Skip to main content
. Author manuscript; available in PMC: 2010 Nov 1.
Published in final edited form as: Anal Biochem. 2009 Jul 9;394(1):92–100. doi: 10.1016/j.ab.2009.07.008

Figure 4.

Figure 4

A CID mass spectrum of the diisopropoxyphosphate-labeled, human serum albumin, tryptic peptide LAK*TYETTLEK. The doubly-charged parent ion at 731.0 amu is designated by the letter P. Sequential neutral loss of isopropylene (42 amu) from the diisopropoxyphosphate parent ion is designated by P1 (709.8 amu) and P2 (688.3 amu). Sequential neutral loss of isopropylene from the b3 ion is indicated by b3c (diisopropoxyphosphate form at 477.6 amu), b3b (monoisopropoxyphosphate form at 435.6 amu), and b3a (phosphate form at 363.6 amu). The values enclosed in the boxes are the masses of the characteristic fragments for diisopropoxyphosphate-labeled lysine. Lysine 351 is covalently modified by diisopropylfluorophosphate.