Mass-Spectrometry Quantification of Protein Biomarkers by Selected Reaction Monitoring

Abstract

Selected reaction monitoring (SRM) is a quantitative MS-based method which recently expanded to analysis of proteins by determination of peptides. The instrumentation consists of a nanoflow liquid chromatograph coupled with nanoelectrospray ionization and a triple-quadrupole mass spectrometer. In principle, the first quadrupole works as a mass filter, transmitting only a selected peptide, which is fragmented in a second quadupole via collision-induced dissociation. The third quadrupole transmits the selected peptide fragments, which are then directed to the detector. This approach enables targeted quantification of tens of proteins in a single analysis with very good sensitivity and selectivity. The SRM becomes a key method in a new targeted-proteomics toolbox. The most important field of its applications lies in the life sciences research where SRM enables fast, accurate and cost-effective determination of proteins in large sets of samples.