1. Department
of Chemistry, University of California, Berkeley, California 94720, United States
2. California
Institute for Quantitative Biosciences, University of California, Berkeley, California 94720, United States
3. Department
of Molecular and Cell Biology, University of California, Berkeley, California 94720, United States
4. Department
of Chemistry, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States