Article pubs.acs.org/biochemistry
Denatured State Ensembles with the Same Radii of Gyration Can Form Significantly Different Long-Range Contacts Bowu Luan,† Nicholas Lyle,‡ Rohit V. Pappu,‡ and Daniel P. Raleigh*,†,§ †
Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States Department of Biomedical Engineering, Washington University in St. Louis, One Brookings Drive, Campus Box 1097, St. Louis, Missouri 63130-4899, United States § Graduate Program in Biochemistry and Structural Biology and Graduate Program in Biophysics, Stony Brook University, Stony Brook, New York 11794, United States ‡
S Supporting Information *
ABSTRACT: Defining the structural, dynamic, and energetic properties of the unfolded state of proteins is critical for an indepth understanding of protein folding, protein thermodynamics, and protein aggregation. Here we analyze long-range contacts and compactness in two apparently fully unfolded ensembles of the same protein: the acid unfolded state of the C-terminal domain of ribosomal protein L9 in the absence of high concentrations of urea as well as the urea unfolded state at low pH. Small angle X-ray scattering reveals that the two states are expanded with values of Rg differing by
