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. Author manuscript; available in PMC: 2011 Sep 1.
Published in final edited form as: Anal Biochem. 2010 May 4;404(1):64–74. doi: 10.1016/j.ab.2010.04.032

Figure 6.

Figure 6

MALDI post-source decay fragmentation spectrum of the human BChE active site peptide labeled at Ser198 with phosphate (monoisotopic mass of 3008.7 amu). The spectrum was taken from an offline HPLC purified fraction of the tryptic digest. The masses are centered over the peaks to which they apply. The y-axis is expanded 6.7-fold for peaks between 0 and 2500 m/z. The symbol Δ indicates ions that contain dehydroalanine in place of serine 198 due to loss of phosphate plus a molecule of water. The y22 ion at 2275.1 amu retains the phosphate on serine 198.