1. Institute of Medical Physics and Biophysics University of Leipzig Härtelstr. 16–18 04107 Leipzig Germany
2. Institute of Biophysical Chemistry Goethe University Frankfurt Germany
3. Center for Biomolecular Magnetic Resonance Goethe University Frankfurt Germany
4. Institute of Biochemistry University of Leipzig Leipzig Germany
5. Berlin Joint Electron Paramagnetic Resonance Laboratory Free University Berlin Germany
6. Department of Pharmacology Vanderbilt University Nashville TN USA