OP-labeled tyrosines

Similar mass spectrometry experiments with pure human and mouse transferrin (Li et al., 2008c), and with human kinesin showed that the OP label was consistently on tyrosine (Table 56.1). Studies with human plasma identified OP labeling on tyrosine in apolipoprotein and alpha-2-glyco-protein. Aggressive treatment of hiunan albumin with FP-biotin and chlorpyrifos oxon led to identification of seven OP-labeled tyrosines (Ding et al, 2008). Finally, we found that synthetic peptides made a covalent bond with DFP, chlorpyrifos oxon, and dichlorvos (Table 56.1). Mass spectrometry conclusively proved that the OP was attached to tyrosine. 

For peptides derived from proteins, six residues on either side of the OP-labeled tyrosine are shown. Synthetic peptides are shown in their complete length. The labeled tyrosine is enclosed in a box. 

An elegant method for identifying OP-labeled tyrosine would be with an OP-tyrosine-specific antibody. A similar antibody toward phospho tyro sine is commercially... 

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