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Articles 781 - 810 of 2100

Full-Text Articles in Chemistry

Dom Control Of Mercury Methylation In The Water Column Of A Meromictic Lake, Madalyn Bozinski May 2019

Dom Control Of Mercury Methylation In The Water Column Of A Meromictic Lake, Madalyn Bozinski

Renée Crown University Honors Thesis Projects - All

The trophic transfer and bioaccumulation of methyl mercury (MeHg) in aquatic ecosystems is a substantial concern, resulting in fish consumption advisories worldwide. Aquatic ecosystems have been identified as the critical environments that breed production of MeHg and low levels of initial accumulation in biota. MeHg production is a microbially-mediated process, occurring primarily at the transition between oxic and anoxic environments. This research aimed to assess the extent to which dissolved organic matter (DOM) affects methylation of mercury in the oligotrophic meromictic lake, Green Lake, in Fayetteville, NY and the warm monomictic lake, Seneca Lake, in Geneva, NY. General physical parameters …

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Multiple Local Σ-Aromaticity Of Nonagermanide Clusters, Nikolay V. Tkachenko, Alexander I. Boldyrev Apr 2019

Multiple Local Σ-Aromaticity Of Nonagermanide Clusters, Nikolay V. Tkachenko, Alexander I. Boldyrev

Chemistry and Biochemistry Faculty Publications

Nonagermanide clusters are widely used in inorganic synthesis and are actively studied by experimentalists and theoreticians. However, chemical bonding of such versatile species is still not completely understood. In our work we deciphered a bonding pattern for various experimentally obtained nonagermanide species. We localized the electron density via the AdNDP algorithm for the model structures ([Ge9]4−, [Ge9{P(NH2)2}3]−, Cu[Ge9{P(NH2)2}3] and Cu(NHC)[Ge9{P(NH2)2}3]) and obtained a simple and chemically intuitive bonding pattern which …

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Generalizing Metallocene Mechanochemistry To Ruthenocene Mechanophores, Ye Sha, Yudi Zhang, Enhua Xu, C Wayne Mcalister, Tianyu Zhu, Stephen L. Craig, Chuanbing Tang Apr 2019

Generalizing Metallocene Mechanochemistry To Ruthenocene Mechanophores, Ye Sha, Yudi Zhang, Enhua Xu, C Wayne Mcalister, Tianyu Zhu, Stephen L. Craig, Chuanbing Tang

Faculty Publications

Recent reports have shown that ferrocene displays an unexpected combination of force-free stability and mechanochemical activity, as it acts as the preferred site of chain scission along the backbone of highly extended polymer chains. This observation raises the tantalizing question as to whether similar mechanochemical activity might be present in other metallocenes, and, if so, what features of metallocenes dictate their relative ability to act as mechanophores. In this work, we elucidate polymerization methodologies towards main-chain ruthenocene-based polymers and explore the mechanochemistry of ruthenocene. We find that ruthenocene, in analogy to ferrocene, acts as a highly selective site of main …

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Interactions Of (My) 6 (M = Zn, Cd; Y = O, S, Se) Quantum Dots With N-Bases, Mariusz Michalczyk, Wiktor Zierkiewicz, Steve Scheiner Apr 2019

Interactions Of (My) 6 (M = Zn, Cd; Y = O, S, Se) Quantum Dots With N-Bases, Mariusz Michalczyk, Wiktor Zierkiewicz, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

(MY)6 clusters, with M = Zn and Cd and Y = O, S, Se, form double-layer drum-like structures containing M–Y covalent bonds. The positive regions near the M atoms attract the N atom of both NH3 and NMe3 so as to form a noncovalent M···N bond. This bond is quite strong, with interaction energies exceeding 35 kcal/mol. The bond strength diminishes with reduced electronegativity of the Y atom (O > S > Se) and is stronger for M = Zn than for Cd. Trimethylation of the base enhances the bond strength. The interaction is dominated by the electrostatic component …

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Department Of Chemistry And Biochemistry 24th Departmental Symposium In Conjunction With The Petersheim Academic Exposition, Seton Hall University Apr 2019

Department Of Chemistry And Biochemistry 24th Departmental Symposium In Conjunction With The Petersheim Academic Exposition, Seton Hall University

Petersheim Academic Exposition

No abstract provided.

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The Nifz Accessory Protein Has An Equivalent Function In Maturation Of Both Nitrogenase Mofe Protein P-Clusters, Emilio Jimenez-Vicente, Zhi-Yong Yang, Julia S. Martin Del Campo, Valarie L. Cash, Lance C. Seefeldt, Dennis R. Dean Apr 2019

The Nifz Accessory Protein Has An Equivalent Function In Maturation Of Both Nitrogenase Mofe Protein P-Clusters, Emilio Jimenez-Vicente, Zhi-Yong Yang, Julia S. Martin Del Campo, Valarie L. Cash, Lance C. Seefeldt, Dennis R. Dean

Chemistry and Biochemistry Faculty Publications

The Mo-dependent nitrogenase comprises two interacting components called the Fe protein and the MoFe protein. The MoFe protein is an α2β2 heterotetramer that harbors two types of complex metalloclusters, both of which are necessary for N2reduction. One type is a 7Fe-9S-Mo-C-homocitrate species designated FeMo-cofactor, which provides the N2-binding catalytic site, and the other is an 8Fe-7S species designated the P-cluster, involved in mediating intercomponent electron transfer to FeMo-cofactor. The MoFe protein's catalytic partner, Fe protein, is also required for both FeMo-cofactor formation and the conversion of an immature form of P-clusters to the …

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Design And Synthesis Of A Novel Lsoxazoline As A Potential Pam-Agonist, Josselyn Roosenberg Apr 2019

Design And Synthesis Of A Novel Lsoxazoline As A Potential Pam-Agonist, Josselyn Roosenberg

Honors Theses

Progression of Alzheimer's disease is associated with a loss of Ml receptor activation in the brain. However, a lack of clinical success following attempts to activate the Ml receptor at the orthosteric site has contributed to a transition towards the allosteric pocket of the receptor. Here, positive allosteric modulators (PAMs) interact to potentiate the acetylcholine response. Recent research proposes that optimization of PAM activity at the expense of intrinsic agonism may posit a means to limit adverse side effects. Therefore, this project proposes a design and synthesis of a novel isoxazoline as a potent PAM agent with weak intrinsic agonism.

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Analysis Of Dl-Amino Acid Ratios In Eggshells Using Reverse Phase-High Pressure Liquid Chromatography, Gergana Milkova Apr 2019

Analysis Of Dl-Amino Acid Ratios In Eggshells Using Reverse Phase-High Pressure Liquid Chromatography, Gergana Milkova

Honors Theses

HPLC methodology was developed to determine the concentrations and ratios of D to L amino acids in emu and ostrich eggshells treated with heat at different temperatures . We aimed to determine an internal standard and how ratios were affected under different conditions. An HPLC method was determined that gave consistent retention times and satisfactory enantioseparation . Calibration curves for each amino acid were developed from single and multi-amino acid containing dilution series producing a model that most closely replicates the eggshell-extracted amino acids.

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Isolation And Characterization Of Novel Arginine-Derived Heterocyclic Amines, Nathaniel Srikureja Apr 2019

Isolation And Characterization Of Novel Arginine-Derived Heterocyclic Amines, Nathaniel Srikureja

Honors Theses

Most known heterocyclic amines (HCAs) are potent mutagens present at significant concentrations in cooked meats, and can be synthesized from burned mixtures of L-creatin(in)e with various amino acids. We hypothesize that novel mutagenic HCAs may be synthesized from a heated plant-based food simulating binary amino acid mL'\:ture: L-arginine and L-threonine. A two-part solid phase extraction was used to separate nitrogen heterocycles from byproducts followed by prep­ HPLC and the Ames mutagenicity assay using Salmonella TA98 to determine the mutagenicity of various isolates. The results indicate that this binary amino acid mixture does not yield a mutagenic sample.

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Synthesis Of An Ideal Inhibitor For The Lpxc Enzyme, Taejun Lee Apr 2019

Synthesis Of An Ideal Inhibitor For The Lpxc Enzyme, Taejun Lee

Honors Theses

Due to the growing need of antibiotics in modern day medicine, this study attempts to apply a method of medicinal chemistry that would create a novel inhibitor for a lesser known target of gram negative bacteria, the LpxC enzyme. This study proposes that a synthetic plan which consists of combining components of different molecules would create a more effective inhibitor. These components include a binding group for the active site of the enzyme, a hydrophobic chain which has been shown to interact with an allosteric site on the LpxC enzyme, and the isoxazoline ring which interacts with the zinc ion. …

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Effects Of Electrical Stimulation On Glioma Cells In Vitro With Implications For Treating Chronic Pain: Development Of A Model System, David C. Platt Apr 2019

Effects Of Electrical Stimulation On Glioma Cells In Vitro With Implications For Treating Chronic Pain: Development Of A Model System, David C. Platt

Theses and Dissertations

Glial cells comprise over 70% of the central nervous system cells and exhibit diverse functions including regulation of synaptic transmission, neuron protection/repair, maintenance of neuronal metabolism, and are implicated in the development of persistent neuropathic pain. In addition, a perturbation in the concentration of intracellular reactive oxygen species (ROS) and reactive nitrogen species (RNS) has likewise been associated with the development of a chronic pain state. This perturbation in ROS/RNS creates an environment of oxidative stress. However, the mechanism by which the pain signal transmission is modulated, and the roles ROS play in the perpetuation of the pain state are …

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Developing Tale Proteins As A Biosensor For Detecting Pathogen Specific Double-Stranded Dna, Kathrine Gaiko Apr 2019

Developing Tale Proteins As A Biosensor For Detecting Pathogen Specific Double-Stranded Dna, Kathrine Gaiko

Mahurin Honors College Capstone Experience/Thesis Projects

Transcription activator-like effector (TALE) proteins are important for DNA binding. They bind to specific nucleotide sequences by the use of two residues in each repeat allowing them to target specific DNA sequences. Their modular structure makes TALEs advantageous over other DNA binding proteins such as zinc finger proteins. Zinc finger proteins (ZFP) use a finger like projection to bind 3-4 subsequence base pairs while TALE proteins use two amino acid residues in each repeat to bind one nucleotide. ZFP can use SEER-Lac system for colorimetric detection, while TALE proteins can use fluorescence labeling with Alexa for detection of binding to …

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Study Of The Effects Of Silver Ions And Silver Nanoparticles On Embryonic Development, Martha Sharisha Johnson Apr 2019

Study Of The Effects Of Silver Ions And Silver Nanoparticles On Embryonic Development, Martha Sharisha Johnson

Biomedical Sciences Theses & Dissertations

This dissertation focuses on the study of the toxicity of metal nanoparticles (NPs) and their ions on the development of zebrafish embryos, aiming to understand unique biological effects of NPs and ions, and design new in vivo assays to characterize the toxicity of these metal NPs and metal ions. Currently, the underlying molecular mechanisms of biological effects of nanomaterials are partially understood. Some studies assume that the toxic effects of NPs can be attributed to the release of their ions. We investigate the effects of silver NPs (Ag NPs) and silver ions (Ag+ ions) on the embryonic development of zebrafish …

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Optical Stability Of 1,1′-Binaphthyl Derivatives, Nikolay V. Tkachenko, Steve Scheiner Mar 2019

Optical Stability Of 1,1′-Binaphthyl Derivatives, Nikolay V. Tkachenko, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

The racemization process of various 1,1′-binaphthyl derivatives is studied by quantum calculations. The preferred racemization pathway passes through a transition state belonging to the Ci symmetry group. The energy barrier for this process is independent of solvation, the electron-withdrawing/releasing power of substituents, or their ability to engage in H-bonds within the molecule. The primary factor is instead the substituent size. The barrier is thus reduced when the −OH groups of 1,1′-bi-2-naphthol are replaced by H. There is a drop in the barrier also when the substituents are moved from the 2,2′ positions to 6,6′, where they will not come …

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Production Of Secondary Organic Aerosol During Aging Of Biomass Burning Smoke From Fresh Fuels And Its Relationship To Voc Precursors, A. T. Ahern, E. S. Robinson, D. S. Tkacik, R. Saleh, L. E. Hatch, K. C. Barsanti, C. E. Stockwell, R. J. Yokelson, A. A. Presto, A. L. Robinson, R. C. Sullivan, N. M. Donahue Mar 2019

Production Of Secondary Organic Aerosol During Aging Of Biomass Burning Smoke From Fresh Fuels And Its Relationship To Voc Precursors, A. T. Ahern, E. S. Robinson, D. S. Tkacik, R. Saleh, L. E. Hatch, K. C. Barsanti, C. E. Stockwell, R. J. Yokelson, A. A. Presto, A. L. Robinson, R. C. Sullivan, N. M. Donahue

Chemistry and Biochemistry Faculty Publications

After smoke from burning biomass is emitted into the atmosphere, chemical and physical processes change the composition and amount of organic aerosol present in the aged, diluted plume. During the fourth Fire Lab at Missoula Experiment, we performed smog-chamber experiments to investigate formation of secondary organic aerosol (SOA) and multiphase oxidation of primary organic aerosol (POA). We simulated atmospheric aging of diluted smoke from a variety of biomass fuels while measuring particle composition using high-resolution aerosol mass spectrometry. We quantified SOA formation using a tracer ion for low-volatility POA as a reference standard (akin to a naturally occurring internal standard). …

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In Situ Measurements Of Trace Gases, Pm, And Aerosol Optical Properties During The 2017 Nw Us Wildfire Smoke Event, Vanessa Selimovic, Robert J. Yokelson, Gavin R. Mcmeeking, Sarah Coefield Mar 2019

In Situ Measurements Of Trace Gases, Pm, And Aerosol Optical Properties During The 2017 Nw Us Wildfire Smoke Event, Vanessa Selimovic, Robert J. Yokelson, Gavin R. Mcmeeking, Sarah Coefield

Chemistry and Biochemistry Faculty Publications

In mid-August through mid-September of 2017 a major wildfire smoke and haze episode strongly impacted most of the NW US and SW Canada. During this period our ground-based site in Missoula, Montana, experienced heavy smoke impacts for ∼ 500h (up to 471μ-3 hourly average PM2.5). We measured wildfire trace gases, PM2.5 (particulate matter ≤2.5μm in diameter), and black carbon and submicron aerosol scattering and absorption at 870 and 401nm. This may be the most extensive real-time data for these wildfire smoke properties to date. Our range of trace gas ratios for δNH3 δCO and δC2H4 δCO confirmed that the smoke …

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Improving Coupled Enzyme Assays With Capillary Electrophoresis, Thu Hoai Nguyen Mar 2019

Improving Coupled Enzyme Assays With Capillary Electrophoresis, Thu Hoai Nguyen

LSU Doctoral Dissertations

The goal of this project is to address limitations of coupled enzyme assays using capillary electrophoresis (CE). In some enzyme assays, it is ineffective to directly detect products and substrates spectroscopically (absorption or fluorescence). Coupling the enzyme-catalyzed reaction of interest with another enzyme-catalyzed reaction allows for indirect detection of product formation or substrate depletion for the target enzyme. While conventional coupled enzyme assays are facile for kinetic measurements, they can be problematic for inhibition screening due to spectral and inhibitor interferences. To address these limitations of coupled assays, CE has been used to develop enzyme assays for acetyl-coenzyme A carboxylase …

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Purification And Characterization Of A Nonspecific Lipid Transfer Protein 1 (Nsltp1) From Ajwain (Trachyspermum Ammi) Seeds, Meshal Nazeer, Humera Waheed, Maria Saeed, Saman Yousuf Ali, M. Iqbal Choudhary, Zaheer Ul-Haq, Aftab Ahmed Mar 2019

Purification And Characterization Of A Nonspecific Lipid Transfer Protein 1 (Nsltp1) From Ajwain (Trachyspermum Ammi) Seeds, Meshal Nazeer, Humera Waheed, Maria Saeed, Saman Yousuf Ali, M. Iqbal Choudhary, Zaheer Ul-Haq, Aftab Ahmed

Pharmacy Faculty Articles and Research

Ajwain (Trachyspermum ammi) belongs to the family Umbelliferae, is commonly used in traditional, and folk medicine due to its carminative, stimulant, antiseptic, diuretic, antihypertensive, and hepatoprotective activities. Non-specific lipid transfer proteins (nsLTPs) reported from various plants are known to be involved in transferring lipids between membranes and in plants defense response. Here, we describe the complete primary structure of a monomeric non-specific lipid transfer protein 1 (nsLTP1), with molecular weight of 9.66 kDa, from ajwain seeds. The nsLTP1 has been purified by combination of chromatographic techniques, and further characterized by mass spectrometry, and Edman degradation. The ajwain nsLTP1 …

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Molecular Rotation In 3 Dimensions At An Air/Water Interface Using Femtosecond Time Resolved Sum Frequency Generation, Yi Rao, Yuqin Qian, Gang-Hua Deng, Ashlie Kinross, Nicholas J. Turro, Kenneth B. Eisenthal Mar 2019

Molecular Rotation In 3 Dimensions At An Air/Water Interface Using Femtosecond Time Resolved Sum Frequency Generation, Yi Rao, Yuqin Qian, Gang-Hua Deng, Ashlie Kinross, Nicholas J. Turro, Kenneth B. Eisenthal

Chemistry and Biochemistry Faculty Publications

This paper presents the first study of the rotations of rigid molecules in 3 dimensions at the air/water interface, using the femtosecond time resolved sum frequency generation (SFG) technique. For the purpose of this research, the aromatic dye molecule C153 was chosen as an example of a molecule having two functional groups that are SFG active, one being the hydrophilic −−C==O group and the other the hydrophobic −−CF3 group. From polarized SFG measurements, the orientations of the two chromophores with respect to the surface normal were obtained. On combining these results with the known relative orientation of the two …

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Total Reflection X-Ray Fluorescence, Martina Schmeling Mar 2019

Total Reflection X-Ray Fluorescence, Martina Schmeling

Chemistry: Faculty Publications and Other Works

Total reflection X-ray fluorescence (TXRF) spectrometry is a non-destructive and surface sensitive multi-element analytical method based on energy dispersive X-ray fluorescence spectrometry with detection limits in the lower picogram range. It utilizes the total reflection of the primary X-ray beam at or below the critical angle of incidence. At this angle, the fluorescence intensity is substantially enhanced for samples present as small granular residue or as thin homogenous layer deposited at the surface of a thick substrate. Generally, two types of application exist: micro- and trace-analysis as well as surface and thin-layer analysis. For micro- and traceanalysis, a small amount …

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Transition State Interactions In A Promiscuous Enzyme: Sulfate And Phosphate Monoester Hydrolysis By Pseudomonas Aeruginosa Arylsulfatase, Bert Van Loo, Ryan Berry, Usa Boonyuen, Mark F. Mohamed, Marko Golicnik, Alvan C. Hengge, Florian Hollfelder Feb 2019

Transition State Interactions In A Promiscuous Enzyme: Sulfate And Phosphate Monoester Hydrolysis By Pseudomonas Aeruginosa Arylsulfatase, Bert Van Loo, Ryan Berry, Usa Boonyuen, Mark F. Mohamed, Marko Golicnik, Alvan C. Hengge, Florian Hollfelder

Chemistry and Biochemistry Faculty Publications

Pseudomonas aeruginosa arylsulfatase (PAS) hydrolyses sulfate and, promiscuously, phosphate monoesters. Enzyme-catalyzed sulfate transfer is crucial to a wide variety of biological processes, but detailed studies of the mechanistic contributions to its catalysis are lacking. We present linear free energy relationships (LFERs) and kinetic isotope effects (KIEs) of PAS and active site mutants that suggest a key role for leaving group (LG) stabilization. In LFERs PASWT has a much less negative Brønsted coefficient (ßleaving group obs-Enz=-0.33) than the uncatalyzed reaction (ßleaving group obs=-1.81). This situation is diminished when cationic active site groups are exchanged for alanine. …

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Student-Faculty Collaborative Research Grant Report, Megan Bestwick Feb 2019

Student-Faculty Collaborative Research Grant Report, Megan Bestwick

Post-Grant Reports

Mitochondria are essential organelles in most eukaryotic cells because of their role in metabolism and the production of ATP by the oxidative phosphorylation (OXPHOS) pathway, as well as other key cellular processes. Metal cofactors, such as copper (Cu) and iron (Fe), are incorporated into OXPHOS protein complexes of yeast located within the inner membrane of the mitochondria. Misincorporation or modulation of these available metals in mitochondrial enzymes leads to the production of reactive oxygen species (ROS). ROS are reactive molecules containing oxygen such as peroxides, superoxide, and hydroxyl radicals. Yeast are a good model for studying aging and the effect …

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A New Multivariate Optical Computing Microelement And Miniature Sensor For Spectroscopic Chemical Sensing In Harsh Environments: Design, Fabrication, And Testing, Christopher M. Jones, Bin Dai, Jimmy Price, Jian Li, Megan Pearl, Bill Soltmann, Michael L. Myrick Feb 2019

A New Multivariate Optical Computing Microelement And Miniature Sensor For Spectroscopic Chemical Sensing In Harsh Environments: Design, Fabrication, And Testing, Christopher M. Jones, Bin Dai, Jimmy Price, Jian Li, Megan Pearl, Bill Soltmann, Michael L. Myrick

Faculty Publications

Multivariate optical computing (MOC) is a compressed sensing technique with the ability to provide accurate spectroscopic compositional analysis in a variety of different applications to multiple industries. Indeed, recent developments have demonstrated the successful deployment of MOC sensors in downhole/well-logging environments to interrogate the composition of hydrocarbon and other chemical constituents in oil and gas reservoirs. However, new challenges have necessitated sensors that operate at high temperatures and pressures (up to 230 °C and 138 MPa) as well as even smaller areas that require the miniaturization of their physical footprint. To this end, this paper details the design, fabrication, and …

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Exposure Characterization Of Haloacetic Acids In Humans For Exposure And Risk Assessment Applications: An Exploratory Study, Shahid Parvez, Jeffrey L. Ashby, Susana Y. Kimura, Susan D. Richardson Feb 2019

Exposure Characterization Of Haloacetic Acids In Humans For Exposure And Risk Assessment Applications: An Exploratory Study, Shahid Parvez, Jeffrey L. Ashby, Susana Y. Kimura, Susan D. Richardson

Faculty Publications

Disinfected water is the major source of haloacetic acids (HAAs) in humans, but their inter- and intra-individual variability for exposure and risk assessment applications is under-researched. Thus, we measured HAAs in cross-sectional and longitudinal urine and water specimens from 17 individuals. Five regulated HAAs—mono-, di-, and trichloroacetic acid (MCAA, DCAA, and TCAA) and mono- and dibromoacetic acid (MBAA and DBAA)—and one unregulated HAA—bromochloroacetic acid (BCAA)—were measured. Urinary DCAA, MBAA, DBAA, and BCAA levels were always below the limits of detection (LOD). Measured levels and interindividual variability of urinary MCAA were higher than urinary TCAA. Longitudinal urinary specimens showed MCAA levels …

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Solvation Thermodynamic Mapping In Computer Aided Drug Design, Steven Ramsey Feb 2019

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 …

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Pretargeted Radioimmunotherapy Utilizing The Inverse Electron Demand Diels-Alder Reaction, Rosemery Membreno Feb 2019

Pretargeted Radioimmunotherapy Utilizing The Inverse Electron Demand Diels-Alder Reaction, Rosemery Membreno

Dissertations, Theses, and Capstone Projects

Radioimmunotherapy capitalizes on the specificity and affinity of antibodies for their antigens to localize radioactivity at the tumor site. One limitation in using antibodies is their long circulation time, which can take days to weeks to fully clear from blood circulation. When a radioisotope is directly conjugated to this immunoglobulin vector, the red marrow and other healthy organs are receiving a constant radiation dose while it is in blood circulation. This not only harms healthy organs, but limits the dose of radioactivity that can be administered thus prolonging treatment. A promising alternative to limit the radiation dose to non-tumor tissue …

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Bisthioether Stapled Peptides Targeting Polycomb Repressive Complex 2 Gene Repression, Gan Zhang Feb 2019

Bisthioether Stapled Peptides Targeting Polycomb Repressive Complex 2 Gene Repression, Gan Zhang

Dissertations, Theses, and Capstone Projects

Interactions between proteins play a key role in nearly all cellular process, and therefore, disruption of such interactions may lead to many different types of cellular dysfunctions. Hence, pathologic protein-protein interactions (PPIs) constitute highly attractive drug targets and hold great potential for developing novel therapeutic agents for the treatment of incurable human diseases. Unfortunately, the identification of PPI inhibitors is an extremely challenging task, since traditionally used small molecule ligands are mostly unable to cover and anchor on the extensive flat surfaces that define those binary protein complexes. In contrast, large biomolecules such as proteins or peptides are ideal fits …

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Analysis Of Oxygen-18 Labeled Phosphate To Study Positional Isotope Experiments Using Lc-Qtof-Ms, Sujatha Chilakala, Iteen Cheng, Ireen Lee, Yan Xu Feb 2019

Analysis Of Oxygen-18 Labeled Phosphate To Study Positional Isotope Experiments Using Lc-Qtof-Ms, Sujatha Chilakala, Iteen Cheng, Ireen Lee, Yan Xu

Chemistry Faculty Publications

A method is proposed in this paper for the determination of oxygen-18 labeled phosphate so that positional isotope experiments using sensitive and rapid liquid chromatography–QTOF–mass spectrometry (LC-QTOF-MS) experiments can be carried out. The positional isotope exchange technique is a useful tool in understanding the mechanisms and kinetics of many enzyme-catalyzed reactions. Detection of the positions and concentration of these exchanged isotopes is the key. Gas chromatography–mass spectrometry (GC-MS) and nuclear magnetic resonance imaging are commonly used analytical techniques for measurement of 18O/16O, 31P and 15N isotope enrichment. Since these techniques either require a time-consuming derivatization …

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Catalytic Mechanism For The Conversion Of Salicylate Into Catechol By The Flavin-Dependent Monooxygenase Salicylate Hydroxylase, Débora M. A. Costa, Stefanya V. Gómez, Simara S. De Araújo, Mozart S. Pereira, Rosemeire B. Alves, Denize C. Favaro, Alvan C. Hengge, Ronaldo A. P. Nagem, Tiago A. S. Brandão Jan 2019

Catalytic Mechanism For The Conversion Of Salicylate Into Catechol By The Flavin-Dependent Monooxygenase Salicylate Hydroxylase, Débora M. A. Costa, Stefanya V. Gómez, Simara S. De Araújo, Mozart S. Pereira, Rosemeire B. Alves, Denize C. Favaro, Alvan C. Hengge, Ronaldo A. P. Nagem, Tiago A. S. Brandão

Chemistry and Biochemistry Faculty Publications

Salicylate hydroxylase (NahG) is a flavin-dependent monooxygenase that catalyzes the decarboxylative hydroxylation of salicylate into catechol in the naphthalene degradation pathway in Pseudomonas putida G7. We explored the mechanism of action of this enzyme in detail using a combination of structural and biophysical methods. NahG shares many structural and mechanistic features with other versatile flavin-dependent monooxygenases, with potential biocatalytic applications. The crystal structure at 2.0 Å resolution for the apo form of NahG adds a new snapshot preceding the FAD binding in flavin-dependent monooxygenases. The kcat/Km for the salicylate reaction catalyzed by the holo form is …

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Speciated And Total Emission Factors Of Particulate Organics From Burning Western Us Wildland Fuels And Their Dependence On Combustion Efficiency, Coty N. Jen, Lindsay E. Hatch, Vanessa Selimovic, Robert J. Yokelson, Robert Weber, Arantza E. Fernandez, Nathan M. Kreisberg, Kelley C. Barsanti, Allen H. Goldstein Jan 2019

Speciated And Total Emission Factors Of Particulate Organics From Burning Western Us Wildland Fuels And Their Dependence On Combustion Efficiency, Coty N. Jen, Lindsay E. Hatch, Vanessa Selimovic, Robert J. Yokelson, Robert Weber, Arantza E. Fernandez, Nathan M. Kreisberg, Kelley C. Barsanti, Allen H. Goldstein

Chemistry and Biochemistry Faculty Publications

Western US wildlands experience frequent and large-scale wildfires which are predicted to increase in the future. As a result, wildfire smoke emissions are expected to play an increasing role in atmospheric chemistry while negatively impacting regional air quality and human health. Understanding the impacts of smoke on the environment is informed by identifying and quantifying the chemical compounds that are emitted during wildfires and by providing empirical relationships that describe how the amount and composition of the emissions change based upon different fire conditions and fuels. This study examined particulate organic compounds emitted from burning common western US wildland fuels …

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