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Articles 5821 - 5850 of 15571

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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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Structural And Functional Characterization Of Sulfonium Carbon-Oxygen Hydrogen Bonding In The Deoxyamino Sugar Methyltransferase Tyim1, Robert J. Fick, Scott Horowitz, Brandon G. Mcdole, Mary C. Clay, Ryan A. Mehl, Hashim M. Al-Hashimi, Steve Scheiner, Raymond C. Trievel Feb 2019

Structural And Functional Characterization Of Sulfonium Carbon-Oxygen Hydrogen Bonding In The Deoxyamino Sugar Methyltransferase Tyim1, Robert J. Fick, Scott Horowitz, Brandon G. Mcdole, Mary C. Clay, Ryan A. Mehl, Hashim M. Al-Hashimi, Steve Scheiner, Raymond C. Trievel

Chemistry and Biochemistry Faculty Publications

The N-methyltransferase TylM1 from Streptomyces fradiae catalyzes the final step in the biosynthesis of the deoxyamino sugar mycaminose, a substituent of the antibiotic tylosin. The high-resolution crystal structure of TylM1 bound to the methyl donor S-adenosylmethionine (AdoMet) illustrates a network of carbon-oxygen (CH•••O) hydrogen bonds between the substrate’s sulfonium cation and residues within the active site. These interactions include hydrogen bonds between the methyl and methylene groups of the AdoMet sulfonium cation and the hydroxyl groups of Tyr14 and Ser120 in the enzyme. To examine the functions of these interactions, we generated Tyr14 to phenylalanine (Y14F) and Ser120 to alanine …

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Molecular Dynamics Simulations Of Substrate Release From Trypanosoma Cruzi Udp-Galactopyranose Mutase, Rodrigo Cossio-Pérez, Gustavo Pierdominici-Sottile, Pablo Sobrado, Juliana Palma Feb 2019

Molecular Dynamics Simulations Of Substrate Release From Trypanosoma Cruzi Udp-Galactopyranose Mutase, Rodrigo Cossio-Pérez, Gustavo Pierdominici-Sottile, Pablo Sobrado, Juliana Palma

Chemistry Faculty Research & Creative Works

The enzyme UDP-galactopyranose mutase (UGM) represents a promising drug target for the treatment of infections with Trypanosoma cruzi. We have computed the Potential of Mean Force for the release of UDP-galactopyranose from UGM, using Umbrella Sampling simulations. The simulations revealed the conformational changes that both substrate and enzyme undergo during the process. It was determined that the galactopyranose portion of the substrate is highly mobile and that the opening/closing of the active site occurs in stages. Previously uncharacterized interactions with highly conserved residues were also identified. These findings provide new pieces of information that contribute to the rational design of …

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Fundamental Limits Of Measuring Single-Molecule Rotational Mobility, Oumeng Zhang, Matthew D. Lew Feb 2019

Fundamental Limits Of Measuring Single-Molecule Rotational Mobility, Oumeng Zhang, Matthew D. Lew

Electrical & Systems Engineering Publications and Presentations

Various methods exist for measuring molecular orientation, thereby providing insight into biochemical activities at nanoscale. Since fluorescence intensity and not electric field is detected, these methods are limited to measuring even-order moments of molecular orientation. However, any measurement noise, for example photon shot noise, will result in nonzero measurements of any of these even-order moments, thereby causing rotationally-free molecules to appear to be partially constrained. Here, we build a model to quantify measurement errors in rotational mobility. Our theoretical framework enables scientists to choose the optimal single-molecule orientation measurement technique for any desired measurement accuracy and photon budget.

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Large Fatty Acid-Derived Aβ42 Oligomers Form Ring-Like Assemblies, Wenhui Xu, Dexter N. Dean, Kelli A. Stockmal, Sarah E. Morgan, Ulrich H.E. Hansmann, Vijayaraghavan Rangachari Feb 2019

Large Fatty Acid-Derived Aβ42 Oligomers Form Ring-Like Assemblies, Wenhui Xu, Dexter N. Dean, Kelli A. Stockmal, Sarah E. Morgan, Ulrich H.E. Hansmann, Vijayaraghavan Rangachari

Faculty Publications

As the primary toxic species in the etiology of Alzheimer disease (AD) are low molecular weight oligomers of Aβ, it is crucial to understand the structure of Aβ oligomers for gaining molecular insights into AD pathology. We have earlier demonstrated that in the presence of fatty acids, Aβ42 peptides assemble as 12-24mer oligomers. These Large Fatty Acid-derived Oligomers (LFAOs) exist predominantly as 12mers at low and as 24mers at high concentrations. The 12mers are more neurotoxic than the 24mers and undergo self-replication, while the latter propagate to morphologically distinct fibrils with succinct pathological consequences. In order to glean into their …

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Metal-Assisted Hydrolysis Reactions Involving Lipids: A Review, Dominique E. Williams, Kathryn B. Grant Feb 2019

Metal-Assisted Hydrolysis Reactions Involving Lipids: A Review, Dominique E. Williams, Kathryn B. Grant

Chemistry Faculty Publications

This report covers major advances in the use of metal ions and complexes to hydrolyze ester and phosphate ester lipid bonds. These metal-based Lewis acids have been investigated as catalysts to isolate fatty acids from biological sources, as probes to study phospholipid bilayer properties, as tools to examine signal transduction pathways, and as lead compounds toward the discovery of therapeutic agents. Metal ions that accelerate phosphate ester hydrolysis under mild conditions of temperature and pH may have the potential to mimic phospholipase activity in biochemical applications.

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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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X-Ray Fluorescence And Emission | Total Reflection X-Ray Fluorescence, Martina Schmeling Feb 2019

X-Ray Fluorescence And Emission | Total Reflection X-Ray Fluorescence, Martina Schmeling

Chemistry: Faculty Publications and Other Works

Total reflection X-ray fluorescence spectrometry (TXRF) is a trace elemental micro analysis technique based on conventional energy dispersive X-ray fluorescence. It has become increasingly popular in the last few decades and is applied in almost every field of trace elemental analysis where low detection limits and multi element capabilities are required. Like all X-ray techniques TXRF is non-destructive making it highly useful and important in areas where samples are precious and/or need to be available for further characterization. The ability of probing extremely small sample amounts makes TXRF a superior analytical technique for samples of limited amount. New table top …

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Substrate-Dependent Photoconductivity Dynamics In A High-Efficiency Hybrid Perovskite Alloy, Ali Moeed Tirmzi, Jeffrey A. Christians, Ryan P. Dwyer, David T. Moore, John A. Marohn Feb 2019

Substrate-Dependent Photoconductivity Dynamics In A High-Efficiency Hybrid Perovskite Alloy, Ali Moeed Tirmzi, Jeffrey A. Christians, Ryan P. Dwyer, David T. Moore, John A. Marohn

Faculty Publications

Films of (FA0.79MA0.16Cs0.05)0.97Pb(I0.84Br0.16)2.97 were grown over TiO2, SnO2, indium tin oxide (ITO), and NiO. Film conductivity was interrogated by measuring the in-phase and out-of-phase forces acting between the film and a charged microcantilever. We followed the films’ conductivity versus time, frequency, light intensity, and temperature (233−312 K). Perovskite conductivity was high and light-independent over ITO and NiO. Over TiO2 and SnO2, the conductivity was low in the dark,increased with light intensity, and persisted for 10’s of seconds after the light …

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Comparison Of Σ-Hole And Π-Hole Tetrel Bonds In Complexes Of Borazine With Th3f And F2to/H2to (T=C,Si,Ge), Jingru Zhang, Qingze Hu, Qing-Zhong Li, Steve Scheiner, Shufeng Liu Feb 2019

Comparison Of Σ-Hole And Π-Hole Tetrel Bonds In Complexes Of Borazine With Th3f And F2to/H2to (T=C,Si,Ge), Jingru Zhang, Qingze Hu, Qing-Zhong Li, Steve Scheiner, Shufeng Liu

Chemistry and Biochemistry Faculty Publications

The complexes between borazine and TH3F/F2TO/H2TO (T=C, Si, Ge) are investigated with high-level quantum chemical calculations. Borazine has three sites of negative electrostatic potential: the N atom, the ring center, and the H atom of the B-H bond, while TH3F and F2TO/H2TO provide the σ-hole and π-hole, respectively, for the tetrel bond. The N atom of borazine is the favored site for both the σ and π-hole tetrel bonds. Less stable dimers include a σ-tetrel bond to the borazine ring center and to the BH proton. The π-hole tetrel-bonded complexes are more strongly bound than aretheirσ-hole counterparts. Due to the …

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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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Viscosities, Diffusion Coefficients, And Mixing Times Of Intrinsic Fluorescent Organic Molecules In Brown Limonene Secondary Organic Aerosol And Tests Of The Stokes–Einstein Equation, Dagny A. Ullmann, Mallory L. Hinks, Adrian M. Maclean, Christopher Butenhoff, James W. Grayson, Kelley Barsanti, Jose L. Jimenez, Sergey A. Nizkorodov, Saeid Kamal, Allan K. Bertram Feb 2019

Viscosities, Diffusion Coefficients, And Mixing Times Of Intrinsic Fluorescent Organic Molecules In Brown Limonene Secondary Organic Aerosol And Tests Of The Stokes–Einstein Equation, Dagny A. Ullmann, Mallory L. Hinks, Adrian M. Maclean, Christopher Butenhoff, James W. Grayson, Kelley Barsanti, Jose L. Jimenez, Sergey A. Nizkorodov, Saeid Kamal, Allan K. Bertram

Physics Faculty Publications and Presentations

Viscosities and diffusion rates of organics within secondary organic aerosol (SOA) remain uncertain. Using the bead-mobility technique, we measured viscosities as a function of water activity (aw) of SOA generated by the ozonolysis of limonene followed by browning by exposure to NH3 (referred to as brown limonene SOA or brown LSOA). These measurements together with viscosity measurements reported in the literature show that the viscosity of brown LSOA increases by 3–5 orders of magnitude as the aw decreases from 0.9 to approximately 0.05. In addition, we measured diffusion coefficients of intrinsic fluorescent organic molecules within brown …

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Synthesis, Biological Evaluation And Molecular Modeling Studies Of Novel Chromone/Aza-Chromone Fused Α-Aminophosphonates As Src Kinase Inhibitors, S. Bapat, N. Viswanadh, M. Mujahid, Amir Nasrolahi Shirazi, Rakesh Tiwari, Keykavous Parang, M. Karthikeyan, M. Muthukrishnan, Renu Vyas Feb 2019

Synthesis, Biological Evaluation And Molecular Modeling Studies Of Novel Chromone/Aza-Chromone Fused Α-Aminophosphonates As Src Kinase Inhibitors, S. Bapat, N. Viswanadh, M. Mujahid, Amir Nasrolahi Shirazi, Rakesh Tiwari, Keykavous Parang, M. Karthikeyan, M. Muthukrishnan, Renu Vyas

Pharmacy Faculty Articles and Research

A series of novel chromone/aza-chromone fused α-aminophosphonate derivatives were synthesized in good yields using silica chloride as the catalyst. All the synthesized compounds were tested for their c-Src kinase inhibitory activity. Aza-chromone compound showed Src kinase inhibition with an IC50 value of 15.8 µM. The compounds were subjected to molecular docking and dynamics simulations to study the atomic level interactions with an unphosphorylated proto-oncogenic tyrosine protein kinase Src (PDB code 1Y57) as well as phosphorylated tyrosine protein kinase Src (PDB code 2H8H). Docking and molecular dynamic results revealed phosphorylated Src tyrosine kinase protein better results than unphosphorylated tyrosine Src kinase …

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Functional Polymers Through Mechanochemistry, Stephen Schrettl, Diedrik W.R. Balkenende, Céline Calvino, Marc Karman, Ana Lavrenova, Laura N. Neumann, Yoshimitsu Sagara, Ester Verde-Sesto, Michela Di Giannantonio, Yoan C. Simon, Katharina M. Fromm, Marco Lattuada, Christoph Weder Feb 2019

Functional Polymers Through Mechanochemistry, Stephen Schrettl, Diedrik W.R. Balkenende, Céline Calvino, Marc Karman, Ana Lavrenova, Laura N. Neumann, Yoshimitsu Sagara, Ester Verde-Sesto, Michela Di Giannantonio, Yoan C. Simon, Katharina M. Fromm, Marco Lattuada, Christoph Weder

Faculty Publications

While coupling mechanical and chemical processes is widespread in living organisms, the idea to harness the mechanically induced dissociation of weak covalent and non-covalent bonds to create artificial materials that respond to mechanical stimulation has only recently gained attention. Here we summarize our activities that mainly revolve around the exploitation of non-covalent interactions in (supramolecular) polymeric materials with the goal to translate mechanical stresses into useful, pre-defined events. Focusing on mechano- chromic polymers that alter their optical absorption or fluorescence properties, several new operating principles, mechanosensitive entities, and materials systems were developed. Such materials are expected to be useful for …

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Extra-Mitochondrial Cu/Zn Superoxide Dismutase (Sod1) Is Dispensable For Protection Against Oxidative Stress But Mediates Peroxide Signaling In Saccharomyces Cerevisiae, Claudia Montllor-Albalate, Alyson E. Colin, Bindu Chandrasekharan, Naimah Bolaji, Joshua L. Andersen, Franklin W. Outten, Amit R. Reddi Feb 2019

Extra-Mitochondrial Cu/Zn Superoxide Dismutase (Sod1) Is Dispensable For Protection Against Oxidative Stress But Mediates Peroxide Signaling In Saccharomyces Cerevisiae, Claudia Montllor-Albalate, Alyson E. Colin, Bindu Chandrasekharan, Naimah Bolaji, Joshua L. Andersen, Franklin W. Outten, Amit R. Reddi

Faculty Publications

Cu/Zn Superoxide Dismutase (Sod1) is a highly conserved and abundant metalloenzyme that catalyzes thedisproportionation of superoxide radicals into hydrogen peroxide and molecular oxygen. As a consequence, Sod1serves dual roles in oxidative stress protection and redox signaling by both scavenging cytotoxic superoxideradicals and producing hydrogen peroxide that can be used to oxidize and regulate the activity of downstreamtargets. However, the relative contributions of Sod1 to protection against oxidative stress and redox signaling arepoorly understood. Using the model unicellular eukaryote, Baker's yeast, we found that only a small fraction ofthe total Sod1 pool is required for protection against superoxide toxicity and that …

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Synthesis And Evaluation Of Novel Iodine-124 Labeled Nucleoside Analogs As Pet Imaging Agents To Predict Response To Gemcitabine Therapy, Kishore Kumar Gangangari Feb 2019

Synthesis And Evaluation Of Novel Iodine-124 Labeled Nucleoside Analogs As Pet Imaging Agents To Predict Response To Gemcitabine Therapy, Kishore Kumar Gangangari

Dissertations, Theses, and Capstone Projects

Gemcitabine (gem) is a nucleoside analog that is used to treat pancreatic cancers (PaCa), which have dismal prognosis and low survival rate. Though gem is used as first line of treatment for PaCa, the response rate is quite low (~30%). Currently, there is no a priori way to determine a responder from a non-responder to gem therapy either invasively or non-invasively. Any biomarker that can act as a prognostic indicator of gem response will greatly aid in selecting responsive patients to gem therapy and provide alternative options such as Folfirinox or other treatments to resistant patient population. Amongst various known …

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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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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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Carbohydrate Polymers As Controlled Release Devices For Pesticides, Soma Chakraborty, Maria Cleofe Neri-Badang Feb 2019

Carbohydrate Polymers As Controlled Release Devices For Pesticides, Soma Chakraborty, Maria Cleofe Neri-Badang

Chemistry Faculty Publications

Controlled release technology addresses problems associated with excessive use of toxic agricultural chemicals. This paper reviews the studies on the use of carbohydrate polymers as controlled release matrices for pesticides. Alginates, starch and its derivatives, chitosan, carboxymethylcellulose and ethylcellulose are some of the natural polymers discussed in this review. The advantages and disadvantages of these polymeric systems as well as the factors that affect pesticide release are presented. A discussion on the polymers’ encapsulation efficiency and release profile is also included, which will aid future researchers in identifying the suitable formulation for controlled release of pesticides. Combination of two polymers, …

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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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Potential Degradation Of Hexabromocyclododecane (Hbcdd) In Sediments: Stereoisomer Specific Reaction Of Hbcdd With Reduced Sulfur Species Or Fe(Ii) Bound To Iron Oxides, Xianmiao Zhang Feb 2019

Potential Degradation Of Hexabromocyclododecane (Hbcdd) In Sediments: Stereoisomer Specific Reaction Of Hbcdd With Reduced Sulfur Species Or Fe(Ii) Bound To Iron Oxides, Xianmiao Zhang

Dissertations, Theses, and Capstone Projects

The individual degradation rates of the three dominant stereoisomers (alpha, beta, gamma) of hexabromocyclododecane (HBCDD) with bisulfide and polysulfides were investigated at pH 9-10 in methanol/water solutions at two different temperatures (25 °C and 40 °C). alpha-HBCDD reacts significantly slower than beta-HBCDD and gamma-HBCDD. It was also observed that the reaction of HBCDD with polysulfides is faster than with bisulfide. For the reaction of HBCDD with bisulfide, the experiments were performed in 20% water/80% methanol, 50% water/50% methanol and 80% water/20% methanol at 40 °C. It was determined that the solvent polarity affects the reaction and the second-order rate constants …

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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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Functionalized Carbon Nanotube Adsorption Interfaces For Electron Transfer Studies Of Galactose Oxidase, Mulugeta B. Wayu, Michael J. Pannell, Najwa Labban, William S. Case, Julie A. Pollack, Michael C. Leopold Feb 2019

Functionalized Carbon Nanotube Adsorption Interfaces For Electron Transfer Studies Of Galactose Oxidase, Mulugeta B. Wayu, Michael J. Pannell, Najwa Labban, William S. Case, Julie A. Pollack, Michael C. Leopold

Chemistry Faculty Publications

Modified electrodes featuring specific adsorption platforms able to access the electrochemistry of the copper containing enzyme galactose oxidase (GaOx) were explored, including interfaces featuring nanomaterials such as nanoparticles and carbon nanotubes (CNTs). Electrodes modified with various self-assembled monolayers (SAMs) including those with attached nanoparticles or amide-coupled functionalized CNTs were examined for their ability to effectively immobilize GaOx and study the redox activity related to its copper core. While stable GaOx electrochemistry has been notoriously difficult to achieve at modified electrodes, strategically designed functionalized CNT-based interfaces, cysteamine SAM-modified electrode subsequently amide-coupled to carboxylic acid functionalized single wall CNTs, were significantly more …

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Proton-Coupled Reduction Of An Iron Nitrosyl Porphyrin In The Protic Ionic Liquid Nanodomain, Abderrahman Atifi, Piotr J. Mak, Michael D. Ryan Feb 2019

Proton-Coupled Reduction Of An Iron Nitrosyl Porphyrin In The Protic Ionic Liquid Nanodomain, Abderrahman Atifi, Piotr J. Mak, Michael D. Ryan

Chemistry Faculty Research and Publications

The one-electron reduction of many molecules becomes much more favorable if combined with proton transfers or strong hydrogen bonding. Protic room temperature ionic liquids (RTILs), which can form nanodomains in solutions with molecular solvents (MS), can provide an efficient avenue for this process. In this work, we report on the voltammetry, UV/visible and resonance Raman spectroelectrochemistryof Fe(TPP)(NO) in the presence of aprotic/protic ammonium-based ionic liquids. While aprotic RTILs did shift the reduction to more positive potentials, similar shifts could be observed at much lower concentrations of diethylmethylammonium triflate (HAmOTf, a protic ionic liquid). Deconvolution of the rotating ring-disk electrode (RRDE) …

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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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Chemistry & Biochemistry Guest Lecture Series, Desmond Murray Jan 2019

Chemistry & Biochemistry Guest Lecture Series, Desmond Murray

Andrews Agenda: Campus News

No abstract provided.

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Dual Geometry Schemes In Tetrel Bonds: Complexes Between Tf4(T = Si, Ge, Sn) And Pyridine Derivatives, Wiktor Zierkiewicz, Mariusz Michalczyk, Rafał Wysokiński, Steve Scheiner Jan 2019

Dual Geometry Schemes In Tetrel Bonds: Complexes Between Tf4(T = Si, Ge, Sn) And Pyridine Derivatives, Wiktor Zierkiewicz, Mariusz Michalczyk, Rafał Wysokiński, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

When an N-base approaches the tetrel atom of TF4(T = Si, Ge, Sn) the latter moleculedeforms from a tetrahedral structure in the monomer to a trigonal bipyramid. The base can situateitself at either an axial or equatorial position, leading to two different equilibrium geometries.The interaction energies are considerably larger for the equatorial structures, up around 50 kcal/mol,which also have a shorter R(T··N) separation. On the other hand, the energy needed to deform thetetrahedral monomer into the equatorial structure is much higher than the equivalent deformationenergy in the axial dimer. When these two opposite trends are combined, it is the axial …

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Development Of Ultrafast Broadband Electronic Sum Frequency Generation For Charge Dynamics At Surfaces And Interfaces, Gang-Hua Deng, Yuqin Qian, Yi Rao Jan 2019

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 …

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