Metabolite Differences
Some background information and list taken directly from an ASMS 2008 Poster, “Frequently Reported Mass Differences and Formula for List Searching in Drug Metabolite Indentification”, by Peter L. Jacobs, N.V. Organon, Oss, The Netherlands
“MS vendor software packages dedicated to metabolite identification all include one or more factory supplied lists with biotransformations for expected metabolite list searching. A rationale for the collection of entries on these lists is usually not given, although the operator is invited to adapt the lists for use in specific projects when needed. The modification of such a list can be based on in silico prediction software1,2 or on prior experience with a given compound or similar compounds of the same class. We created lists of frequently observed mass differences and formula based on the occurrence in metabolic reactions reported in literature and explored their application in metabolite identification projects.”
| Rel Form | Name | Shift (Da) | Defect (mDa) |
| +O | Oxidation | +15.9949 | -5 |
| +O2 | 2x Oxidation | +31.9899 | -10 |
| +C6H8O6 | Glucuronidation | +176.0320 | +32 |
| +C6H8O6 | Oxidation + Glucuronidation | +192.0270 | +27 |
| -CH2 | Demethylation | -14.0156 | +16 |
| +O -H2 | Oxidation +Dehydrogenation | +13.9792 | -21 |
| -H2 | Dehydrogenation | -2.0157 | +16 |
| +H2 | Hydrogenation | +2.0157 | +16 |
| -C2H4 | 2x Demethylation | -28.0313 | +31 |
| +H2O2 | Hydrolysis + Oxidation (double bond) | +34.0055 | +6 |
| +O2 -H2 | Carboxylation | +29.9742 | -26 |
| +H2O | Hydrolysis | +18.0106 | +11 |
| +O -CH2 | Oxidation + Demethylation | +1.9793 | -21 |
| +O4S | Oxidation + Sulfation | +95.9517 | -48 |
| +O3S | Sulfation | +79.9568 | -43 |
| +C10H15N3O6S1 | Glutathione Conjugation | +305.0680 | +68 |
| -C2H2O | Deacetylation | -42.0106 | +11 |
| +H4 | 2x Hydrogenation | +4.0313 | +31 |
| +O -C2H4 | Oxidation + 2x Demethylation | -12.0364 | +36 |
| -O | Reduction | -15.9949 | -5 |
| +H2O3 | Hydrolysis + 2x Oxidation | +50.0004 | 0 |
| -C3H6 | Depropylation | -42.0470 | +47 |
| +C5H6O6 | Demethylation + Glucuronidation | +162.0160 | +16 |
| +CH2 | Methylation | +14.0156 | +16 |
| +O3 | 3x Oxidation | +47.9848 | -15 |
| +C10H17N3O7S | Oxidation + Glutathione | +323.0790 | +79 |
| -C2H2 | Oxidation + Deacetylation | -26.0157 | +16 |
| +C2H2O | Acetylation | +42.0106 | +11 |
| +C6H8O8 | 2x Oxidation + Glucuronidation | +208.0220 | +22 |
| +C10H17N3O6S | Glutathione Conjugation (addition) | +307.0840 | +84 |
| +O3 -H2 | 3x Oxidation + Dehydrogenation | +45.0055 | +6 |
| -C4H8 | Debutylation | -56.0626 | +63 |
| +C6H10O6 | Glucuronidation + Hydrogenation | +178.0480 | +48 |
| +CH2O2 | Aromatic Oxidation | +46.0055 | +6 |
| +O -HN | Oxidative Deamination | 0.9840 | -16 |
| -C | Demethylation + Hydrogenation | -12.0000 | 0 |
| +H2 -O | Hetero oxide reduction + Hydrogenation | -13.9793 | -21 |
| +HO3P | Phosphorylation | +79.9664 | -34 |
| +O -CH4 | Oxidation + Demethylation + Dehydrogenation | -0.0364 | +36 |
| -C2H4O | Deacetylation + Dehydrogenation | -44.0262 | +26 |
| +H3O9P3 | Triphosphorylation | +239.8990 | -101 |
| +CH2O | Methylation + Oxidation | +30.0106 | +11 |
| +C5H7NO3S | Acetylcysteination | +161.0150 | +15 |
| -CH4 | Demethylation + Dehydrogenation | -16.0313 | +31 |
| +C2H2O2 | Acetylation + Oxidation | +58.0055 | +6 |
| +H2 -O2 | N-reduction (nitro group) | -29.9742 | -26 |
| -C4H6 | Debutylation + Hydrogenation | -54.0470 | +47 |
| +C5H9NO4S | Oxidation + Acetylcysteination (addition) | +179.0250 | +25 |
| +C6H6O8 | Carboxylation + Glucuronidation | +206.0060 | +6 |
| +C5H6O7 | Demethylation + Oxidation + Glucuronidation | +178.0110 | +11 |