1. Department of Chemistry & Biochemistry, University of California, San Diego, CA 92093, USA
2. Center for AIDS Research, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
3. Departments of Microbiology, Immunology, and Molecular Genetics, Molecular Biology Institute, and California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA