Five tyrosines and two serines in human albumin are labeled by the organophosphorus agent FP-biotin

Shi Jian Ding, John Carr, James E. Carlson, Larry Tong, Weihua Xue, Yifeng Li, Lawrence M. Schopfer, Bin Li, Florian Nachon, Oluwatoyin Asojo, Charles M. Thompson, Steven H. Hinrichs, Patrick Masson, Oksana Lockridge

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47 Scopus citations

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.

Original languageEnglish (US)
Pages (from-to)1787-1794
Number of pages8
JournalChemical Research in Toxicology
Volume21
Issue number9
DOIs
StatePublished - Sep 2008

ASJC Scopus subject areas

  • Toxicology

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    Ding, S. J., Carr, J., Carlson, J. E., Tong, L., Xue, W., Li, Y., Schopfer, L. M., Li, B., Nachon, F., Asojo, O., Thompson, C. M., Hinrichs, S. H., Masson, P., & Lockridge, O. (2008). Five tyrosines and two serines in human albumin are labeled by the organophosphorus agent FP-biotin. Chemical Research in Toxicology, 21(9), 1787-1794. https://doi.org/10.1021/tx800144z