Physical Chemistry Commons^™

Studies Of The Rectification Behavior Of The Pdt Ligand And The Active Site Of Msrp, Laura J. Ingersol

Chemistry and Chemical Biology ETDs

Molybdenum (Mo) is an essential element that plays an important role in global nitrogen, carbon, and sulfur cycles with a critical role in human metabolism and ecological balance. It becomes catalytically active when complexed with the pyranopterin dithiolene ligand (PDT), forming the nearly ubiquitous molybdenum cofactor (Moco). The complex biosynthetic pathway of Moco, its presence in all three domains of life, and its role as a constituent cofactor in the last universal common ancestor (LUCA) all point toward the importance of the PDT in the development of life on Earth. Molybdoenzymes catalyze the two-electron oxidation or reduction of substrates that …

Indolizine Donor-Based Dyes For Applications In Fluorescence Biological Imaging, William Meador

Honors Theses

NIR emissive fluorophores are intensely researched due to their potential to replace modern imaging procedures. Many molecular strategies have been employed in the literature to optimize fluorophores for deeper NIR absorption and emission, biocompatibility, and higher fluorescence quantum yields. Amongst the fluorophores studied to date, proaromatic indolizine donors are attractive alternatives to traditional alkyl amine and indoline based donors due to their 1) lower energy absorption and emission facilitated by proaromaticity, 2) large Stokes shifts due to increased dihedral angles about the π-system, 3) ease of functionalization and capacity for bioconjugation at the phenyl ring, and 4) potential for further …

Thermodynamics Of Ligand Binding And Global Structural Stability Of Human Serum Albumin, Matthew Walter Eskew

Dissertations and Theses

Protein structure is integral to its function. For the past 70 years differential scanning calorimetry has been used to measure protein structural stability. More recently it has been used to study macromolecular interactions. Interactions between proteins and ligands can manifest on differential scanning calorimetry melting curves or thermograms. Utilizing differential scanning calorimetry thermograms to detect or diagnose diseases has been a major goal in disease diagnostics. However, correlating specific ligand-protein interactions, as manifested in a thermogram, with a disease-specific plasma thermogram, has proven elusive.

Modified human serum albumin was utilized to develop a process to capture and retrieve ligands from …

Effects Of Resin Chemistries On The Selective Removal Of Industrially Relevant Metal Ions Using Wafer-Enhanced Electrodeionization, Humeyra B. Ulusoy Erol, Christa N. Hestekin, Jamie A. Hestekin

Chemical Engineering Faculty Publications and Presentations

Wafer-enhanced electrodeionization (WE-EDI) is an electrically driven separations technology that occurs under the influence of an applied electric field and heavily depends on ion exchange resin chemistry. Unlike filtration processes, WE-EDI can be used to selectively remove ions even from high concentration systems. Because every excess ion transported increases the operating costs, the selective separation offered by WE-EDI can provide a more energy-efficient and cost-effective process, especially for highly concentrated salt solutions. This work reports the performance comparison of four commonly used cation exchange resins (Amberlite IR120 Na⁺, Amberlite IRP 69, Dowex MAC 3 H⁺, and …

The Quantitative Assessment Of Pond Scum: An Examination Of The Biogeochemistry Of Phosphorus Cycling In The Belgrade Lakes, Abbey M. Sykes

Honors Theses

The internal recycling phosphorus in freshwater lake bottom sediments represents a significant source of hypolimnetic phosphorus (P) release for many of Maine’s lakes. In summer months, Maine lakes often thermally stratify and the lake hypolimnion develops anoxia, leading to a reduction in redox potential at the sediment-water interface. These reducing conditions facilitate the reductive dissolution of ferric iron, and, since phosphorus is often present in freshwater lake sediments as solid FeOOH-PO₄ complexes, results in release of soluble phosphorus into the water column. Our current study presents field and laboratory data from sediment fractionation extractions designed to quantify concentrations of …

Activity Of Saccharomyces Cerevisiae By Single Entity Electrochemistry, John Lutkenhaus

Graduate Research Posters

According to the Centers of Disease Control and Prevention, antibiotics decrease in effectiveness as bacteria gain resistance for previously treatable illnesses. Currently, antibiotic susceptibility is typically carried out via the Kirby-Bauer method. Even with automation, this process requires two incubation periods so a less time-consuming technique is desirable. Single entity electrochemistry (SEE) detects changes in current when collisions of individual particles at an ultramicroelectrode (UME) are linked with an electrochemical event. Our group has obtained step-like and spike-like responses of Saccharomyces cerevisiae at the UME surface as a result of adsorption and desorption, respectively. This response is due to the …

Huntingtin Aggregation At Interfaces Associated With Membranes And Organelles, Adewale Vincent Adegbuyiro

Graduate Theses, Dissertations, and Problem Reports (ETD)

Huntington’s Disease (HD) is a genetic neurodegenerative disease caused by the expansion of polyglutamine (polyQ) domain within the first exon (exon1) of the huntingtin (htt) protein. Due to this mutation within the polyQ domain, htt aggregates into various toxic species such as oligomers, fibrils, and other amorphous aggregates. While the aggregation of htt strongly correlates with polyQ length, other factors, e.g. interaction with membranes or organelles and posttranslational modifications (PTMs), modulate aggregation. The first 17 N-terminal amino acids (Nt17) that precede the polyQ in htt-exon1 enhances aggregation and facilitated binding of htt to membranous organelles, promoting morphological changes and disfunction. …

Understanding The Relationship Between Local Environmental Changes And The Function Of The Ph Low Insertion Peptide, Violetta Burns Casamayor

Graduate Theses, Dissertations, and Problem Reports (ETD)

Cancer is the second leading cause of death in the US with over 1.7 million new cases each year. Current cancer treatments tend to also target healthy tissues due to similarities with cancerous ones, resulting in acute side effects. Early detection is the best approach towards defeating cancer, however, modern imaging techniques require sizeable samples, often implying a late stage in the disease. One common attribute of tumors is their acidic microenvironment, which can be taken advantage of.

The pH Low Insertion Peptide (pHLIP) is a membrane-active peptide that can take advantage of the acidic microenvironment surrounding cancer cells. pHLIP …

Applied Molecular Dynamics: From Targeting Viral Helicases, To Understanding The Interactions Of Cucurbituril Complexes In Ionic Solutions, Bryan Raubenolt

LSU New Orleans Theses and Dissertations

Molecular Dynamics simulations are a highly useful tool in helping understand the fundamental interactions present in a variety of chemical systems. The work discussed here illustrates it’s use in determining the conformational dynamics of the Zika and SARS-Cov-2 helicase in a physiological environment, largely in an effort to discover inhibitors capable of rendering the protein inert. Additionally, we show how it can be used to understand paradoxical trends in the anion-induced precipitation of Cucurbituril cavitands.

Viral helicases are motor proteins tasked with unwinding the viral dsRNA, a crucial step in preparing the strand to be translatable by host cells. By …

Single‐Molecule 3d Orientation Imaging Reveals Nanoscale Compositional Heterogeneity In Lipid Membranes, Jin Lu, Hesam Mazidi, Tianben Ding, Oumeng Zhang, Matthew D. Lew

Electrical & Systems Engineering Publications and Presentations

In soft matter, thermal energy causes molecules to continuously translate and rotate, even in crowded environments, thereby impacting the spatial organization and function of most molecular assemblies, such as lipid membranes. Directly measuring the orientation and spatial organization of large collections (>3000 molecules μm⁻²) of single molecules with nanoscale resolution remains elusive. In this paper, we utilize SMOLM, single‐molecule orientation localization microscopy, to directly measure the orientation spectra (3D orientation plus “wobble”) of lipophilic probes transiently bound to lipid membranes, revealing that Nile red's (NR) orientation spectra are extremely sensitive to membrane chemical composition. SMOLM images resolve …

Synthesis And In Vitro Studies Of Polycaprolactone-Coated Superparamagnetic Iron Oxide Nanoparticles For Magnetic Hyperthermia Therapy, Nasab Ziba Hedayat

Student Works (2020-2029)

Research has garnered a great interest in utilization of superparamagnetic iron oxide nanoparticles (SPIONs) as magnetic nano-heating agents in hyperthermia cancer therapy by profiting from high apoptosis vulnerability of cancer cells at elevated temperatures. However, low oxidation resistance and high agglomeration tendency negatively affect magnetic characteristics of nanoparticles and subsequently their clinical efficiency. Particle surface modifications are potential approaches to endow SPIONs a range of desirable properties including high colloidal dispersity, low aggregation tendency, cytocompatibility, and high oxidation resistance. Currently, polymer coating has led to decrease magnetic hyperthermia efficiency through formation of intermediate layer between nanoheating agents and targeted cells. …

Study Of Pharmaceutical Tablets Using Raman Mapping, Kyle Joseph Pauly

Honors Theses

Covalent bonds are the strongest type of bonds holding molecules together. Based on the pattern of bonding of the molecule, the atoms associated with the bond will vibrate at a specific frequency. Utilizing vibrational spectroscopy, such as Raman spectroscopy, these unique vibrational frequencies can be used to detect the presence of analytes over a selected area. Furthermore, the intensities of the vibrational modes can be tracked to comparatively quantify the concentration of analytes at various locations. This is a method of great importance due to its ability to compare pharmaceutical tablets synthesized with different techniques. Here, the presence and concentration …

Spectroscopic And Computational Studies Of The Agricultural Active Ingredient Dicamba, James Johnson

Honors Theses

3,6-dichloro-2-methoxy benzoic acid, more commonly known as Dicamba, is the active ingredient in an array of pesticides used on farmlands across the globe. Dicamba’s mode of action works by mimicking the plant hormone auxin, which is synonymous to growth hormones in mammals. The mimicking of auxin results in excessive elongation and growing, which is eventually fatal for plants when the rate of growth can no longer be sustained. Dicamba has risen in prominence in recent years due to drift damage as a result of Dicamba’s high volatility. Having the ability to identify Dicamba is crucial for the agricultural industry. The …

Correlating The Physicochemical Properties Of Magnesium Stearate With Tablet Dissolution And Lubrication, Julie L. Calahan

Theses and Dissertations--Pharmacy

Magnesium stearate (MgSt) is the most commonly used pharmaceutical excipient and is present in over half the tablet formulations on the market. In spite of its popularity as an effective lubricant, it has been repeatedly recognized that there is significant variability between MgSt samples, which can cause inconsistent lubrication between batches of MgSt. The hypothesis of this research is that the batch-to-batch variability in tablet lubrication and dissolution observed in tablet formulations containing different MgSt samples can be correlated with differences in MgSt physicochemical properties (fatty acid salt composition, crystal hydrate form, particle size and surface area). Developing correlations between …

Development Of A Novel Highly-Sensitive Brucellosis Sensor Based On Surface Plasmon Resonance Spectroscopy, Amal Kasry, Ihab Adly, Asharf Sayour, Hossam Sayour

Nanotechnology Research Centre

Brucellosis is considered a significant health threat, it is an infectious disease caused by the bacteria Brucella, which can spread from animals to humans causing severe diseases. Through this project, we aim to develop a very highly sensitive biosensor to detect Brucella early before spreading. This sensor is based on surface plasmon resonance (SPR) technique, which is used to analyze kinetics of interaction between biomolecules. It can detect down to picomolar concentrations of some proteins.

Factors Influencing Huntingtin Aggregation At Surfaces: Implications For Huntington’S Disease, Sharon E. Groover

Graduate Theses, Dissertations, and Problem Reports (ETD)

Huntington’s Disease (HD) is a genetic, neurodegenerative disease characterized by an abnormal polyglutamine (polyQ) expansion in the first exon of the huntingtin protein (htt). The polyQ domain facilitates aggregation and initiates the formation of a diverse collection of aggregate species, including fibrils, oligomers and annular aggregates. The first 17 amino acids of htt (Nt17) directly flank the polyQ domain and is a key factor in htt’s association to membranous structures. In addition to Nt17 being an amphipathic αhelix, it also promotes aggregation through self-association and contains numerous posttranslational modifications (PTMs) that can modulate toxicity and subcellular localization. For in depth …

The Effects Of Membrane Physicochemical Properties On Huntingtin Membrane Association And Downstream Aggregation, Maryssa Beasley

Graduate Theses, Dissertations, and Problem Reports (ETD)

Huntington’s Disease (HD) is a fatal neurodegenerative disorder caused by an expanded glutamine repeat region (polyQ) within the huntingtin protein (htt). As a result of the expanded polyQ domain, htt associates into a variety of toxic aggregate species. The polyQ domain of htt is flanked at the N-terminal end by 17 amino acids (Nt17) that adopt an amphipathic α-helical structure in the presence of binding partners such as lipid membranes. In addition to comprising a lipid binding domain, the Nt17 amphipathic α -helix has been directly implicated in htt aggregation initiation via self-association with other Nt17 α -helices. Due to …

Effects Of The Dihydrouracil Lesion On Dna Using 1h/31p 1d And 2d Solution Nmr, Benjamin M. Boyd

Graduate Theses/Dissertations

The effects of the dihydrouracil lesion in DNA were studied using two dimensional NMR spectroscopy. The sequence used was based off of the Drew-Dickerson Dodecamer, with the cytosine in the three position replaced by a dihydrouracil. All of the nonexchangeable proton chemical shifts, with the exception of the H2, H5’, and H5’’, of the lesioned DNA were identified using NOESY spectra and then compared to the chemical shift values of the Drew Dickerson Dodecamer. The largest differences in chemical shifts were observed in the nucleotides neighboring the lesion, both within the strand and on the opposite strand. The imino exchangeable …

Minimalistic Peptide-Based Supramolecular Systems Relevant To The Chemical Origin Of Life, Daniela Kroiss

Dissertations, Theses, and Capstone Projects

All forms of life are based on biopolymers, which are made up of a selection of simple building blocks, such as amino acids, nucleotides, fatty acids and sugars. Their individual properties govern their interactions, giving rise to complex supramolecular structures with highly specialized functionality, including ligand recognition, catalysis and compartmentalization. In this thesis, we aim to answer the question whether short peptides could have acted as precursors of modern proteins during prebiotic evolution. Using a combination of experimental and computational techniques, we screened a large molecular search space for peptide sequences that are capable of forming supramolecular complexes with adenosine …

Crystal Structure Of Zymonic Acid And A Redetermination Of Its Precursor, Pyruvic Acid, Dominik Heger, Alexis J. Eugene, Sean R. Parkin, Marcelo I. Guzman

Chemistry Faculty Publications

The structure of zymonic acid (systematic name: 4-hy­droxy-2-methyl-5-oxo-2,5-di­hydro­furan-2-carb­oxy­lic acid), C₆H₆O₅, which had previously eluded crystallographic determination, is presented here for the first time. It forms by intra­molecular condensation of parapyruvic acid, which is the product of aldol condensation of pyruvic acid. A redetermination of the crystal structure of pyruvic acid (systematic name: 2-oxo­propanoic acid), C₃H₄O₃, at low temperature (90 K) and with increased precision, is also presented [for the previous structure, see: Harata et al. (1977). Acta Cryst. B33, 210–212]. In zymonic acid, the hy­droxy­lactone ring …

Solvation Thermodynamic Mapping In Computer Aided Drug Design, Steven Ramsey

Dissertations, Theses, and Capstone Projects

The displacement of water from surfaces upon biomolecular recognition and association makes a significant contribution to the free energy changes of these processes. We therefore posit that accurate characterization of local structural and thermodynamic molecular water properties can improve computational model accuracy and predictivity of recognition and association processes. In this thesis, we discuss Solvation Thermodynamic Mapping (STM) methods that we have developed using inhomogeneous fluid solvation theory (IST) to better characterize active site water structural and thermodynamic properties on protein surfaces and the open source tools that we have developed, GIST-CPPTRAJ and SSTMap, which implement these methods which we …

Development Of Ultrafast Broadband Electronic Sum Frequency Generation For Charge Dynamics At Surfaces And Interfaces, Gang-Hua Deng, Yuqin Qian, Yi Rao

Chemistry and Biochemistry Faculty Publications

Understandings of population and relaxation of charges at surfaces and interfaces are essential to improve charge collection efficiency for energy conversion, catalysis, and photosynthesis. Existing time-resolved surface and interface tools are limited to either under ultrahigh vacuum or in a narrow wavelength region with the loss of spectral information. There lacks an efficient time-resolved surface/interface-specific electronic spectroscopy under ambient conditions for the ultra fast surface/interface dynamics. Here we developed a novel technique for surface/interface-specific broadband electronic sum frequency generation (ESFG). The broadband ESFG was based on a stable two-stage BiB₃O₆ crystal-based optical parametric amplifier, which generates a …

Structure And Thermodynamics Of Polyglutamine Peptides And Amyloid Fibrils Via Metadynamics And Molecular Dynamics Simulations, Riley Workman

Electronic Theses and Dissertations

Aggregation of polyglutamine (polyQ)-rich polypeptides in neurons is a marker for nine neurodegenerative diseases. The molecular process responsible for the formation of polyQ fibrils is not well understood and represents a growing area of study. To enable development of treatments that could interfere with aggregation of polyQ peptides, it is crucial to understand the molecular mechanisms by which polyQ peptides aggregate into fibrils. Many experimental techniques have been employed to probe polyQ aggregation, however, observations from these studies have not lead to a unified understanding of the properties of these systems, instead yielding competing, fragmented theories of polyQ aggregation. This …

Cross Photoreaction Of Glyoxylic And Pyruvic Acids In Model Aqueous Aerosol, Sha-Sha Xia, Alexis J. Eugene, Marcelo I. Guzman

Chemistry Faculty Publications

Aerosols of variable composition, size, and shape are associated with public health concerns as well as with light-particle interactions that play a role in the energy balance of the atmosphere. Photochemical reactions of 2-oxocarboxylic acids in the aqueous phase are now known to contribute to the total secondary organic aerosol (SOA) budget. This work explores the cross reaction of glyoxylic acid (GA) and pyruvic acid (PA) in water, the two most abundant 2-oxocarboxylic acids in the atmosphere, under solar irradiation and dark thermal aging steps. During irradiation, PA and GA are excited and initiate proton-coupled electron transfer or hydrogen abstraction …

Study Of The Visual Adaptation Mechanism In Marine Species With The Change Of Habitation Depth., Demid Osipov, Daniil Moshnikov

The International Student Science Fair 2018

The goal of our work was to determine the principal mechanisms that provide the difference in visual perception of two marine species that live on different depths: T. Pacificus and O. Vulgaris. In nature, visual perception of species that live deeper is shifted towards the blue region. This is related to the fact that red, orange and yellow light is absorbed more strongly by water than the blue light. On the other hand, the visual perception spectrum of an animal is determined by the absorption spectrum of the "light sensor" located in rods and cones of its eye retina. These …

Oxidation Of Substituted Catechols At The Air-Water Interface: Production Of Carboxylic Acids, Quinones, And Polyphenols, Elizabeth A. Pillar, Marcelo I. Guzman

Chemistry Faculty Publications

Anthropogenic activities contribute benzene, toluene, and anisole to the environment, which in the atmosphere are converted into the respective phenols, cresols, and methoxyphenols by fast gas-phase reaction with hydroxyl radicals (HO(•)). Further processing of the latter species by HO(•) decreases their vapor pressure as a second hydroxyl group is incorporated to accelerate their oxidative aging at interfaces and in aqueous particles. This work shows how catechol, pyrogallol, 3-methylcatechol, 4-methylcatechol, and 3-methoxycatechol (all proxies for oxygenated aromatics derived from benzene, toluene, and anisole) react at the air-water interface with increasing O3(g) during τc ≈ 1 μs contact time and contrasts their …

Reactivity Of Ketyl And Acetyl Radicals From Direct Solar Actinic Photolysis Of Aqueous Pyruvic Acid, Alexis J. Eugene, Marcelo I. Guzman

Chemistry Faculty Publications

The variable composition of secondary organic aerosols (SOA) contributes to the large uncertainty for predicting radiative forcing. A better understanding of the reaction mechanisms leading to aerosol formation such as for the photochemical reaction of aqueous pyruvic acid (PA) at λ ≥ 305 nm can contribute to constrain these uncertainties. Herein, the photochemistry of aqueous PA (5-300 mM) continuously sparged with air is re-examined in the laboratory under comparable irradiance at 38° N at noon on a summer day. Several analytical methods are employed to monitor the time series of the reaction, including (1) the derivatization of carbonyl (C═O) functional …

Enhancement Of The Physicochemical Properties Of Pt(Dien)(Nucleobase) (2+) For Hivncp7 Targeting, S. D. Tsotsoros, P. B. Lutz, A. G. Daniel, E. J. Peterson, R. E. F. De Paiva, E. Rivera, Y. Qu, C. A. Bayse, N. P. Farrell

Chemistry & Biochemistry Faculty Publications

Physicochemical properties of coordination compounds can be exploited for molecular recognition of biomolecules. The inherent π-π stacking properties of [Pt(chelate)(N-donor)]²⁺([PtN₄]) complexes were modulated by systematic variation of the chelate (diethylenetriamine and substituted derivatives) and N-donor (nucleobase or nucleoside) in the formally substitution-inert PtN₄ coordination sphere. Approaches to target the HIV nucleocapsid protein HIVNCp7 are summarized building on (i) assessment of stacking interactions with simple tryptophan or tryptophan derivatives to (ii) the tryptophan-containing C-terminal zinc finger and (iii) to the full two-zinc finger peptide and its interactions with RNA and DNA. The xanthosine nucleoside was identified …

A Kinetic Study Of Regulation Of Glua1 Homomeric And Heteromeric Ampa Receptors By 2,3-Benzodiazepines, Yin-Shuo (Andrew) Wu

Legacy Theses & Dissertations (2009 - 2024)

AMPA receptors are a subtype of the ionotropic glutamate receptor family. They are ligand-gated or glutamate-activated, transmembrane ion channels that mediate the majority of excitatory synaptic transmission in the central nervous system. AMPA receptors are essential for neuronal development and brain functions, including learning and memory. Over-activation of calcium permeable AMPA receptors has been linked to some neurological diseases such as stroke, Alzheimer’s disease and amyotrophic lateral sclerosis. Inhibitors of glutamate receptors are therefore drug candidates for the potential treatment of these neurological diseases. One of the most promising classes of AMPA receptor antagonists is 2,3-benzodiazepine derivatives, thought to be …

Using Low-Coherence Interferometry To Monitor Cell Invasion In An In-Vitro Model System, Behnaz Davoudi Nasab

Honors Undergraduate Theses

In an optically random system, such as naturally occurring and man-made media, light undergoes pronounced multiple scattering. This phenomenon has shown a remarkable potential in characterizing complex materials. In this regime, scattering occurs from each individual center of the scattering and independent scattering events lead to multiple light scattering. This phenomenon is often described as a random walk of photons and can be modeled in terms of a diffusion equation based on the radiative transfer theory. In this thesis, we used optical path-length spectroscopy (OPS), which is an experimental method to obtain the path-length probability density of the propagating light …