1. Department of Biophysics I Regensburg Center for Biochemistry University of Regensburg Universitätsstrasse 31 93051 Regensburg Germany
2. Institute for Molecular Biosciences Goethe-University Frankfurt Max-von-Laue-Str. 9 60438 Frankfurt/M. Germany
3. Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI) University of Innsbruck Innsbruck Austria