Proteome complexity hampers protein biomarker identification, noted John C. Rogers, Ph.D., manager of mass spectrometry reagents at Thermo Fisher Scientific. “As we looked at what was problematic in biomarker research, we also wanted to differentiate with good science. Where are the pain points? Sample prep and data analysis are the leading culprits. We want to give scientists the right tools for proteomics success.”
Thermo Scientific cysTMT Mass Tag Reagents are thiol-reactive isobaric tags for labeling reduced cysteine residues to perform multiplex quantitative mass spectrometry analysis of protein expression.
When used in combination with the Immobilized Anti-TMT Antibody Resin, cysTMT tags reportedly allow specific labeling, enrichment, and quantitation of cysteine-containing peptides and proteins from complex mixtures of protein samples. Because of the relative proportion of cysteine residues in protein mixtures, it is a beneficial strategy to reduce sample complexity before MS analysis.
For TMT-labeled proteins and peptides, this can be accomplished using an immobilized anti-TMT monoclonal antibody that has high affinity (Kd<100 pM) for the reporter region of the TMT Reagent.
“Enrichment of labeled peptides by this method results in fewer peptides identified per protein but can significantly increase the number of unique proteins identified, making identification and quantitation of low abundance proteins easier,” said Dr. Rogers. “In addition to improving the dynamic range of sample analysis, cysTMT reagents can also be used to assess the oxidation or S-nitrosylation state of cysteine residues.
“When you look at the three things everyone is trying to optimize—sensitivity, scalability, and comprehensiveness—you have to understand that you can’t have all three. There is a trade-off. We choose to optimize for sensitivity and relevance during discovery, then sensitivity and scalability during assay development and validation. We are pushing for relevant proteins.”