1. Graduate Group in Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
2. Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
3. Department of Physics, University of Texas at Dallas, Richardson, Texas 75801, United States
4. Department of Chemistry and Biochemistry, University of Texas at Dallas, Richardson, Texas 75801, United States
5. Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
6. Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States