title: Dimensions, energetics, and denaturant effects of the protein unstructured state.
abstract: Determining the energetics of the unfolded state of a protein is essential for understanding the folding mechanics of ordered proteins and the structure-function relation of intrinsically disordered proteins. Here, we adopt a coil-globule transition theory to develop a general scheme to extract interaction and free energy information from single-molecule fluorescence resonance energy transfer spectroscopy. By combining protein stability data, we have determined the free energy difference between the native state and the maximally collapsed denatured state in a number of systems, providing insight on the specific/nonspecific interactions in protein folding. Both the transfer and binding models of the denaturant effects are demonstrated to account for the revealed linear dependence of inter-residue interactions on the denaturant concentration, and are thus compatible under the coil-globule transition theory to further determine the dimension and free energy of the conformational ensemble of the unfolded state. The scaling behaviors and the effective θ-state are also discussed.
authors.affiliation: College of Chemistry and Molecular Engineering, Center for Quantitative Biology, and Beijing National Laboratory for Molecular Sciences (BNLMS), Peking University, Beijing, 100871, China.
authors.forename: Maodong
authors.initials: M
authors.lastname: Li
authors.affiliation: College of Chemistry and Molecular Engineering, Center for Quantitative Biology, and Beijing National Laboratory for Molecular Sciences (BNLMS), Peking University, Beijing, 100871, China.
authors.forename: Zhirong
authors.initials: Z
authors.lastname: Liu
mesh_terms: D031541:Fluorescence Resonance Energy Transfer; D011487:Protein Conformation; D011489:Protein Denaturation; D017510:Protein Folding; D055550:Protein Stability; D011506:Proteins / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D011506:Proteins
keywords: binding model; coil-globule transition; protein denaturation; single-molecule FRET; transfer model