The EDyP team unveils PSAQ+1, a new generation of the PSAQ approach for absolute protein quantification by mass spectrometry, published in Analytical Chemistry.
The idea: a protein standard carrying a single 13C label, just 1.003 Da away from the natural peptide. This tiny mass shift lets the endogenous peptide and its labeled standard be coisolated and cofragmented in a single MS/MS scan, using a very narrow isolation window (0.4 m/z), instead of two, cutting analysis time in half while reducing background interference.
The method is supported by rPSAQ, a new open-source R package that decodes the resulting composite MS/MS signals. On a model protein, it delivered accurate quantification over 3+ orders of magnitude (R² > 0.9999), opening promising perspectives for biomarker and biotherapeutic analysis in complex biological samples
PSAQ+1: Absolute Protein Quantification Using a 13C1‑Labeled Protein Standard, Coisolation of Peptide Pairs and LC-PRM
David Pérez Compte,∇ Anne-Marie Hesse,∇ Benoit Gilquin, Marie Courçon, Yohann Couté, Michel Jaquinod, Christophe Bruley,* and Virginie Brun*
https://doi.org/10.1021/acs.analchem.6c02932
