Bioanalytics of formulated proteins
Due to a lack of stability or tissue specificity of pharmacologically relevant proteins, their formulation and administration have so far been severely restricted [1]. This results in a great interest in innovative formulation processes that lead to stabilization and improved bioavailability of protein-based drugs. In a collaborative project of the SPP1934 with the Department of Pharmaceutical Technology and Biopharmacy of the University of Bonn, funded by the Deutsche Forschungsgemeinschaft (DFG), we focus on the analysis of formulated peptides and proteins. In addition to structural elucidation, it is required to investigate stability, activity, and in-vitro release kinetics of the target substances. The model peptides/proteins used in the project possess post-translational modifications (PTMs), such as several disulfide bridges, the correct linking of which is essential for the tertiary structure and therefore also for the activity of these substances. The preservation of correct disulfide bridges plays a decisive role in establishing efficient formulation methods and developing suitable analytical standards [2].
However, systematical investigations on the influence of formulation processes on disulfide bridges of cysteine-rich peptides/proteins and other PTMs as well as on the resulting bioactivities are largely missing. In this regard, combinations of different methods, including LC-coupled mass spectrometry, amino acid analysis, and N-terminal protein sequencing according to Edman will be used. The latter method was particularly neglected in the last decades and only rarely combined with MS methods. For such analyses, our group can rely on a protein sequencer model PPSQ-53A from Shimadzu, which was procured as part of the Core Facility "Protein Synthesis and Bioanalytics". We would like to contribute to better reliability of structural and functional analyses of formulated peptides and proteins as examples of drug-relevant biomacromolecules by extending the methodological toolbox within this project.
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[2] Heimer, P., Tietze, A. A., Bäuml, C. A., Resemann, A., Mayer, F.J., Suckau, D., Ohlenschläger, O., Tietze, D., Imhof, D., Anal. Chem. 90 (2018) 3321–3327.