Table I.
Assignment of the NVP-modified amino acid residues from HSA and Hb that were identified by MALDI-TOF-TOF-MS analyses of the tryptic peptides.
| Protein | Observed massa(Da) |
Theoretical mass of the unmodified peptide(Da) |
Mass increase (Da) |
Peptide sequenceb | NVP- modified residue |
|---|---|---|---|---|---|
| HSA | 937.55 | 673.38 | 264.17 | AWAVAR (237-242) |
W238 |
| 1731.99 | 1467.84 | 264.15 | RHPDYSVVLLLR (361-372) |
H362 | |
| 1782.98 | 1518.78 | 264.20 | LDELRDEGKASSAK (206-219) |
K214 | |
| 2047.12 | 1783.08 | 264.04 | ERQIKKQTALVELVK (544-558) |
K548 or K 549 |
|
|
| |||||
| Hb | 1538.91 | 1274.73 | 264.18 | LLVVYPWTQR (32-41; Hb B) |
W38 |
| 1793.93 | 1529.74 | 264.19 | VGAHAGEYGAEALER (18-32; Hb A) |
H21 | |
| 2793.43 | 2529.22 | 264.21 | GTFATLSELHCDKLHVDPENFR (84-105; Hb B) |
S90 | |
a
Compared to the theoretical mass of the corresponding unmodified peptide, each peptide had an NVP-specific mass increment (ca. 264.28 Da).
b
The modified amino acid residues are highlighted in each peptide sequence.