1. Departments of Biochemistry, Medical Biophysics and Molecular & Medical Genetics and Protein Engineering Network, Centres of Excellence, University of Toronto, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada, Division of Molecular and Structural Biology, Ontario Cancer Institute, 610 University Avenue, Toronto, Ontario M5G 2M9, Canada, Institut für Biochemie II, Fakultät für Naturwissenschaftliche Medizin, Universität Heidelberg, Im Neuenheimer Feld 328, D-69120 Heidelberg, FRG, and Department...