modified L-tyrosine residue iTRAQ4plex-115 reporter+balance reagent acylated residue iTRAQ4plex-115 reporter+balance reagent O4'-acylated tyrosine 144.0995941162109375 144.100006103515625 307.162933349609375 307.170013427734375 iTRAQ4plex115 Y 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. iTRAQ115 (4-methylpiperazin-1-yl)acetyl PSI-MOD none Applied Biosystems iTRAQ(TM) multiplexed quantitation chemistry H 12 (12)C 6 (13)C 1 (14)N 1 (15)N 1 (18)O 1 MOD:01495 A protein modification that effectively replaces the O4'-hydrogen atom of a tyrosine residue with the Applied Biosystems iTRAQ4plex-115 reporter+balance group. Accurate mass for 115 iTRAQ115Y H 21 (12)C 15 (13)C 1 (14)N 2 (15)N 1 (16)O 2 (18)O 1 artifact iTRAQ4plex reporter+balance reagent O-acylated residue