Fig 3. Comparison of deconvoluted tandom MS/MS spectra of untreated (a) vs modified (b) rhBD-2 peptide RYKQIGTCGLPGTK (23–36) after trypsin digestion of the rhBD-2 protein.

The modified hBD-2 peptide was previously incubated in 100 μM MGO at 37°C for 72 h. The presence of the b1 ion with a +54 Da mass shift and unmodified doubly protonated y13 shows that modification of this peptide occurred at Arg²³.