1. Department of Chemistry, Center for RNA Molecular Biology, and Department of Biochemistry, Microbiology, and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
2. Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
3. Department of Chemistry and Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois 60637, United States
4. Laboratory for Biomolecular Simulation Research, Institute for Quantitative Biomedicine, Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey 08854-8087, United States