Multiplexed temporal quantification of the human plasma peptidome

The plasma peptidome contains the entire complement of low molecular weight endogenous peptides derived from secretion, protease activity and post-translational modifications and is a rich source of biomarkers and novel bioactives. To examine the utility of peptidomics we have examined the effects of exercise on the peptidome because exercise is thought to convey many of its physiological benefits via the blood stream. Deep peptidomic analysis was achieved using 2D LC-MS/MS with multiple fragmentation methods and included identification of post-translational modifications and multiplexed temporal quantification. We show the plasma peptidome is subject to transient changes during exercise on a time-scale of minutes that is rapidly reversible during recovery. Known peptide hormones were acutely regulated including insulin, glucagon, ghrelin, bradykinin, cholecystokinin, secretogranins and many others. Acute regulation of proteases and post-translational modifications including glycosylation were observed. These data reveal the power of peptidomic quantification to temporally quantify bioactive peptides, biomarkers and proteolytic activity during pathophysiological processes.