TY - JOUR
T1 - Tyrosines of human and mouse transferrin covalently labeled by organophosphorus agents
T2 - A new motif for binding to proteins that have no active site serine
AU - Li, Bin
AU - Schopfer, Lawrence M.
AU - Grigoryan, Hasmik
AU - Thompson, Charles M.
AU - Hinrichs, Steven H.
AU - Masson, Patrick
AU - Lockridge, Oksana
N1 - Funding Information:
C.M.T.; and the Direction Générale de l’Armement of the French Ministry of Defense (DGA grant 03co010-05/PEA01 08 7) to P.M.
PY - 2009
Y1 - 2009
N2 - The expectation from the literature is that organophosphorus (OP) agents bind to proteins that have an active site serine. However, transferrin, a protein with no active site serine, was covalently modified in vitro by 0.5mM 10-fluoroethoxyphosphinyl-N-biotinamido pentyldecanamide, chlorpyrifos oxon, diisopropylfluorophosphate, dichlorvos, sarin, and soman. The site of covalent attachment was identified by analyzing tryptic peptides in the mass spectrometer. Tyr 238 and Tyr 574 in human transferrin and Tyr 238, Tyr 319, Tyr 429, Tyr 491, and Tyr 518 in mouse transferrin were labeled by OP. Tyrosine in the small synthetic peptide ArgTyrThrArg made a covalent bond with diisopropylfluorophosphate, chlorpyrifos oxon, and dichlorvos at pH 8.3. These results, together with our previous demonstration that albumin and tubulin bind OP on tyrosine, lead to the conclusion that OP bind covalently to tyrosine, and that OP binding to tyrosine is a new OP-binding residue. The OP-reactive tyrosines are activated by interaction with Arg or Lys. It is suggested that many proteins in addition to those already identified may be modified by OP on tyrosine. The extent to which tyrosine modification by OP can occur in vivo and the toxicological implications of such modifications require further investigation.
AB - The expectation from the literature is that organophosphorus (OP) agents bind to proteins that have an active site serine. However, transferrin, a protein with no active site serine, was covalently modified in vitro by 0.5mM 10-fluoroethoxyphosphinyl-N-biotinamido pentyldecanamide, chlorpyrifos oxon, diisopropylfluorophosphate, dichlorvos, sarin, and soman. The site of covalent attachment was identified by analyzing tryptic peptides in the mass spectrometer. Tyr 238 and Tyr 574 in human transferrin and Tyr 238, Tyr 319, Tyr 429, Tyr 491, and Tyr 518 in mouse transferrin were labeled by OP. Tyrosine in the small synthetic peptide ArgTyrThrArg made a covalent bond with diisopropylfluorophosphate, chlorpyrifos oxon, and dichlorvos at pH 8.3. These results, together with our previous demonstration that albumin and tubulin bind OP on tyrosine, lead to the conclusion that OP bind covalently to tyrosine, and that OP binding to tyrosine is a new OP-binding residue. The OP-reactive tyrosines are activated by interaction with Arg or Lys. It is suggested that many proteins in addition to those already identified may be modified by OP on tyrosine. The extent to which tyrosine modification by OP can occur in vivo and the toxicological implications of such modifications require further investigation.
KW - Mass spectrometry
KW - Plasma
KW - Sarin
KW - Soman
KW - Transferrin
KW - Tyrosine residue
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U2 - 10.1093/toxsci/kfn211
DO - 10.1093/toxsci/kfn211
M3 - Article
C2 - 18930948
AN - SCOPUS:58049194183
SN - 1096-6080
VL - 107
SP - 144
EP - 155
JO - Toxicological Sciences
JF - Toxicological Sciences
IS - 1
ER -