1. Department of Chemistry, Drexel University, 3141 Chestnut Street, Philadelphia, Pennsylvania 19026, CNISM and Department of Physical and Astronomical Sciences, University of Palermo, Via Archirafi 36, 90123 Palermo, Italy, Department of Biochemistry and Molecular Biology, Dalhousie University, Nova Scotia, Canada B3H 4H7, and Department of Biochemistry and Biophysics and Johnson Research Foundation, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania 19104-6059