1. Physical Biochemistry, Department of Chemistry, Darmstadt University of Technology, Petersenstrasse 22, D-64287 Darmstadt, Germany, Department of Biochemistry, Faculty of Pharmaceutical Sciences, Toho University, Miyama 2-2-1, Funabashi, Chiba, 274-8510 Japan, and Charité-Universitätsmedizin Berlin, Clinical Neurobiology, Eschenallee 3, D-14050 Berlin, Germany