mTRAQ reporter+balance reagent acylated residue mTRAQ light reporter+balance reagent acylated residue (12)C 7 H 12 (14)N 2 (16)O 1 (4-methylpiperazin-1-yl)acetyl 140.089996337890625 140.0949554443359375 A protein modification that effectively replaces a hydrogen atom of a residue with the Applied Biosystems mTRAQ light reporter+balance group. Applied Biosystems mTRAQ(TM) reagent MOD:01864 PSI-MOD The reagent consists of a reporter group, a balance group and a protein reactive N-oxysuccinimide group. The reporter group, an isotopically labeled 1,4-dimethylpiperazine, is connected to a carbonyl balance group that is isotopically labeled to produce a nominally isobaric combined modification. Unimod:888 X artifact mTRAQ heavy modifications with monoisotopic mass differences that are nominally equal at 140.094963 Da