1. Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave. Rm. 16-561, Cambridge, Massachusetts 02139, United States
2. Preclinical Imaging & Testing Facility, Koch Institute at MIT, 77 Massachusetts Ave. Rm. 76-188, Cambridge, Massachusetts 02139, United States
3. Department of Chemistry, X-ray Diffraction Facility, 77 Massachusetts Ave. Rm 2-325, Cambridge, Massachusetts 02139, United States
4. Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712-1224, United States