Mass Spectrometry of Putrescine, Spermidine, and Spermine Covalently Attached to Francisella tularensis Universal Stress Protein and Bovine Albumin
Table 4
Putrescine modified peptides in bovine serum albumin that are labeled by the action of microbial transglutaminase.
BSA peptide
Labeled residue
Polyamine
Signature ions, Da
Discriminant score
GLVLIAFSQY
Q53
Putrescine
4.75
IAFSQYLQQCPFDEHVK
Q57
Putrescine
6.97
LIAFSQYLQQCPFDEHVK
Q57
Putrescine
6.52
GLVLIAFSQYLQQCPFDEH
Q57
Putrescine
6.90
GLVLIAFSQYLQQCPFDEHVKVK
Q57
Putrescine
4.41
YNGVFQECCQAEDK
Q193
Putrescine
6.45
YICDNQDTISSK
Q291
Putrescine
155
6.57
PENLPPLTADFAEDKDVCKNYQEAK
Q343
Putrescine
8.63
HLVDEPQNLIK
Q408
Putrescine
5.79
HLVDEPQNLIKQNCDQFEK
Q413
Putrescine
9.01
LGEYGFQNAL
Q427
Putrescine
200
5.20
GEYGFQNALIVR
Q427
Putrescine
129, 155, 200
6.52
LGEYGFQNALIVR
Q427
Putrescine
155, 200
8.21
VPQVSTPTLVEVSR
Q440
Putrescine
6.64
PDTEKQIK
Q545
Putrescine
155, 200
6.06
TLPDTEKQIK
Q545
Putrescine
5.63
TFHADICTLPDTEKQIK
Q545
Putrescine
5.85
KQTALVELLK
Q549
Putrescine
155
4.68
LVVSTQTAL
Q603
Putrescine
155
5.58
Cysteines are carbamidomethylated, adding 57 Da to the mass of the peptide. 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].