Targeted Quantification of Peptides Using Miniature Mass Spectrometry

Abstract

Proteomics by mass spectrometry (MS) allows for the identification of amino acid/peptide sequences in complex mixtures. Peptide analysis and quantitation enables screening of protein biomarkers and targeted protein biomarker analysis for clinical applications. Whereas miniature mass spectrometers have primarily demonstrated point-of-care analyses with simple procedures aiming at drugs and lipids, it would be interesting to explore their potential in analyzing proteins and peptides. In this work, we adapted a miniature MS instrument for peptide analysis. A mass range as wide as 100−2000 m/z was achieved for obtaining peptide spectra using this instrument with dual linear ion traps. MS 2 and MS 3 can be performed to analyze a wide range of peptides. The parameters of pressure, electric potentials, and solution conditions were optimized to analyze peptides with molecular weights between 900 and 1800 Da. The amino acid sequences were identified using both beam-type and in-trap collision-induced dissociation, and the results were comparable to those obtained by a commercial quadrupole time-of-flight mass spectrometer. With product ion monitoring scan mode, peptide quantitation was performed with a limit of detection of 20 nM achieved for the Met peptide. The method developed has also been applied to the analysis of the trypsin-digested cell lysate of SKBR3 cells with a low expression level of the Met gene.

Recent advances in on-site mass spectrometry analysis for clinical applications

“…For analysis of peptides as potential biomarkers, a calibration curve was established for Met peptide by using 100 ppb of trypsin digested mouse liver protein (MLP) as background peptides ( Fig. 4 f) [ 84 ]. The Met peptide concentration varied from 50 nM to 5 M and a good linearity was observed throughout all concentrations with R-squared values >0.99.…”

Portable mass spectrometry system: instrumentation, applications, and path to ‘omics analysis

“…Recently, Chiang et al. reported targeted quantification of peptides using a dual LIT mass spectrometer [218]. In addition, efforts in miniaturizing mass spectrometers can lead to significantly more compact and less costly benchtop instrumentation which can be applied to ‘omics projects.…”

Fast protein analysis enabled by high-temperature hydrolysis

“…[42][43][44][45][46][47][48][49] Recently, we also explored the application of miniature mass spectrometers in quantitation of synthetic peptides with molecular weights larger than 1500 Da. 50 However, due to the sophistication of sample preparation procedures, fast analysis of proteins and digested peptides by miniature MS is still difficult.…”