Table II. Sequence ions from the MS/MS analysis of the tryptic peptides 246–256 derived from RF2(ceThr246) and RF2(ceAla246).
| Residue No. | RF2(ceThr246) |
RF2(ceAla246) |
|||
|---|---|---|---|---|---|
| m/z | m/z | ||||
| Y1 | 256 | 175.15 | Arg | 175.16 | Arg |
| Y2 | 255 | 289.17 | Asn | 289.20 | Asn |
| Y3 | 254 | 388.25 | Val | 388.27 | Val |
| Y4 | 253 | 525.31 | His | 525.31 | His |
| Y5 | 252 | 667.39 | Gln + 14.02 | 667.37 | Gln + 14.00 |
| Y6 | 251 | 724.41 | Gly | 724.39 | Gly |
| Y7 | 250 | 781.44 | Gly | 781.41 | Gly |
| Y8 | 249 | 852.47 | Ala | 852.44 | Ala |
| Y9 | 248 | 909.50 | Gly | 909.46 | Gly |
| Y10 | 247 | 996.53 | Ser | 996.51 | Ser |
| (M + H)+ | 246 | 1097.59 | Thr | 1067.55 | Ala |
The mass difference between ions Y4 and Y5 is 14 a.m.u. higher than the residual mass of glutamine in both series of sequence ions.