title: Salt-stabilized globular protein structure in 7 M aqueous urea solution.
abstract: A 7 M aqueous urea solution of the 63-residue N-terminal domain of the 434-repressor at pH 7.5 and 18 degrees C contains a mixture of about 10% native, folded protein and 90% unfolded protein. Interconversion between the two conformations is slow on the NMR chemical shift time scale, so that observation of separate resonances can be used to monitor the equilibrium between folded and unfolded protein when changing the solution conditions. In this paper we describe the influence of various salts or non-ionic compounds on this conformational equilibrium. Solution conditions are described which contain a homogenous preparation of the folded protein in the presence of 6 to 7 M urea, providing a basis for an NMR structure determination in concentrated urea and for studies of the solvation of the folded protein in mixed water/urea/salt environments.
authors.affiliation: Institut für Molekularbiologie und Biophysik, Eidgenössische Technische Hochschule-Hönggerberg, Zürich, Switzerland.
authors.forename: V
authors.initials: V
authors.lastname: Dötsch
authors.forename: G
authors.initials: G
authors.lastname: Wider
authors.forename: G
authors.initials: G
authors.lastname: Siegal
authors.forename: K
authors.initials: K
authors.lastname: Wüthrich
mesh_terms: D001435:Bacteriophages / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D017510:Protein Folding; D012097:Repressor Proteins / Q000737:chemistry*; D012996:Solutions; D014508:Urea; D014764:Viral Proteins
chemical_list: C063367:434-repressor protein, Bacteriophage 434; D012097:Repressor Proteins; D012996:Solutions; D014764:Viral Proteins; D014508:Urea