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Exercise MSMS4


iTRAQ quantitation


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Data from an ESI quadrupole TOF instrument. Cysteine unmodified. Search Swiss-Prot with precursor and fragment tolerances of 0.2 Da, Trypsin/P with 2 missed cleavages, and iTRAQ 4plex quantitation method.


Right-click this link: MSMS4.mgf, and choose Save target as or Save link as


  • The iTRAQ modifications are specified inside the quantitation method. You don’t need to select them in the search form


  1. Are all four reporter ions being used?
  2. Why are some ratios shown in bold face?
  3. Would normalisation be a good idea for this example?
  4. How is iTRAQ modification to Tyr used in the method?


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