iTRAQ8plex-116 reporter+balance reagent acylated residue iTRAQ8plex-116 reporter+balance reagent O3-acylated serine 304.205352783203125 304.209991455078125 391.237396240234375 391.239990234375 artifact none (4-methylpiperazin-1-yl)acetyl A protein modification that effectively replaces an O3-hydrogen atom of a serine residue with the Applied Biosystems iTRAQ8plex-116 reporter+balance group. S MOD:01554 PSI-MOD H 24 (12)C 7 (13)C 7 (14)N 3 (15)N 1 (16)O 3 H 29 (12)C 10 (13)C 7 (14)N 4 (15)N 1 (16)O 5 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 balance group that is isotopically labeled to produce a nominally isobaric combined modification. iTRAQ8plex reporter+balance reagent O-acylated residue O3-acylated L-serine