Quantitative analysis of backbone dynamics in a crystalline protein from nitrogen-15 spin-lattice relaxation.
A detailed analysis of nitrogen-15 longitudinal relaxation times in microcrystalline proteins is presented. A theoretical model to quantitatively interpret relaxation times is developed in terms of motional amplitude and characteristic time scale. Different averaging schemes are examined in order to propose an analysis of relaxation curves that takes into account the specificity of MAS experiments. In particular, it is shown that magic angle spinning averages the relaxation rate experienced by a single spin over one rotor period, resulting in individual relaxation curves that are dependent on the orientation of their corresponding carousel with respect to the rotor axis. Powder averaging thus leads to a nonexponential behavior in the observed decay curves. We extract dynamic information from experimental decay curves, using a diffusion in a cone model. We apply this study to the analysis of spin-lattice relaxation rates of the microcrystalline protein Crh at two different fields and determine differential dynamic parameters for several residues in the protein.
Giraud
Nicolas
N
Laboratoire de Chimie (UMR 5182 CNRS/ENS Lyon), Laboratoire de Recherche Conventionné du CEA (DSV 23V/DSM 0432), Ecole Normale Supérieure de Lyon, Lyon, France.
Blackledge
Martin
M
Goldman
Maurice
M
Böckmann
Anja
A
Lesage
Anne
A
Penin
François
F
Emsley
Lyndon
L
D001426:Bacterial Proteins / Q000737:chemistry*; D008958:Models, Molecular; D009587:Nitrogen Isotopes; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D010750:Phosphoproteins / Q000737:chemistry*; D011487:Protein Conformation; D013816:Thermodynamics
D001426:Bacterial Proteins; C118042:Crh protein, Bacillus subtilis; D009587:Nitrogen Isotopes; D010750:Phosphoproteins