Quantitative Isotopically Labeled Tags for Precise Proteomic Analysis via Mass Spectrometry

Peptide tagging is a technique in proteomics where specific tags are attached to peptides to enhance their detection and analysis. These tags typically consist of an ionization head, a linker, and reporter group, which together improve the peptide's ionization efficiency and detectability in mass spectrometry. By facilitating more accurate identification and quantification of peptides, peptide tagging is crucial for studying protein functions and identifying biomarkers for disease diagnosis and monitoring. Conventional tags, with a mass range of 100-300 Da, often fail to ionize and recognize smaller peptides efficiently, leading to undetected low-abundance biomarkers. To address this, we developed Quantitative Isotopically Labeled tags (QUAIL) with relatively larger mass and better reporter group, significantly improving sensitivity in mass spectrometry (MS)-based diagnostics. QUAIL also enhances multiplexing efficiency, allowing for the simultaneous analysis of multiple samples, thus saving time and resources. We evaluated QUAIL tagging efficiency by experimenting different solvents, temperatures, and incubation times to optimize the tagging process. The successful tagging reaction was confirmed by direct infusion on a SCIEX QTRAP 4500 mass spectrometer. The potential of QUAIL to improve diagnosis and early disease detection is substantial, particularly in identifying minute quantities of biomarkers. For example, tagging peptides from Amyloid Beta for Alzheimer's and Hemoglobin A1c for diabetes could facilitate early diagnosis and intervention. This research highlights QUAIL's promising potential in biological research and medical diagnostics, paving the way for more efficient and accurate disease prediction.