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. 2015 Feb 5;87(5):2535–2541. doi: 10.1021/ac504685y

Figure 4.

Figure 4

Identification of Cys-73 of thioredoxin 1 as an alkylation target site by aHNE in RKO cells. (A) MS1 spectrum of an aHNE-triazol-hexanoic acid modified peptide from thioredoxin 1. Doubly charged monoisotopic precursors of light and heavy labeled the peptide are observed at m/z 730.3588 (red) and 733.3686 (blue), respectively, with mass errors less than 1.0 ppm. (B) XIC are shown for changes in the same aHNE-modified peptides from thioredoxin with the profiles for light- and heavy-labeled peptides in red and blue, respectively. (C) Characteristic fragmentation of the light-labeled modified peptide and its HCD MS/MS spectrum. A zoom window displays the diagnostic fragment ion (DFI) peak (m/z 292.2). The asterisks on the annotated ions indicate water losses from the corresponding b- and y-ion fragments.