Open Access. Powered by Scholars. Published by Universities.®

Chemistry Commons

Open Access. Powered by Scholars. Published by Universities.®

2019

Discipline
Institution
Keyword
Publication
Publication Type
File Type

Articles 991 - 1020 of 1773

Full-Text Articles in Chemistry

Multiplexed Paper Microfluidics For Titration And Detection Of Ingredients In Beverages, Manas Ranjan Gartia, Alisha Prasad Mar 2019

Multiplexed Paper Microfluidics For Titration And Detection Of Ingredients In Beverages, Manas Ranjan Gartia, Alisha Prasad

Faculty Publications

Food safety and access to systematic approaches for ensuring detection of food hazards is an important issue in most developing countries. With the arrival of paper-based analytical devices (mu PADs) as a promising, rapid, easy-to-use, and low-cost analytical tool, we demonstrated a simple microfluidic-based titration study for the analysis of packaged fruit juices. Similar, to the titration experiments using traditional glassware in chemistry laboratories, in this study the titration experiments were developed using paper microfluidics for the analysis of several analytes such as pH, vitamin C, sugars, and preservatives present in the packaged fruit juices. The allergen found commonly in …


Table Of Contents Mar 2019

Table Of Contents

Journal of the South Carolina Academy of Science

No abstract provided.


Lake Sediment Analysis At Heron Haven Nature Center, Erik Lato Mar 2019

Lake Sediment Analysis At Heron Haven Nature Center, Erik Lato

UNO Student Research and Creative Activity Fair

Understanding the chemical composition of a wetland sanctuary lakebed can help us understand how recent developments may have changed the chemical composition. Due to recent dredging by the U.S. Army Corps of Engineers and previous research on water composition at Heron Haven, the goal of this project was to determine the chemical composition as a function of sediment depth. The concentration of seven different metals and nutrients were analyzed in terms of depth. The aluminum, iron, and phosphate concentrations had no real discernible concentration change as a function of depth. There is some hint of a steady increase of manganese …


Investigating Daily Variation In Lotic Prairie Ecosystems, Dominick Caniglia Mar 2019

Investigating Daily Variation In Lotic Prairie Ecosystems, Dominick Caniglia

UNO Student Research and Creative Activity Fair

The goal of this project is to investigate the hydrochemistry of the prairie stream system at Glacier Creek Preserve, namely to determine the chemical behavior as it varies over time. Past sampling revealed annual/seasonal trends, which prompted this study investigating possible changes over the course of a day. To accomplish this, water samples were taken hourly for a twelve hour period in September and November 2018, and were analyzed at the Durham Science Center. All samples were obtained at the furthest downstream site available. The main focus was to study alkalinity and dissolved mineral content. Preliminary data suggests that alkalinity …


Synthesis Of A Sulfur Variant For Treatment Of Trypanosomiasis, Carlos Vera-Esquivel Mar 2019

Synthesis Of A Sulfur Variant For Treatment Of Trypanosomiasis, Carlos Vera-Esquivel

UNO Student Research and Creative Activity Fair

Previous work in our lab has found diphenyl ether benzylamines showed a successful response with a micromolar concentration of our lead compound to treat the deadly Trypanosamiosis rhodesience. Furthermore, mammalian cell lines saw promising resistance towards damages. The goal of this study was to synthesize a diphenyl thio benzylamine variant. This variant was more active toward T. b. rhodesience but showed more toxicity to both rat 10 (IC50 mM) and human cell lines (HFF, HC-04, U-2 OS, and HEK293). The selectivity index (ratio of toxicity to activity in the same concentration units (SI)) …


On The Limited Role Of Electronic Support Effects In Selective Alkyne Hydrogenation: A Kinetic Study Of Au/MoX Catalysts Prepared From Oleylamine-Capped Colloidal Nanoparticles, James E. Bruno, K. B. Sravan Kumar, Nicolas S. Dwarica, Alexander Hüther, Zhifeng Chen, Clemente S. Guzman Iv, Emily R. Hand, William C. Moore, Robert M. Rioux, Lars C. Grabow, Bert D. Chandler Mar 2019

On The Limited Role Of Electronic Support Effects In Selective Alkyne Hydrogenation: A Kinetic Study Of Au/MoX Catalysts Prepared From Oleylamine-Capped Colloidal Nanoparticles, James E. Bruno, K. B. Sravan Kumar, Nicolas S. Dwarica, Alexander Hüther, Zhifeng Chen, Clemente S. Guzman Iv, Emily R. Hand, William C. Moore, Robert M. Rioux, Lars C. Grabow, Bert D. Chandler

Chemistry Faculty Research

We report a quantitative kinetic evaluation and study of support effects for partial alkyne hydrogenation using oleylaminecapped Au colloids as catalyst precursors. The amine capping agents can be removed under reducing conditions, generating supported Au nanoparticles of ~2.5 nm in diameter. The catalysts showed high alkene selectivity (>90%) at all conversions during alkyne partial hydrogenation. Catalytic activity, observed rate constants, and apparent activation energies (25– 40 kJ/mol) were similar for all Au catalysts, indicating support effects are relatively small. Alkyne adsorption, probed with FTIR and DFT, showed adsorption on the support was associated with hydrogen-bonding interactions. DFT calculations indicate …


Optoelectronic, Aggregation, And Redox Properties Of Double-Rotor Boron Difluoride Hydrazone Dyes, Daniela Cappello, Denis A.B. Therien, Viktor N. Staroverov, Francois Lagugne-Labarthet, Joe Gilroy Mar 2019

Optoelectronic, Aggregation, And Redox Properties Of Double-Rotor Boron Difluoride Hydrazone Dyes, Daniela Cappello, Denis A.B. Therien, Viktor N. Staroverov, Francois Lagugne-Labarthet, Joe Gilroy

Chemistry Publications

We develop the chemistry of boron difluoride hydrazone dyes (BODIHYs) bearing two aryl substituents and explore their properties. The low-energy absorption bands (λmax = 427–464 nm) of these dyes depend on the nature of the N-aryl groups appended to the BODIHY framework. Electron-donating and extended p-conjugated groups cause a red shift, whereas electron-withdrawing groups result in a blue shift. The title compounds were weakly photoluminescent in solution and strongly photoluminescent as thin films (λPL = 525–578 nm) with quantum yields of up to 18% and lifetimes of 1.1–1.7 ns, consistent with the dominant radiative decay through fluorescence. …


Bioassay-Guided Isolation And Structure Elucidation Of Fungicidal And Herbicidal Compounds From Ambrosia Salsola (Asteraceae), Frank R. Fronczek Mar 2019

Bioassay-Guided Isolation And Structure Elucidation Of Fungicidal And Herbicidal Compounds From Ambrosia Salsola (Asteraceae), Frank R. Fronczek

Faculty Publications

The discovery of potent natural and ecofriendly pesticides is one of the focuses of the agrochemical industry, and plant species are a source of many potentially active compounds. We describe the bioassay-guided isolation of antifungal and phytotoxic compounds from the ethyl acetate extract of Ambrosia salsola twigs and leaves. With this methodology, we isolated and identified twelve compounds (four chalcones, six flavonols and two pseudoguaianolide sesquiterpene lactones). Three new chalcones were elucidated as (S)-beta-Hydroxy-2,3,4,6'-tetrahydroxy-5-methoxydihydrochalcone (salsolol A), (S)-beta-Hydroxy-2',4,4',6'-tetrahydroxy-3-methoxydihydrochalcone (salsolol B), and (R)-alpha, (R)-beta-Dihydroxy-2,3,4,4,6'-pentahydroxydihydrochalcone (salsolol C) together with nine known compounds: balanochalcone, six quercetin derivatives, confertin, and neoambrosin. Chemical structures were determined …


Selective Catalysis By Polymer-Supported Ruthenium Nanoparticlesand New Ligand Design For Cooperative And Bimetallic Catalysis, Seyed Hadi Nazari Mar 2019

Selective Catalysis By Polymer-Supported Ruthenium Nanoparticlesand New Ligand Design For Cooperative And Bimetallic Catalysis, Seyed Hadi Nazari

Theses and Dissertations

The abstract is the summary of three different projects all centered around the generalidea of catalysis which is the general theme of research in the Michaelis laboratory. The firstproject focuses on development of a new heterogeneous catalyst for selective catalysis. In theMichaelis lab, we were interested in the potential of nanoparticle catalysts for regioselectivetransformations. We showed that polymer supported ruthenium nanoparticles performed as areliable catalyst for regioselective reduction of azide to amine. In our study of regioselectivereduction of multiple azide containing substrates, we observed that in presence of ourruthenium nanoparticle catalysts, the least sterically hindered azide group reduced to aminefunctional …


Facile And Efficient Synthesis Of Thiosemicarbazone Derivatives With Functionalized Pendant Amines., Anna E Davis Mar 2019

Facile And Efficient Synthesis Of Thiosemicarbazone Derivatives With Functionalized Pendant Amines., Anna E Davis

College of Arts & Sciences Senior Theses

Bis-thiosemicarbazones are an important class of ligands for the synthesis of transition metal complexes with applications in medicine and electrochemistry.1,2 Among the most studied of these complexation ligands is diacetyl-2,3-bis(N4-methyl-3-thiosemicarbazone) (denoted as ATSM, 1, Figure 1).2,3 Derivatives of 1 with various amines in place of the methylamine of ATSM have previously been reported, including diacetyl (N4-methylthiosemicarbazone-N4′-dimethylthio-semicarbazone) (denoted as ATSM/DM, 2).4 In this work, we pursue the development of a library of ATSM derivatives with a variety of functionalized pendant amines with a range of electronic and steric …


Seasonal Origins Of Soil Water Used By Trees, Scott T. Allen, James W. Kirchner, Sabine Braun, Rolf T. W. Siegwolf, Gregory R. Goldsmith Mar 2019

Seasonal Origins Of Soil Water Used By Trees, Scott T. Allen, James W. Kirchner, Sabine Braun, Rolf T. W. Siegwolf, Gregory R. Goldsmith

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Rain recharges soil water storages and either percolates downward into aquifers and streams or is returned to the atmosphere through evapotranspiration. Although it is commonly assumed that summer rainfall recharges plant-available water during the growing season, the seasonal origins of water used by plants have not been systematically explored. We characterize the seasonal origins of waters in soils and trees by comparing their midsummer isotopic signatures (δ2H) to seasonal isotopic cycles in precipitation, using a new seasonal origin index. Across 182 Swiss forest sites, xylem water isotopic signatures show that summer rain was not the predominant water source …


Pharmacological Aspects Of Resveratrol, Raisa Ramirez, Debasish Bandyopadhyay Mar 2019

Pharmacological Aspects Of Resveratrol, Raisa Ramirez, Debasish Bandyopadhyay

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Resveratrol [(E)-5-(4-hydroxystyryl) benzene-1,3-diol], also known as 3,4′,5-trihydroxystilbene also known as resveratrol is classified as a phytoalexin in plants such as nuts, cocoa, berries and grapes for self-defense against injury and pathogenic attacks by bacteria and fungi. Research on this compound did not gain popularity until the 1990s when a published paper implied the relationship between resveratrol and the decrease in cardiovascular complications due to the consumption of grape fermented wine in French populations. This observation sparked research on resveratrol even though its concentration in wine is relatively low, leading to the realization that resveratrol has potential for benefits in other …


Applications Of Pattern Recognition Entropy (Pre) And Informatics To Data Analysis, Shiladitya Chatterjee Mar 2019

Applications Of Pattern Recognition Entropy (Pre) And Informatics To Data Analysis, Shiladitya Chatterjee

Theses and Dissertations

The primary focus of my work is the application of informatics methods to the fields of materials science and analytical chemistry. The statistical analysis of data has become increasingly important in understanding the properties of materials and analytes. Statistical methods like principal component analysis (PCA) and multivariate curve resolution (MCR) are widely used for analysis in chemistry and other fields given their ability to categorize spectra in an unsupervised way. PCA is relatively easy to apply and has appealing mathematical properties. However, the results can be challenging to interpret, even for experienced users. In contrast, MCR results can be more …


Voc Emission Factors From 3d Printers - Abs (Acrylonitrile-Butadiene-Styrene) Type Filaments, Dean Lay Feb 2019

Voc Emission Factors From 3d Printers - Abs (Acrylonitrile-Butadiene-Styrene) Type Filaments, Dean Lay

LSU Master's Theses

Acrylonitrile-butadiene-styrene (ABS) is a polymer that is widely used in many plastic products and is receiving new attention due to its use as a filament for fused deposition modelling (FDM) 3D printers. It has been shown to emit potentially dangerous volatile organic compounds (VOCs) when heated at temperatures used in the 3D printing process. Many new products are becoming available that contain various additives to the polymer matrix, which have an unknown effect on the emission profiles and rates. In this study a method is developed using a modified system for thermal diagnostic studies (STDS) to evaluate VOC emission from …


Protein Ions Generated By Native Electrospray Ionization: Comparison Of Gas Phase, Solution, And Crystal Structures., Maryam Bakhtiari, Lars Konermann Feb 2019

Protein Ions Generated By Native Electrospray Ionization: Comparison Of Gas Phase, Solution, And Crystal Structures., Maryam Bakhtiari, Lars Konermann

Chemistry Publications

Experiments and molecular dynamics (MD) simulations in the literature indicate that gaseous proteins generated by electrospray ionization (ESI) can retain native-like structures. However, the exact properties of these ions remain to be explored. Focusing on ubiquitin and lysozyme, we examined several pertinent questions. (1) We applied solvent MD runs to test whether the X-ray structures of both proteins are affected by crystal packing. Main and side-chain orientations were retained in solution, providing a justification for the hitherto unscrutinized approach of relying on crystal data for "solution" versus gas-phase comparisons. (2) Most earlier gas-phase protein MD investigations employed short (ns) simulation …


Current Status And Prospect Of Battery Configuration In Li-S System, Jia-Hang Chen, Hui-Jun Yang, Cheng Guo, Jiu-Lin Wang Feb 2019

Current Status And Prospect Of Battery Configuration In Li-S System, Jia-Hang Chen, Hui-Jun Yang, Cheng Guo, Jiu-Lin Wang

Journal of Electrochemistry

Commercial lithium-ion batteries (LIBs) are incapable of satisfying the increasing demand for emerging electronic devices due to their limited energy density. Among the next-generation batteries, lithium-sulfur (Li-S) batteries are becoming a promising energy-storage system due to their high theoretical energy density and natural abundance of sulfur. However, the shuttle of soluble polysulfide intermediates between two electrodes, as well as the problem on Li metal anode,lower the utilization of active material and lead to the loss of specific capacity and rapid capacity fading. All the above challenges limit the further application of Li-S batteries. Recently, various novel battery configurations have been …


Applications Of Advanced Imaging Technologies For Critical Issues Of All-Solid-State Lithium Battery Studies, Yi-Bo Zhao, Hui-Hui Liu, Song-Liang Chen, Shou-Hang Bo Feb 2019

Applications Of Advanced Imaging Technologies For Critical Issues Of All-Solid-State Lithium Battery Studies, Yi-Bo Zhao, Hui-Hui Liu, Song-Liang Chen, Shou-Hang Bo

Journal of Electrochemistry

All-solid-state lithium batteries have attracted much attention for their high energy density and good safety. To increase their efficiency and prolong their service life, it is necessary to achieve high ion conductivity at the electrode/electrolyte interface and in the electrolyte, as well as to eliminate dendrites growth in the battery. Based on the critical requirements outlined above, this paper discusses the applications of advanced imaging technologies in relevant studies. Recent progresses in investigations of all-solid-state lithium batteries by imaging techniques including electron microscopy, scanning probe microscopy, X-ray tomography, magnetic resonance imaging and optical microscopy are summarized.


Recent Progress On Tio2-Based Anode Materials For Sodium-Ion Batteries, Si-Tian Lian, Jian-Shuai Lv, Qiang Yu, Guang-Wu Hu, Zhuo Chen, Liang Zhou, Li-Qiang Mai Feb 2019

Recent Progress On Tio2-Based Anode Materials For Sodium-Ion Batteries, Si-Tian Lian, Jian-Shuai Lv, Qiang Yu, Guang-Wu Hu, Zhuo Chen, Liang Zhou, Li-Qiang Mai

Journal of Electrochemistry

Titanium dioxide (TiO2) represents a stable, low-cost, and nontoxic anode material for sodium-ion batteries (SIBs). However, the low electrical conductivity limits its electrochemical activity (specific capacity) and rate capability, hindering its widespread applications. In this article, we show that different crystal forms of TiO2 have different pore structures, resulting in the distinct sodium storage capacities. Accordingly, the article introduces how TiO2 microstructures influence sodium storage. The nanoparticle structure can improve the rate performance of the material due to its short ion diffusion distance, and the internal cavity of the hollow structure is beneficial to cycle stability. …


Recent Progress In Vanadium-Based Electrode Materials, Meng-Lei Sun, Da-Qi Zhang, Jin-Kui Feng, Jiang-Feng Ni Feb 2019

Recent Progress In Vanadium-Based Electrode Materials, Meng-Lei Sun, Da-Qi Zhang, Jin-Kui Feng, Jiang-Feng Ni

Journal of Electrochemistry

It is an important solution to solve energy storage problems by developing inexpensive and safe lithium-ion and sodium-ion batteries with superior performance. Vanadium-based electrode materials are promising electrode materials because of diversified chemical valences, open structures and high theoretical capacities. In the past few years, vanadium-based electrode materials such as oxides, sulfides, and phosphates have achieved a considerable development in the battery field, It is,  therefore, necessary to summarize their recent research progress. In this review, we particularly highlight the key challenges that are facing in the application of vanadium materials, such as low ion diffusion coefficient and poor structural …


Recent Progress In Key Materials For Room-Temperature Sodium-Ion Batteries, Fan-Fan Wang, Xiao-Bin Liu, Long Chen, Cheng-Cheng Chen, Yong-Chang Liu, Li-Zhen Fan Feb 2019

Recent Progress In Key Materials For Room-Temperature Sodium-Ion Batteries, Fan-Fan Wang, Xiao-Bin Liu, Long Chen, Cheng-Cheng Chen, Yong-Chang Liu, Li-Zhen Fan

Journal of Electrochemistry

Sodium-ion batteries (SIBs) have attracted tremendous attention in large-scale energy storage applications due to their resource advantages. However, Na+ is larger and heavier than Li+, which will limit its reversible reaction with the electrode materials and result in poor electrochemical performance. Thus, developing stable and high-efficiency electrode materials is the key to promoting the practical application of SIBs. Furthermore, the optimization of electrolyte is essential for the construction of high-safety and long-lifespan SIBs. In this review, we mainly summarize the recent advancements of electrode materials and electrolytes for room-temperature SIBs and discuss their challenges and possible resolution strategies. We hope …


Recent Developments In Surface/Interface Modulation And Structure-Performance Relationship Of Cathode Catalysts For Li-Air Batteries, Rui Gao, Jun-Kai Wang, Zhong-Bo Hu, Xiang-Feng Liu Feb 2019

Recent Developments In Surface/Interface Modulation And Structure-Performance Relationship Of Cathode Catalysts For Li-Air Batteries, Rui Gao, Jun-Kai Wang, Zhong-Bo Hu, Xiang-Feng Liu

Journal of Electrochemistry

Lithium-air battery has been considered to be one of the most promising secondary battery systems because of its high energy density. However, the sluggish kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) on the cathode, and the high overpotential, poor cycle stability and low rate capacity have severely blocked the development and application of Li-air battery. One of the effective strategies to alleviate these issues is to develop cathode catalysts for Li-air batteries. The design and development of bifunctional cathode catalysts with high activity and efficiency on both ORR and OER is highly desired for Li-air …


Synthesis Of Flower-Like Vanadium Disulfide For Lithium Storage Application, Pan Li, Jian Liu, Wei-Yi Sun, Hai-Xia Li, Zhan-Liang Tao Feb 2019

Synthesis Of Flower-Like Vanadium Disulfide For Lithium Storage Application, Pan Li, Jian Liu, Wei-Yi Sun, Hai-Xia Li, Zhan-Liang Tao

Journal of Electrochemistry

In order to improve the electrochemical properties of vanadium disulfide (VS2) as an electrode material in Li-ion battery, the flower-like VS2 was prepared by a one-step hydrothermal method with the addition of polyethylene glycol 400. The phase and morphology of the product were characterized by using X-ray diffraction and field emission scanning electron microscopy. During the growth process, it was observed that the flower-like VS2 was interspersed with several hexagonal vanadium disulfide nanosheets, which had a high specific surface area and excellent structural stability. The flower-like VS2 was used for the cathode material test in …


Ni/Mn3O4/Nimn2O4 Double-Shelled Hollow Spheres Embedded Into Reduced Graphene Oxide As Advanced Anodes For Sodium-Ion Batteries, Chong Yan, Hua-Ri Kou, Bo Yan, Xiao-Jing Liu, De-Jun Li, Xi-Fei Li Feb 2019

Ni/Mn3O4/Nimn2O4 Double-Shelled Hollow Spheres Embedded Into Reduced Graphene Oxide As Advanced Anodes For Sodium-Ion Batteries, Chong Yan, Hua-Ri Kou, Bo Yan, Xiao-Jing Liu, De-Jun Li, Xi-Fei Li

Journal of Electrochemistry

Delicately building the unique nanocomposite with the combination of hollow structure and reduced graphene oxide (rGO) is highly desirable and still remains a great challenge in the field of energy conversion and storage. In this work, Ni/Mn3O4/NiMn2O4 double-shelled hollow spheres coated by rGO (denoted as R-NMN) have been successfully synthetized via one-step rapid solvothermal treatment followed by subsequent annealing for the first time. Served as anodes for sodium ion batteries (SIBs), the R-NMN composite containing 25wt% rGO exhibits a high discharge capacity of 187.8 mAh·g-1 after 100 cycles at 50 mA·g-1 …


Preface On Special Issue Of Next-Generation Secondary Batteries, Zhen Zhou, Quan-Feng Dong Feb 2019

Preface On Special Issue Of Next-Generation Secondary Batteries, Zhen Zhou, Quan-Feng Dong

Journal of Electrochemistry

No abstract provided.


A Comparative Study Of Pre-Lithiated Hard Carbon And Soft Carbon As Anodes For Lithium-Ion Capacitors, Zhao Li, Xian-Zhong Sun, Wen-Jie Liu, Xiong Zhang, Kai Wang, Yan-Wei Ma Feb 2019

A Comparative Study Of Pre-Lithiated Hard Carbon And Soft Carbon As Anodes For Lithium-Ion Capacitors, Zhao Li, Xian-Zhong Sun, Wen-Jie Liu, Xiong Zhang, Kai Wang, Yan-Wei Ma

Journal of Electrochemistry

Lithium-ion capacitor (LIC) has emerged to be one of the most promising electrochemical energy storage devices. Presently, activated carbon (AC) is the mostly used cathode material for LIC. Nevertheless, various carbonaceous materials can be used as anode materials, such as hard carbon (HC) and soft carbon (SC). Therefore, HC and SC with different structural and electrochemical characteristics have been investigated as the anode materials of LICs in this work. Compared with the HC electrode, the SC electrode showed higher electronic conductivity and reversible capacity. The rate capabilities of the two carbonaceous materials as a function of coating thickness have been …


Cvd Preparation And Application Of 3d Graphene In Electrochemical Energy Storage, Yong-Kang Xia, Ming-Yuan Gu, Hong-Guan Yang, Xin-Zhi Yu, Bing-An Lu Feb 2019

Cvd Preparation And Application Of 3d Graphene In Electrochemical Energy Storage, Yong-Kang Xia, Ming-Yuan Gu, Hong-Guan Yang, Xin-Zhi Yu, Bing-An Lu

Journal of Electrochemistry

Three-dimensional (3D) graphene combinations with the excellent intrinsic properties of graphene and the 3D micro/nano porous structures provide a graphene foam with high specific surface area, excellent mechanical strength and fast electron and mass transports. The 3D graphene foam and its composite nanomaterials are widely used in the fields of nano-electronics, energy storage, chemical and biological sensing. The 3D graphene foam prepared by chemical vapor deposition (CVD) method is of high purity and crystallinity.  In this review, a brief overview in the CVD preparations of 3D graphene and properties of CVD prepared 3D graphene based nanomaterials in electrochemical energy storage …


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. …


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 …


Models Of Chromatographic Retention Of Isoquinoline Derivatives, I.Kh. Ruziev, N.K. Muhamadiyev Feb 2019

Models Of Chromatographic Retention Of Isoquinoline Derivatives, I.Kh. Ruziev, N.K. Muhamadiyev

Scientific Journal of Samarkand University

The chromatographic retention derivatives of pyrimidinone and isoquinoline was studied under conditions of reversed-phase HPLC variant. The retention factors were determined for different eluent compositions (CH3CN, CH3OH, and H2O). The dependence of retention on the concentration of an organic modifier in the mobile phase was studied. The applicability of known retention models to the studied chromatographic systems has been established.


Effect Various Factors On The Alkylation Reaction Of 2-Amino 6-Methyl(Phenyl)Pyrimidine-4-Ones., K.A. Zahidov, Z.U. Samarov, J.J. Javharov, O.U. Urinov Feb 2019

Effect Various Factors On The Alkylation Reaction Of 2-Amino 6-Methyl(Phenyl)Pyrimidine-4-Ones., K.A. Zahidov, Z.U. Samarov, J.J. Javharov, O.U. Urinov

Scientific Journal of Samarkand University

Alkylation of polident anions of 2-amino 6-methyl(phenyl)pyrimidine-4-ones with “soft” (methyl iodide) and “hard” (methyltozilate) alkilation agents have been systematically studied. It was shown the nature of solvents influnce on reactivity and the direction of alkylation.