Physical Sciences and Mathematics Commons^™

Contributions Of Tunneling In 8Π-6Π Electrocyclic Cascade Reactions Of Bicyclo[4.2.0]Octa-2,4-Diene Moieties, Ishika Jain, Claire Castro, William L. Karney

Featured Student Work

Six-electron electrocyclic reactions usually require relatively high temperatures; however recent research has shown that such reactions can occur at significantly lower temperatures in biosynthetic and biomimetic pathways. Pathways resulting in bicyclo[4.2.0]octa-2,4-diene moieties arise from thermally allowed 8π-6π electrocyclization cascade reactions of 1,3,5,7-octatetraenes, as in the biosynthesis of endiandric acids, elysiapyrones, and numerous other natural products. We report multidimensional tunneling calculations to explore the possible contribution of heavy-atom tunneling (e.g. by carbon) to biosynthetic pathways and biomimetic syntheses, and thus to provide a more complete picture of biochemical kinetics. M06-2X/cc-pVDZ calculations on the 8π-6π cascade cyclizations of methylated octatetraene model systems …

A Critical Inter-Subunit Interaction For The Transmission Of The Allosteric Signal In The Agrobacterium Tumefaciens Adp-Glucose Pyrophosphorylase, Hiral Patel, Gabriela Martinez-Ramirez Ms., Emily Dobrzynski, Alberto A. Iglesias, Dali Liu, Miguel Ballicora

Chemistry: Faculty Publications and Other Works

ADP-glucose pyrophosphorylase is a key regulatory enzyme involved in starch and glycogen synthesis in plants and bacteria, respectively. It has been hypothesized that inter-subunit communications are important for the allosteric effect in this enzyme. However, no specific interactions have been identified as part of the regulatory signal. The enzyme from Agrobacterium tumefaciens is a homotetramer allosterically regulated by fructose 6-phosphate and pyruvate. Three pairs of distinct subunit-subunit interfaces are present. Here we focus on an interface that features two symmetrical interactions between Arg11 and Asp141 from one subunit with residues Asp141 and Arg11 of the neighbor subunit, respectively. Previously, scanning …

Halide Exchange And Transport In Halide Perovskite Lattices, Temban Acha Billy

Department of Chemistry: Dissertations, Theses, and Student Research

In recent years, metal-halide perovskites (MHPs) have risen quickly to prominence as promising materials across a variety of fields, from photovoltaics to optoelectronics in general. We show here a facile solution growth for creating a variety of mixed halide MAPbBr_3-xI_x crystals, which we will use to study halide exchange and transport in halide perovskites. We generated a calibration curve between the optical response and chemical composition in mixed Br/I MHPs at room temperature. All mixed Br/I MHP crystals were subjected to measurements of photoluminescence (PL) and Raman spectroscopy. A subset of mixed-halide MHP crystals exhibited multiple emission …

Calcium Bistriflimide-Mediated Sulfur (Vi)–Fluoride Exchange (Sufex): Mechanistic Insights Toward Instigating Catalysis, Nicholas Ball, Brian Han, Samuel R. Khasnavis, Matthew Nwerem, Michael Bertagna, O Maduka Ogba

Pomona Faculty Publications and Research

We report a mechanistic investigation of calcium bistriflimide-mediated sulfur(VI)–fluoride exchange (SuFEx) between sulfonyl fluorides and amines. We determine the likely pre-activation resting state─a calcium bistriflimide complex with ligated amines─thus allowing for corroborated calculation of the SuFEx activation barrier at ∼21 kcal/mol, compared to 21.5 ± 0.14 kcal/mol derived via kinetics experiments. Transition state analysis revealed: (1) a two-point calcium-substrate contact that activates the sulfur(VI) center and stabilizes the leaving fluoride and (2) a 1,4-diazabicyclo[2.2.2]octane additive that provides Brønsted-base activation of the nucleophilic amine. Stable Ca–F complexes upon sulfonamide formation are likely contributors to inhibited catalytic turnover, and a proof-of-principle redesign …

Understanding Rapid Intercalation Materials One Parameter At A Time, Wessel Van Den Bergh, Morgan Stefik

Faculty Publications

Demand for fast, energy-dense storage drives the research into nanoscale intercalation materials. Nanomaterials accelerate kinetics and can modify reaction path thermodynamics, intercalant solubility, and reversibility. The discovery of intercalation pseudocapacitance has opened questions about their fundamental operating principles. For example, are their capacitor-like current responses caused by storing energy in special near-surface regions or rather is this response due to normal intercalation limited by a slower faradaic surface-reaction? This review highlights emerging methods combining tailored nanomaterials with the process of elimination to disambiguate cause-and-effect at the nanoscale. This method is applied to multiple intercalation pseudocapacitive materials showing that the timescales …

High Performance Liquid Chromatography Monitoring Reaction Kinetics, Ken Overway, Mary Ruth Shifflett

Chemistry Faculty Scholarship

To develop a chromatographic method to characterize enantioselective kinetics, the reaction between aromatic aldehydes and ephedrine will be monitored with High Performance Liquid Chromatography (HPLC). First, develop kinetics analysis procedure with the HPLC, the decomposition of aspartame was observed with citrate and phosphate buffers. The procedure produced an activation energy in the presence of phosphate buffer of 71.9 kJ/mol with a -0.126 % error. The aromatic aldehyde, benzaldehyde, and ephedrine were run through a stereospecific column to separate peaks with various mobile phases. A more nonpolar mobile phase is required for better peak and retention time separation.

Solvent Effects In Phenol Hydrogenation On A Supported Ruthenium Catalyst, Daniel Mckeon

Honors College

Growing concerns around climate have piqued interest in using biobased alternatives in place of fuels and chemicals traditionally made from petroleum. Lignocellulosic biomass has been noted for its potential as a biobased chemical precursor in the context of a biorefinery. It can be pyrolyzed to yield an oil, but catalytic upgrading is required to lower oxygen content to suitable levels. Ruthenium supported on titania has been identified as a catalyst suitable for hydrodeoxygenation of oxygenated aromatic pyrolysis products in the liquid phase. In liquid phase reactions, intermolecular attractions between the solvent and the reactants can significantly change chemical activities and …

Analysis Of Copper(Ii) Using The Ascorbate/Oxygen System – A Valuable Undergraduate Resource, Sean Tobin, John Cassidy, Kevin Kurian, Tony Betts

Articles

In deionised water, ascorbic acid (AH−), through oxidation by oxygen in the presence of copper(II), was found to degrade with zero-order kinetics. The magnitude of the reaction rate varied directly with the copper(II) concentration. At a higher pH (7.4), the same reaction was found to be pseudo-first order. Once again, the magnitude of the rate increased linearly with copper(II) concentration at a micromolar level. Dissolved oxygen levels, in excess AH− and trace copper(II), displayed similar kinetics under both conditions. Monitoring of either AH− levels or dissolved oxygen concentration was found to be a useful novel undergraduate practical laboratory for trace …

Visible Light Generation And Mechanistic Investigation Of High-Valent Metal-Oxo Species Supported By Different Ligands, Seth Ellis Klaine

Masters Theses & Specialist Projects

Numerous transition metal catalysts have been designed as biomimetic model compounds for the active site of metalloenzymes found throughout Nature, most notably cytochrome P450 monooxygenases that carry out the oxidative transformations of organic substrates with near-perfect chemo-, regio-, and stereo-selectivity. The primary active oxidants in catalytic and enzymatic cycles are fleeting high-valent metal-oxo intermediates where the oxo ligand can transfer to an organic substrate in a process known as oxygen atom transfer (OAT).

In the present work, porphyrin-manganese(III), salen-chromium(III), and salenmanganese( III) derivatives were successfully synthesized and spectroscopically characterized using 1H NMR and UV-Vis spectroscopies. A facile photochemical approach was …

State-To-State Inelastic Rotational Cross Sections In Five-Atom Systems With The Multiconfiguration Time Dependent Hartree Method, Steve Ndengue, Yohann Scribano, Fabien Gatti, Richard Dawes

Chemistry Faculty Research & Creative Works

We present a MultiConfiguration Time Dependent Hartree (MCTDH) method as an attractive alternative approach to the usual quantum close-coupling method that approaches some computational limits in the calculation of rotational excitation (and de-excitation) between polyatomic molecules (here collisions between triatomic and diatomic rigid molecules). We have performed a computational investigation of the rotational (de-)excitation of the benchmark rigid rotor H₂O-H₂ system on a recently developed Potential Energy Surface of the complex using the MCTDH method. We focus here on excitations and de-excitations from the 0₀₀, 1₁₁, and 1₁₀ states of H_{2 …}

Leaving Ligand Effects On Reactivity And Solubility Of Monofunctional Platinum(Ii) Anticancer Complexes, Heidi Linn Hruska Millay

Masters Theses & Specialist Projects

Monofunctional platinum(II) complexes, such as phenanthriplatin and pyriplatin, have notably different characteristics from the bifunctional anticancer complexes, such as cisplatin and oxaliplatin, which have detrimental toxicities and resistance associated with them. The unique properties of the monofunctional complexes may be exploited to target cancer cells without producing the toxic side effects associated with the current FDA-approved platinum-based anticancer drugs. To advance the understanding of these monofunctional platinum(II) complexes, this study replaced the chloride leaving ligand with an acetate group, which should increase solubility and alter the rate of reactivity with key amino acid and nucleotide targets. Phenanthriplatin and pyriplatin compounds …

H2 Oxidation Over Supported Au Nanoparticle Catalysts: Evidence For Heterolytic H2 Activation At The Metal-Support Interface, Todd N. Whittaker, K. B. Sravan Kumar, Christine Peterson, Meagan N. Pollock, L. C. Grabow, Bert D. Chandler

Chemistry Faculty Research

Water adsorbed at the metal-support interface (MSI) plays an important role in multiple reactions. Due to its importance in CO preferential oxidation (PrOx), we examined H₂ oxidation kinetics in the presence of water over Au/TiO₂ and Au/Al₂O₃ catalysts, reaching the following mechanistic conclusions: (i) O₂ activation follows a similar mechanism to that proposed in CO oxidation catalysis; (ii) weakly adsorbed H₂O is a strong reaction inhibitor; (iii) fast H₂ activation occurs at the MSI, and (iv) H₂ activation kinetics are inconsistent with traditional dissociative H₂ chemisorption on metals. Density …

Electrochemical Investigation Of The Kinetics Of Chloride Substitution Upon Reduction Of [Ru(Porphyrin)(No)Cl] Complexes In Thf., Jeremy R. Zink, E G. Abucayon, Anthony R. Ramuglia, Arghavan Fadamin, James E. Eilers, George B. Richter-Addo, Michael J. Shaw

SIUE Faculty Research, Scholarship, and Creative Activity

The electrochemistry of several ruthenium porphyrin nitrosyl chloride complexes [Ru(por)(NO)Cl] have been examined in tetrahydrofuran. The complexes undergo 1-electron irreversible reductions which result in the diffusion-limited substitutions of the chloride ligands for THF. This chloride metathesis is reversible in the presence of added NBu₄Cl, and equilibrium constants and rate constants for chloride loss have been estimated. These parameters correlate with the NO stretching frequencies of the parent complexes, with more electron-donating porphyrin ligands favouring chloride loss from the reduced complexes. The [Ru(por)(NO)(THF)] products of the reductions can be detected by IR, EPR and visible spectroscopies. These species undergo …

Fluoroethoxy-1,4-Diphenethylpiperidine And Piperazine Derivatives: Potent And Selective Inhibitors Of [3H]Dopamine Uptake At The Vesicular Monoamine Transporter-2, Emily R. Hankosky, Shyam R. Joolakanti, Justin R. Nickell, Venumadhav Janganati, Linda P. Dwoskin, Peter A. Crooks

Pharmaceutical Sciences Faculty Publications

A small library of fluoroethoxy-1,4-diphenethyl piperidine and fluoroethoxy-1,4-diphenethyl piperazine derivatives were designed, synthesized and evaluated for their ability to inhibit [³H]dopamine (DA) uptake at the vesicular monoamine transporter-2 (VMAT2) and dopamine transporter (DAT), [³H]serotonin (5-HT) uptake at the serotonin transporter (SERT), and [³H]dofetilide binding at the human-ether-a-go-go-related gene (hERG) channel. The majority of the compounds exhibited potent inhibition of [³H]DA uptake at VMAT2, with Ki values in the nanomolar range (K_i = 0.014–0.073 μM). Compound 15d exhibited the highest affinity (K_i = 0.014 μM) at VMAT2, and had 160-, 5-, …

Mechanistic Insights Into The Reaction Of Chlorination Of Tryptophan Catalyzed By Tryptophan 7-Halogenase., Tatyana Karabencheva-Christova, Juan Torras, Adrian J Mulholland, Alessio Lodola, Christo Christov

Michigan Tech Publications

Tryptophan 7-halogenase catalyzes chlorination of free tryptophan to 7-chlorotryptophan, which is the first step in the antibiotic pyrrolnitrin biosynthesis. Many biologically and pharmaceutically active natural products contain chlorine and thus, an understanding of the mechanism of its introduction into organic molecules is important. Whilst enzyme-catalyzed chlorination is accomplished with ease, it remains a difficult task for the chemists. Therefore, utilizing enzymes in the synthesis of chlorinated organic compounds is important, and providing atomistic mechanistic insights about the reaction mechanism of tryptophan 7-halogenase is vital and timely. In this work, we examined a mechanism for the reaction of tryptophan chlorination, performed …

Synthesis, Kinetic And Catalytic Studies Of Manganese Complexes With Corrole And Porphyrin Ligands, Haleh Jeddi

Masters Theses & Specialist Projects

High-valent transition metal-oxo intermediates play a significant role in the catalytic cycle of the ubiquitous cytochrome P450 enzymes and in biomimetic catalytic systems. In this work, manganese(III) porphyrin and corrole systems (2) were synthesized and characterized by UV-vis absorbance and 1H-NMR, matching literaturereported spectroscopic data. Manganese(V)-oxo corroles (3) and a manganese(IV)-oxo porphyrin (4) were successfully generated by chemical oxidation using mchloroperoxybenzoic acid (m-CPBA), and their oxidation reactions with organic reductants were comparatively investigated. Results from single-turnover kinetic studies indicate that in the tris(pentafluorophenyl)corrole system (3a), the active oxidizing intermediate differs in different solvents. The active oxidizing intermediate in acetonitrile is …

Kinetics And Reaction Mechanisms For Methylidyne Radical Reactions With Small Hydrocarbons, Joao Marcelo Lamim Ribeiro

FIU Electronic Theses and Dissertations

The chemical evolution with respect to time of complex macroscopic mixtures such as interstellar clouds and Titan’s atmosphere is governed via a mutual competition between thousands of simultaneous processes, including thousands of chemical reactions. Chemical kinetic modeling, which attempts to understand their macroscopic observables as well as their overall reaction mechanism through a detailed understanding of their microscopic reactions and processes, thus require thousands of rate coefficients and product distributions. At present, however, just a small fraction of these have been well-studied and measured; in addition, at the relevant low temperatures, such information becomes even more scarce. Due to the …

Removal Of Arsenic From Water Using Synthetic Fe7s8 Nanoparticles, Jesus Cantu, Louis E. Gonzalez, Jacqueline Goodship, Monica Contreras, Meera Joseph, Cameron Garza, Thomas Eubanks, Jason Parsons

Chemistry Faculty Publications and Presentations

In the present study, pyrrhotite was used to remove arsenite and arsenate from aqueous solutions. The Fe7S8 was synthesized using a solvothermal synthetic method and it was characterized using XRD and SEM micrographs. Furthermore, the particle size for the nanomaterial Fe7S8 was determined to be 29.86 ± 0.87 nm using Scherer’s equation. During the pH profile studies, the optimum pH for the binding of As (III) and As (V) was determined to be pH 4. Batch isotherm studies were performed to determine the binding capacity of As(III) and As(V), which was determined to be 14.3 mg/g and 31.3 mg/g respectively …

Mechanistic Binding Insights For 1-Deoxy-D-Xylulose-5-Phosphatesynthase, The Enzyme Catalyzing The First Reaction Of Isoprenoid Biosynthesis In The Malaria-Causing Protists, Plasmodium Falciparum And Plasmodium Vivax, Matthew R. Battistini, Christopher Shoji, Sumit Handa, Leonid Breydo, David J. Merkler

Chemistry Faculty Publications

We have successfully truncated and recombinantly-expressed 1-deoxy-D-xylulose-5-phosphate synthase (DXS) from both Plasmodium vivax and Plasmodium falciparum. We elucidated the order of substrate binding for both of these ThDP-dependent enzymes using steady-state kinetic analyses, dead-end inhibition, and intrinsic tryptophan fluorescence titrations. Both enzymes adhere to a random sequential mechanism with respect to binding of both substrates: pyruvate and D-glyceraldehyde-3-phosphate. These findings are in contrast to other ThDP-dependent enzymes, which exhibit classical ordered and/or ping-pong kinetic mechanisms. A better understanding of the kinetic mechanism for these two Plasmodial enzymes could aid in the development of novel DXS-specific inhibitors that might prove useful …

Measurement Of Antioxidant Activity Toward Superoxide In Natural Waters, D. Whitney King, Emma Berger, Zachary Helm, Eleanor Irish, Kenneth Mopper

Chemistry & Biochemistry Faculty Publications

Antioxidants are a class of molecules that provide a protective function against reactive oxygen species (ROS) in biological systems by out competing physiologically important molecules for ROS oxidation. In natural waters, the reactivity of antioxidants gives an estimate of oxidative stress, and may determine the reactivity and distribution of reactive oxidants. We present an analytical method to measure antioxidant activity in natural waters through the competition between ascorbic acid, an antioxidant, and MCLA, a chemiluminescent probe for superoxide. A numerical kinetic model of the analytical method has been developed to optimize analytical performance. Measurements of antioxidant concentrations in pure and …

The Critical Role Of Water At The Gold-Titania Interface In Catalytic Co Oxidation, Johnny Saavedra, H. Doan, Christopher J. Pursell, L. C. Grabow, Bert D. Chandler

Chemistry Faculty Research

We provide direct evidence of a water-mediated reaction mechanism for room-temperature CO oxidation over Au/TiO2 catalysts. A hydrogen/deuterium kinetic isotope effect of nearly 2 implicates O-H(D) bond breaking in the rate-determining step. Kinetics and in situ infrared spectroscopy experiments showed that the coverage of weakly adsorbed water on TiO2 largely determines catalyst activity by changing the number of active sites. Density functional theory calculations indicated that proton transfer at the metal-support interface facilitates O2 binding and activation; the resulting Au-OOH species readily reacts with adsorbed Au-CO, yielding Au-COOH. Au-COOH decomposition involves proton transfer to water and was suggested to be …

Identification Of An Active Site-Bound Nitrile Hydratase Intermediate Through Single Turnover Stopped-Flow Spectroscopy, Natalie Gumataotao, Misty L. Kuhn, Natalia Hajnas, Richard C. Holz

Chemistry Faculty Research and Publications

Stopped-flow kinetic data were obtained for the iron-type nitrile hydratase from Rhodococcus equi TG328-2 (ReNHase) using methacrylonitrile as the substrate. Multiple turnover experiments suggest a three-step kinetic model that allows for the reversible binding of substrate, the presence of an intermediate, and the formation of product. Microscopic rate constants determined from these data are in good agreement with steady state data confirming that the stopped-flow method used was appropriate for the reaction. Single turnover stopped-flow experiments were used to identify catalytic intermediates. These data were globally fit confirming a three-step kinetic model. Independent absorption spectra acquired between 0.005 …

Application Of Glycyrrhiza Glabra Root As A Novel Adsorbent In The Removal Of Toluene Vapors: Equilibrium, Kinetic, And Thermodynamic Study, Fazel Mohammadi-Moghadam, Mohammad Mehdi Amin,, Mehdi Khiadani, Fariborz Momenbeik, Heshmatollah Nourmoradi, Mohammad Sadegh Hatamipour

Research outputs 2013

The aim of this paper is to investigate the removal of toluene from gaseous solution through Glycyrrhiza glabra root (GGR) as a waste material. The batch adsorption experiments were conducted at various conditions including contact time, adsorbate concentration, humidity, and temperature. The adsorption capacity was increased by raising the sorbent humidity up to 50 percent. The adsorption of toluene was also increased over contact time by 12 h when the sorbent was saturated. The pseudo-second-order kinetic model and Freundlich model fitted the adsorption data better than other kinetic and isotherm models, respectively. The Dubinin-Radushkevich (D-R) isotherm also showed that the …

Removal Of Heavy Metals Using Modified Limestone Media: Zinc And Cadmium, Keerthy Mandadi

Masters Theses & Specialist Projects

Heavy metal contamination is a serious concern throughout the world. Increased concentrations in drinking water have many negative impacts on human health. Limestone is an inexpensive and simple media for removing high concentrations of heavy metals from drinking water supplies. Ferric based media is commonly used to remove zinc, cadmium, lead, arsenic and other heavy metals. The drinking water standards set by the US EPA for cadmium, zinc and arsenic are 0.005 mg/L, 5 mg/L and 0.010 mg/L respectively. Bangladesh, parts of India, China and the United States have high concentrations of arsenic in drinking water. Although many technologies exist …

Transient Ru-Methyl Formate Intermediates Generated With Bifunctional Transfer Hydrogenation Catalysts, Richard H. Perry, Kristen R. Brownell, Konstantin Chingin, Thomas J. Cahill Iii, Robert M. Waymouth, Richard N. Zare

Chemistry and Physics Faculty Articles

Desorption electrospray ionization (DESI) coupled to high-resolution Orbitrap mass spectrometry (MS) was used to study the reactivity of a (β-amino alcohol)(arene)RuCl transfer hydrogenation catalytic precursor in methanol (CH₃OH). By placing [(p-cymene)RuCl₂]₂ on a surface and spraying a solution of β-amino alcohol in methanol, two unique transient intermediates having lifetimes in the submillisecond to millisecond range were detected. These intermediates were identified as Ru (II) and Ru (IV) complexes incorporating methyl formate (HCOOCH₃). The Ru (IV) intermediate is not observed when the DESI spray solution is sparged with Ar gas, indicating that …

Nmr Line Shapes And Multi-State Binding Equilibria, Evgeni Kovrigin

Chemistry Faculty Research and Publications

Biological function of proteins relies on conformational transitions and binding of specific ligands. Protein-ligand interactions are thermodynamically and kinetically coupled to conformational changes in protein structures as conceptualized by the models of pre-existing equilibria and induced fit. NMR spectroscopy is particularly sensitive to complex ligand-binding modes—NMR line-shape analysis can provide for thermodynamic and kinetic constants of ligand-binding equilibria with the site-specific resolution. However, broad use of line shape analysis is hampered by complexity of NMR line shapes in multi-state systems. To facilitate interpretation of such spectral patterns, I computationally explored systems where isomerization or dimerization of a protein (receptor) molecule …

Formation And Stability Of Atmospherically Relevant Isoprene-Derived Organosulfates And Organonitrates, Adam I. Darer, Neil C. Cole-Filipiak, Alison E. O'Connor, Matthew J. Elrod

Faculty & Staff Scholarship

Isoprene is the precursor for number of alcohol, organosulfate, and organonitrate species observed in ambient secondary organic aerosol (SOA). Recent laboratory and field work has suggested that isoprene-derived epoxides may be crucial intermediates that can explain the existence of these compounds in SOA. To confirm this hypothesis, the specific hydroxy epoxides observed in gas phase isoprene photooxidation experiments (as well as several other related species) were synthesized and the bulk phase aqueous reactions of these species in the presence of sulfate and nitrate were studied via nuclear magnetic resonance (NMR) techniques. The results indicate that both primary and tertiary organosulfates …

Enhanced Oxygen Activation Over Supported Bimetallic Au-Ni Catalysts, Bert D. Chandler, Cormac G. Long, John D. Gilbertson, Christopher J. Pursell, G. Vijayaraghavan, K. J. Stevenson

Chemistry Faculty Research

New bimetallic Ni-Au supported nanoparticle catalysts were prepared by using dendrimer templated nanoparticles. Amine-terminated generation 5 polyamidoamine (PAMAM) dendrimers were anchored to a commercial silica with a siloxane linked anhydride. The dendrimer was then alkylated and used to template Ni-Au nanoparticles, which were subsequently extracted into organic solution as thiol monolayer protected clusters (MPCs). Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) indicated bimetallic nanoparticles of about 2 nm in size. Nanoparticles were deposited onto P-25 TiO2, and the capping thiol ligands were removed under flowing H2. DRIFTS infrared spectra of adsorbed CO showed only Au on the catalyst …

Methyl Septanoside Hydrolysis As A Measure Of Carbohydrate Ring Flexibility: Substrate Synthesis And Kinetics Analysis, Shawn Michael Miller

Honors Scholar Theses

A number of seven-membered ring systems have been found to have promising enzyme inhibiting properties. The common explanation for their efficacy is the apparent improved flexibility that the ring-system has over smaller rings. In an attempt to probe the validity of this hypothesis, unnatural seven-membered ring carbohydrates have been generated and subjected to kinetics analysis using hydrolysis. In particular, methyl α- and β-D-glycero-D-guloseptanoside were subjected to acid-catalyzed hydrolysis and monitored via HNMR experiments. The rate constants of the reactions were determined and compared to the hydrolysis rate constants of comparable pyranose carbohydrates and found to be significantly faster, indicating an …

Patterning High Surface Area Silica With Lysozyme: Adsorption Kinetics, Fluorescence Quenching, And Protein Readsorption Studies To Evaluate The Templated Surface, Rachel M. Greer, Brittni A. Scruggs, R Alan May, Bert D. Chandler

Chemistry Faculty Research

A method was developed for using an inexpensive and widely available protein, hen egg white lysozyme, as a patterning agent for commercial high surface area silicas. The basic patterning methodology involved spontaneous adsorption of the protein from aqueous solution, alkylation of the uncovered surface with an alkylsiloxane, and protein desorption in a slightly alkaline solution of morpholine. Adsorption kinetic studies using Bradford assays assisted in determining protein deposition conditions. These studies were generally consistent with results on more planar silica surfaces and indicated that the protein quickly and strongly adsorbs along its long axis at low surface coverages. A modified …