1. Department of Chemistry and Theoretical Chemistry Institute, University of Wisconsin, Madison, 1101 University Ave, Madison, Wisconsin 53706, Theoretische Physik, Universität Paderborn, Warburger Str. 100, 33098 Paderborn, Germany, Department of Pathology, Harvard Medical School, 200 Longwood Ave. Massachusetts 02115, Department of Chemistry, University of New Mexico, Albuquerque, New Mexico 87131, and Department of Molecular Biophysics, German Cancer Research Center D-69115 Heidelberg, Germany