Christian Schöneich

Mechanisms of free radical reactions, peptide and protein stability

Christian Schöneich's research focuses on the oxidative post-translational modification of proteins in vitro and in vivo. These are generally carried out by reactive oxygen species and/or reactive nitrogen species. In vivo, such oxidative modifications accompany physiological disorders associated with biological aging or disease. While major scientific advances have been made through the sequencing of the human genome, it has been recognized that in many cases only the detailed characterization and quantification of the protein complement (the "proteome") will lead to an accurate understanding of human disease and aging. Moreover, in addition to quantification of the expression levels of certain proteins a detailed map of their post-translational modifications is necessary. Such research is carried out in our group. We are using state-of-the-art analytical proteomics and tandem mass spectrometry techniques to characterize post-translationally modified proteins in tissue. Experiments involve two-dimensional gel--electrophoresis and two-dimensional HPLC separations, coupled to MALDI-TOF or electrospray ionization mass spectrometry analysis on either Q-TOF2 or ion trap instrumentation. We are currently involved in the building of an interdisciplinary "Proteomics Center" at the University of Kansas, which, by Fall 2004, will be equipped with the newest generations of MALDI-TOF/TOF, MALDI-QqTOF and linear ion trap instruments. For the quantification of distinct post-translational modifications, we are designing specific labeling chemistries, which allow the targeted enrichment of specifically modified peptides from complex biological samples. For example, we have recently characterized specific S-glutathiolated sequences of a membrane protein, the sarco/endoplasmic reticulum Ca-ATPase, as a result of exposure to the biological messenger nitric oxide (NO). An additional focus of our research is to understand the actual mechanisms of oxidation, and the effect of protein structure on these reactions. In vivo, only selected proteins suffer oxidative modifications, which may be the result of chemical selectivity, protein structure, the rates of protein turnover, and/or specific protein-protein interactions.

In vitro, i.e. in pharmaceutical formulations, protein oxidation presents an important stability problem. We are interested to generate a database which relates oxidation sensitivity to specific structural elements of proteins. With such a database at hand, we can potentially predict the stability of new protein products, facilitating pharmaceutical development. To achieve such a database, we are studying oxidative protein stability for proteins in (a) solution, (b) in polymeric matrices, and (c) in the solid state

Research Interests

• Protein Stability
• Protein Oxidation
• Proteomics
• Reactive Oxygen Species
• Free Radicals
• Reaction Mechanisms
• Protein Analysis
• Physical Organic Chemistry