Profiling of Thiol-Containing Compounds by Stable Isotope Labeling Double Precursor Ion Scan Mass Spectrometry

Abstract

Here we developed a novel strategy of isotope labeling in combination with high-performance liquid chromatography-double precursor ion scan mass spectrometry (IL-LC-DPIS-MS) analysis for nontargeted profiling of thiol-containing compounds. In this strategy, we synthesized a pair of isotope labeling reagents (ω-bromoacetonylquinolinium bromide, BQB; ω-bromoacetonylquinolinium-d7 bromide, BQB-d7) that contain a reactive group, an isotopically labeled moiety, and an ionizable group to selectively label thiol-containing compounds. The BQB and BQB-d7 labeled compounds can generate two characteristic product ions m/z 218 and 225, which contain an isotope tag and therefore were used for double precursor ion scans in mass spectrometry analysis. The peak pairs with characteristic mass differences can be readily extracted from the two precursor ion scan (PIS) spectra and assigned as potential thiol-containing candidates, which facilitates the identification of analytes. BQB and BQB-d7 labeled thiol-containing compounds can be clearly distinguished by generating two individual ion chromatograms. Thus, thiol-containing compounds from two samples labeled with different isotope reagents are ionized at the same time but recorded separately by mass spectrometry, offering good identification and accurate quantification by eliminating the MS response fluctuation and mutual interference from the two labeled samples. Using the IL-LC-DPIS-MS strategy, we profiled the thiol-containing compounds in beer and human urine, and 21 and 103 thiol candidates were discovered in beer and human urine, respectively. In addition, 9 and 17 thiol candidates in beer and human urine were successfully identified by further comparison with thiol standards or tandem mass spectrometry analysis. Taken together, the IL-LC-DPIS-MS method is demonstrated to be a promising strategy in the profiling of compounds with identical groups in metabolomics study.

Metabolite Analysis and Histology on the Exact Same Tissue: Comprehensive Metabolomic Profiling and Metabolic Classification of Prostate Cancer

“…In our work, we applied dansylation LC-MS to profile the amine/phenol submetabolome of tissue extracts and detected 4090 peak pairs or metabolites. The use of other labeling methods to target other groups of submetabolomes2021222324 should further increase the overall coverage. We note that only a fraction of the tissue extract is needed to perform one labeling LC-MS experiment; one extract should be sufficient to carry out multiple labeling reactions.…”

Quantitative Metabolome Analysis Based on Chromatographic Peak Reconstruction in Chemical Isotope Labeling Liquid Chromatography Mass Spectrometry

“…We implemented this method by developing a software program, IsoMS-Quant, for automatic peak ratio calculation. IsoMS-Quant is demonstrated to provide better precision and accuracy for both untargeted and targeted metabolic profiling work using CIL LC-MS. IsoMS-Quant, along with IsoMS and Zero-fill, forms a complete workflow for rapid processing of raw LC-MS data generated by CIL LC-MS. 21 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Table 1. Results of targeted quantification of 20 metabolites in a human serum sample by LC-MS analysis of a mixture of the 12 C-labeled sample and the 13 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 ...…”

Current trends in isotope‐coded derivatization liquid chromatographic‐mass spectrometric analyses with special emphasis on their biomedical application

“…However, these reagents are also used for the labeling of amino acids. Takach, O'shea, and Liu, Huang, Cai, Yuan, and Feng () utilized iTRAQ reagents coupled with UPLC–MS/MS for the quantification of amino acids in rodent biofluids and tissues. They used duplex iTRAQ reagents, comprising an ionizable reporter group ( N ‐methylpiperazine) with a mass number of 114 or 115 Da bonded with a carbonyl group with a mass number of 31 or 30 Da for conferring mass balance to the reagent (145 Da) in addition to the amine‐reactive group (NHS ester).…”