1. Center
for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, California 92093, United States
2. Program
in Chemical Biology, University of Michigan, Ann Arbor, Michigan 48109, United States
3. Skaggs
School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, San Diego, California 92093, United States
4. Department
of Chemistry, The Scripps Research Institute, La Jolla, California 92037, United States
5. Department
of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States