1. Institute for Biophysical Chemistry, Centre for Biomolecular Magnetic Resonance, Goethe University, D-60325 Frankfurt am Main, Germany.
2. Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, D-69120 Heidelberg, Germany.
3. Department of Molecular and Cellular Biology, Harvard University, Northwest Laboratories, Cambridge, MA 02138, USA.
4. Merck KGaA, Merck Serono, Molecular Interactions and Biophysics, D-64293 Darmstadt, Germany.