The low-molecular-weight range of the blood proteome was identified as one of the promising candidates for biomarker identification. However, Villanueva and co-workers showed that not only these small peptides can serve as highly sensitive biomarkers for e.g. early disease detection, but also the activity of related proteases and the kinetics of their proteolytic reactions. In this project we take the idea further and will construct mathematical models which describe porteolytic reactions and their kinetic parameters based on time-series analyzes coming from mass spectrometry measurements. Eventually we want to establish new tools for the early detection of cancer that complement currently available methods.