Table 1.
Mass spectrometry identification of carbonylation on the 75 kDa subunit
| AA# | AA % coverage | SPI % | Peptide sequence | Modification | m/z (Da) measured | MH+ (Da) matched | |
|---|---|---|---|---|---|---|---|
| Control | 69 | 48 | 83.1 | (R)LSVAGNCRmCLVEIEK(A) [100%] | m-Oxidized methionine | 594.2989 | 1780.8803 |
| 48 h KA | 69 | 55 | 77.2 | (R)LSVAGNcrMCLVEIEK(A) [100%] | c-Carbamidomethyl; r-GSA | 593.6242 | 1778.8673 |
| 1 week KA | 69 | 48 | 83.1 | (R)LSVAGNCRmCLVEIEK(A) [75%] | m-Oxidized methionine | 594.2989 | 1780.8803 |
| 1 week KA | 69 | 38 | 64.3 | (R)LSVAGNcrMCLVEIEK(A) [25%] | c-Carbamidomethyl; r-GSA | 593.623 | 1778.8682 |
| 6 week KA | 69 | 62 | 84 | (R)LSVAGNcrMCLVEIEK(A) [100%] | c-Carbamidomethyl; r-GSA | 593.6244 | 1778.8674 |
A GSA (carbonylation) PTM was identified by QTOF MS analysis on a single peptide, (R)LSVAGNCRMCLVEIEK(A), at arginine (r) 76. This modification occurred 100% of the time at 48 h, 25% at 1 week, and 100% at 6 week during epileptogenesis; n = 4 rats/group. AA = amino acid; Da, Dalton; KA, kainate; MH+ = expected protonated ions; m/z = mass to charge ratio; SPI = spectral peak intensity.