| Plasma peptides are found to be rich in a human plasma sample, and contain status information of a variety of diseases. The discovered metabolic peptide markers including GLP-1, GIP, Glucagon, and Ghrelin, are potentially developed for clinical and pharmacokinetic applications. However, these potential metabolic peptide biomarkers like other peptides in plasma samples are subject to preanalytical variability, specifically instability caused by intrinsic proteolysis. The proteolytic instability may result in a barrier in translating discovered biomarkers from research into applications and/or misleading pharmacokinetic data. Using time-course MS analysis, we have characterized the digestion kinetics of each peptide as a Sequential Multiple-Step Reaction (SMSR) caused by intrinsic plasma peptidases. We also developed a time-course MALDI-TOF MS method to evaluate the stability of a potential peptide marker from sample to spectrum. We further developed a technology to minimize this variability and instability using DPP-IV, esterase, and other protease inhibitors in the blood collection tube. Stabilization of plasma peptides, including GLP-1, GIP, Glucogan, and “active” Ghrelin enable them to be used to better understand pharmacokinetic data and potential biomarkers for Diabetic disease. |
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