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. Author manuscript; available in PMC: 2012 Nov 18.
Published in final edited form as: J Proteomics. 2011 Aug 22;74(12):2745–2759. doi: 10.1016/j.jprot.2011.08.009

Figure 2.

Figure 2

MS spectra showing complete trypin-catalyzed 18O labeling. Three and four major pairs of peptides at LC elution time of approximately 25 min (A) and 38 min (B), respectively, were detected in the defined mass ranges from a fraction of forward 18O-labeled sample. The corresponding peaks of the same peptides from the reverse labeling are shown in C and D, respectively.