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. 2017 Nov 17;3(11):eaao3013. doi: 10.1126/sciadv.aao3013

Fig. 1. Example of product-ion (MS/MS) spectra that identify oxidative modifications of PSII residues.

Fig. 1

Product-ion (MS/MS) spectra of the oxidized CP43 peptide 362GPwLEPLRGPNGLDLD378K (top) and the unmodified form of the peptide (bottom). The oxidation (+15.9949 Da) was localized to 364W. Note that 372N contains the common deamidation modification (+0.9840 Da) according to both spectra. The fragment maps and corresponding labeled b- and y-ions show the convincing fragmentation series obtained at high mass accuracy (~0.02 Da), allowing highly confident peptide identification and unambiguous residue-level localization of the oxidative modification. Lowercase lettering in the amino acid sequence indicates the site of oxidation (see figs. S1 to S3 for additional example spectra). m/z, mass/charge ratio.