Skip to main content
. Author manuscript; available in PMC: 2011 Aug 1.
Published in final edited form as: J Appl Toxicol. 2010 Aug;30(6):559–565. doi: 10.1002/jat.1526

Figure 3.

Figure 3

MSMS spectrum of the aged dichlorvos labeled tryptic peptide of BChE derived from serum of a dichlorvos poisoned patient. The quadruply charged parent ion has 756.6 m/z. The y9 and y10 transition ions are present. In addition a series of b and y ions are present that fit the masses of the active site tryptic peptide of BChE. The doubly-charged y22+2 ion at 1145.2 m/z carries the aged dichlorvos (monomethoxyphosphate) on Ser 198. The triply and doubly charged ions labeled with the symbol Δ contain dehydroalanine in place of Ser 198. They have lost the OP plus a molecule of water during collision with gas molecules in the mass spectrometer. Facile loss of the organophosphorus agent plus a molecule of water to produce dehydroalanine is a characteristic feature of modified serine. The masses of the ions labeled with the symbol Δ support the conclusion that the modified residue is Ser 198.