title: PHOS-select iron affinity beads enrich peptides for the detection of organophosphorus adducts on albumin.
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 Fe(3+) 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 Fe(3+) beads is a method with potential application to diagnosis of OP pesticide and nerve agent exposure in humans, mice, and guinea pigs.
authors.affiliation: Eppley Institute, University of Nebraska Medical Center , Omaha, Nebraska 68198-5950, United States.
authors.forename: Wei
authors.initials: W
authors.lastname: Jiang
authors.forename: Yaroslav A
authors.initials: YA
authors.lastname: Dubrovskii
authors.forename: Ekaterina P
authors.initials: EP
authors.lastname: Podolskaya
authors.forename: Ekaterina A
authors.initials: EA
authors.lastname: Murashko
authors.forename: Vladimir
authors.initials: V
authors.lastname: Babakov
authors.forename: Florian
authors.initials: F
authors.lastname: Nachon
authors.forename: Patrick
authors.initials: P
authors.lastname: Masson
authors.forename: Lawrence M
authors.initials: LM
authors.lastname: Schopfer
authors.forename: Oksana
authors.initials: O
authors.lastname: Lockridge
mesh_terms: D000818:Animals; D002846:Chromatography, Affinity; D005782:Gels / Q000737:chemistry; D006168:Guinea Pigs; D006801:Humans; D007502:Iron Chelating Agents / Q000737:chemistry*; D051379:Mice; D009943:Organophosphorus Compounds / Q000032:analysis* / Q000737:chemistry* / Q000633:toxicity; D010455:Peptides / Q000032:analysis / Q000737:chemistry* / Q000302:isolation & purification; D012709:Serum Albumin / Q000737:chemistry*
chemical_list: D005782:Gels; D007502:Iron Chelating Agents; D009943:Organophosphorus Compounds; D010455:Peptides; D012709:Serum Albumin