Translational and rotational diffusion of proteins by NMR

NMR provides a method to study the dynamics of proteins and the possibility of gaining an insight into their function. This thesis is concerned with the accurate and reproducible measurement of translational and rotational diffusion of proteins, and methods for the analysis of this data that enable proper and reliable conclusions to be drawn. The research is divided into two parts, diffusion and relaxation.;The basic pulsed gradient spin echo (PGSE) experiment to measure diffusion has been known for some time. A number of problems exist, however, when attempting to make accurate and reproducible diffusion coefficient measurements of proteins in aqueous solution. It is shown that the non-linearity of the magnetic field gradient can be overcome by the use of slice selection to select a region of the sample that experiences a linear gradient enabling accurate and reproducible diffusion coefficient measurements to be made. New heteronuclear diffusion experiments are also designed that allow the diffusion coefficient of a single component of a multi-component system to be studied. These new experiments enable diffusion to be used, for the first time, to measure a binding constant for a protein-peptide interaction. Experimental diffusion data has been collected that allows standard plots to be produced from which the molecular weight and solvent accessible surface area (SASA) can be calculated. These plots have been used to quantify several examples of self-association and conformational change.;The measurement of 15N relaxation data for protein G has been performed and analysed using the model-free approach.