Table II. Mass spectrometric analyses of the partially purified P protein.
P protein (20 μ g) was treated with 0.5 or 1 mm GSNO for 15 min. After removing the excess of GSNO, the protein was digested with trypsin and analyzed as described in “Materials and Methods.” Six peptides belonging to the P subunit (P1 gene) of the GDC showed a mass difference compared with the expected one of 305 D, which corresponds to the addition of one −GS group. No peptide showed a shift of 29 D (−NO) in the mass. The asterisks indicate peptides that showed a shift in mass after both the GSNO treatments.
| Peptide Sequence | Peptide Identification Probability | Modifications Identified by Spectrum | Actual Peptide Mass | Peptide Start | Peptide Stop |
| % | |||||
| FCDALISIR | 95 | GSH (+305) | 1,341.61 | 942 | 950 |
| FCGFDHIDSLIDATVPK | 95 | GSH (+305) | 2,181.97 | 97 | 113 |
| TFCIPHGGGGPGMGPIGVK | 95 | GSH (+305) | 2,085.94 | 775 | 793 |
| DKATSNICTAQALLANMAAMYAVYHGPAGLK* | 95 | GSH (+305) | 3,498.65 | 395 | 425 |
| CSDAHAIADAASK* | 95 | GSH (+305) | 1,563.63 | 463 | 475 |
| LVCTLLPEEEQVAAAVSA | 95 | GSH (+305) | 2,147.02 | 1,020 | 1,037 |