Table 2.
Putative Y-nitrated peptides identified by MALDI-TOF from 2D gel-excised spots
| Description | AGI identifier | Peptide sequence | Error | Signal-to-noise | Mr (observed) (unmodified) | Mr (observed) | Shift | Modification |
| Rubisco activase, chloroplast precursor | At2g39730 | 351R.VYDDEVR.K359 | 0.01 | 110 | 895.34 | 940.41 | +45.07 | NitroY (+45) |
| 72R.GLAYDTSDDQQDITR.G88 | –0.05 | 25 | 1697.66 | 1744.66 | +46.97 | 2 Deamination (+2) NitroY (+45) | ||
| Serine hydroxymethyl transferase | At4g13930 | 160K.VNFTTGYIDYDKLEEK.A177 | 0.03 | 60 | 1934.83 | 2025.92 | +91.09 | Deamination (+1)2 NitroY (+90) |
| Transketolase, putative* | At3g60750 | 333K.ANSYSVHGAALGEKEVEATR.N354 | 0.15 | 57 | (2090.15) | 2135.15 | (+45) | NitroY (+45) |
| Glyceraldehyde-3-phosphate dehydrogenase, cytosolic | At3g04120 | 313K.LVSWYDNEWGYSSR.V328 | –0.06 | 50 | 1761.72 | 1806.72 | +45 | NitroY (+45) |
| Probable mannitol dehydrogenase | At4g39330 | 133K.NYGGYSENIVVDQR.F148 | –0.04 | 27 | 1613.63 | 1658.70 | +45.07 | NitroY (+45) |
| Rubisco large chain precursor** | AtCg00490 | 236K.GHYLNATAGTCEEMIK.R253 | 0.04 | 25 | (1794.84) | 1839.84 | (+45) | NitroY (+45) |
Samples containing 3-nitroY immunopurified proteins were separated by 2-DE and identified by MALDI-TOF as described in the Materials and methods. The AGI identifiers for each identified protein are included along with the corresponding Y-nitrated peptide sequence (the residues susceptible to Y nitration are underlined and unequivocal nitration of Y is indicated in bold). Error (difference between the experimental and calculated masses); signal-to-noise ratio, relative molecular mass (Mr) observed for the modified and the corresponding unmodified peptide that appeared in the same MASCOT search. Values in parentheses indicate the absence of the unmodified peptide. The mass shift (Shift) and the modifications of the corresponding peptide with their respective mass increases are also shown. Those proteins that have been previously reported as nitrated in other plant systems have been marked with a single (Chaki et al., 2009) or double asterisk (Cecconi et al.. 2009).