Chemistry Commons^™

Phosphorylation Of P27kip1 Regulates Assembly And Activation Of Cyclin D1-Cdk4, Michelle D. Larrea, Jiyong Liang, Thiago G. Da Silva, Feng Hong, Shan H. Shao, Kathy Han, D. Dumont, Joyce M. Slingerland

Chemistry and Physics Faculty Articles

p27 mediates Cdk2 inhibition and is also found in cyclin D1-Cdk4 complexes. The present data support a role for p27 in the assembly of D-type cyclin-Cdk complexes and indicate that both cyclin D1-Cdk4-p27 assembly and kinase activation are regulated by p27 phosphorylation. Prior work showed that p27 can be phosphorylated by protein kinase B/Akt (PKB/Akt) at T157 and T198. Here we show that PKB activation and the appearance of p27pT157 and p27pT198 precede p27-cyclin D1-Cdk4 assembly in early G₁. PI3K/PKB inhibition rapidly reduced p27pT157 and p27pT198 and dissociated cellular p27-cyclin D1-Cdk4. Mutant p27 allele products lacking phosphorylation at …

Molecular-Orientation-Dependent Ac Stark Effect And Its Impact On Multiphoton Processes, Xi Chu

Chemistry and Biochemistry Faculty Publications

We study the dependence of the ac Stark shifts of electronic energies on the molecular orientation relative to the polarization direction of an incident intense laser field, using a three-dimensional non-Hermitian Floquet method and H(2)+ as a model system. Simultaneously, we also study the orientation-dependent high-order harmonic generation (HHG) and multiphoton ionization (MPI). We find that with the presence of near-one-photon resonance, the Stark effect strongly mixes electronic states of different symmetries to create quasienergy states (QESs). The orientation dependence of multiphoton processes, in which these QESs play an important role, becomes complex. Population transfer is better achieved with aligned …

Fluorescence Sensor Array For Metal Ion Detection Based On Various Coordination Chemistries: General Performance And Potential Application, Zhuo Wang, Manuel A. Palacios, Pavel Anzenbacher Jr.

Chemistry Faculty Publications

A sensor array containing 9 cross-reactive sensing fluorescent elements with different affinity and selectivity to 10 metal cations (Ca2+, Mg2+, Cd2+, Hg2+, Co2+, Zn2+, Cu2+, Ni2+, Al3+, Ga3+) is described. The discriminatory capacity of the array was tested at different ranges of pH and at different cation concentrations using linear discriminant analysis (LDA). Qualitative identification of cations can be determined with over 96% of accuracy in a concentration range covering 3 orders of a magnitude (5-5000 mu M). Quantitative analysis can be achieved with over 90% accuracy in the concentration range between 10 and 5000 mu M. The array performance …

6:1 Aspect Ratio Silicon Pillar Based Thermal Neutron Detector Filled With 10B, R. J. Nikolic, A. M. Conway, C. E. Reinhart, R. T. Graff, T. F. Wang, N. Deo, Barry Chin Li Cheung

Barry Chin Li Cheung Publications

Current helium-3 tube based thermal neutron detectors have shortcomings in achieving simultaneously high efficiency and low voltage while maintaining adequate fieldability performance. By using a three-dimensional silicon p-i-n diode pillar array filled with boron-10 these constraints can be overcome. The fabricated pillar structured detector reported here is composed of 2 μm diameter silicon pillars with a 4 μm pitch and height of 12 μm. A thermal neutron detection efficiency of 7.3+/−0.6% and a neutron-to-gamma discrimination of 10⁵ at 2 V reverse bias were measured for this detector. When scaled to larger aspect ratio, a high efficiency device is possible.

Synthetic Studies Directed Toward Amphidinol 2: Elucidation Of The Relative Configuration Of The C1–C10 Fragment, Praveen Kommana, Seung Won Chung, William A. Donaldson

Chemistry Faculty Research and Publications

Model compounds (11 and 12) for the C1–C10 tetrahydropyran fragment of amphidinol 2 were prepared from (2S)-benzyloxypropanal in 9 steps. The synthetic route relied on diastereoselective diene-aldehyde cycloaddition, stereoselective C-allylation, and reagent based enantioselective aldehyde allylation. Comparison of the NMR spectra for models 11 and 12 with that for amphidinol 2 indicated that the C1–C10 segment of the natural product possesses the 2R^*,4R^*,6R^*,7S^*,8R^*,10S^* relative configuration.

Fire Retardancy Of Melamine And Zinc Aluminum Layered Double Hydroxide In Poly(Methyl Methacrylate), Charles Manzi-Nshuti, Jeanne Hossenlopp, Charles Wilkie

Chemistry Faculty Research and Publications

The thermal and fire properties of PMMA modified with various loadings of melamine or zinc aluminum undecenoate LDH were evaluated using TGA, DTA and cone calorimetry. The additives were characterized by X-ray diffraction, TGA, FT-IR and elemental analysis. While the two additives are very effective with this polymer, a higher loading of melamine (30%) is required to reach a good reduction in PHRR (47%) relative to the pure polymer, while with the LDH, 10% loading is enough to obtain a similar reduction. The combinations of these additives in PMMA reveal that the time to PHRR and the amount of smoke …

Resonance Raman Spectroscopic Studies Of Hydroperoxo Derivatives Of Cobalt-Substituted Myoglobin, Piotr J. Mak, James R. Kincaid

Chemistry Faculty Research and Publications

Recent progress in generating and stabilizing reactive heme protein enzymatic intermediates by cryoradiolytic reduction has prompted application of a range of spectroscopic approaches to effectively interrogate these species. The impressive potential of resonance Raman spectroscopy for characterizing such samples has been recently demonstrated in a number of studies of peroxo- and hydroperoxo-intermediates. While it is anticipated that this approach can be productively applied to the wide range of heme proteins whose reaction cycles naturally involve these peroxo- and hydroperoxo-intermediates, one limitation that sometimes arises is the lack of enhancement of the key intraligand ν(O–O) stretching mode in the native …

Colloquium Discusses Development Of A New Diabetes Treatment, Heather Lindquist ’09

News and Events (Discontinued Series)

No abstract provided.

Oriented Cell Growth On Self-Assembled Bacteriophage M13 Thin Films, Jianhua Rong, L. Andrew Lee, Kai Li, Brandon Harp, Charlene M. Mello, Zhongwei Niu, Qian Wang

Faculty Publications

Fibrillar M13 bacteriophages were used as basic building blocks to generate thin films with aligned nanogrooves, which, upon chemical grafting with RGD peptides, guide cell alignment and orient the cell outgrowth along defined directions.

Reduction Of Toxicity In The Premature Neonate Addociated With Aluminum As A Contaminant Of Total Parenteral Nutrition Solution, Sujittra Srisung

Dissertations

Aluminum (Al) is the third most common element in the Earth?s crust. It is widely consumed in water, foods, and drugs. However, in humans, the uptake of aluminum into the body and its deposition in tissues has been linked to conditions of medical concern, including many neurological disorders such as dialysis dementia, Alzheimer?s disease, Parkinson?s dementia and Down?s syndrome. Premature neonates who receive intravenous feeding (TPN) are at a high risk for Al toxicity because the TPN solutions are contaminated with Al3+, which is not excreted effectively due to poor kidney development in these patients. The FDA has recommended regulations …

The Original Build Up Of Genetic Information By Rna Recombination, Eric John Hayden

Dissertations and Theses

This research demonstrates chemical reactions of RNA molecules that allow them to increase in length, from non-catalytic oligomers to complex RNA enzymes. The purpose of this research was to explain the origin of large RNA polymers required for life to begin in the proposed "RNA World". To do this, the Azoarcus group I ribozyme was engineered to catalyze phosphodiester exchange reactions that result in the recombination of short oligomer substrates marked by ^5'CAU^3' recognition tags.

To demonstrate the ability to produce catalytic RNA sequences through recombination, substrate oligomers were synthesized that could produce ribozymes if large portions of …

Metallomesogens: Supramolecular Design Via Alkyl-Rich Metal Complexes, Juan Noveron

Selected Works Temporary Series

Molecules that use non-covalent interactions to self-organize into supramolecular structures have the potential to generate functional materials with a broad range of applications. This review article focuses on the design and synthesis of molecules that use transition metal ions and long alkyl chains to direct the formation of ordered supramolecular phases. This unique combination of coordination bonds and alkyl interdigitation provide exceptional control over intermolecular interactions and can generate nanoscale molecular order as liquid crystalline states, Langmuir-Blodgett films on surfaces, highly ordered lyotropic phases such as metallo-micelles in water and reverse metallo-micelles in organic media. The synthetic strategy for alkane-rich …

Use Of Boron Compounds To Precipitate Uranium From Water, David A. Atwood

Chemistry Faculty Patents

A method is provided for removing uranium from water. The method includes the mixing of a boron reagent with water contaminated with uranyl dication ions, leading to removal of the uranium from that water.

Metallomesogens: Supramolecular Design Via Alkyl-Rich Metal Complexes, Juan Noveron

Departmental Papers (Chemistry)

Molecules that use non-covalent interactions to self-organize into supramolecular structures have the potential to generate functional materials with a broad range of applications. This review article focuses on the design and synthesis of molecules that use transition metal ions and long alkyl chains to direct the formation of ordered supramolecular phases. This unique combination of coordination bonds and alkyl interdigitation provide exceptional control over intermolecular interactions and can generate nanoscale molecular order as liquid crystalline states, Langmuir-Blodgett films on surfaces, highly ordered lyotropic phases such as metallo-micelles in water and reverse metallo-micelles in organic media. The synthetic strategy for alkane-rich …

Environmental Effects On Corrosion Properties Of Alloy 22, Mano Misra

Publications (YM)

This document presents detailed technical report for four Subtasks that were conducted independently. All four Subtasks investigated environmental effects on corrosion properties of Alloy 22. The four Subtasks that were investigated are as follows: Subtask 1: Experimental Determination of Parameters for the General Corrosion Model. Subtask 2: Corrosion under Dust Deposits Containing Hygroscopic Salts. Subtask 3: Heated Electrode Approach for the Study of Corrosion Under Aggressive Conditions. Subtask 4: Effect of Hydrogen Permeation on the Stability of the Passive Film of Alloy 22.

Simple Molecule-Based Fluorescent Sensors For Vapor Detection Of Tnt, Grigory V. Zyryanov, Manuel A. Palacios, Pavel Anzenbacher Jr.

Chemistry Faculty Publications

1,4-Diarylpentiptycenes (1a-e) were synthesized from 1,4-dichloro- or 1,4-difluoro-2,5-diarylbenzene derivatives by double base-promoted dehydrohalogenation to give corresponding arynes, which in the presence of anthracene undergo cycloaddition providing 1,4-diarylpentiptycenes in moderate overall yields. The resulting 1,4-diarylpentiptycenes show fluorescence modulated by the 1,4-aryl residues. The fluorescence is quenched in the presence of vapors of nitroaromatic compounds suggesting potential application in sensing of explosives.

Iron Oxide Deposits Associated With The Ectosymbiotic Bacteria In The Hydrothermal Vent Shrimp Rimicaris Exoculata, Laure Corbari, Marie Anne Cambon-Bonavita, Gary J. Long, Fernande Grandjean, Magali Zbinden, Françoise Gaill, Philippe Compère

Chemistry Faculty Research & Creative Works

The Rimicaris exoculata shrimp is considered as a primary consumer that dominates the fauna of most Mid-Atlantic Ridge (MAR) hydrothermal ecosystems. These shrimps harbour in their gill chambers an important ectosymbiotic community of chemoautotrophic bacteria associated with iron oxide deposits. The structure and elemental composition of the mineral concretions associated with these bacteria have been investigated by using LM, ESEM, TEM STEM and EDX microanalyses. The nature of the iron oxides in shrimps obtained from the Rainbow vent field has also been determined by Mössbauer spectroscopy. This multidisciplinary approach has revealed that the three layers of mineral crust in the …

The Discovery-Oriented Approach To Organic Chemistry. 7. Rearrangement Of Trans-Stilbene Oxide With Bismuth Trifluoromethanesulfonate And Other Metal Triflates, Ram Mohan, James Christensen, Matthew Huddle, Jamie Rogers, Herbie Yung

Scholarship

A microscale discovery-oriented experiment illustrating the rearrangement of trans-stilbene oxide using non-corrosive metal triflates as catalysts has been developed. The use of CDCl₃ as the reaction solvent eliminates the need for any workup and avoids the use of highly toxic boron trifluoride etherate as a catalyst and additional reaction solvent.

Phase Transitions In Lafeaso: Structural, Magnetic, Elastic, And Transport Properties, Heat Capacity And Mössbauer Spectra, Michael A. Mcguire, Andrew D. Christianson, Athena S. Sefat, Brian C. Sales, Mark D. Lumsden, Rongying Jin, Edward Andrew Payzant, David G. Mandrus, Yanbing Luan, Veerle M. Keppens, Vijayalaksmi Varadarajan, Joseph W. Brill, Raphäel P. Hermann, M. T. Sougrati, Fernande Grandjean, Gary J. Long

Chemistry Faculty Research & Creative Works

We present results from a detailed experimental investigation of LaFeAsO, the parent material in the series of “FeAs” based oxypnictide superconductors. Upon cooling, this material undergoes a tetragonal-orthorhombic crystallographic phase transition at ~160 K followed closely by an antiferromagnetic ordering near 145 K. Analysis of these phase transitions using temperature dependent powder x-ray and neutron-diffraction measurements is presented. A magnetic moment of ~0.35µ_B per iron is derived from Mössbauer spectra in the low-temperature phase. Evidence of the structural transition is observed at temperatures well above the transition temperature (up to near 200 K) in the diffraction data as well …

Photorefractivity In A Polymeric Composite Photosensitized With Nis Nanocrystals, Tyler M. Fears, Charles Anderson, Jeffrey G. Winiarz

Chemistry Faculty Research & Creative Works

The photorefractive performance of a polymeric composite photosensitized through the inclusion of NiS nanocrystals is described. The nanocrystals were characterized using visible-absorption spectroscopy, energy-dispersive x-ray spectroscopy, and transmission electron microscopy. We further demonstrate the ability to enhance various aspects of the composite's photorefractive performance by performing ligand exchange on the nanocrystals prior to their incorporation into the polymer composite. This procedure resulted in a lowering of the overmodulation voltage from ~70 to ~50 V/µm without affecting the maximum diffraction efficiency of ~40%. An increase in the two-beam-coupling gain coefficient was similarly observed, increasing from 38 to 79 cm−1. The photoconductivities …

An Integrated Approach To The Toxicity Evaluation Of Irish Marine Sediment - Chemical Assessment, Michelle Giltrap

Doctoral

This project was a collaborative project between the Marine Institute (MI) in Galway and Radiation and Environmental Science Centre (RESC) in the Technological University Dublin (DIT). In Ireland, at present, sediment quality assessments are generally reliant on chemical analysis alone with limited bioassay techniques available to further characterise the sediment. Some causative agents of toxicity to biological organisms are below analytical detection limits. Integration of bioassay data with chemical analysis is essential in order to complete a full ecotoxicological assessment of the quality of the marine environment. This project describes the chemical analysis of marine sediment for persistent pollutants from …

Linear Dichroism In Resonant Inelastic X-Ray Scattering To Molecular Spin-Orbit States, Renaud Guillemin, Stephane Carniato, Wayne C. Stolte, Loic Journel, Richard Taieb, Dennis W. Lindle, Marc Simon

Chemistry and Biochemistry Faculty Research

Polarization-dependent resonant inelastic x-ray scattering (RIXS) is shown to be a new probe of molecular-field effects on the electronic structure of isolated molecules. A combined experimental and theoretical analysis explains the linear dichroism observed in Cl 2p RIXS following Cl 1s excitation in HCl and CF₃Cl as due to molecular-field effects, including singlet-triplet exchange, indicating polarized-RIXS provides a direct probe of spin-orbit-state populations applicable to any molecule.

Use Of Fluorinated Functionality In Enzyme Inhibitor Development: Mechanistic And Analytical Advantages, David B. Berkowitz, Kannan R. Karukurichi, Roberto De La Salud-Bea, David L. Nelson, Christopher D. Mccune

David Berkowitz Publications

On the one hand, owing to its electronegativity, relatively small size, and notable leaving group ability from anionic intermediates, fluorine offers unique opportunities for mechanism-based enzyme inhibitor design. On the other, the “bio-orthogonal” and NMR-active 19-fluorine nucleus allows the bioorganic chemist to follow the mechanistic fate of fluorinated substrate analogues or inhibitors as they are enzymatically processed. This article takes an overview of the field, highlighting key developments along these lines. It begins by highlighting new screening methodologies for drug discovery that involve appropriate tagging of either substrate or the target protein itself with ¹⁹Fmarkers, that then report back …

Tetrahymena Thermophila And Candida Albicans Group I Intron-Derived Ribozymes Can Catalyze The Trans-Excision-Splicing Reaction, P. Patrick Dotson Ii, Ashley K. Johnson, Stephen M. Testa

Chemistry Faculty Publications

Group I intron-derived ribozymes can catalyze a variety of non-native reactions. For the trans-excision-splicing (TES) reaction, an intron-derived ribozyme from the opportunistic pathogen Pneumocystis carinii catalyzes the excision of a predefined region from within an RNA substrate with subsequent ligation of the flanking regions. To establish TES as a general ribozyme-mediated reaction, intron-derived ribozymes from Tetrahymena thermophila and Candida albicans, which are similar to but not the same as that from Pneumocystis, were investigated for their propensity to catalyze the TES reaction. We now report that the Tetrahymena and Candida ribozymes can catalyze the excision of a …

Inside Unlv, Diane Russell, Shane Bevell, Michelle Mouton, Erin O'Donnell, Mamie Peers, Grace Russell, Deana Waddell

Inside UNLV

No abstract provided.

Non-Canonical Binding Of Calmodulin To Aquaporin-0: Implications For Channel Regulation, Steve Reichow, Tamir Gonen

Chemistry Faculty Publications and Presentations

Aquaporins (AQPs) are a family of ubiquitous membrane channels that conduct water across cell membranes. AQPs form homo-tetramers containing four functional and independent water pores. Aquaporin-0 (AQP0) is expressed in the eye lens where its water permeability is regulated by calmodulin (CaM). Here we use a combination of biochemical methods and NMR spectroscopy to probe the interaction between AQP0 and CaM. We show CaM binds the AQP0 C-terminal domain in a calcium dependent manner. We demonstrate that only two CaM molecules bind a single AQP0 tetramer in a non-canonical fashion, suggesting a form of co-operativity between AQP0 monomers. Based on …

Flame-Retarded Polystyrene: Investigating Chemical Interactions Between Ammonium Polyphosphate And Mgal Layered Double Hydroxide, Calistor Nyambo, Everson Kandare, Dongyan Wang, Charles A. Wilkie

Chemistry Faculty Research and Publications

Potential flame retardants, MgAl-LDH and ammonium polyphosphate (APP), were added to neat polystyrene (PS) individually or in combinations at weight fractions no greater than 10%. Structural morphologies of MgAl-LDH and the corresponding PS nanocomposites were established via X-ray diffraction (XRD) and transmission electron microscopy (TEM). Thermogravimetric analysis (TGA) and cone calorimetry were used to study the thermal stability and fire performance of the composites. Time to ignition is greatly reduced for PS composites when compared to the virgin polymer. Synergistic effects were observed in both TGA and cone calorimetry for formulations containing both MgAl-LDH and APP. Physical and chemical interactions …

Global Conformational Dynamics In Ras, Casey O'Connor, Evgenii L. Kovrigin

Chemistry Faculty Research and Publications

Ras and its homologues are central to regulation of a multitude of cellular processes. Ras in complex with GTP binds and activates its downstream signaling partners. ³¹P NMR studies indicated that the Ras−GTP conformation is heterogeneous on a millisecond time scale, but details of its conformational dynamics remain unknown. Here we present evidence that the conformational exchange process in human H-Ras complexed with GTP mimic GppNHp is global, encompassing most of the GTPase catalytic domain. The correlated character of conformational dynamics in Ras opens opportunities for understanding allosteric effects in Ras function.

2,9-Bis(1,3-Benzothia­Zol-2-Yl)-1,10-Phenanthroline Dichloro­Methane Disolvate, Jesmin Akther, Sergey V. Lindeman, Mohammad Rezaul Karim

Chemistry Faculty Research and Publications

In the title compound, C₂₆H₁₄N₄S₂·2CH₂Cl₂, the two pendant benzothia­zole groups are slightly twisted with respect to the phenanthroline core [dihedral angles = 1.03 (7) and 9.05 (5)°]. Weak inter­molecular C-HN and C-HCl inter­actions occur in the crystal structure.

Development Of Pharmacophore And Comfa Studies For Sigma2 Receptor Ligands, Laura Ann Wirpsza

Theses

This study describes the development of a pharmacophore and CoMIFA model for sigma 2 (σ₂) receptor ligands. CoMFA studies were performed for 32 bioactive σ₂ receptor ligands using the radioligand [H 3] (+) DTG in the presence of pentazocine. The pharmacophore was derived using Distance Comparisons (DISCOtech) from eight partially to highly active ~2 receptor ligands. All 32 compounds were calculated in three methods: AMi, HFI3~21G*, and B3LYP/3~21G* methods. These methods run in Gaussian 98 determined the geometry optimization and electrostatic charges for each molecule. CoMFA maps were developed using SYBYL ver. 7.2 to compare the electrostatic …