1. Department of Chemistry & Biochemistry, and NSF Center for Theoretical Biological Physics, University of California San Diego, La Jolla, CA 92093‐0365, USA
2. Department of Pharmacology, and NSF Center for Theoretical Biological Physics, University of California San Diego, La Jolla, CA 92093‐0365, USA
3. Biomedical Sciences Program, University of California San Diego, La Jolla, CA 92093‐0365, USA
4. Howard Hughes Medical Institute, University of California San Diego, La Jolla, CA 92093‐0365, USA
5. Department of Chemistry, Hamilton College, Clinton, NY 13323, USA
6. Department of Chemistry, University of Illinois at Urbana–Champaign, 600 South Mathews Avenue, Urbana, IL 61801, USA