title: Five tyrosines and two serines in human albumin are labeled by the organophosphorus agent FP-biotin.
abstract: Tyrosine 411 of human albumin is an established site for covalent attachment of 10-fluoroethoxyphosphinyl- N-biotinamidopentyldecanamide (FP-biotin), diisopropylfluorophosphate, chlorpyrifos oxon, soman, sarin, and dichlorvos. This work investigated the hypothesis that other residues in albumin could be modified by organophosphorus agents (OP). Human plasma was aggressively treated with FP-biotin; plasma proteins were separated into high and low abundant portions using a proteome partitioning antibody kit, and the proteins were digested with trypsin. The FP-biotinylated tryptic peptides were isolated by binding to monomeric avidin beads. The major sites of covalent attachment identified by mass spectrometry were Y138, Y148, Y401, Y411, Y452, S232, and S287 of human albumin. Prolonged treatment of pure human albumin with chlorpyrifos oxon labeled Y138, Y150, Y161, Y401, Y411, and Y452. To identify the most reactive residue, albumin was treated for 2 h with DFP, FP-biotin, chlorpyrifos oxon, or soman, digested with trypsin or pepsin, and analyzed by mass spectrometry. The most reactive residue was always Tyr 411. Diethoxyphosphate-labeled Tyr 411 was stable for months at pH 7.4. These results will be useful in the development of specific antibodies to detect OP exposure and to engineer albumin for use as an OP scavenger.
authors.affiliation: Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska 68198, USA.
authors.forename: Shi-Jian
authors.initials: SJ
authors.lastname: Ding
authors.forename: John
authors.initials: J
authors.lastname: Carr
authors.forename: James E
authors.initials: JE
authors.lastname: Carlson
authors.forename: Larry
authors.initials: L
authors.lastname: Tong
authors.forename: Weihua
authors.initials: W
authors.lastname: Xue
authors.forename: Yifeng
authors.initials: Y
authors.lastname: Li
authors.forename: Lawrence M
authors.initials: LM
authors.lastname: Schopfer
authors.forename: Bin
authors.initials: B
authors.lastname: Li
authors.forename: Florian
authors.initials: F
authors.lastname: Nachon
authors.forename: Oluwatoyin
authors.initials: O
authors.lastname: Asojo
authors.forename: Charles M
authors.initials: CM
authors.lastname: Thompson
authors.forename: Steven H
authors.initials: SH
authors.lastname: Hinrichs
authors.forename: Patrick
authors.initials: P
authors.lastname: Masson
authors.forename: Oksana
authors.initials: O
authors.lastname: Lockridge
mesh_terms: D000418:Albumins / Q000737:chemistry*; D001710:Biotin / Q000031:analogs & derivatives* / Q000737:chemistry; D004390:Chlorpyrifos / Q000031:analogs & derivatives / Q000737:chemistry; D002853:Chromatography, Liquid; D018360:Crystallography, X-Ray; D004006:Dichlorvos / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007531:Isoflurophate / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D009943:Organophosphorus Compounds / Q000737:chemistry*; D015203:Reproducibility of Results; D012524:Sarin / Q000737:chemistry; D012694:Serine / Q000737:chemistry*; D012999:Soman / Q000737:chemistry; D013194:Staining and Labeling; D053719:Tandem Mass Spectrometry; D014443:Tyrosine / Q000737:chemistry*
chemical_list: C403065:10-(fluoroethoxyphosphinyl)-N-(biotinamidopentyl)decanamide; D000418:Albumins; D009943:Organophosphorus Compounds; D007531:Isoflurophate; D014443:Tyrosine; D012694:Serine; C009618:O,O-diethyl O-3,5,6-trichloro-2-pyridyl phosphate; D001710:Biotin; D004006:Dichlorvos; D012999:Soman; D012524:Sarin; D004390:Chlorpyrifos