Protein structural changes characterized by high-pressure, pulsed field gradient diffusion NMR spectroscopy
| Autor: | Ad Bax, Iva Pritišanac, Venkatraman Ramanujam, Jinfa Ying, T. Reid Alderson |
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| Rok vydání: | 2019 |
| Předmět: |
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Molecular Nuclear and High Energy Physics Self-diffusion Protein Folding Materials science Protein Conformation Diffusion Hydrostatic pressure Biophysics Synucleins Thermodynamics 010402 general chemistry 01 natural sciences Biochemistry Article 030218 nuclear medicine & medical imaging 03 medical and health sciences 0302 clinical medicine Hydrostatic Pressure Urea Nuclear Magnetic Resonance Biomolecular Ubiquitin Relaxation (NMR) Nuclear magnetic resonance spectroscopy Hydrogen-Ion Concentration Condensed Matter Physics Random coil 0104 chemical sciences Intrinsically Disordered Proteins Protein folding Pulsed field gradient |
| Zdroj: | J Magn Reson |
| ISSN: | 1096-0856 |
| Popis: | Pulsed-field gradient NMR spectroscopy is widely used to measure the translational diffusion and hydrodynamic radius (R(h)) of biomolecules in solution. For unfolded proteins, the R(h) provides a sensitive reporter on the ensemble-averaged conformation and the extent of polypeptide chain expansion as a function of added denaturant. Hydrostatic pressure is a convenient and reversible alternative to chemical denaturants for the study of protein folding, and enables NMR measurements to be performed on a single sample. While the impact of pressure on the viscosity of water is well known, and our water diffusivity measurements agree closely with theoretical expectations, we find that elevated pressures increase the R(h) of dioxane and other small molecules by amounts that correlate with their hydrophobicity, with parallel increases in rotational friction indicated by (13)C longitudinal relaxation times. These data point to a tighter coupling with water for hydrophobic surfaces at elevated pressures. Translational diffusion measurement of the unfolded state of a pressure-sensitized ubiquitin mutant (VA2-ubiquitin) as a function of hydrostatic pressure or urea concentration shows that R(h) values of both the folded and the unfolded states remain nearly invariant. At ca 23 Å, the R(h) of the fully pressure-denatured state is essentially indistinguishable from the urea-denatured state, and close to the value expected for an idealized random coil of 76 residues. The intrinsically disordered protein (IDP) α-synuclein shows slight compaction at pressures above 2 kbar. Diffusion of unfolded ubiquitin and α-synuclein is significantly impacted by sample concentration, indicating that quantitative measurements need to be carried out under dilute conditions. |
| Databáze: | OpenAIRE |
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