Dynamics and Chemical Shielding in a Small Protein from NMR Spin Relaxation Experiments

Title of Dissertation: Dynamics and Chemical Shielding in a Small Protein from NMR Spin Relaxation Experiments Jennifer Blake Hall, Doctor of Philosophy, 2006 Directed By: Prof. David Fushman Department of Chemistry and Biochemistry NMR spin relaxation spectroscopy is a proven method for characterization of the timescales and amplitudes of intramolecular motions in proteins. In a typical NMR relaxation experiment, the significant contributions to relaxation of the N spin are from the H-N dipolar interaction with the covalently attached amide proton and from the anisotropic component of the N chemical shielding tensor, the N chemical shielding anisotropy (CSA). Herein I suggest novel schemes for the measurement of CSA/dipolar crosscorrelation rates in proteins and for direct nitrogen-detected relaxation measurements. I also conduct a series of established NMR N spin relaxation experiments on a small protein, the B3 domain of Streptococcal protein G, in order to measure the overall rotational diffusion tensor of this domain, to quantify any conformational exchange type motion of backbone amides occurring in this protein on the μs-ms timescale, and to determine the N backbone amide CSAs in this protein in solution and quantify the effect of residue-to-residue variations in the N CSA on model-free motional parameters which describe motions on the ps-ns timescale. DYNAMICS AND CHEMICAL SHIELDING IN A SMALL PROTEIN FROM NMR SPIN RELAXATION EXPERIMENTS