Exploring adduct formation between human serum albumin and eleven organophosphate ester flame retardants and plasticizers using MALDI-TOF/TOF and LC-Q/TOF

Shaogang Chu, Margaret R. Baker, Gladys Leong, Robert J. Letcher, Shirley J. Gee, Bruce D. Hammock, Qing X. Li

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

Organophosphate (OP) and organophosphate ester (OPE) adducts of albumin are valuable biomarkers for retrospective verification of exposure. In the present study, our goal was to determine whether OPE flame retardants (OPE FRs) and OPE plasticizers can covalently bind to human serum albumin (HSA), which would allow the resulting adducts to be used to evaluate exposure. Eleven OPE FRs and plasticizers were examined in a HSA-adduct in vitro assay. Pure HSA was incubated with the target OPEs, as well as with an OP insecticide (profenofos) positive control. After enzymatic cleavage with pepsin or Glu-C, the digested albumin was analyzed by matrix-assisted laser desorption ionization tandem time-of-flight mass spectrometry (MALDI-TOF/TOF-MS) and liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-Q-ToF-MS). Under optimized HSA assay conditions, tyrosine adducts were formed at Y411 and Y148/Y150 with a characteristic mass shift for phosphorylation (Δm/z 166) for the profenofos positive control. However, no such phosphorylated peptides were detected for the 11 target OPEs. This negative result suggests that these OPEs have very different affinities from the OP insecticide. They are less reactive or they may specifically interact with other proteins.

Original languageEnglish (US)
Pages (from-to)169-177
Number of pages9
JournalChemosphere
Volume180
DOIs
StatePublished - Aug 1 2017

Keywords

  • Biomarker
  • Flame retardant
  • Human serum albumin
  • Organophosphate ester
  • Plasticizer
  • Protein adduct

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry

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