TABLE 1.
Molecular formula of ions used for quantification of labeled and unlabeled amino acids
Isotopic contribution of unlabeled metabolite signal was subtracted from the signal response of 15N-labeled metabolites in all cases.
| Metabolite | Q-ion molecular formula | 14N Q-ion | 15N Q-ion | Isotope % contribution |
|---|---|---|---|---|
| Alanine | Si2C11H26NO2 | 260 | 261 | 23 |
| Aspartate | Si3C18H40NO4 | 418 | 419 | 36 |
| Glutamate | Si3C19H43N2O3 | 432 | 433 | 38 |
| Glycine | Si2C10H24NO2 | 246 | 247 | 22 |
| Isoleucine | Si2C14H32NO2 | 302 | 303 | 27 |
| Leucine | Si2C14H32NO2 | 302 | 303 | 26 |
| Lysine | Si3C20H42N3O2 | 431 | 433 | 18 |
| Phenylalanine | Si2C17H30NO2 | 336 | 337 | 30 |
| Proline | SiC8H14NO2 | 184 | 185 | 15 |
| Serine | Si3C17H40NO3 | 390 | 391 | 35 |
| Threonine | Si3C18H42NO3 | 404 | 405 | 36 |
| Tyrosine | Si3C23H44NO3 | 466 | 467 | 42 |
| Valine | Si2C11H26NO2 | 260 | 261 | 23 |