Thesis (Ph. D.)--University of Canterbury, 2006. / Typescript (photocopy). "20-July-2006." Includes bibliographical references. Also available via the World Wide Web.

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 159-176).

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (leaves 167-181).

Thesis (Ph.D.) Mississippi State University. Department of Chemistry. / Title from title screen. Includes bibliographical references.

The work described in this thesis focused on the use of nuclear magnetic resonance spectroscopy (NMR) to study two classes of metallo enzymes - the Fe(II)- and 2oxoglutarate (2OG)-dependent dioxygenases and the metallo β-lactamases (MBLs). These enzymes are involved in clinically important biological processes, i.e. the hypoxic response and antimicrobial resistance, respectively. Both protein systems are interesting from an NMR perspective because they have dynamic regions involved in catalysis and ligand interactions. The work included mechanistic studies, protein-ligand interaction studies, and method development for inhibitor discovery. NMR was applied to study the human prolyl hydroxylase domain-containing protein 2 (PHD2), which is crucially involved in the chronic hypoxic response. The results reveal that binding of the C- and the N-terminus of the oxygen dependent degradation domains CODD and NODD, respectively, induce different interactions with PHD2. The substitution of a single amino acid, as occurs with PHD2 variants linked to erythrocytosis and breast cancer, can alter the selectivity of PHD2 towards its ODD substrates. Studies with the Trichoplax adhaerens PHD provide insights into the evolutionary substrate preference of the PHDs. Using ¹³C-labelled peptidyl-substrates; NMR was applied to investigate proposed 'alternative' PHD2 substrates/interaction partners. The product release mechanism of PHD2 was investigated using NMR; the results reveal that the presence of 2OG strongly discriminates between the binding of CODD and hydroxylated CODD to PHD2. NMR was also applied to monitor PHD2 kinetics and inhibition. Competition and displacement assays were designed and applied to investigate PHD inhibitor binding modes. Comparative studies on the activities and selectivities of PHD inhibitors in clinical trials should aid in the work on the therapeutic manipulation of the natural hypoxic response. Protein-observe ¹9F-NMR was used to study the São Paolo MBL (SPM-1). The results provide new structural insights into SPM-1 catalysis and the requirements for inhibitor development. They also reveal that the hydrolysed β-amino acid products of MBL catalysis can bind to SPM-1. They illustrate the utility of ¹⁹F-NMR for detecting metal chelation, which is not always readily tractable in studies on metallo enzyme inhibition, new binding modes, and stereoisomer binding/epimerisation in solution. The interaction of a cyclobutanone analogue, a broad-spectrum MBL inhibitor, with SPM-1 was investigated. A combination of ¹H, ¹⁹F, ¹³C-NMR and crystallographic analyses reveal that cyclobutanone binding may mimic formation of the oxyanion tetrahedral intermediate in β-lactam hydrolysis. The susceptibility of avibactam, the first clinically useful non-β-lactam β-lactamase inhibitor, to MBL-catalysed hydrolysis was studied. The results reveal that avibactam is not an MBL inhibitor and a poor substrate of most members of all three clinically relevant subclasses of MBLs. In some cases, avibactam undergoes slow hydrolysis in a process different from that observed with serine β-lactamases. Overall, the results illustrate the utility of NMR for studying dynamic aspects of enzyme catalysis and inhibitor binding.

Changes in the metabolic state of the brain can occur, for example, as a result of neuronal activity or in pathologies such as cancer. In these cases, an altered energy demand can lead to changes in neurochemical concentrations detectable using proton magnetic resonance spectroscopy (¹H-MRS). This thesis explores in vivo ¹H-MRS methods for detection of such changes in the healthy and diseased brain. Specifically, this thesis aims to develop methods with semi-LASER localisation, thereby minimising the negative effects of chemical shift displacement and field inhomogeneity on spectral acquisition. Firstly, a Hadamard-encoded semi-LASER method for simultaneous measurement from two regions was developed at 7 T. Slice profiles, with low chemical shift displacement and small amounts of signal overlap, were revealed in phantom and in vivo. This was then implemented in a study of neurochemical change during positive and negative blood oxygen level-dependent (BOLD) responses. Negative BOLD responses are thought to reflect regions of neuronal suppression. A small decrease in ascorbate, as well as the T2*-induced linebroadening of several spectra, were observed in these regions. Furthermore, increases in glutamate and lactate were detected in positive BOLD regions. These findings suggested that negative BOLD may not be generated by an increase in local GABA concentration. Secondly, an optimised semi-LASER sequence (TE = 110 ms) at 3 T was shown to improve localisation of the oncometabolite 2-hydroxyglutarate (2-HG) - a product of IDH-mutation found in the majority of gliomas. This resulted in improved detection of 2-HG in patients compared to an existing technique. The method was also compared to 7 T, where benefits of an increased spectral resolution resulted in significantly better detection of 2-HG along with associated metabolites. This thesis highlights the importance of robust localisation for performing sensitive in vivo ¹H-MRS neurochemical measurement in the human brain.

Semiconductive metal oxides are of great importance in environmental remediation and electronics because of their ability to generate charge carriers when excited with appropriate energy. The electronic structure, light absorption and charge transport properties have made the transition metal oxides an attractive material as photocatalyst. Recently, facet-engineering by morphology control has been intensively studied as an efficient approach to further enhance their photocatalytic performance. However, various processing steps and post-treatments used in the preparation of facet-engineered particles may generate different surface active sites which may affect their photocatalysis. Moreover, many traditional techniques (PL, EPR and XPS) used for materials characterization (oxygen vacancy, hydroxyl group, cation, etc.) are not truly surface specific but analyzing a range from surface few layers to bulk. Accordingly, they can only provide very limited information on chemical states of the surface active features and their distribution among facets, causing difficulties to unambiguously correlate facet-dependent results with activity. As a result, this often leads to different interpretations amongst researchers during the past decades. As the publications of titanium and zinc ranked top two among studies of first row of transition oxides in the past decades, this thesis will firstly review on the disagreements generated among researchers when they correlated the performance of ZnO and TiO₂ with their facet activities based on traditional techniques. As there are shortcomings of these techniques in producing truly facet-dependent features, some results can be misleading and with no cross-literature comparison. To address these issues, we have developed a new technique "probe-molecule-assisted NMR" which allows a genuine differentiation of surface active sites from various facets. This surface-fingerprint technique has been demonstrated to provide both qualitative (chemical shift) and quantitative (peak intensity) information on the concentration and distribution of truly surface features among facets. In light of the new technique, this thesis will revisit the facet-dependent photocatalytic properties and shed light on these issues.

Orientador: Isabele Rodrigues Nascimento / Coorientador: Lourdes Campaner dos Santos / Banca: Maysa Furlan / Banca: Jairo Kenupp Bastos / Resumo: O gênero Aristolochia (Aristolochiaceae) apresenta 92 espécies distribuídas em todo território brasileiro. Essas espécies são conhecidas na medicina popular por serem abortivas, antiofídicas, estomáquicas, anti-inflamatórias, antiasmáticas, antissépticas, expectorantes, sedativas, depurativas e por ajudarem no emagrecimento. O objetivo deste trabalho foi contribuir para o conhecimento da composição química da espécie Aristolochia warmingii Mast. As folhas de A. warmingii foram secas, moídas e submetidas a sucessivas extrações, à temperatura ambiente, com hexanos, acetona e etanol. O extrato acetônico foi submetido a diferentes processos cromatográficos (CC, CCD e CLAE), que resultaram no isolamento de 30 substâncias: quatorze lignanas tetraidrofurofurânicas, nove lignanas tetraidrofurânicas, uma lignana dibenzilbutirolactônica, quatro neolignanas diidrobenzofurânicas, uma dilignana tetraidrofurânica e um derivado butirolactônico. Quatorze dessas substâncias estão sendo descritas pela primeira vez na literatura. A elucidação estrutural foi baseada em métodos espectroscópicos e espectrométricos (RMN de 1H e 13C, EM, UV, DCE e IV). / Abstract: The Aristolochia genus (Aristolochiaceae) presents 92 species distributed in Brazilian lands. These species are known in folk medicine for being abortifacients, antiophidics, stomachics, anti-inflammatories, antiasthmatics, antiseptics, expectorants, sedatives, and in slimming therapies. The objective of this work was to contribute to the knowledge of the chemical composition of Aristolochia warmingii Mast. The A. warmingii leaves were dried, ground and extracted successively at room temperature with hexanes, acetone and ethanol. The acetone extract was subjected to different chromatographic procedures (CC, TLC and HPLC), and resulted in the isolation of 30 compounds: fourteen tetrahydrofurofuran, nine tetrahydrofuran and one dibenzylbutyrolactone lignans, four dihydrobenzofuran neolignans, one tetrahydrofuran dilignan, and one butyrolactone derivative. Fourteen of these compounds are being described for the first time in the literature. The chemical structures were determined by spectroscopic and spectrometric methods (1H and 13C NMR, MS, UV, ECD, and IR). / Mestre

Superheated water has been used successfully as an eluent in liquid chromatography and has been coupled to various modes of detection, ultraviolet (UV), fluorescence, and nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS). A number of compounds were examined on poly(styrene-divinylbenzene) (PS-OVB), polybutadiene (PBO), and octadecylsilyl bonded silica (OOS) column with isothermal and temperature programmes.

abstract: Atmospheric particulate matter has a substantial impact on global climate due to its ability to absorb/scatter solar radiation and act as cloud condensation nuclei (CCN). Yet, little is known about marine aerosol, in particular, the carbonaceous fraction. In the present work, particulate matter was collected, using High Volume (HiVol) samplers, onto quartz fiber substrates during a series of research cruises on the Atlantic Ocean. Samples were collected on board the R/V Endeavor on West&ndash;East (March&ndash;April, 2006) and East&ndash;West (June&ndash;July, 2006) transects in the North Atlantic, as well as on the R/V Polarstern during a North&ndash;South (October&ndash;November, 2005) transect along the western coast of Europe and Africa. The aerosol total carbon (TC) concentrations for the West&ndash;East (Narragansett, RI, USA to Nice, France) and East&ndash;West (Heraklion, Crete, Greece to Narragansett, RI, USA) transects were generally low over the open ocean (0.36&plusmn;0.14 &mu;g C/m3) and increased as the ship approached coastal areas (2.18&plusmn;1.37 &mu;g C/m3), due to increased terrestrial/anthropogenic aerosol inputs. The TC for the North&ndash;South transect samples decreased in the southern hemisphere with the exception of samples collected near the 15th parallel where calculations indicate the air mass back trajectories originated from the continent. Seasonal variation in organic carbon (OC) was seen in the northern hemisphere open ocean samples with average values of 0.45 &mu;g/m3 and 0.26 &mu;g/m3 for spring and summer, respectively. These low summer time values are consistent with SeaWiFS satellite images that show decreasing chlorophyll a concentration (a proxy for phytoplankton biomass) in the summer. There is also a statistically significant (p<0.05) decline in surface water fluorescence in the summer. Moreover, examination of water&ndash;soluble organic carbon (WSOC) shows that the summer aerosol samples appear to have a higher fraction of the lower molecular weight material, indicating that the samples may be more oxidized (aged). The seasonal variation in aerosol content seen during the two 2006 cruises is evidence that a primary biological marine source is a significant contributor to the carbonaceous particulate in the marine atmosphere and is consistent with previous studies of clean marine air masses. / Dissertation/Thesis / M.S. Chemistry 2011