Notice: IonSource


Mass Spectrometry Educational Resource




- De Novo Peptide Sequencing Tutorial 


Example Spectrum

part two, mid mass


As we move into the mid spectrum range the intensity of the b ions increase, see Figure 1 below.  The b ions in Figure 1 are losing water and ammonia which is consistent with S (-18) and Q (-17) residues.  Peaks consistent with a ions are also observed at -28u from two of the b ions.

Figure 1.


The predominant ion in the mid range is the y ion.  Notice that only ammonia loss (-17)  is noted for the y ions in Figure 2. The -17u loss is consistent for fragments containing the residues K, Q and N.  Also note that the greatest ammonia loss is observed for fragment y9 which contains the greatest number of these residues.

Figure 2.


Shall we proceed onto the high mass range of the spectrum?  Let's.




TOC / IS homepage





Reference Figures

b and y Ion Table


Full Fragment Spectrum











e-mail the  with all inquiries
home | terms of use (disclaimer) 
Copyright � 2012 IonSource  All rights reserved. 
Last updated:  Monday, February 01, 2016 11:04:38 AM














Hit Counter