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Articles 1 - 13 of 13
Full-Text Articles in Physical Sciences and Mathematics
Modeling The Bioactivation And Subsequent Reactivity Of Drugs, Tyler Brian Hughes
Modeling The Bioactivation And Subsequent Reactivity Of Drugs, Tyler Brian Hughes
Arts & Sciences Electronic Theses and Dissertations
Metabolism can convert drugs to harmful reactive metabolites that conjugate to DNA and off-target proteins. Reactive metabolites are a significant driver of both drug candidate attrition and withdrawal from the market of already approved drugs. Unfortunately, reactive metabolites are difficult to study in vivo, because they are transitory and generally do not circulate. Instead, this work computationally models both metabolism and reactivity. Using deep learning, predictive models were developed for the metabolic formation of quinones and epoxides, which together account for about half of known reactive metabolites. Additionally, an accurate model of DNA and protein reactivity was constructed, which predicts …
Radiolabeled Nanohydroxyapatite As A Platform For The Development Of New Pet Imaging Agents, Stacy Lee Queern
Radiolabeled Nanohydroxyapatite As A Platform For The Development Of New Pet Imaging Agents, Stacy Lee Queern
Arts & Sciences Electronic Theses and Dissertations
Positron emission tomography (PET) imaging utilizes drugs labeled with positron emitters to target and evaluate different biological processes occurring in the body. Tailoring medicine to the individual allows for higher quality of care with better diagnosis and treatment and is a key purpose for advancing research into developing new platforms for PET imaging agents. A PET nuclide of high interest for the development of these agents is 89Zr. This can be attributed to the long half-life of 3.27 days and low positron energy of 89Zr.
In this work, we developed a production method for 89Zr using Y sputtered coins that …
Mechanisms Of Calcium Phosphate Mineralization On Biological Interfaces And Their Engineering Applications, Doyoon Kim
Mechanisms Of Calcium Phosphate Mineralization On Biological Interfaces And Their Engineering Applications, Doyoon Kim
McKelvey School of Engineering Theses & Dissertations
All living organisms utilize phosphorus (P) as an essential component of their cell membranes, DNA and RNA, and adenosine triphosphate. Bones, in addition to bearing loads, play an important role in balancing P levels in our bodies. In bones, a network of collagen templates and calcium phosphate (CaP) nanocrystals builds hierarchical levels, from nano- to macroscale. Within this architecture, the thermodynamic properties of CaP minerals are influential. Despite the importance of nucleation, growth, and crystallization in collagen structures for tissue development, little kinetic study of these processes has been conducted due to the limited in situ techniques for monitoring these …
Kcnq1/Kcne1 Interaction In The Cardiac Iks Channel And Its Physiological Consequences, Jiajing Xu
Kcnq1/Kcne1 Interaction In The Cardiac Iks Channel And Its Physiological Consequences, Jiajing Xu
McKelvey School of Engineering Theses & Dissertations
Dynamic conformational changes of ion channel proteins during activation gating determine their function as carriers of current. The relationship between these molecular movements and channel function over the physiological timescale of the action potential (AP) has not been fully established due to limitations of existing techniques. We constructed a library of possible cardiac IKs protein conformations and applied a combination of protein segmentation and energy linearization to study this relationship computationally. Simulations reproduced the effects of the beta-subunit (KCNE1) on the alpha-subunit (KCNQ1) dynamics and function, observed in experiments. Mechanistically, KCNE1 increased the probability of “visiting” conducting pore conformations on …
Photophysical Characterization And Wavelength Tuning Of Natural And Synthetic Oxobacteriochlorins And Biohybrids, Don Hood
Arts & Sciences Electronic Theses and Dissertations
ABSTRACT OF THE DISSERTATION
Photophysical Characterization and Wavelength Tuning of Natural and Synthetic Oxobacteriochlorins and Biohybrids
By
Donald L. Hood
Doctor of Philosophy in Chemistry
Washington University in St. Louis, 2018
Dr. Dewey Holten, Chairperson
Herein is discussed the theoretical and practical unpinnings of photophysical behaviors and kinetic constants for tetrapyrrole macrocycles, to wit, porphyrins, chlorins, and bacteriochlorins. Understanding the characteristic photophysical response of tetrapyrroles to changes in environment or substituents is important to designing synthetic chromophores with tunable absorption wavelengths and for preparing useful biohybrids of natural photosynthetic light antennas combined with unnatural chromophores attached to the light antenna …
Anodic Cyclization Reaction: Manipulation Of Reaction Pathway And Efforts To Radical Cation And Radical Intermediate, Ruozhu Feng
Anodic Cyclization Reaction: Manipulation Of Reaction Pathway And Efforts To Radical Cation And Radical Intermediate, Ruozhu Feng
Arts & Sciences Electronic Theses and Dissertations
In recent years, synthetic chemists have been expressing significant interest in electro-organic synthetic methods. This interest is being fueled by the existence of an increasing number of successful methods in the literature and the availability of new electrochemical equipment that removes the barrier to attempting an electrolysis reaction for the first time. Yet while these developments have fueled growth in some areas of electro-organic synthesis (the recycling of chemical catalysts for example), other areas remain underdeveloped. One such area is the exploration of reactions that can be triggered directly as an electrode surface without the use of any chemical reagent. …
Synthesis And Integration Of Oligoviologens Into Hydrogel Actuators, Kevin Liles
Synthesis And Integration Of Oligoviologens Into Hydrogel Actuators, Kevin Liles
Arts & Sciences Electronic Theses and Dissertations
Interest in the development of soft-material artificial molecular muscles has inspired scientists to pursue novel stimuli-responsive systems capable of undergoing change in the physical and mechanical properties of a material in response to external stimuli. This interest has been driven primarily by advances, or the desire for advances, in fields such as soft robotics, microfluidics, and bio-compatible drug-delivery systems. In this work, redox-responsive viologens and their ability to form stable radical-cation complexes were evaluated as a method of actuation in stimuli-responsive materials, specifically hydrogels.
First, a brief overview of hydrogel actuators is covered, with some examples given of the broad …
Building On Nature: Spectroscopic Studies Of Photosynthesis-Inspired Pigments, Fused Light Harvesting Proteins, And Bacterial Reaction Center Mutants, Kaitlyn Faries
Arts & Sciences Electronic Theses and Dissertations
Photosynthesis is the dominant form of solar energy conversion on the planet, making it critical to understand the fundamentals of the process in order to effectively mimic and improve upon it for human energy needs. The initial stages of photosynthesis include light harvesting and chemical conversion of that harvested energy via electron transport, with both of these stages relying on pigments (or chromophores) such as chlorophyll and specific protein architectures for the processes. In this work, the fundamental underpinnings of photosynthetic light harvesting and electron transport are explored via spectroscopy of various photosynthetic systems with altered natural pigments and proteins. …
An Nmr Study Of Co2 Dynamics And Structural Characterization Of Porous Materials, Robert M. Marti
An Nmr Study Of Co2 Dynamics And Structural Characterization Of Porous Materials, Robert M. Marti
Arts & Sciences Electronic Theses and Dissertations
Nuclear magnetic resonance (NMR) has proven to be a versatile and powerful analytical tool to study many areas of interest to the scientific community, such as molecular dynamics and structural characterization. In this dissertation, NMR was used as a probe for CO2 dynamics in metal-organic frameworks. Variable temperature (VT) NMR was used to determine molecular dynamics of CO2, going as low as 8 K. In the fast motion regime, where the CO2 hopping rate is fast compared to the NMR experiment time, 13CO2 inside of Mg-MOF-74 still exhibits a chemical shift anisotropy (CSA) powder pattern. However, there is a certain …
Spin Alignment Generated In Inelastic Nuclear Reactions, Daniel Hoff
Spin Alignment Generated In Inelastic Nuclear Reactions, Daniel Hoff
Arts & Sciences Electronic Theses and Dissertations
The spin alignment of inelastically excited 7Li projectiles, when the target remains in its ground state, was determined through angular-correlation measurements between the breakup fragments of 7Li_ (_ + t). It was found that 7Li_ is largely aligned along the beam axis (longitudinal) in this type of inelastic reaction, regardless of the target. This longitudinal alignment is well described by DWBA calculations, which can be explained by an angular-momentum-excitation-energy mismatch condition. These calculations also explain the longitudinal spin alignment of excited nuclei in several other systems, showing the phenomenon is more general. The experiment involving 7Li was performed at the …
Polarizable Force Field Development, And Applications To Conformational Sampling And Free Energy Calculation, Zhi Wang
Arts & Sciences Electronic Theses and Dissertations
The parameters of monovalent ions for the AMOEBA force field were revised. High level quantum mechanics results, relative solvation free energies of monovalent ions, lattice energies and lattice constants of salt crystals were used to calibrate the parameters. The revised parameters were validated against the quantum optimized structures and energies of ion-water dimers and ion-water clusters, and against thermodynamic properties of salt solutions at different concentrations measured in experiments, e.g. mean ionic activity coefficients, self-diffusion coefficients of water. In the simulations the sodium ion is found to qualitatively differ from larger cations in aqueous solution. Direct ionic interactions are predominant …
Instrumentation For Cryogenic Dynamic Nuclear Polarization And Electron Decoupling In Rotating Solids, Faith Joellen Scott
Instrumentation For Cryogenic Dynamic Nuclear Polarization And Electron Decoupling In Rotating Solids, Faith Joellen Scott
Arts & Sciences Electronic Theses and Dissertations
Dynamic nuclear polarization (DNP) increases the sensitivity of nuclear magnetic resonance (NMR) using the higher polarization of electron radical spins compared to nuclear spins. The addition of electron radicals for DNP to the sample can cause hyperfine broadening, which decreases the resolution of the NMR resonances due to hyperfine interactions between electron and nuclear spins. Electron decoupling has been shown to attenuate the effects of hyperfine coupling in rotating solids. Magic angle spinning (MAS) DNP with electron decoupling requires a high electron Rabi frequency provided by a high-power microwave source such as a frequency-agile gyrotron. This dissertation describes the development …
Mass Spectrometry-Based Strategies For Protein Characterization: Amyloid Formation, Protein-Ligand Interactions And Structures Of Membrane Proteins In Live Cells, Ke Li
Arts & Sciences Electronic Theses and Dissertations
Mass spectrometry (MS)-based protein footprinting characterizes protein structure and protein-ligand interactions by interrogating protein solvent-accessible surfaces by using chemical reagents as probes. The method is highly applicable to protein or protein-ligand complexes that are difficult to study by conventional means such as X-ray crystallography and nuclear magnetic resonance. In this dissertation, we describe the development and application of MS-based protein footprinting from three perspectives, including I) protein aggregation and amyloid formation (Chapter 2-3), II) protein-ligand interactions (Chapter 4-5), and III) in-cellulo structures and dynamic motion of membrane proteins (Chapter 6). Fast Photochemical Oxidation of Proteins (FPOP) is the main methodology …