Biochemistry Research International

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 peptideLabeled residuePolyamineSignature ions, DaDiscriminant score
IVDFQHSIEQEAKQ55Putrescine1555.79
PSIVDFQHSIEQEAKQ55Spermidine 9.07
APSIVDFQHSIEQEAKQ55Putrescine2008.38
APSIVDFQHSIEQEAKQ55Spermidine2128.66
APFAPSIVDFQHSIEQEAKQ55Putrescine2008.42
APSIVDFQHSIEQEAKQ60Spermine 4.36
APSIVDFQHSIEQEAKQ60Spermidine 6.10
PFAPSIVDFQHSIEQEAKQ60Spermidine 7.25
PFAPSIVDFQHSIEQEAKQ60Spermine 6.34
QANVDVLVVRQ267Spermine 5.58
QANVDVLVVRQ267Putrescine1296.34
SILHQANVDVLVVRQ267Putrescine 6.96
FFLGSTANSILHQANVDVLVVRQ267Putrescine 11.60
FFLGSTANSILHQANVDVLVVRQ267Spermine 6.25
FFLGSTANSILHQANVDVLVVRQ267Spermidine1868.29
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].