1. Laboratory of Biophysical Chemistry of Macromolecules, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland;
2. Department of Physics, Biophysics Graduate Program, Ohio State Biochemistry Graduate Program, and Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210-1117, USA;