Table 1. Most Commonly Observed PTMs of the FASP-Digested Synovial Fluid Samples Based on the Most Frequent Single Features.
| rank | modification and position (N-terminal; C-terminal; acceptor amino acid) | modification mass (Da) | no. MS/MS events | modified sites of possible (%) |
|---|---|---|---|---|
| 1 | Carbamidomethyl (C) | 57.0215 | 13 201 | 100.0 |
| 2 | Deamidated (N) | 0.9840 | 1024 | 8.7 |
| 3 | Acetyl at N-term | 42.0106 | 563 | 2.9 |
| 4 | Carbamidomethyl at N-term | 57.0215 | 535 | 2.7 |
| 5 | Glu → pyro-Glu at N-term | –18.0106 | 522 | 24.1 |
| 6 | Deamidated (Q) | 0.9840 | 440 | 2.9 |
| 7 | Carbamyl (K) | 43.0058 | 434 | 2.0 |
| 8 | Carbamidomethyl (K) | 57.0215 | 420 | 1.9 |
| 9 | Carbamyl at N-term | 43.0058 | 416 | 2.1 |