1. Department
of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California 92037, United States
2. Program
in Chemical Biology, The University of Michigan, Ann Arbor, Michigan 48109, United States
3. Department
of Biochemistry and Chemistry, Duke University School of Medicine, 307
Research Drive, Nanaline H. Duke Building, Durham, North Carolina 27710, United States