Development of NMR methodology for the study of complex molecular and biomolecular systems

Thesis

Nuclear magnetic resonance (NMR) is amongst the most powerful and versatile spectroscopic tools for characterising biological systems. A key advantage of NMR techniques is that in addition to being sensitive to structural features of biomolecules through their chemical shift, chemical exchange and relaxation processes allow dynamic molecular properties to be studied. Techniques have also been developed to facilitate the characterisation of translational diffusion with NMR, through the application of pulsed field gradients.

In this thesis we develop and apply NMR methods for studying biomolecular systems. Firstly, in Chapter 2, we introduce an experimental protocol and model for the analysis of cellular systems from the diffusional properties of the water within them. In addition to reporting diffusion coefficients, this analysis also provides information on cell radii, abundance and permeability. A drawback of NMR compared to other spectroscopic techniques is its relative insensitivity. One way of improving this is through chemical exchange saturation transfer (CEST) experiments where the presence of lowly concentrated species is effectively read out through its interactions with a highly concentrated species. In Chapter 3 we show how this experiment can be used to follow changes in a range of solution properties. The diffusion and CEST experiments are combined in Chapter 4, where we introduce the novel diffusion-weighted CEST experiment. Here, the diffusion weighting is used to differentiate between compartments, while the CEST component of the experiment characterises properties of each of the compartments.

In Chapters 5 and 6, modern NMR techniques are used to characterise dynamical features of ¹⁵N-labelled proteins. Experiments employed in this section include a fast dynamics analysis as well as CPMG and R_1ρ relaxation dispersion experiments. Collectively, these experiments provide important insights into the behaviour of the proteins with atomic-level resolution.

Authors: Karunanithy, G

• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: Nuclear Magnetic Resonance (NMR)
• Subjects: Biophysics; Chemistry