title: Long-lived states to monitor protein unfolding by proton NMR.
abstract: The relaxation of long-lived states (LLS) corresponds to the slow return to statistical thermal equilibrium between symmetric and antisymmetric proton spin states. This process is remarkably sensitive to the presence of external spins and can be used to obtain information about partial unfolding of proteins. We detected the appearance of a destabilized conformer of ubiquitin when urea is added to the protein in its native state. This conformer shows increased mobility in the C-terminus, which significantly extends the lifetimes of proton LLS magnetisation in Ser-65. These changes could not be detected by conventional measurements of T(1) and T(2) relaxation times of protons, and would hardly be sensed by carbon-13 or nitrogen-15 relaxation measurements. Conformers with similar dynamic and structural features, as revealed by LLS relaxation times, could be observed, in the absence of urea, in two ubiquitin mutants, L67S and L69S.
authors: Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne, EPFL, Batochime, 1015 Lausanne, Switzerland.
authors: Aurélien
authors: A
authors: Bornet
authors: Puneet
authors: P
authors: Ahuja
authors: Riddhiman
authors: R
authors: Sarkar
authors: Laetitia
authors: L
authors: Fernandes
authors: Sonia
authors: S
authors: Hadji
authors: Shirley Y
authors: SY
authors: Lee
authors: Aydin
authors: A
authors: Haririnia
authors: David
authors: D
authors: Fushman
authors: Geoffrey
authors: G
authors: Bodenhausen
authors: Paul R
authors: PR
authors: Vasos
mesh_terms: D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D056004:Molecular Dynamics Simulation; D009154:Mutation; D019906:Nuclear Magnetic Resonance, Biomolecular; D055550:Protein Stability; D058767:Protein Unfolding; D011522:Protons; D013997:Time Factors; D025801:Ubiquitin / Q000737:chemistry* / Q000235:genetics; D014508:Urea / Q000737:chemistry
chemical_list: D011522:Protons; D025801:Ubiquitin; D014508:Urea