title: Conformational dynamics of the trp-cage miniprotein at its folding temperature.
abstract: The folding temperature of the trp-cage mini-protein was determined to be in the range 311-317 K depending on the method used. Our study is focused on determining the structure and dynamics of the polypeptide chain close to its unfolding or melting temperature. At T = 305 K, Trp6-Arg16 and Trp6-Pro12 long-range interactions are observed, and at T = 313 K, only the Trp6-Arg16 interactions remain, while all of mentioned interactions are observed in the native state of the protein. Partial (at T = 305 K) and complete (at T = 313 K) melting of the N-terminal α-helix is observed, manifested by the appearance of minor sets of signals in NMR spectra. Our key findings are: (i) conformational phase transition (melting point) could be described as a cooperative breaking of the Trp6-Pro12 long-range hydrophobic interaction and the melting of the N-terminal α-helix; (ii) many ROE signals corresponding to local or short-range interactions vanish rapidly with temperature increase; however, long-range interaction such as Trp6-Arg16 remains until 313 K. The presence of the native long-range interaction at 313 K makes that conformational ensemble resemble a very diffuse native state structure, but it is not a simple mixture of the folded and unfolded states, as could be expected on the basis of the common two-state folding mechanism.
authors.affiliation: Laboratory of Biopolymer Structure, Intercollegiate Faculty of Biotechnology, University of Gdańsk and Medical University of Gdańsk, Kładki 24, 80-922 Gdańsk, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Hałabis
authors.forename: Wioletta
authors.initials: W
authors.lastname: Żmudzińska
authors.forename: Adam
authors.initials: A
authors.lastname: Liwo
authors.forename: Stanisław
authors.initials: S
authors.lastname: Ołdziej
mesh_terms: D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D019906:Nuclear Magnetic Resonance, Biomolecular; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry*; D011487:Protein Conformation; D017510:Protein Folding; D013696:Temperature
chemical_list: D010455:Peptides