UC San Diego

Nuclear magnetic resonance (NMR) spectroscopy is a powerful analytical technique and can be used to analyze anything from small molecules to large polymers and proteins. This non-destructive tool is useful in many fields of research from basic science to applied work. In this thesis, NMR is applied in a multitude of ways including analyzing small molecule structure, backbone fingerprinting of polymeric material, and protein ligand interactions and dynamics.In the first two chapters of this thesis, amorphous melanin polymers are analyzed by solid-state NMR cross polarization 13C experiments. Through this technique we identify types and distributions of carbon within a sample and correlate proposed starting material with fingerprints of complex, chemoenzymatically generated melanins. We also use solid-state NMR to estimate purity of extracted melanin samples from marine melanin species by identification of components of marine tissue material. The third chapter of this thesis investigates how a predicted toxic metabolite, methylene diphenyl diamine, is biodegraded over time by microbial organisms and communities by analyzing the nitrogen state changes. Using an 15N labeled small molecule and 15N INEPT experiments, nitrogen environment changes are observed for monitoring a how this molecule is metabolized after feeding studies to microbial communities and thus identifying new insights into the biodegradation process. In this work NMR and LCMS are combined toward a possible explanation of how methylene diphenyl diamine is altered after potential release from bio-based polyurethane biodegradation. In the final chapter of this thesis, NMR is used to monitoring carrier protein-ligand dynamics by employing a site specific 15N labeled probe. Synthetic organic chemistry is utilized to develop a versatile 15N tool which can be applied to various carrier protein dependent systems through a simple modification. NMR’s capability to monitor dynamic changes of a system over time is used to trace the chemical shift change of a minor state of a ligand in a carrier protein dependent system, allowing for more concrete insight into sequestration and chain flipping dynamics. 15N CEST experiments are used to extract data about ligand dynamics which mimic the native substrates of fatty acid biosynthesis, a model carrier protein dependent system.