1. Center for Biomolecular Structure and Organization, Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA
2. Basic Research Laboratory, National Cancer Institute, Frederick, MD 21702, USA
3. One Moon Scientific, Inc., Westfield, NJ 07090, USA
4. Structural Biology Initiative, Advanced Science Research Center at the Graduate Center of the City University of New York, New York, NY 10031, USA