1. Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
2. Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
3. School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
4. Department of Biochemistry and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States