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. Author manuscript; available in PMC: 2017 Aug 16.
Published in final edited form as: Anal Chem. 2016 Aug 8;88(16):8158ā€“8165. doi: 10.1021/acs.analchem.6b01901

Figure 4.

Figure 4

Variable energy CID analysis of unmodified and N-terminally carbamylated, SPITC-and FBDSA-modified (a) RRLIEDAEpYAARG-NH2 (2+) and (b) RQpSVELHSPQSLPR (2+). Normalized precursor abundances are plotted as a function of increasing collision energy. The CID product ion spectra are shown for RQpSVELHSPQSLPR (2+) in the following states: (c) unmodified, (d) carbamylated (*), and (e) FBDSA Schiff base modified (ā—†). The addition of ā€œ-Pā€ to the label indicates loss of phosphate.