1. Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California 90095, United States
2. Department of Chemistry, University of California Riverside, Riverside, California 92521, United States
3. Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California 92037, United States
4. Department of Biological Chemistry, University of California Los Angeles, Los Angeles, California 90095, United States