1 Department of Chemistry, The Scripps Research Institute, La Jolla, CA 92037, USA; Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA.
2 Department of Chemistry, The Scripps Research Institute, La Jolla, CA 92037, USA; Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA; The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA. Electronic address: [email protected].