Table 2.
20S Proteasome S-Glutathiolated Cysteine Residues
| Subunits - position | Cys-SG | Peptide sequence | Monoisotopic ion [M+H]+GSH | m/z ratio detected | Error (ppm) |
|---|---|---|---|---|---|
| PT-SG | |||||
| α5 | |||||
| 73–86 | Cys76 | R.HIGCAMSGLTADAR.S | 1707.728 | 569.914 | 17.5 |
| 94–122 | Cys117 | R.TAAVTHNLYYDEDINVESLTQSVCDLALR.F | 3558.638 | 890.415 | 11.2 |
| 212–224 | Cys221 | K.LDENNAQLSCITK.Q | 1753.778 | 585.264 | 11.4 |
| α6 | |||||
| 66–82 | Cys66 | K.CDEHMGLSLAGLAPDAR.V | 2060.888 | 687.634 | 9.7 |
| α7 | |||||
| 42–52 | Cys42 | K.CNDGVVFAVEK.L | 1485.638 | 743.322 | 6.7 |
| 73–86 | Cys76 | R.HIGCVYSGLIPDGR.H | 1791.818 | 597.944 | 11.1 |
| nPT-SG | |||||
| α5 | |||||
| 73–86 | Cys76 | R.HIGCAMSGLTADAR.S | 1707.81 | 569.94 | 52.7 |
| 206–224 | Cys221 | K.QVMEEKLDENNAQLSCITK.Q | 2513.10 | 1257.62 | 35.8 |
The 20SPT preparations were treated with 10 mM GSH (PT-SG) or were natively S-glutathiolated (nPT-SG). All subunits containing Cys residues identified on the two-dimensional electrophoresis gel coupled to MS-fingerprinting were digested with trypsin followed by an LC-Q-ToF-MS analysis.
GSH, glutathione; PT-SG, in vitro S-glutathiolated 20S proteasome.