1. Department of Chemistry and Biochemistry University of Delaware Brown Laboratories Newark DE 19716 USA
2. Pittsburgh Center for HIV Protein Interactions University of Pittsburgh School of Medicine 1051 Biomedical Science Tower 3, 3501 Fifth Avenue Pittsburgh PA 15261 USA
3. Department of Structural Biology University of Pittsburgh School of Medicine 1051 Biomedical Science Tower 3, 3501 Fifth Avenue Pittsburgh PA 15261 USA
4. Bruker Biospin Corporation 15 Fortune Drive Billerica MA USA