FIGURE 6.

MS/MS spectra of synthetic peptides. The spectra show the fragmentation patterns of the peptide dephosphorylation. Peptides A–C corresponded to the short α-crystallin A sequence of the Hyp(P)-containing peptide. Peptides D–F had the same sequence but were elongated by an additional arginine at the N terminus. Tau peptides G–I corresponded to a completely different sequence (see Table 3). Peptides in the top row (A, D, and G) contained trans-4-Hyp(P); peptides in the middle row (B, E, and H) contained trans-3-Hyp(P); and the peptides in the bottom row (C, F, and I) contained cis-4-Hyp(P).