Table II. MS/MS fragment ions generated from the N-terminal Lys-C peptide of native Gαs (m/z 973.58).
| Sequence | Fragment ion | m/zcalc | m/zfound |
|---|---|---|---|
| Palm-G | B1 | 296.3 | 296.1 |
| Palm-GC | B2 | 456.3 | 456.2 |
| Palm-GCL | B3 | 569.4 | 569.0 |
| Palm-GCLG | B4 | 626.4 | 626.3 |
| Palm-GCLGNS | B6* | 810.4 | 810.8 |
| K | Y1” | 147.1 | 146.8 |
| SK | Yo2 | 216.1 | 215.6 |
| SK | Y2” | 234.1 | 233.6 |
| NSK | Y3* | 331.2 | 330.8 |
| NSK | Y3” | 348.2 | 348.6 |
| GNSK | Y4* | 388.2 | 388.0 |
| GNSK | Y4” | 405.2 | 404.5 |
| LGNSK | Y5* | 501.3 | 501.4 |
| LGNSK | Y5” | 518.3 | 518.0 |
| CLGNSK | Y6* | 661.3 | 660.9 |
| CLGNSK | Y6” | 678.3 | 678.4 |
Based on the single-charge precursor ion the MS/MS spectrum showed N-terminal and C-terminal fragment ion series B1–B6 and Y1–Y6, respectively. (*) and (o) indicate the neutral loss of 17 and 18 mass units, respectively. Cysteine was modified by carbamidomethylation.