1. Department of Structural Biology University of Pittsburgh School of Medicine 3501 Fifth Ave. Pittsburgh PA 15261 USA
2. Pittsburgh Center for HIV Protein Interactions University of Pittsburgh School of Medicine 1051 Biomedical Science Tower 3, 3501 Fifth Ave. Pittsburgh PA 15261 USA
3. State Key Laboratory of Elemento-Organic Chemistry College of Chemistry Nankai University 300071 Tianjin China
4. Collaborative Innovation Center of Chemical Science and Engineering (Tianjin) Nankai University 300071 Tianjin China