Targeted proteomics has received much attention because of the highly-sensitive, quantitative detection of proteins and post-translational modifications (PTMs). Quantification by targeted proteomics relies on mass spectrometry and isotope-labeled internal standards. In addition to traditional standards comprised of recombinant proteins or synthetic peptides, artificial proteins composed of concatenated peptides (QconCATs) were recently introduced as a conceptually new material for use as an internal standard. The design, the expression, the characterization, and the application of QconCATs have been thoroughly reviewed elsewhere. The focus of this review is to describe two new trends in the use of QconCATs as internal standards: (1) the need of natural flanking sequences for every Q-peptide included in the QconCAT; and, (2) the benefits of stoichiometric incorporation of PTMs in the QconCAT. These developments in QconCATs have not received much attention so far, but show great promise for future advances in targeted proteomics.
Citation: Trac-Trends in Analytical Chemistry
Pub Type: Journals
Mass spectrometry, Multiple reaction monitoring, Standards, QconCAT, Unnatural amino acid