Database Search Exercises > Exercise SQ2  
 
 

Exercise SQ2

Topic

A trickier sequence tag search

Experimental

A protein mixture (not alkylated) was separated on a 2D gel. A spot was extracted, digested with trypsin, and analysed on a ESI-QUAD-TOF. A tag has been interpreted from one of the MS/MS spectra. Precursor m/z is 703.74 with charge 2+. The low mass end of the tag starts at m/z 147.07. Residue code i means I or L. Search Swiss-Prot with precursor and fragment mass tolerances of 0.5 Da

sequence tag

Tips

  • If you cannot get a match with a standard tag, try an error tolerant tag

Questions

  1. What is the peptide sequence?
  2. Are there any alternative solutions?
  3. If so, how do you choose a preferred solution?

 

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