The Effects of Blast Exposure on Protein Deimination in the Brain

Figure 3

Mapping of protein deimination sites by neutral loss. Tryptic peptides were fragmented by collision-induced dissociation, and resulting spectra were analyzed for a neutral loss of 43 Da, reflecting the loss of isocyanic acid as a fragmentation product of citrulline (upper panel). The representative spectrum shown here depicts the Y and B ion spectra of GFAP peptide, TVEMrDGEVIK, with the neutral loss peak observed for the deiminated arginine (r) at 625.8 Da. Because the parent peptide ion was doubly charged in this case, the observed neutral loss in the spectrum was 21.5 Da, reflecting 43 Da/2.