Research Article
Mass Spectrometry of Putrescine, Spermidine, and Spermine Covalently Attached to Francisella tularensis Universal Stress Protein and Bovine Albumin
Table 3
Polyamine modified peptides in rUsp/His6 that are labeled by the action of microbial transglutaminase.
| Polyaminated rUsp/His6 peptide | Labeled residue | Polyamine | Signature ions, Da | Discriminant score |
| IVDFQHSIEQEAK | Q55 | Putrescine | 155 | 5.79 | PSIVDFQHSIEQEAK | Q55 | Spermidine | | 9.07 | APSIVDFQHSIEQEAK | Q55 | Putrescine | 200 | 8.38 | APSIVDFQHSIEQEAK | Q55 | Spermidine | 212 | 8.66 | APFAPSIVDFQHSIEQEAK | Q55 | Putrescine | 200 | 8.42 | APSIVDFQHSIEQEAK | Q60 | Spermine | | 4.36 | APSIVDFQHSIEQEAK | Q60 | Spermidine | | 6.10 | PFAPSIVDFQHSIEQEAK | Q60 | Spermidine | | 7.25 | PFAPSIVDFQHSIEQEAK | Q60 | Spermine | | 6.34 | QANVDVLVVR | Q267 | Spermine | | 5.58 | QANVDVLVVR | Q267 | Putrescine | 129 | 6.34 | SILHQANVDVLVVR | Q267 | Putrescine | | 6.96 | FFLGSTANSILHQANVDVLVVR | Q267 | Putrescine | | 11.60 | FFLGSTANSILHQANVDVLVVR | Q267 | Spermine | | 6.25 | FFLGSTANSILHQANVDVLVVR | Q267 | Spermidine | 186 | 8.29 |
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A discriminant score greater than 0.0 is considered to be strong evidence for a correct match of the peptide sequence to the MS/MS spectrum [ 11]. |