1. Department
of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
2. Program
in Physical Biology, Eunice Kennedy Shriver National Institute of
Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, United States
3. Centre
for Molecular Simulation, Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada T2N 1N4
4. Department
of Biochemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, United States