PHOS-select iron affinity beads enrich peptides for the detection of organophosphorus adducts on albumin

Wei Jiang, Yaroslav A. Dubrovskii, Ekaterina P. Podolskaya, Ekaterina A. Murashko, Vladimir Babakov, Florian Nachon, Patrick Masson, Lawrence M Schopfer, Oksana Lockridge

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Abstract

Albumin is covalently modified by organophosphorus toxicants (OP) on tyrosine 411, but less than 1% of albumin is modified in humans by lethal OP doses that inhibit 95% of plasma butyrylcholinesterase. A method that enriches OP-modified albumin peptides could aid analysis of low dose exposures. Soman or chlorpyrifos oxon treated human plasma was digested with pepsin. Albumin peptides were enriched by binding to Fe3+ beads at pH 11 and eluted with pH 2.6 buffer. Similarly, mouse and guinea pig albumin modified by chlorpyrifos oxon were digested with pepsin and enriched by binding to Fe 3+ beads. Peptides were identified by MALDI-TOF/TOF mass spectrometry. PHOS-select iron affinity beads specifically enriched albumin peptides VRY411TKKVPQVST and LVRY411TKKVPQVST in a pepsin digest of human plasma. The unmodified as well as OP-modified peptides bound to the beads. The binding capacity of 500 μL of beads was the pepsin digest of 2.1 μL of human plasma. The limit of detection was 0.2% of OP-modified albumin peptide in 0.43 μL of plasma. Enrichment of OP-modified albumin peptides by binding to Fe3+ beads is a method with potential application to diagnosis of OP pesticide and nerve agent exposure in humans, mice, and guinea pigs.

Original languageEnglish (US)
Pages (from-to)1917-1925
Number of pages9
JournalChemical Research in Toxicology
Volume26
Issue number12
DOIs
Publication statusPublished - Dec 16 2013

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ASJC Scopus subject areas

  • Toxicology

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