (two died immediately and two later in hospital). Isopropyl methylphosphonic acid was identified at levels sufficient for full scan mass spectra to be obtained using a benchtop quadmpole mass spectrometer (46). Methylphosphonic acid was also identified. Some two years later, methylphosphonic acid 

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