Mass-spectra data in this tutorial is provided in the form of peak list files. Two peak list formats are commonly used, DTA, and MGF. A comprehensive description of these file formats ia available here. Both DTA and MGF are simple text based formats containing the mass spectra that will be used by the search engine to identify peptides and proteins.
Click here for an example DTA file. Each spectrum begins with the parent mass and charge and is followed by a series of pairs of numbers (fragment ion masses and their intensity)
Click here for an example MGF file. Each spectrum is recorded between BEGIN IONS and END IONS
[Intact peptide mass] [Peptide charge]
[Peptide fragment ion mass] [intensity]
...
[Space]
[Intact peptide mass] [Peptide charge]
[Peptide fragment ion mass] [abundance]
Click here for an example DTA file.
BEGIN IONS
PEPMASS=[precursor mass]
CHARGE=2+
TITLE=Spectrum1
[fragment mass] [fragment intensity]
...
END IONS
Click here for an example MGF file.
A more comprehensive description of these file formats is available here.