1. Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, Michigan 48109, United States
2. Biophysics Program, University of Michigan, Ann Arbor, Michigan 48109, United States
3. Departments of Biological Sciences and Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, United States
4. Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States