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Articles 1321 - 1350 of 2574

Full-Text Articles in Chemistry

Choline Chloride Eutectics: Low Temperature Applications, Kaila M. Kuehn, Camille M. Massmann, Natalie R. Sovell Jan 2017

Choline Chloride Eutectics: Low Temperature Applications, Kaila M. Kuehn, Camille M. Massmann, Natalie R. Sovell

The Journal of Undergraduate Research

Deep eutectic solvents (DESs) have a lower melting point than each of their individual components due to ion dipole interactions or hydrogen bonding. Traditionally, DES are used for processing metals through plating and have many synthesis applications. DES are able to be substituted for hazardous solvents that are traditionally used for metal plating and synthesis. This, along with many other advantageous properties, appear promising for the use of DESs as solvents or for use in electrochemical systems, particularly at low temperatures. Choline chloride:propylene glycol was a novel DES synthesized and analyzed for its properties, including melting point, viscosity, conductivity, heat …


The Analysis Of Flavor Compounds In Green Tea Using Ice Concentration Linked With Extractive Stirrer (Icecles), Abdullah H. Alluhayb Jan 2017

The Analysis Of Flavor Compounds In Green Tea Using Ice Concentration Linked With Extractive Stirrer (Icecles), Abdullah H. Alluhayb

Electronic Theses and Dissertations

Sample preparation of target components from food samples is one of the most difficult steps in this type of analysis. Many extraction techniques have been used for this purpose, such as liquid-liquid extraction (LLE), accelerated solvent extraction (ASE), microwave-assisted extraction (MAE), solid-phase extraction (SPE), solid-phase microextraction (SPME), and stir bar sorptive extraction (SBSE). Although each of these techniques works well, they each have a number of disadvantages, including selectivity, relatively high cost, long preparation time, and matrix effects. Ice concentration linked with extractive stirrer (ICECLES) is a promising new sample preparation technique, especially for the extraction of relatively polar compounds, …


Further Development Of Raman Spectroscopy For Body Fluid Investigation : Forensic Identification, Limit Of Detection, And Donor Characterization, Claire K. Muro Jan 2017

Further Development Of Raman Spectroscopy For Body Fluid Investigation : Forensic Identification, Limit Of Detection, And Donor Characterization, Claire K. Muro

Legacy Theses & Dissertations (2009 - 2024)

The challenges to forensic body fluid analysis have placed limitations on the type of information that investigators can acquire and how that information can be collected. In recent years, Raman spectroscopy has proven itself useful for characterizing body fluids. In 2008, a large-scale investigation was undertaken to explore the use of Raman spectroscopy as a means of identifying body fluids. This work resulted in multidimensional Raman spectroscopic signatures for the five main body fluids: semen, peripheral blood, saliva, vaginal fluid, and sweat. These studies were incredibly successful and created the foundation for years of continued research. Accordingly, the studies included …


Structure And Characterization Of A Class 3b Proline Utilization A: Ligand-Induced Dimerization And Importance Of The C-Terminal Domain For Catalysis, David A. Korasick, Thameesha T. Gamage, Shelbi Christgen, Kyle M. Stiers, Lesa J. Beamer, Michael T. Henzl, Donald F. Becker, John J. Tanner Jan 2017

Structure And Characterization Of A Class 3b Proline Utilization A: Ligand-Induced Dimerization And Importance Of The C-Terminal Domain For Catalysis, David A. Korasick, Thameesha T. Gamage, Shelbi Christgen, Kyle M. Stiers, Lesa J. Beamer, Michael T. Henzl, Donald F. Becker, John J. Tanner

Department of Chemistry: Faculty Publications

The bifunctional flavoenzyme proline utilization A (PutA) catalyzes the two-step oxidation of proline to glutamate using separate proline dehydrogenase (PRODH) and L-glutamate-y-semialdehyde dehydrogenase active sites. Because PutAs catalyze sequential reactions, they are good systems for studying how metabolic enzymes communicate via substrate channeling. Although mechanistically similar, PutAs vary widely in domain architecture, oligomeric state, and quaternary structure, and these variations represent different structural solutions to the problem of sequestering a reactive metabolite. Here, we studied PutA from Corynebacterium freiburgense (CfPutA), which belongs to the uncharacterized 3B class of PutAs.A2.7A˚ resolution crystal structure showed the canonical arrangement of PRODH, L-glutamate-y-semialdehyde dehydrogenase, …


Purification And Analysis Of A Pteroic Acid Conjugate, Naveen Kumar Ganji Jan 2017

Purification And Analysis Of A Pteroic Acid Conjugate, Naveen Kumar Ganji

All Capstone Projects

(FR) is overexpressed on the cell membrane in cancer tissues and activated macrophages associated with rheumatoid conditions. However, FR is restricted in normal healthy tissues. Folic acid has shown high affinity to folate receptors and thus can be used in targeting the tumor cells. Folic acid residue, pteroic acid is also used in several studies that are involved in targeting cancer cells. Several examples include technetium -99m radiotracer labelled pteroyl-lys conjugates, pteroic acid-conjugated nitroheterocyclic phosphoramidates..

In this project, we were successfully able to conjugate pteroic acid with polyethylene Glycol-Amine to create an elegant building block(pte-PEG-amine) for synthesis of future imaging …


Impact Of Timber Harvest On Mercury Mobilization In A Mixed Pine And Hardwood Forest And Adjacent Lake In Mississippi, Mary Kristen Dickerson Jan 2017

Impact Of Timber Harvest On Mercury Mobilization In A Mixed Pine And Hardwood Forest And Adjacent Lake In Mississippi, Mary Kristen Dickerson

Electronic Theses and Dissertations

With 65% of land area covered in forest, Mississippi is a leader in the timber industry. Whereas forestry provides numerous benefits for humans and wildlife, forest harvest has been hypothesized to increase mercury (Hg) mobilization to aquatic systems. In a forest, Hg mostly accumulates in the upper layer of soil, where associates with organic matter. This top soil is exposed after clear-cutting and thus more susceptible to runoff. Harvest may also change the net balance between Hg methylation and demethylation by microorganisms through changes in redox conditions and addition of carbon sources from decaying logging residues. To better understand the …


Quantitative Analysis Of Tobacco-Specific Nitrosamines And Their Precursor Alkaloids In Tobacco Extracts, Celeste T. Wilkinson Jan 2017

Quantitative Analysis Of Tobacco-Specific Nitrosamines And Their Precursor Alkaloids In Tobacco Extracts, Celeste T. Wilkinson

Theses and Dissertations

Tobacco-specific nitrosamines (TSNA) are carcinogenic constituents derived from alkaloids in tobacco. Researchers are actively exploring several avenues to reduce TSNA levels in tobacco products like moist snuff tobacco. The focus of the research presented within is the quantitative analysis of TSNA in tobacco, specifically N’-nitrosonornicotine (NNN), 4-(methylnitrosamino)-1(3-pyridyl)-1-butanone (NNK), N’-nitrosoanatabine (NAT), and N’-nitrosoanabasine (NAB).

Tobacco alkaloids and nitrosamines in tobacco are currently analyzed by different instrumentation due to orders of magnitude difference in their concentrations, chromatographic separation challenges due to structural similarities, and similar mass fragmentation patterns. An analytical column using silica and 1,2-bis(siloxy)ethane hybrid particles of 1.7 µm size is …


Nitric Oxide Release From Poly(Lactic-Co-Glycolic Acid) Nanoparticles And Titanium Alloy, Nina A. Reger Jan 2017

Nitric Oxide Release From Poly(Lactic-Co-Glycolic Acid) Nanoparticles And Titanium Alloy, Nina A. Reger

Electronic Theses and Dissertations

Current methods for the treatment of bacterial infection involve the use of systemic antibiotics, which are high concentrations of antibiotics delivered over a long period time. Unfortunately, the use of systemic antibiotics can cause harmful side effects to the patient and increases the possibility for antibiotic resistance. The delivery of antibiotics or alternative antimicrobial compounds, such as nitric oxide, directly to the site of infection would decrease the amount of antibiotic necessary to treat a bacterial infection.

Poly (lactic-co-glycolic acid)/polyvinyl alcohol nanoparticles and a titanium- aluminum-vanadium metal oxide alloy implant were surface functionalized to deliver nitric oxide. Polymer nanoparticles can …


Micro-Spectroscopy Of Bio-Assemblies At The Single Cell Level, Jeslin Kera Jan 2017

Micro-Spectroscopy Of Bio-Assemblies At The Single Cell Level, Jeslin Kera

Honors Undergraduate Theses

In this thesis, we investigate biological molecules on a micron scale in the ultraviolet spectral region through the non-destructive confocal absorption microscopy. The setup involves a combination of confocal microscope with a UV light excitation beam to measure the optical absorption spectra with spatial resolution of 1.4 μm in the lateral and 3.6 μm in the axial direction. Confocal absorption microscopy has the benefits of requiring no labels and only low light intensity for excitation while providing a strong signal from the contrast generated by the attenuation of propagating light due to absorption. This enables spatially resolved measurements of single …


Application Of Factorial Design In The Analysis Of Factors Influencing Textile Dye Adsorption On Activated Carbon, Eid A. Alkhatib, Penny A. Snetsinger, Ahmad Alanazi, Sarah Aanonsen Jan 2017

Application Of Factorial Design In The Analysis Of Factors Influencing Textile Dye Adsorption On Activated Carbon, Eid A. Alkhatib, Penny A. Snetsinger, Ahmad Alanazi, Sarah Aanonsen

Chemistry & Physics Faculty Publications

In this study, the use of factorial design software is applied to evaluate efficiently factors influencing the adsorption capacity of activated carbon in treating textile dyes. Activated carbon is usually used to treat wastewater effluents from textile industries in order to remove textile dyes before discharge into the environment. Most treatment facilities, particularly large industrial or wastewater treatment facilities use continuous flow reactors or packed columns to treat the dye. Due to the limited residence time in these types of reactors, adsorption equilibrium is not necessarily reached, and the absorption rate becomes an important factor in this treatment process. Other …


Approaches Toward Novel 1,2,3-Triazole Sensors For The Detection Of Anions And Heavy Metal Cations, Richard D. Govan Jan 2017

Approaches Toward Novel 1,2,3-Triazole Sensors For The Detection Of Anions And Heavy Metal Cations, Richard D. Govan

College of Graduate Studies: Theses & Dissertations

Cations and anions play pivotal roles in biological and physiological processes, however an imbalance in concentration of any ion can be detrimental. Therefore, research into the selective recognition of anions and heavy metal cations has acquired much attention. One approach involves the use of chemosensors. Upon interaction with targeted analytes, chemosensors produce a distinct response, in some cases a fluorescent or colorimetric signal. The 1,2,3-triazole unit has much potential as a chemical sensor due to its unique photophysical properties. The specificity, selectivity, and signaling mechanism of triazole sensors can be tuned with conjugation in the motif and choice and placement …


Influence Of Magnetic Nanoparticles And Magnetic Stress On An Ionic Liquid Electrospray Source, Kurt Joseph Terhune Jan 2017

Influence Of Magnetic Nanoparticles And Magnetic Stress On An Ionic Liquid Electrospray Source, Kurt Joseph Terhune

Dissertations, Master's Theses and Master's Reports

Two electrospray sources were developed to operate on an ionic liquid ferrofluid; one source was a pressure‑fed capillary electrospray source and the other was a novel electrospray source which used a magnetically‑induced instability to produce a peak from which an electric field could extract electrospray. Multiple characteristics of electrospray operation were examined for both sources using faraday plates/cups, a quartz crystal microbalance, a retarding potential analyzer, and a time-of-flight mass spectrometer. The ILFF electrosprays for a capillary source were shown to operate in a mixed ion/droplet regime. The mass flow of the electrospray beam was primarily transported by larger particles …


Caffeine Used As A Tracer Of Wastewater Contamination In South Florida, Stephanie Spence Jan 2017

Caffeine Used As A Tracer Of Wastewater Contamination In South Florida, Stephanie Spence

Honors Program Theses

In this study, a method was developed to analyze caffeine levels of water samples collected in Miami, Florida. The method was used to determine caffeine concentrations in reclaimed water samples and environmental water samples using on-line solid phase extraction (SPE) high pressure liquid chromatography (HPLC) high resolution mass spectrometry (HRMS). The rising use and disposal of pharmaceuticals and personal care products are becoming a concern as contaminants increasingly enter lakes, streams, and rivers without proper removal by traditional wastewater treatment processes. Caffeine may be used as a chemical tracer to indicate the presence of contamination in water samples and to …


Exposure Of Commercial Titanium Dioxide And Copper Hydroxide Nanomaterials On Basil (Ocimum Basilicum): A Life Cycle And Transgenerational Study, Wenjuan Tan Jan 2017

Exposure Of Commercial Titanium Dioxide And Copper Hydroxide Nanomaterials On Basil (Ocimum Basilicum): A Life Cycle And Transgenerational Study, Wenjuan Tan

Open Access Theses & Dissertations

Although thousands of reports have shown that engineered nanomaterials (ENMs) can alter several agronomical, physiological, and biochemical parameters in plant and mammal systems, the effects of long-term exposure and varietal responses are scarce. Titanium dioxide nanoparticles (nano-TiO2) and copper hydroxide nanoparticles [nano-Cu(OH)2], which are widely used in agriculture, medicine, food industry, textile, among other areas, are among the ENMs with high production and consumption globally. Though reports indicate that these ENMs affected plant development and metabolism, their interactions with basil (Ocimum basilicum) are unknown. Basil is a popular culinary herb worldwide, featured in Asian and European cuisine and has more …


Self-Assembled Architecture Of Natural Organic Matter, Cynthia Johnson-Edler Jan 2017

Self-Assembled Architecture Of Natural Organic Matter, Cynthia Johnson-Edler

Electronic Theses and Dissertations

This investigation focuses on the determination of the architecture of the natural organic matter (NOM) contained within a soft coal-like material, an agricultural soil and a peat material. NOM has been extracted from bulk materials, fractionated, reassembled, then characterized by 13C Solid State NMR, Pulsed-Field Gradient NMR (PFG-NMR), and Small Angle Neutron Scattering (SANS). Interpretation of the data obtained by SANS has established that the majority of the components of NOM are mass fractals in solution and surface fractals in the solid state. Surface-to-volume ratios calculated with PFGNMR data indicate the NOM components studied have varying disk-like shapes. These …


Metabolomic Profiling Of Chiari Malformation Type I: Comparison Of Bioinformatic Programs For Untargeted Analysis, Hunter W. Korsmo Jan 2017

Metabolomic Profiling Of Chiari Malformation Type I: Comparison Of Bioinformatic Programs For Untargeted Analysis, Hunter W. Korsmo

Williams Honors College, Honors Research Projects

Chiari Malformation Type I is a neurodegenerative trait that can result from disease or from acquiring. Metabolomic analysis was done on normal pressure hydrocephalous and Chiari CSF samples using LC-MS and multiple bioinformatic programs. After analysis from multiple programs, we were able to analyze the stringency in statistical algorithms done by each program and determined qualities that are shared between programs that offer multiple details. We identified dysregulation in glucuronated metabolites in CSF of Chiari versus NPH. Using LC-MS, we established the experimental MS/MS of glucuronic acid in attempt to identify similarities in mass-to-charge features primarily identified. We could not …


Criegee Intermediate-Hydrogen Sulfide Chemistry At The Air/Water Interface, Manoj Kumar, Jie Zhong, Joseph S. Francisco, Xiao Cheng Zeng Jan 2017

Criegee Intermediate-Hydrogen Sulfide Chemistry At The Air/Water Interface, Manoj Kumar, Jie Zhong, Joseph S. Francisco, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

We carry out Born–Oppenheimer molecular dynamic simulations to show that the reaction between the smallest Criegee intermediate, CH2OO, and hydrogen sulfide (H2S) at the air/water interface can be observed within few picoseconds. The reaction follows both concerted and stepwise mechanisms with former being the dominant reaction pathway. The concerted reaction proceeds with or without the involvement of one or two nearby water molecules. An important implication of the simulation results is that the Criegee-H2S reaction can provide a novel non-photochemical pathway for the formation of a C–S linkage in clouds and could be a …


Amino Acid Catabolism In Staphylococcus Aureus And The Function Of Carbon Catabolite Repression, Cortney R. Halsey, Shulei Lei, Jacqueline K. Wax, Mckenzie K. Lehman, Austin S. Nuxoll, Laurey Steinke, Marat Sadykov, Robert Powers, Paul D. Fey Jan 2017

Amino Acid Catabolism In Staphylococcus Aureus And The Function Of Carbon Catabolite Repression, Cortney R. Halsey, Shulei Lei, Jacqueline K. Wax, Mckenzie K. Lehman, Austin S. Nuxoll, Laurey Steinke, Marat Sadykov, Robert Powers, Paul D. Fey

Department of Chemistry: Faculty Publications

Staphylococcus aureus must rapidly adapt to a variety of carbon and nitrogen sources during invasion of a host. Within a staphylococcal abscess, preferred carbon sources such as glucose are limiting, suggesting that S. aureus survives through the catabolism of secondary carbon sources. S. aureus encodes pathways to catabolize multiple amino acids, including those that generate pyruvate, 2-oxoglutarate, and oxaloacetate. To assess amino acid catabolism, S. aureus JE2 and mutants were grown in complete defined medium containing 18 amino acids but lacking glucose (CDM). A mutation in the gudB gene, coding for glutamate dehydrogenase, which generates 2-oxoglutarate from glutamate, significantly reduced …


Laterally Extended Atomically Precise Graphene Nanoribbons With Improved Electrical Conductivity For Efficient Gas Sensing, Mohammad Mehdi Pour, Andrey Lashkov, Adrian Radocea, Ximeng Liu, Tao Sun, Alexey Lipatov, Rafal A. Korlacki, Mikhail Shekhirev, Narayana R. Aluru, Joseph W. Lyding, Victor Sysoev, Alexander Sinitskii Jan 2017

Laterally Extended Atomically Precise Graphene Nanoribbons With Improved Electrical Conductivity For Efficient Gas Sensing, Mohammad Mehdi Pour, Andrey Lashkov, Adrian Radocea, Ximeng Liu, Tao Sun, Alexey Lipatov, Rafal A. Korlacki, Mikhail Shekhirev, Narayana R. Aluru, Joseph W. Lyding, Victor Sysoev, Alexander Sinitskii

Department of Chemistry: Faculty Publications

Narrow atomically precise graphene nanoribbons hold great promise for electronic and optoelectronic applications, but the previously demonstrated nanoribbon-based devices typically suffer from low currents and mobilities. In this study, we explored the idea of lateral extension of graphene nanoribbons for improving their electrical conductivity. We started with a conventional chevron graphene nanoribbon, and designed its laterally extended variant. We synthesized these new graphene nanoribbons in solution and found that the lateral extension results in decrease of their electronic bandgap and improvement in the electrical conductivity of nanoribbon-based thin films. These films were employed in gas sensors and an electronic nose …


Nanomaterials As Stationary Phases And Supports In Liquid Chromatography: A Review, Sandya Beeram, Elliott Rodriguez, Suresh Doddavenkatanna, Zhao Li, Allegra Pekarek, Darin Peev, Kathryn Goerl, Gianfranco Trovato, Tino Hofmann, David S. Hage Jan 2017

Nanomaterials As Stationary Phases And Supports In Liquid Chromatography: A Review, Sandya Beeram, Elliott Rodriguez, Suresh Doddavenkatanna, Zhao Li, Allegra Pekarek, Darin Peev, Kathryn Goerl, Gianfranco Trovato, Tino Hofmann, David S. Hage

Department of Chemistry: Faculty Publications

The development of various nanomaterials over the last few decades has led to many applications for these materials in liquid chromatography (LC). This review will look at the types of nanomaterials that have been incorporated into LC systems and the applications that have been explored for such systems. A number of carbon-based nanomaterials and inorganic nanomaterials have been considered for use in LC, ranging from carbon nanotubes, fullerenes and nanodiamonds to metal nanoparticles and nanostructures based on silica, alumina, zirconia and titanium dioxide. Many ways have been described for incorporating these nanomaterials into LC systems. These methods have included covalent …


A Surface-Stabilized Ozonide Triggers Bromide Oxidation At The Aqueous Solution-Vapour Interface, Luca Artiglia, Jacinta Edebeli, Fabrizio Orlando, Shuzhen Chen, Ming-Tao Lee, Pablo Corral Arroyo, Anina Gilgen, Thorsten Bartels-Rausch, Armin Kleibert, Mario Vazdar, Marcelo Andrea Carignano, Joseph S. Francisco, Paul B. Shepson, Ivan Gladich, Markus Ammann Jan 2017

A Surface-Stabilized Ozonide Triggers Bromide Oxidation At The Aqueous Solution-Vapour Interface, Luca Artiglia, Jacinta Edebeli, Fabrizio Orlando, Shuzhen Chen, Ming-Tao Lee, Pablo Corral Arroyo, Anina Gilgen, Thorsten Bartels-Rausch, Armin Kleibert, Mario Vazdar, Marcelo Andrea Carignano, Joseph S. Francisco, Paul B. Shepson, Ivan Gladich, Markus Ammann

Department of Chemistry: Faculty Publications

Oxidation of bromide in aqueous environments initiates the formation of molecular halogen compounds, which is important for the global tropospheric ozone budget. In the aqueous bulk, oxidation of bromide by ozone involves a [Br•OOO−] complex as intermediate. Here we report liquid jet X-ray photoelectron spectroscopy measurements that provide direct experimental evidence for the ozonide and establish its propensity for the solution-vapor interface. Theoretical calculations support these findings, showing that water stabilizes the ozonide and lowers the energy of the transition state at neutral pH. Kinetic experiments confirm the dominance of the heterogeneous oxidation route established by this precursor …


Cytotoxic Polyketides With An Oxygen-Bridged Cyclooctadiene Core Skeleton From The Mangrove Endophytic Fungus Phomosis Sp. A818, Wei Zhang, Baobing Zhao, Liangcheng Du, Yuemao Shen Jan 2017

Cytotoxic Polyketides With An Oxygen-Bridged Cyclooctadiene Core Skeleton From The Mangrove Endophytic Fungus Phomosis Sp. A818, Wei Zhang, Baobing Zhao, Liangcheng Du, Yuemao Shen

Department of Chemistry: Faculty Publications

Plant endophytic microorganisms represent a largely untapped resource for new bioactive natural products. Eight polyketide natural products were isolated from a mangrove endophytic fungus Phomosis sp. A818. The structural elucidation of these compounds revealed that they share a distinct feature in their chemical structures, an oxygen-bridged cyclooctadiene core skeleton. The study on their structure–activity relationship showed that the α,β-unsaturated δ-lactone moiety, as exemplified in compounds 1 and 2, was critical to the cytotoxic activity of these compounds. In addition, compound 4 might be a potential agonist of AMPK (5'-adenosine monophosphate-activated protein kinase).


Chemoselective Alteration Of Fluorophore Scaffolds As A Strategy For The Development Of Ratiometric Chemodosimeters, Xinqi Zhou, Lauren Lesiak, Rui Lai, Jon R. Beck, Jia Zhao, Christian Elowsky, Hui Li, Cliff I. Stains Jan 2017

Chemoselective Alteration Of Fluorophore Scaffolds As A Strategy For The Development Of Ratiometric Chemodosimeters, Xinqi Zhou, Lauren Lesiak, Rui Lai, Jon R. Beck, Jia Zhao, Christian Elowsky, Hui Li, Cliff I. Stains

Department of Chemistry: Faculty Publications

Ratiometric sensors generally couple binding events or chemical reactions at a distal site to changes in the fluorescence of a core fluorophore scaffold. However, such approaches are often hindered by spectral overlap of the product and reactant species. We provide a strategy to design ratiometric sensors that display dramatic spectral shifts by leveraging the chemoselective reactivity of novel functional groups inserted within fluorophore scaffolds. As a proof-of-principle, fluorophores containing a borinate (RF620) or silanediol (SiOH2R) functionality at the bridging position of the xanthene ring system are developed as endogenous H2O2 sensors. Both …


The Future Of Nmr-Based Metabolomics, John L. Markley, Rafael Bruschweiler, Arthur S. Edison, Hamid R. Eghbalnia, Robert Powers, Daniel Raftery, David S. Wishart Jan 2017

The Future Of Nmr-Based Metabolomics, John L. Markley, Rafael Bruschweiler, Arthur S. Edison, Hamid R. Eghbalnia, Robert Powers, Daniel Raftery, David S. Wishart

Department of Chemistry: Faculty Publications

The two leading analytical approaches to metabolomics are mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy. Although currently overshadowed by MS in terms of numbers of compounds resolved, NMR spectroscopy offers advantages both on its own and coupled with MS. NMR data are highly reproducible and quantitative over a wide dynamic range and are unmatched for determining structures of unknowns. NMR is adept at tracing metabolic pathways and fluxes using isotope labels. Moreover, NMR is non-destructive and can be utilized in vivo. NMR results have a proven track record of translating in vitro findings to in vivo clinical …


Resolving The Cofactor-Binding Site In The Proline Biosynthetic Enzyme Human Pyrroline-5-Carboxylate Reductase 1, Emily M. Christensen, Sagar M. Patel, David A. Korasick, Ashley C. Campbell, Kurt L. Krause, Donald F. Becker, John J. Tanner Jan 2017

Resolving The Cofactor-Binding Site In The Proline Biosynthetic Enzyme Human Pyrroline-5-Carboxylate Reductase 1, Emily M. Christensen, Sagar M. Patel, David A. Korasick, Ashley C. Campbell, Kurt L. Krause, Donald F. Becker, John J. Tanner

Department of Chemistry: Faculty Publications

Pyrroline-5-carboxylate reductase (PYCR) is the final enzyme in proline biosynthesis, catalyzing the NAD(P)H-dependent reduction of [?]1-pyrroline-5-carboxylate (P5C) to proline. Mutations in the PYCR1 gene alter mitochondrial function and cause the connective tissue disorder cutis laxa. Furthermore, PYCR1 is overexpressed in multiple cancers, and the PYCR1 knock-out suppresses tumorigenic growth, suggesting that PYCR1 is a potential cancer target. However, inhibitor development has been stymied by limited mechanistic details for the enzyme, particularly in light of a previous crystallographic study that placed the cofactor-binding site in the C-terminal domain rather than the anticipated Rossmann fold of the N-terminal domain. To fill this …


Indole-Induced Reversion Of Intrinsic Multiantibiotic Resistance In Lysobacter Enzymogenes, Yong Han, Yan Wang, Yameng Yu, Haotong Chen, Yuemao Shen, Liangcheng Du Jan 2017

Indole-Induced Reversion Of Intrinsic Multiantibiotic Resistance In Lysobacter Enzymogenes, Yong Han, Yan Wang, Yameng Yu, Haotong Chen, Yuemao Shen, Liangcheng Du

Department of Chemistry: Faculty Publications

Lysobacter species are a group of environmental bacteria that are emerging as a new source of antibiotics. One characteristic of Lysobacter is intrinsic resistance to multiple antibiotics, which had not been studied. To understand the resistance mechanism, we tested the effect of blocking two-component regulatory systems (TCSs) on the antibiotic resistance of Lysobacter enzymogenes, a prolific producer of antibiotics. Upon treatment with LED209, an inhibitor of the widespread TCS QseC/QseB, L. enzymogenes produced a large amount of an unknown metabolite that was barely detectable in the untreated culture. Subsequent structural elucidation by nuclear magnetic resonance (NMR) unexpectedly revealed that …


Synthesis Of Cerium Oxide Nanorods, Chin Li Cheung, Zane Charles Gernhart Jan 2017

Synthesis Of Cerium Oxide Nanorods, Chin Li Cheung, Zane Charles Gernhart

Department of Chemistry: Faculty Publications

Cerium oxide nanorods having a variety of aspect ratios can be produced by providing a first mixture that includes a cerium precursor material, and using microwave to heat the first mixture to a first temperature for a period of time to produce first plurality of cerium oxide nanorods having a first range of aspect ratios. A second mixture that includes a cerium precursor material heated using microwave to a second temperature for a period of time to produce second plurality of cerium oxide nanorods having a second range of aspect ratios. The first plurality of cerium oxide nanorods and the …


Human Serine Racemase Structure/Activity Relationship Studies Provide Mechanistic Insight And Point To Position 84 As A Hot Spot For Β-Elimination Function, David L. Nelson, Greg A. Applegate, Matthew L. Beio, Danielle L. Graham, David B. Berkowitz Jan 2017

Human Serine Racemase Structure/Activity Relationship Studies Provide Mechanistic Insight And Point To Position 84 As A Hot Spot For Β-Elimination Function, David L. Nelson, Greg A. Applegate, Matthew L. Beio, Danielle L. Graham, David B. Berkowitz

Department of Chemistry: Faculty Publications

There is currently great interest in human serine racemase, the enzyme responsible for producing the NMDA co-agonist D-serine. Reported correlation of D-serine levels with disorders including Alzheimer’s disease, ALS, and ischemic brain damage (elevated D-serine) and schizophrenia (reduced D-serine) has further piqued this interest. Reported here is a structure/activity relationship study of position Ser84, the putative re-face base. In the most extreme case of functional reprogramming, the S84D mutant displays a dramatic reversal of β-elimination substrate specificity in favor of L-serine over the normally preferred L-serine-O-sulfate (~1200-fold change in kcat/Km …


Assessment Of Metabolic Changes In Mycobacterium Smegmatis Wild Type And Alr Mutant Strains: Evidence For A New Pathway Of D-Alanine Biosynthesis., Darrell D. Marshall, Steven Halouska, Denise K. Zinniel, Robert J. Fenton, Katie Kenealy, Harpreet K. Chahal, Govardhan Rathnaiah, Raul G. Barletta, Robert Powers Jan 2017

Assessment Of Metabolic Changes In Mycobacterium Smegmatis Wild Type And Alr Mutant Strains: Evidence For A New Pathway Of D-Alanine Biosynthesis., Darrell D. Marshall, Steven Halouska, Denise K. Zinniel, Robert J. Fenton, Katie Kenealy, Harpreet K. Chahal, Govardhan Rathnaiah, Raul G. Barletta, Robert Powers

Department of Chemistry: Faculty Publications

In mycobacteria, D-alanine is an essential precursor for peptidoglycan biosynthesis. The only confirmed enzymatic pathway to form D-alanine is through the racemization of L-alanine by alanine racemase (Alr, EC 5.1.1.1). Nevertheless, the essentiality of Alr in Mycobacterium tuberculosis and Mycobacterium smegmatis for cell survivability in the absence of D-alanine has been a point of controversy with contradictory results reported in the literature. To address this issue, we examined the effects of alr inactivation on the cellular metabolism of M. smegmatis. The M. smegmatis alr insertion mutant TAM23 exhibited essentially identical growth to wild type mc2155 in the …


Transcriptional And Antagonistic Responses Of Biocontrol Strain Lysobacter Enzymogenes Oh11 To The Plant Pathogenic Oomycete Pythium Aphanidermatum, Yangyang Zhao, Guoliang Qian, Yuan Chen, Liangcheng Du, Fengquan Liu Jan 2017

Transcriptional And Antagonistic Responses Of Biocontrol Strain Lysobacter Enzymogenes Oh11 To The Plant Pathogenic Oomycete Pythium Aphanidermatum, Yangyang Zhao, Guoliang Qian, Yuan Chen, Liangcheng Du, Fengquan Liu

Department of Chemistry: Faculty Publications

Lysobacter enzymogenes is a ubiquitous, beneficial, plant-associated bacterium emerging as a novel biological control agent. It has the potential to become a new source of antimicrobial secondary metabolites such as the Heat-Stable Antifungal Factor (HSAF), which is a broad-spectrum antimycotic with a novel mode of action. However, very little information about how L. enzymogenes detects and responds to fungi or oomycetes has been reported. An in vitro confrontation bioassay between the pathogenic oomycete Pythium aphanidermatum and the biocontrol bacterial strain L. enzymogenes OH11 was used to analyze the transcriptional changes in the bacteria that were induced by the oomycetes. Analysis …