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