Figure 2. (a) Processed tandem mass spectrometry data for the peptide DLRSWTAADTAAQISQ.
The tandem mass spectrum was obtained f&m the doubly charged ion [M + 2Hl+* at m/z 868. The
200 most abundant ions are shown in the graphical display. A 10-u window around the precursor
ion at m/z 868 has been removed. The abundances of fragment ions within 1 u of each other are
equalized to the higher value. (b) A graphical display of the reconstructed data used for the
correlation analysis for the amino acid sequence DLKSWTAADTAAQISQ. A magnitude of 50.0 is
assigned to the predicted mass-to-charge ratio values for the type-b and -IJ ions and ions with
mass-to-charge ratios il u from the type-b and y ions are assigned a value of 25.0. The neutral
losses of water and ammonia and the n-type ions are assigned values of 10.0. (c) A graphical display
of the processed experimental tandem mass spectrum used in the correlation analysis. A 10-u region
around the precursor ion is removed. The spechum is then divided into 10 equal sections and the
ion abundances in each section are normalized to 50.0. Cd) A graphical display of the result of the
cross-correlation function for the spectrom displayed in Figure Zb and E. The final score attributed to
the analysis is the value at T = 0 minus the mean of the cross-correlation function over the range
-75< 7< 75.