1. School of Medicine, Department of Biochemistry, and Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
2. Department of Chemistry and Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
3. Department of Chemistry, Binghamton University, Binghamton, New York 13902, United States
4. Laboratory of Medicinal Chemistry, KU Leuven, Rega Institute for Medical Research, Minderbroedersstraat 10, Leuven 3000, Belgium