1. Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, Departments of Medicine and Pathology, University of California—San Diego, La Jolla, California 92093, Department of Chemistry and Biochemistry, San Diego State University, San Diego, California 92182, and The Queensland Institute of Medical Research, 300 Herston Road, Brisbane, Australia