Insight into Biological Small-Molecule Activation from Enzymes, Model Complexes, and X-ray Spectroscopy

Thesis (Ph.D.)--University of Washington, 2016-08

This dissertation covers the investigation of biological strategies for activating inert small molecules. Chapters 1 and 2 respectively present an introduction to some notable biological systems of interest and the X-ray spectroscopic techniques used in their study. Chapter 3 focuses on the application of X-ray spectroscopy and density functional theory to investigate the underlying mechanisms of O-O bond activation by a manganese complex. Chapter 4 presents the discovery of a key structural feature of the vanadium-containing active site of V-dependent nitrogenases, and Chapter 5 provides a detailed comparison of the electronic structures of the Mo- and V-containing nitrogenase cofactors based on spectroscopic characterization of both enzymes and synthetic metallocubane models. Chapter 6 covers a fundamental study of the X-ray absorption and emission spectroscopic features of vanadium ions, providing a basis for the spectroscopic investigation of vanadium-containing enzymes, including nitrogenase. This work contains novel research into the structure-function relationship in both biological and synthetic systems that promote the activation of inert, abundant small molecules. The insight obtained from these studies may help to advance scientific understanding of the complex functions of transition metal ions in biological catalysis.