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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
191

Size and Morphology Variation in Multiferroic MOFs: A Magnetic, Dielectric and Spectroscopic Study

Unknown Date (has links)
This dissertation is organized in two parts. The first part summarizes work in a newly developed synthetic route to perovskite-like MOFs, offering control over particle size and morphology. The second part of the dissertation cover spectroscopic work done to elucidate the nature of the ferroelectric transition in this family of metal-organic frameworks. / A Dissertation submitted to the Department of Chemistry and Biochemistry in partial fulfillment of the Doctor of Philosophy. / Fall Semester 2015. / November 9, 2015. / Condensed Matter Physics, Materials Science, Physical Chemistry / Includes bibliographical references. / Naresh Dalal, Professor Directing Dissertation; Irinel Chiorescu, University Representative; Geoffrey Strouse, Committee Member; Lei Zhu, Committee Member; Ken Knappenberger, Committee Member.
192

Isolation of Marine Siderophores by Immobilized Metal Affinity Chromatography

Unknown Date (has links)
This dissertation details the isolation of marine siderophores by Immobilized Metal Affinity Chromatography (IMAC). Siderophores are biologically produced, low molecular weight (400 Da-1000Da), strong iron-binding ligands. These compounds are thought to form strong complexes with [greater than]95% of the dissolved Fe(III) in the oceans and therefore play extremely important roles in the biological uptake and biogeochemical cycling of Fe in the oceans. The challenges with isolating these ligands from seawater is they are present in very low concentrations (nM) in a matrix with a very high ionic strength (~0.7M). The most important considerations for isolating siderophores are selectivity, concentrating, and desalting. In this work, we studied the use of Immobilized Metal Affinity Chromatography (IMAC) followed by Solid-Phase Extraction (SPE) to isolate and concentrate marine siderophores from natural seawater samples. The theory behind the IMAC extraction technique is that organic compounds that form complexes with particular metal cations can be isolated and/or separated via their attraction to a cation chelating resin that has been pre-loaded with the metal cation of interest. To recover the organic compounds from the IMAC resin, elution conditions are chosen based on the analyte of interest and involves either ligand competition or stripping the column of the metal at low pH. In the case of Fe-IMAC, the best method to use was a competing ligand, in this case ethylenediaminetetraacetic acid (EDTA), since acid elution would generate an eluate with a very high ([greater than]50mM) total dissolved Fe(III) concentration that would interfere with subsequent processing and analysis. By using a high EDTA concentration (50mM) the column could be eluted effectively. The Fe-binding ligands in the EDTA eluate were further concentrated via extraction on a silica C-18 resin column (SPE) which will concentrate free ligands and ligand metal complexes that are sufficiently hydrophobic. This "purifies" the IMAC eluate by extracting the analytes of interest from the EDTA eluent. After rinsing with water, the organic compounds were eluted from the SPE column with HPLC-grade methanol, thereby converting the sample matrix to methanol which is easy to dry down for further concentration and is easy to analyze using electrospray ionization mass spectrometry (ESI-MS). Method development and method validation measurements were performed using (+)Electrospray Ionization(ESI) Time of Flight Mass Spectrometry (MS) and (+)ESI-Quattro MS. Open ocean samples were analyzed using (+)ESI Fourier Transform Ion Cyclotron MS. In addition to the internal standard (desferrioxamine B), we found evidence for the presence of three known siderophores (ferrioxamine A1/A2, agrobactin, and ferrioxamine X1) in a seawater sample from the central North Atlantic Ocean. / A Dissertation submitted to the Department of Chemistry and Biochemistry in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Fall Semester 2015. / July 30, 2015. / IMAC, Immobilized Metal Affinity Chromatography, marine dissolved organic matter, Siderophores, solid phase extraction, SPE / Includes bibliographical references. / William M. Landing, Professor Co-Directing Dissertation; William T. Cooper, Professor Co-Directing Dissertation; Vincent Salters, University Representative; Alan G. Marshall, Committee Member; Albert Stiegman, Committee Member.
193

Tandem Processes Involving an Alkynogenic Fragmentation and Applications in Sesquiterpene Syntheses

Unknown Date (has links)
This dissertation focuses on the development of novel chemical reactions for enhancing the efficiency of synthesis. In particular, we disclose the development of a tandem fragmentation-olefination reaction for the synthesis of 1,6-enynes and its applications to the syntheses of several natural products. The first chapter reviews fragmentation methodologies for the preparation of alkynes, with insights and discussion in historical aspects, mechanisms, stereoelectronics, and tactics. The second chapter starts with a brief background on values of 1,6-enynes leading to various cyclic and polycyclic structures, currently available methods for the preparation of 1,6-enynes, and challenges these methods are facing, especially in preparing neopentyl tethered 1,6-enynes. Then we describe our development of the tandem fragmentation-olefination reaction, which took advantage of tandem process to overcome intermediate instability, providing the final products more efficiently. In chapter 3, this method was applied in the syntheses of several natural products, either to showcase the efficiency of the methodology or to supply material with potential bioactivities. In case of alcyopterosin A, the synthesis was shortened by half when compared with previous approaches. We also have established a divergent approach to both illudalic acid and illudinine. The approach relies on two key transformations: a tandem fragmentation-Knoevenagel condensation and an inversed electron demand intramolecular dehydrogenative Diels-Alder reaction. / A Dissertation submitted to the Department of Chemistry and Biochemistry in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Fall Semester 2015. / November 11, 2015. / fragmentation reaction, natural products, sesquiterpene, tandem/cascade/domino reaction, total synthesis / Includes bibliographical references. / Gregory B. Dudley, Professor Directing Dissertation; Don Levitan, University Representative; Igor Alabugin, Committee Member; Brian Miller, Committee Member.
194

Assessment of the Utility of Chemical Pretreatments for Estimating Carbon and Phosphorus Sequestration in Soils by 13C and 31P NMR Spectrscopy

Unknown Date (has links)
Sandy soils are a major forest resource in the southeastern U.S and intensive forest management is escalating; yet the effect of forest management on soil organic carbon (SOC) is not well documented. It is unclear to what degree root and aboveground litter inputs add to SOC; and if the relative importance of an input source changes with forest management. All these questions add to the ongoing discussion on the role of the soil in SOC storage and sequestration, as well as the impact of forest management. Investigating the questions described above will allow us to better understand SOC sequestration and protection. In the first part of this work we have characterized labile and recalcitrant SOC pools from upland and wetland forests by acid hydrolysis (6 M HCl, 1 M HCl) and hot-water extraction. 13C nuclear magnetic resonance (NMR) spectroscopy was used to quantify the effect of acid hydrolysis and hot-water extraction on recalcitrant and labile carbon pools. Burial of phosphorus associated with organic matter has been reported as a major mechanistic sink for phosphorus in wetlands. Wetland soils tend to accumulate organic matter due to the production of detrital (plant) material from wetland biota and the suppressed rates of decomposition. Soil accretion rates for constructed wetlands are on the order of millimeters per year, although accretion rates in productive natural systems such as the Everglades have been reported as high as one centimeter per year or more. Current design of constructed wetlands for phosphorus removal is based upon this soil accretion. The rate of phosphorus accretion through this process is used to calculate the area needed to meet designed effluent criteria. However, although much of the phosphorus added to wetlands is retained within the system, this can serve as a phosphorus source to the water column for long periods of time, even after external loads are reduced. Wetlands are often used as `buffer zones' between agricultural areas and adjacent water bodies. The long-term effectiveness of these wetlands to retain and store phosphorus in stable forms depends upon interacting biogeochemical processes in water, detrital layers, and soil. Recognizing that detrital tissue and soil organic matter are the dominant components of wetlands, the breakdown of these materials and the release of nutrients have direct bearing on water quality and productivity of the ecosystem. Relationships developed between processes and physical and chemical properties of detrital plant tissue and soil organic matter can be incorporated into predictive models for extrapolation of results to other sites. The second phase of the research summarized in this dissertation addresses this important issue, and has several unique themes. First, the organic phosphorus forms in a range of wetland ecosystems and their relationships with soil physical and chemical properties have never been studied. We have addressed these issues here by employing state-of-the-art NMR techniques to provide insight into the forms of inorganic and organic phosphorus and organic carbon in recently accreted and native Everglades soils. Second, rarely have linkages been developed between organic carbon and organic phosphorus forms as they relate to their stability under a range of environmental perturbations, but this is of key importance for understanding the biogeochemistry of organic phosphorus in the environment. This research therefore provided information on the composition and stability of soil organic phosphorus and carbon in wetlands, again using primarily NMR techniques. Liquid chromatography and high resolution time-of-flight mass spectrometry were also used to validate the NMR studies. / A Dissertation submitted to the Department of Chemistry and Biochemistry in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Degree Awarded: Summer Semester, 2007. / Date of Defense: July 2, 2007. / Acid Hydrolysis, 31P NMR, 13C NMR, Sequestration / Includes bibliographical references. / William T. Cooper, Professor Directing Dissertation; William M. Landing, Outside Committee Member; John G. Dorsey, Committee Member; Joseph B. Schlenoff, Committee Member; Sanford A. Safron, Committee Member.
195

The Intrinsic Dynamics of Arginine Kinase

Unknown Date (has links)
Arginine kinase reversibly catalyzes phosphoryl transfer between ATP and arginine, thus providing a mechanism for buffering ATP levels in cells with high or variable energy requirements. X-ray crystal structures of a substrate-free and transition state analog form of arginine kinase suggest large conformational changes upon substrate binding. Steady state enzyme kinetics show that arginine kinase follows a random, bimolecular bimolecular kinetic mechanism with a turnover rate of ~135 sec¬¬-1. While the crystal structures have provided a wealth of information about the conformational changes of arginine kinase, they provide little to no data on dynamics. Crystal structures provide static snapshots at endpoints of rather complex equilibria. The link between enzyme dynamics and function is increasingly apparent but still remains relatively unexplored. Recently developed NMR techniques which probe dynamics on the micro- to millisecond timescale have provided insight into connection between dynamics and catalysis in a number of systems. The work presented in this dissertation is an NMR-based investigation into the dynamics or arginine kinase. Expression and purification of arginine kinase enriched with 15N, 13C, and 2H, a requirement for the NMR experiments, was achieved. Another prerequisite, resonance assignment, was accomplished using a standard suite of triple resonance NMR experiments and urea-induced unfolding and refolding to allow for back-exchange of amide deuterons in the core with solvent protons. Backbone amide resonances were assigned for 329 of 344 assignable residues. At the time, arginine kinase was one of the five largest monomeric units to be assigned. Using 15N transverse relaxation dispersion experiments, the dynamics of substrate-free arginine kinase were probed. These experiments implicate a number of residues, which cluster in four regions of the enzyme, in slow micro- to millisecond timescale dynamics. Most interesting is the loop spanning residues I182-G209, which the crystal structures show undergoes a large conformational change to interact with substrate nucleotide. The rate of exchange for this loop was found to be approximately 800 sec-1, on the same order as turnover, indicating that the motion associated with this loop may be a rate-limiting step upon catalysis. Furthermore, the changes associated with binding of substrates have been probed by substrate titrations in conjunction with 2D [15N, 1H]-TROSY spectroscopy. These experiments, which segregate the conformational changes seen in the crystal structures into those induced by binding of individual substrates, show that phosphagen and nucleotide binding elicits relatively independent changes in the N-terminal and C-terminal domains, respectively. The loop spanning residues I182-C201, however, appears to be affected by both substrates. Interestingly, this is the same loop relaxation dispersion experiments implicate in slow dynamics. As a bimolecular enzyme representative of a large enzyme class, the transferases, the amenability of arginine kinase to both x-ray crystallography and NMR make it a unique model system for understanding the connections between dynamics and function. The work described here outlines the potentially rate limiting intrinsic dynamics of arginine kinase and changes induced by substrate binding. These results highlight the importance of dynamics and reflect the growing view that enzymes have evolved both structure and dynamics simultaneously. / A Dissertation submitted to the Department of Chemistry and Biochemistry in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Degree Awarded: Spring Semester, 2008. / Date of Defense: December 13, 2007. / Enzyme Dynamics, Relaxation Dispersion, Conformational Change, Arginine Kinase / Includes bibliographical references. / Michael S. Chapman, Professor Co-Directing Dissertation; Timothy M. Logan, Professor Co-Directing Dissertation; W. Ross Ellington, Outside Committee Member; John G. Dorsey, Committee Member.
196

Molecular Characterization of Marine and Terrestrial Dissolved Organic Matter Using Ultrahigh Resolution Mass Spectrometry

Unknown Date (has links)
Various analytical techniques have been employed to probe the chemical identity and characteristics of complex Dissolved Organic Matter (DOM) mixtures. With continuing advances in readily available highly developed mass spectrometers, the amount of information generated for analysis is steadily rising. Currently, Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS) at high magnetic field (> 9 Tesla), is the only advanced analytical technique capable of ultrahigh resolution and mass accuracy that can distinguish upwards of 10,000 spectral peaks. This technique facilitates the identification of thousands of unambiguous molecular formulae for complex DOM. The most commonly used ionization method, Electrospray Ionization (ESI), has proven to be an excellent source for DOM ionization prior to MS analysis. ESI coupled to FT-ICR-MS provides an ideal combination necessary for investigating and characterizing DOM from unique natural environments. 9 Tesla), is the only advanced analytical technique capable of ultrahigh resolution and mass accuracy that can distinguish upwards of 10,000 spectral peaks. This technique facilitates the identification of thousands of unambiguous molecular formulae for complex DOM. The most commonly used ionization method, Electrospray Ionization (ESI), has proven to be an excellent source for DOM ionization prior to MS analysis. ESI coupled to FT-ICR-MS provides an ideal combination necessary for investigating and characterizing DOM from unique natural environments. DOM represents the largest reservoir of organic carbon stored in the oceans. Its source has been proposed to originate from marine primary and bacterial production, with limited land-derived contributors. Marine DOM is a complex mixture of biomolecules that either exist naturally or have been transformed from living and decaying organisms in the ocean. Previous research has identified only a small portion of deep sea DOM, due to the complexity of the mixture and lack of advanced techniques available; however, ultrahigh resolution mass spectrometry has succeeded for DOM characterization where other techniques have failed. In Chapter 3, we compare ultrahigh resolution mass spectra of marine DOM isolated from two sites in the Weddell Sea (Antarctica) using ESI and Atmospheric Pressure Photoionization (APPI). These spectra, obtained on a 9.4 Tesla FT-ICR-MS, indicate the two ionization techniques are complementary. Ions produced by APPI extend to higher carbon undersaturation compared to ESI, indicated by higher double-bond equivalence minus oxygen (DBE-O) values, while ions in the ESI spectra are more oxygenated. Moreover, many sulfur-containing compounds were efficiently ionized by ESI but not detected by APPI. These results show that the differences in mass spectra obtained by ESI and APPI FT-ICR-MS are significant and that both are necessary to obtain a complete description of the molecular composition of marine DOM. Peatlands are extraordinary carbon reservoirs due to their sequestration and emission of greenhouse gases. Chapter 4 depicts the importance of investigating the molecular characterization of terrestrial DOM from the Glacial Lake Agassiz Peatlands (GLAP) of northern Minnesota, to reveal the potentially pivotal role it plays in global carbon cycling. ESI-FT-ICR-MS was used to identify the qualitative differences between DOM in fen and bog porewaters of the Red Lake II system in the GLAP. Approximately 80% of molecular composition observed in surface porewater was maintained throughout the bog profile (0.17 to 2.50m). The qualitative stability of the molecular composition of DOM was accompanied by a quantitative increase in Dissolved Organic Carbon (DOC) with depth. The composition of DOM in the fen was significantly different at depth with slightly varying DOC levels. Using Aromaticity Index (AI) values we identified condensed aromatic phenol-type compounds in the porewaters of both peatlands. Surface bog and deep fen DOM had surprising similar molecular compositions. We suggest that enzymatic degradation via phenol oxidase and slower hydrologic transport down the bog vertical profile are responsible for the observed variations in DOM composition. In Chapter 5, molecular composition and optical properties were correlated for two samples of DOM from different peat formations in the GLAP. Fen and bog DOM were analyzed using 9.4 T FT-ICR-MS to determine the aromatic content as a function of depth. UV/Vis absorbance and Excitation Emission Matrix Fluorescence Spectroscopy (EEMS) were used to identify changes in the optical properties associated with the chromophoric fractions of DOM (CDOM). Higher specific UV absorbance (SUVA) at 254 nm indicated more abundant aromatic content for surface bog and deep fen DOM. EEMS results were also found to be in agreement with the absorption spectra and molecular characterization as determined by FT-ICR-MS. The strong correlations we have observed suggest that optical spectroscopy techniques represent an effective surrogate approach to characterizing DOM provided some detailed molecular information is available for calibrating the observed correlations. Finally, comparative analysis of sample preparatory methods for ESI-FT-ICR-MS is presented for terrestrial DOM in Chapter 6. Freeze drying and solid phase extraction using a modified styrene divinyl benzene polymer sorbent (Varian PPL) were considered. Molecular composition was determined using a 9.4Tesla ESI-FT-ICR-MS for Red Lake II fen and bog DOM of the GLAP. 78% of the DOM composition was found to be common to both freeze dried and SPE Bog 0.17m. The unique SPE Bog 0.17m molecular formulas were characterized by higher aromaticity index values and higher DBE-O values which correspond to more aromatic and condensed structures. Similar results were observed for Fen 2.50m DOM. Mass spectral comparisons of SPE DOM and salt water treated SPE DOM produced 93% and 94% common molecular formulas for Fen 2.50m and Bog 0.17m respectively. No outstanding signature originating from the SPE cartridge or by saltwater contributions was identified. The results emphasize the ability of SPE to elute a more representative and effectively prepared DOM sample for high resolution ESI-FT-ICR-MS. / A Dissertation submitted to the Department of Chemistry and Biochemistry in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Degree Awarded: Summer Semester 2009. / Date of Defense: July 2, 2009. / Fourier Transform Ion Cyclotron Resonance Mass Spe, Peatlands, Dissolved Organic Matter / Includes bibliographical references. / William T. Cooper III, Professor Directing Dissertation; Jeffrey P. Chanton, Outside Committee Member; Robert L. Fulton, Committee Member; Naresh Dalal, Committee Member.
197

Modulating Electron Trasnfer Dynamics at Dye-Semiconductor Interfaces / Modulating Electron Transfer Dynamics at Dye-Semiconductor Interfaces

Unknown Date (has links)
Electron transfer dynamics at the nanocrystalline semiconducting metal oxide interface plays a pivotal role in diverse applications such as dye-sensitized solar cells (DSSCs), dye-sensitized photoelectric solar cells (DSPECs), sensors and electrochromic thin films. Controlling intermolecular electron transfer at the interface is a critical task, capable of profoundly influencing the efficiency of these applications. Structural control via various physical and chemical design were demonstrated to effectively influence the electron transfer rates at these interfaces. Of these approaches, in situ molecular assembly has emerged as an appealing strategy due to the simple preparation to form complex rigid structure that traditionally requires design of one large molecule elaborated with multiple components. In molecular assembly, molecules are adhered to a nanocrystalline metal oxide surface utilizing similar binding motifs and molecular structure-property relationships at the interface to achieve disparate electron transfer dynamics outcomes. In this dissertation, we demonstrated the use of self-assembled bilayer as a scaffold to influence the interfacial electron transfer rates to further our goal of enhancing the productive kinetics while inhibiting the unproductive pathways. By utilizing self-assembled bilayers, we achieved electron transfer modulation while preserving the individual molecule’s electronic structure and property. Chapter 1 is an introductory chapter that lays the foundation of operation principles of DSSCs, electron transfer events at the photoanode, and the physical parameters that govern these processes. Notably, the importance of molecular structural control and a brief history of past approaches are introduced at the end of Chapter 1 as an inspiration for self-assembled bilayers. The remaining chapters take deeper dives into different strategies of varying individual components’ electrochemical properties in order to influence the overall physical properties of the film. We modified the chemical structure of the bridging molecules to influence the electron tunneling rate. For example, Chapters 2 and 3 explore the effect on the electron transfer rate of tuning the distance and energy parameters of bridge molecules by employing self-assembled bilayers. Various properties of the bilayer structure are examined in Chapter 4 and 5, which describe the fundamental studies we have done to investigate role of metal liking ions in the self-assembled bilayers. Together the results in these chapters present an architectural alternative for supramolecular assembly designed to influence electron transfer dynamics in a fully functioning DSSC, and it serves as a foundation for future development of DSSC design. / A Dissertation submitted to the Department of Chemistry and Biochemistry in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Spring Semester 2018. / April 2, 2018. / Includes bibliographical references. / Kenneth Hanson, Professor Directing Dissertation; Zhiyong Liang, University Representative; Michael Roper, Committee Member; Joseph B. Schlenoff, Committee Member.
198

Understanding Pt•••Pt and Pt•••Au metallophilic interactions in single salt and double salt complexes using photophysical tools

Buntrock, Valerie 22 March 2016 (has links)
Seven [Pt(tpy)X]Y (X=Cl, Y=Cl•2H2O, X=Cl, Y=Cl•DMSO, X=Cl, Y=PF6, X=Cl, Y=SbF6, X=Cl, Y=SbF6•CH3CN, X=Br, Y= Br•2H2O, and X=Br, Y=PF6) complexes were prepared and characterized. Structural analysis shows consistent patterns in Pt^...Pt interactions that vary slightly depending on the coordinating halogen, X, counteranion, Y, and lattice solvent. Diffuse reflectance was used to identify solid-state ^1MMLCT absorption bands, and the relationship between Pt-Pt distance and ^1MMLCT absorption energy will be discussed. Metallophilic Pt^...Au interactions in [Pt(tpy)X][AuX'2] (X=X'=CN, X=Cl, X'=C6F5, X=Br, X'=C6F5, X=I, X'=C6F5) double salts were investigated. Structural characterization showed Pt^...Au metallophilic interactions were only observed in X=X'=CN, while Pt^...Pt interactions were observed in X=I, X'=C6F5. The closest contacts in X=Cl, X'=C6F5 and X=Br, X'=C6F5 were between the Lewis acidic Pt center of the cation and a Lewis basic ortho carbon of the pentafluorophenyl group on the anion. Photophysical characterization showed MMLCT features in the solid-state but only monomeric MLCT features localized on the [Pt]+ and [Au]- units in solution. The chromophore [Pt(tpy)(CCPh)]^+ was studied in [Pt][Au(C6F5)2] and [Pt][Pt(C^N)(CN)2] (C^N = ppy, F2ppy, or bzq) double salts. Structural characterization showed formation of a channel of [Pt(tpy)(CCPh)]+ moieties supported by metallophilic interactions in [Pt][Au(C6F5)2] and [Pt][Pt(F2ppy)(CN)2]. Solution electronic absorption spectra showed MLCT features centered on the cation and anion units for all four complexes. An additional ^1MMLCT band near 520 nm is present in the solid-state arising from Pt^...Pt interactions formed between cation units. Three [Pt(tpy)Cl][Pt(C^N)(CN)2] (C^N = ppy, F2ppy, and bzq) double salts were prepared and characterized. A new solution MMLCT feature was identified for all three double salts using UV-vis and fluorescence spectroscopy. Support of solution cation and anion association using solution conductivity and dynamic light scattering measurements will be discussed.
199

The 3D Solution Structure of the C Terminal Domain of Diphtheria Toxin Repressor: in the Free and Bound Forms

Unknown Date (has links)
Diphtheria toxin repressor protein (DtxR) is a 226 amino acid protein that regulates the genes for iron uptake in Corynebacterium diphtheria and also regulates the Diphtheria toxin production. The known functions of this protein include binding divalent metals, dimerazation, and DNA binding. All these functions are accounted for by the N terminal domain of the protein. The C terminal domain was not well defined in early crystal structures but by 2000 both crystallography and NMR agreed that the C terminal domain has an SH3 like fold. This has led us to investigate the possible role of the C terminal domain as a "switch" for the activation of DtxR. We propose that the C terminal domain binds to the linker between the N and C terminal domains of this protein and stabilizes the monomeric form of DtxR. Once this region is released by the C terminal domain the N terminal domain most have some sort of "folding event" then metal is bound and dimerazation can take place. To investigate the mechanism of binding to this linker region by the C terminal domain two protein constructs were made one from residues D144-L226 and the other from D110-L226. The first construct would be the Free form and the second would be the bound form thus given us insight into the mechanism of binding. Here the 3D solution structures of these two domains and a comparison is presented. / A Dissertation submitted to the Department of Chemistry in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Degree Awarded: Spring Semester, 2003. / Date of Defense: January 27, 2003. / Diphtheria Toxin Repressor Protein (DtxR), Iron Uptake / Includes bibliographical references. / Timothy M. Logan, Professor Directing Dissertation; Piotr G. Fajer, Outside Committee Member; Michael Blaber, Committee Member; Naresh Dalal, Committee Member.
200

Use of Inorganic Quantum Dot-Cationic Liposome Hybrids for the Delivery and Expression of Calcium-Sequestering Parvalbumin into Mammalian Cell Cultures

Unknown Date (has links)
Left Ventricular Diastolic Dysfunction is one of the main causes of Heart Failure. It is caused by a defect in the relaxation of cardiac muscle usually as the result of failure of the heart cells to remove cytoplasmic Ca2+ following muscle contraction. This defect is corrected by the presence of Ca2+ sequestering Parvalbumin Major Isoform I (Parvalbumin), a naturally occurring soluble protein in skeletal muscle, which then binds free Ca2+, resulting in increased rates of diastolic relaxation. Since Parvalbumin does not naturally occur in cardiac tissue, ectopic expression through gene therapy provides a vehicle to deliver the gene needed to express this therapeutic protein. This has been accomplished by others using viral vectors but due to the problems associated with viral delivery, non-viral delivery methods are becoming more popular. Cationic Liposomes are a commonly used non-viral method of gene delivery and due to their physical and chemical properties inorganic nano-particles are attracting much interest in the field as well. It is the aim of this research to investigate whether cationic liposomes containing organic-phase fluorescent CdSe/ZnS quantum dots can be used as an efficient method of gene delivery into mammalian cells with built-in optical tracers. Organic-phase CdSe/ZnS was synthesized, purified and encapsulated into liposomes using various ratios of 1,2 – dioleoyl – 3 – trimethylammonium – propane (DOTAP), 1,2 – dioleoyl – sn – glycero – 3 – phosphoethanolamine (DOPE), Cholesterol and 3β – [N – (N', N' – dimethylaminoethan) – carbamoyl] cholesterol (DC-Chol) and used to deliver circular plasmid DNA coding for a Parvalbumin-mCherry fusion protein into Chinese Hamster Ovary (CHO) cells. We are able to show that using this system of cationic liposome-quantum dot hybrids we are able to deliver and express the target gene. / A Thesis submitted to the Department of Chemistry and Biochemistry in partial fulfillment of the requirements for the degree of Master of Science. / Degree Awarded: Summer Semester, 2010. / Date of Defense: June 7, 2010. / Use of Inorganic Quantum Dot-Cationic Liposome Hy, Left Ventricular Diastolic Dysfunction, Gene Therapy, Cardiac, Transgenic, Transgene, Parvalbumin, Calcium, Gene Delivery, Expression / Includes bibliographical references. / Geoffrey Strouse, Professor Directing Thesis; Timothy Logan, Committee Member; Hong Li, Committee Member.

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