The thesis research described herein employs electronic structure theory to develop a better understanding of reaction mechanisms of interest to materials scientists, biochemists and toxicologists. In Chapter 2, the tools of electronic structure theory have been used to provide a better understanding of the mechanism for zinc oxide chemical vapor deposition via a radical mechanism. The data provide new information on the reactivity of diethylzinc and the possible side products formed during radical-initiated polymerization of zinc oxide. This information will be helpful to scientists seeking to optimize CVD reaction conditions in order to produce high quality zinc oxide films. Chapter 3 describes a computationally efficient method for calculating the site-specific p K a of DNA and RNA nucleobases and predicts a significant difference in the relative acidity of specific protons within the Gh and Sp oxidation products. These data should prove useful to biochemists seeking to explain the differences in observed mutagenicity of these two adducts.
Chapters 4 and 5 describe the results of studies mapping the energetics of the formation of three mutagenic species: 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FAPyG), spiroiminodihydantoin (Sp) and guanidinohydantoin (Gh) from the DNA nucleobase, guanine. Chapter 6 provides an overview of a study evaluating the potential energy surface for the formation of spiroiminodihydantoin from guanidinohydantoin under conditions typically used for the storage of experimental samples. Work evaluating possible mechanisms of formation of guanine:lysine adducts as a model for DNA:protein crosslinks is described in Chapter 7. For experimentalists seeking to understand the underlying processes by which DNA is damaged, this new information offers a molecule-scale glimpse of potentially key, albeit transient, intermediates formed along each pathway. This new insight may lead to exploration of techniques designed to isolate and identify these compounds and confirm the proposed reaction mechanism, or, alternatively, to pursue alternative ways of reducing DNA damage by preventing the formation of these intermediates.
