Covalent binding of organophosphorothioates to albumin: a new perspective for OP-pesticide biomonitoring

We here report on the covalent binding of various organophosphorothioate (OPT) pesticides to albumin at in vitro exposure levels that did not give rise to butyrylcholinesterase inhibition. Adduct formation occurred at the Tyr-411 residue of albumin, as was firmly corroborated by LC-tandem MS analysi...

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Bibliographic Details
Published in:Archives of toxicology 2009-11, Vol.83 (11), p.1031-1036
Main Authors: Noort, D, Hulst, A. G, van Zuylen, A, van Rijssel, E, van der Schans, M. J
Format: Article
Language:English
Subjects:
Binding sites
Biological and medical sciences
Biomarkers
Biomedical and Life Sciences
Biomedicine
Chromatography, Liquid - methods
Environmental Health
Environmental Monitoring - methods
Humans
Medical sciences
Occupational Medicine/Industrial Medicine
Organothiophosphorus Compounds - analysis
Organothiophosphorus Compounds - metabolism
Pesticides
Pesticides - analysis
Pesticides - metabolism
Pesticides, fertilizers and other agrochemicals toxicology
Pharmacology/Toxicology
Protein Binding
Proteins
Serum Albumin - metabolism
Short Communication
Tandem Mass Spectrometry - methods
Toxicology
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Summary:We here report on the covalent binding of various organophosphorothioate (OPT) pesticides to albumin at in vitro exposure levels that did not give rise to butyrylcholinesterase inhibition. Adduct formation occurred at the Tyr-411 residue of albumin, as was firmly corroborated by LC-tandem MS analysis of a pepsin digest of OPT-modified albumin. It cannot be excluded that other (tyrosine) residues become modified as well. A convenient method for mass spectrometric determination of the OPT tyrosine adduct has also been developed based on the pronase digestion of albumin and subsequent LC-tandem MS analysis of the digest. The resulting tyrosine phosphorothioate ester displayed favorable chromatographic and mass spectrometric properties for sensitive analysis. In vitro exposure levels of parathion and chlorpyrifos down to 1 μM could readily be assessed. The remarkable affinity of OPTs for albumin opens the way for a more complete assessment of OP pesticide exposure.
ISSN:0340-5761
1432-0738
DOI:10.1007/s00204-009-0456-5