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Exercise MSMS4

Topic

iTRAQ quantitation

Requirements

User access to any Mascot server, including the Matrix Science public web site

Experimental

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.

Data

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

Tips

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

Questions

  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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