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. Author manuscript; available in PMC: 2013 Sep 4.
Published in final edited form as: Anal Chem. 2012 Aug 20;84(17):7469–7478. doi: 10.1021/ac301572t

Figure 1.

Figure 1

Previously there were only 6 TMT reagents available (highlighted in light grey). Due to complications arising from the preferred fragmentation pathways of ETD, the TMT-127, and -129 reporter ions were recently modified such that a 13C was exchanged for a 15N (dark grey). Though the new and old TMT-127 and -129 reagents only differ by ~6.32 mDa, high resolution mass spectrometers are capable of resolving these neighboring isobaric isotopologues.