1. Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana 46556, United States
2. Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
3. Department of Chemistry and Institute of Biochemistry, Carleton University, Ottawa, ON K1S 5B6, Canada
4. Department of Physics and Astronomy, University of Notre Dame, Notre Dame, Indiana 46556, United States