TMT Labeling for the Masses: A Robust and Cost-efficient, In-solution Labeling Approach

Area of Science:

• Proteomics
• Chemical Biology
• Analytical Chemistry

Background:

• Isobaric stable isotope labeling, such as tandem mass tags (TMTs), is crucial for quantitative proteomic studies.
• Large-scale experiments, including proteoform analysis and patient cohort studies, require reproducible peptide quantification.
• High reagent costs associated with traditional TMT labeling limit its application in extensive studies.

Purpose of the Study:

• To develop and validate a cost-effective and robust protocol for TMT labeling.
• To significantly reduce the amount of TMT labeling reagent required.
• To maintain high labeling efficiency and reproducibility.

Main Methods:

• Systematic evaluation of under- and overlabeling across various peptide quantities (12.5–800 μg) and TMT-to-peptide ratios.
• Optimization of reaction volumes to maintain specific TMT and peptide concentrations (≥10 mM and ≥2 g/l, respectively).
• Benchmarking the optimized protocol against the vendor's recommended procedure using deep-scale proteome and phosphoproteome analysis.

Main Results:

• A novel TMT labeling protocol reducing reagent requirements by an eightfold factor was developed.
• Labeling efficiencies exceeding 99% were achieved with TMT-to-peptide ratios as low as 1:1 (wt/wt) under optimized conditions.
• Excellent intra- and interlaboratory reproducibility was demonstrated.
• The optimized protocol was successfully applied to deep-scale proteome and phosphoproteome analysis of patient-derived xenograft tumor tissue.

Conclusions:

• The developed protocol offers a robust, cost-effective solution for TMT labeling in large-scale proteomic studies.
• Reduced reagent consumption significantly lowers the overall experimental cost.
• The protocol ensures high-quality, reproducible quantitative proteomic data, facilitating complex biological investigations.