1. Department of Chemistry and Biochemistry, The Ohio State University, 100 W. 18th Avenue, Columbus, Ohio 43210, United States
2. Department of Chemistry, University of Connecticut, Unit 3060, Storrs, Connecticut 06269-3060, United States
3. Department of Molecular Biophysics and Biochemistry, Yale University, 333 Cedar St., New Haven, Connecticut 06510, United States
4. Microbial Sciences Institute, Yale University, 840 West Campus Drive, West Haven, Connecticut 06516, United States