Cresyl saligenin phosphate makes multiple adducts on free histidine, but does not form an adduct on histidine 438 of human butyrylcholinesterase

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Cresyl saligenin phosphate (CBDP) is a suspected causative agent of "aerotoxic syndrome", affecting pilots, crew members and passengers. CBDP is produced in vivo from ortho-containing isomers of tricresyl phosphate (TCP), a component of jet engine lubricants and hydraulic fluids. CBDP irreversibly inhibits butyrylcholinesterase (BChE) in human plasma by forming adducts on the active site serine (Ser-198). Inhibited BChE undergoes aging to release saligenin and o-cresol. The active site histidine (His-438) was hypothesized to abstract o-hydroxybenzyl moiety from the initial adduct on Ser-198. Our goal was to test this hypothesis. Mass spectral analysis of CBDP-inhibited BChE digested with Glu-C showed an o-hydroxybenzyl adduct (+106 amu) on lysine 499, a residue far from the active site, but not on His-438. Nevertheless, the nitrogen of the imidazole ring of free l-histidine formed a variety of adducts upon reaction with CBDP, including the o-hydroxybenzyl adduct, suggesting that histidine-CBDP adducts may form on other proteins.

Original languageEnglish (US)
Pages (from-to)103-107
Number of pages5
JournalChemico-Biological Interactions
Issue number1
Publication statusPublished - Mar 25 2013



  • Aging
  • Butyrylcholinesterase
  • CBDP
  • Histidine
  • TCP
  • o-Hydroxybenzyl

ASJC Scopus subject areas

  • Toxicology

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