IonSource Table Immonium Ions

 

Diagnostic Ions observed at the low end of an MS/MS or source CID spectrum which are used to give clues as to the presence of specific amino acid residues in a peptide sequence.
Low Mass Ions Observed in Electrosapray Triple Quad MS/MS Spectra Reported by Don Hunt's Laboratory at the University of Virginia .
Amino Acid Low Mass Ion

Low mass marker ions will have this general structure 

Pro (Arg, Asn) 70
Val 72
Lxx 86
Met  104
His 110
Phe 120
CMC 134
Tyr 136
Trp 159
Lys y1 147 Look at the low end of the spectrum for these y1 ions.  If you have performed a trypsin digest then one of these ions should be present in the MS/MS fragmentation spectrum and this will reveal the C-terminal residue.  Hint: The N-terminal b1 ion is never observed but often the b1 ion can be observed after acetylation of the peptide.
Arg y1 175
Low Mass Diagnostic Ions Observed with MALDI and PSD, Reported by Karl Clauser at the UCSF
Amino Acid Low Mass Ion Ranked by Mass
Asp 88   60 S   110 H
Arg 70, 73, 87,100,112,185   70 R   112 R
Asn 87   70 P   117 W
CMC 134   72 V   120 F
His 110   73 R   126 P
Lxx 86   74 T   129 K
Lys, Gln 84,101,129   84 K   129 Q
Met 104   84 Q   130 W
Phe 120   86 Lxx   134 CMC
Pro 70, 126   87 R   136 Y
Ser 60   87 N   159 W
Thr 74   88 D   170 W
Trp 117, 130, 159, 170   100 R   185 R
Tyr 136   101 K   - -
Val 72   101 Q   - -
- -   104 M   - -
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Last updated:  Tuesday, January 19, 2016 02:49:33 PM