(13)C isotope tagged reagent (15)N isotope tagged reagent isotope tagged sufhydryl reagent modified cysteine cysTMT6plex reporter+balance reagent cysteine disulfide A protein modification that effectively replaces a residue sulfhydryl hydrogen with a Thermo Scientific cysTMT6plex reporter+balance group. C MOD:01821 PSI-MOD S-(2-{3-[2-(2,6-dimethylpiperidin-1-yl)acetamido]propanamido}ethyl)sulfanyl The reagent consists of a reporter group, a balance group and a protein sulfhydryl reactive pyridine disulfanyl group. The reporter group, an isotopically labeled 1,2,6-trimethylpiperidine, is connected to a 3-(carbonylamino)propanoyl balance group that is isotopically labeled to produce a nominally isobaric combined modification. Unimod:985 artifact cysTMT6plex cysteine-reactive Sixplex Tandem Mass Tag(TM)