1. Contribution from the J.W. Goethe University, Frankfurt, Center for Biomolecular Magnetic Resonance (BMRZ), Biocenter N230, Marie-Curie-Str. 9, 60439 Frankfurt, Germany, Department of Experimental Medicine, Section of Chemistry and Structural Biochemistry, University of Parma, 43100 Parma, Italy, Department of Biochemistry and Molecular Biology, University of Parma, 43100 Parma, Italy, Department of Biochemistry, Tufts University, School of Medicine, 136 Harrison Avenue, Boston, Massachusetts, and CR UK...