Toward Real-TimeProteomics: Blood to Biomarker Quantitationin under One Hour

Multistep multihour tryptic proteolysis has limited the utility of bottom-up proteomics for cases that require immediate quantitative information. The power of proteomics to quantify biomarkers of health status cannot practically assist in clinical care if the dynamics of disease outpaces the turnaround of analysis. The recently available hyperthermoacidic archaeal (HTA) protease “Krakatoa” digests samples in a single 5 to 30 min step at pH 3 and >80 °C in conditions that disrupt most cells and tissues, denature proteins, and block disulfide reformation thereby dramatically expediting and simplifying sample preparation. The combination of quick single-step proteolysis with high-throughput dual-trapping single analytical column (DTSC) liquid chromatography–mass spectrometry (LC–MS) returns actionable data in less than 1 h from collection of unprocessed biofluid. The systematic evaluation of this methodology finds that over 160 proteins are quantified in less than 1 h from 1 μL of whole blood. Furthermore, labile Angiotensin I and II bioactive peptides along with a panel of protein species can be measured at 8 min intervals with a 20 min initial lag using targeted MS. With these methods, we analyzed serum and plasma from 53 individuals and quantified Angiotensin I and II and over 150 proteins including at least 46 that were not detected with trypsin. We discuss some of the implications of real-time proteomics including the immediate potential to advance several clinical and research applications.