1. Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0340, United States
2. Department of Chemistry, University of California, Irvine, Irvine, California 92697, United States
3. Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, California 92697, United States