Thermo Scientific iodoTMTsixplex Isobaric Mass Tag Labeling Kit contains iodoTMT™ reagents and associated materials for the irreversible labeling of sulfhydryl groups. Iodoacetyl Tandem Mass Tag™ Reagents enable selective labeling of cysteine-containing peptides for multiplexed sample quantitation using LC-MS/MS analysis.

The iodoTMT Reagents are sets of isobaric (mass and structure) isomers that are iodoacetyl-activated for covalent, irreversible labeling of sulfhydryl (—SH) groups. Similar to iodoacetamide, iodoTMT Reagents react specifically with reduced cysteines (Cys) in peptides and proteins and enable quantitation of the relative abundance of cysteine modifications, such as S-nitrosylation and the oxidation of disulfide bonds.

The Thermo Scientific iodoTMTzero Label Reagent allows testing and optimization of sample preparation, labeling, fractionation and MS fragmentation for peptide identification and reporter detection without using the more costly isotope-labeled compounds.

Features of the iodoTMT Reagents:
• Specific—only reacts with sulfhydryl groups (reduced, unmodified cysteine residues)
• Irreversible—labeled proteins and peptides are not susceptible to reducing agents
• Flexible—options for duplex isotopic (MS) or sixplex isobaric (MS/MS) quantitation
• Versatile—can be used to study cysteine modifications (e.g. di-sulfide bridges, S-nitrosylation)

To selectively analyze the cysteine-labeled peptides, the sample may be enriched using the Thermo Scientific Immobilized Anti-TMT Antibody Resin (Cat. No. 90076) and TMT Elution Buffer (Cat. No. 90104). This approach of selective thiol-labeling and affinity enrichment is similar to isotope-coded affinity tags (ICAT™ Method) but allows for affinity enrichment with a non-biological tag and higher multiplex quantitation.