1. Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
2. Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
3. Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana 47405, United States
4. Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, United States
5. Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37235, United States
6. Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States