1. Institute for Clinical Chemistry, Medical Faculty, University of Cologne, Kerpener Str. 62, 50937 Cologne, Germany
2. Institute for Biochemistry, Department of Chemistry, Faculty of Mathematics and Natural Sciences, University of Cologne, Zuelpicher Str. 47a, 50674 Cologne, Germany
3. Center for Molecular Biosciences, University of Cologne, Zuelpicher Str. 47a, 50674 Cologne, Germany