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Articles 901 - 930 of 2100

Full-Text Articles in Chemistry

Elucidation Of Substrate Binding To Photolyase From Sulfolobus Solfataricus Using Isothermal Titration Calorimetry, Amanda Rose Kuerzi May 2018

Elucidation Of Substrate Binding To Photolyase From Sulfolobus Solfataricus Using Isothermal Titration Calorimetry, Amanda Rose Kuerzi

Theses, Dissertations and Culminating Projects

DNA photolyase is a DNA repair enzyme commonly found across the kingdom of life. Binding studies for the hyperthermophilic photolyase derived from Sulfolobus solfataricus (SsPL) may serve to illuminate how DNA photolyase can adapt over a large temperature range. In the first section of this study, the thermodynamics of substrate binding for SsPL in a choline chloride buffer were determined using isothermal titration calorimetry. Using the Counter-Ion Condensation Concept as a model, ionic strength studies were performed to separate the binding interactions into electrostatic, and nonelectrostatic components. The electrostatic interactions do not appear to make a significant contribution to the …


The Effects Of Passive Integrated Transponder Tagging On Cortisol Release In The Gulf Killifish, Fundulus Grandis, Ariel Marcelo Hernandez May 2018

The Effects Of Passive Integrated Transponder Tagging On Cortisol Release In The Gulf Killifish, Fundulus Grandis, Ariel Marcelo Hernandez

Senior Honors Theses

Due to its ease of use, low cost, and essentially limitless number of unique codes, PIT tagging has become the favored technique for tagging individuals in biological studies. However, studies employing PIT tagging generally assume that stress due to the implantation and presence of a PIT tag has no influence on the experimental results. This study investigated the effects of PIT tagging on levels of the stress hormone cortisol in the Gulf Killifish, Fundulus grandis, an estuarine fish of the Gulf of Mexico that is prone to daily or seasonal environmental stressors. Cortisol was measured non-invasively by extracting and …


Evaluation Of Cafo Dairy Manure Treatment To Reduce Nutrient Transport, Jenna Laib Apr 2018

Evaluation Of Cafo Dairy Manure Treatment To Reduce Nutrient Transport, Jenna Laib

Honors Projects

Excess amounts of phosphorus and nitrogen flowing into Lake Erie from agricultural fields in Northwest Ohio has led to several harmful algal blooms (HABs). One potential source of those nutrients is manure applied to fields for fertilizer. Manure from confined animal feeding operations (CAFOs) is 95-98% water with only ~3% solids and nutrients, thus physical transportation is expensive relative to the value of the agricultural nutrients. Furthermore, once manure nutrients are applied to agricultural fields, they are relatively easily mobilized to waterways by precipitation. More than 800 lab-scale tests have been used to optimize the treatment of CAFO manure with …


Practical Spectrophotometric Assay For The Dape-Encoded N-Succinyl-L,L-Diaminopimelic Acid Desuccinylase, A Potential Antibiotic Target, Tahira K. Heath, Marlon R. Lutz Jr., Cory T. Reidl, Estefany R. Guzman, Claire A. Herbert, Boguslaw P. Nocek, Richard C. Hotz, Kenneth W. Olsen, Miguel A. Ballicora, Daniel P. Becker Apr 2018

Practical Spectrophotometric Assay For The Dape-Encoded N-Succinyl-L,L-Diaminopimelic Acid Desuccinylase, A Potential Antibiotic Target, Tahira K. Heath, Marlon R. Lutz Jr., Cory T. Reidl, Estefany R. Guzman, Claire A. Herbert, Boguslaw P. Nocek, Richard C. Hotz, Kenneth W. Olsen, Miguel A. Ballicora, Daniel P. Becker

Chemistry: Faculty Publications and Other Works

A new enzymatic assay for the bacterial enzyme succinyl-diaminopimelate desuccinylase (DapE, E.C. 3.5.1.18) is described. This assay employs N6-methyl-N2-succinyl-L,L-diaminopimelic acid (N6-methyl-L,L-SDAP) as the substrate with ninhydrin used to detect cleavage of the amide bond of the modified substrate, wherein N6-methylation enables selective detection of the primary amine enzymatic product. Molecular modeling supported preparation of the mono-N6-methylated-L,L-SDAP as an alternate substrate for the assay, given binding in the active site of DapE predicted to be comparable to the endogenous substrate. The alternate substrate for the assay, N6 …


Department Of Chemistry And Biochemistry 23rd Departmental Symposium In Conjunction With The Petersheim Academic Exposition, Seton Hall University Apr 2018

Department Of Chemistry And Biochemistry 23rd Departmental Symposium In Conjunction With The Petersheim Academic Exposition, Seton Hall University

Petersheim Academic Exposition

No abstract provided.


Shaping Light In Backward-Wave Nonlinear Hyperbolic Metamaterials, Thomas George, Alexander Popov, Sergey Myslivets, Vitaly Slabko, Victor Tkachenko Apr 2018

Shaping Light In Backward-Wave Nonlinear Hyperbolic Metamaterials, Thomas George, Alexander Popov, Sergey Myslivets, Vitaly Slabko, Victor Tkachenko

Chemistry & Biochemistry Faculty Works

Backward electromagnetic waves are extraordinary waves with contra-directed phase velocity and energy flux. Unusual properties of the coherent nonlinear optical coupling of the phase-matched ordinary and backward electromagnetic waves with contra-directed energy fluxes are described that enable greatly-enhanced frequency and propagation direction conversion, parametrical amplification, as well as control of shape of the light pulses. Extraordinary transient processes that emerge in such metamaterials in pulsed regimes are described. The results of the numerical simulation of particular plasmonic metamaterials with hyperbolic dispersion are presented, which prove the possibility to match phases of such coupled guided ordinary and backward electromagnetic waves. Particular …


Cation Exchange Capacity Determination: Comparative Study Of Three Methods, Lillie Zech Apr 2018

Cation Exchange Capacity Determination: Comparative Study Of Three Methods, Lillie Zech

Undergraduate Research Conference

No abstract provided.


Synthesis Of Oxygenated Boronic Acid Substituted A-Cyanostilbenes For Use As Antibacterial, Yewon Kim Apr 2018

Synthesis Of Oxygenated Boronic Acid Substituted A-Cyanostilbenes For Use As Antibacterial, Yewon Kim

Honors Theses

Stilbenes are naturally occurring compounds that have exhibited antibacterial activity, although the biological effect of various stilbenes differs for Gram-positive and Gram-negative strains of bacteria. In prior research, cyanostilbenes have shown slight antibacterial activity (Brownlee, et al. 1943). This project aims to explore whether hybrid oxygenated a-cyanostilbenes possessing a boronic acid pharmacophore exhibits significant antibacterial activity (Das et al. 2013). The biological activity against Staphylocococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) was tested using the Kirby-Bauer text. No inhibition of E. coli growth was shown while S. aureus was partially inhibited.


Evaluating Mutagenicity Of Burned Arginine-Based Heterocyclic Amines And Anti-Mutagenicity Effect Of Chinese Medicinal Herbs, Rayford C. Alva Apr 2018

Evaluating Mutagenicity Of Burned Arginine-Based Heterocyclic Amines And Anti-Mutagenicity Effect Of Chinese Medicinal Herbs, Rayford C. Alva

Honors Theses

From the unexpected finding that cooked grains and meat substitutes elicit a mutagenic response in Salmonella typhimurium TA98, our work has been aimed at deconstructing this finding via a survey of heated binary amino acid combinations, involving arginine, a plant-based amino acid. secondly, our work has looked towards sing phytochemical extracts from traditional Chinese medicinal herbs to inhibit the mutagenic activity of heterocyclic amines (main culprit for mutagenicity in meat). Two fractions from the burned products of arginine and phenylalanine (RF-HCA-06 and -07) were statistically significant inducers of mutagenesis; Scutellaria barbata and Oldenlandia diffusa, both separately and together, were statistically …


Elemental Analysis Of Beer Manufactured In Virginia Satellite Breweries, Jennifer Wiliams Apr 2018

Elemental Analysis Of Beer Manufactured In Virginia Satellite Breweries, Jennifer Wiliams

Student Scholar Showcase

Financial incentives from the state and wider distribution potential have lured many west coast brewers to open satellite breweries in Virginia. Quality control is crucial for any brewery and especially important in satellite breweries that need to imitate the standard set by the parent brewery. Zinc, magnesium, iron, sodium manganese, and calcium are trace elements found in wort and are essential for enzymes that catalyze fermentation reactions. These elements protect against cell stress, play a crucial role in flocculation, and can affect the flavoring and coloration of beer. Barley, water, and hops are the sources of these elements in beer. …


Elastin-Like Polypeptide Fusion Tag As A Protein-Dependent Solubility Enhancer Of Cysteine-Knot Growth Factors, Tamina L. Johnson Apr 2018

Elastin-Like Polypeptide Fusion Tag As A Protein-Dependent Solubility Enhancer Of Cysteine-Knot Growth Factors, Tamina L. Johnson

USF Tampa Graduate Theses and Dissertations

Elastin-like peptide (ELP) fusions promote therapeutic delivery and efficacy. Recombinant proteins, like neurotrophins, lack bioavailability, have short in vivo half-lives, and require high manufacturing costs. Fusing recombinant proteins with genetically encodable ELPs will increase bioavailability, enhance in vivo solubilization, as well as provide a cost-effective method for purification without the need for chromatography. During expression of neurotrophin-ELP (N-ELP) fusions, dense water-insoluble aggregates known as inclusion bodies (IBs) are formed. Inclusion bodies are partially and misfolded proteins that usually require denaturants like Urea for solubilization. Strong denaturants arrest ELPs stimuli-responsive property and increase unwanted aggregation, making purification difficult, yet possible. The …


Evaluation Of Controlled-Release Nitrogen And Potassium Fertilizer In Louisiana Sugarcane Production, Samuel Kwakye Apr 2018

Evaluation Of Controlled-Release Nitrogen And Potassium Fertilizer In Louisiana Sugarcane Production, Samuel Kwakye

LSU Master's Theses

Sugarcane (Saccharum spp) production is an integral part of Louisiana's economy. Proper fertilizer management, particularly nitrogen (N) and potassium (K), optimizes sugarcane production. An experiment was established in 2015 at the LSU AgCenter Sugar Research Station in St. Gabriel, Louisiana to: (1) assess the effect of N and K fertilizer sources on sugarcane yield and quality parameters, and (2) monitor the changes in inorganic N and K levels in the soil at different sugarcane growth stages. The experiment was arranged in a randomized complete block design on a Sharkey clay soil and complete randomized design on a Commerce …


Biomimetic Studies Of Oxidation Reactions By Metalloporphyrins Through Ligand Effect And Kinetic Studies Of Photo-Generated Porphyrin-Iron(Iv)- Oxocompound Ii Models, Dharmesh J. Patel Apr 2018

Biomimetic Studies Of Oxidation Reactions By Metalloporphyrins Through Ligand Effect And Kinetic Studies Of Photo-Generated Porphyrin-Iron(Iv)- Oxocompound Ii Models, Dharmesh J. Patel

Masters Theses & Specialist Projects

High-valent iron(IV)-oxo porphyrins are the central oxidizing species in hemecontaining enzymes and synthetic oxidation catalysts. Many transition metal complexes have been extensively studied as models of the ubiquitous cytochrome P450 enzymes to probe the sophisticated oxygen atom transfer (OAT) mechanism as well as to invent enzyme-like oxidation catalysts. In this work, two metalloporphyrin complexes have been successfully synthesized, and spectroscopically characterized. A new photochemical entry to porphyrin-iron(IV)-oxo derivatives, commonly referred to as compound II models, was also investigated in two porphyrin ligands that differ in electronic and steric environments. As determined by their distinct UV-vis spectra and kinetic behaviors, iron(IV)-oxo …


Untargeted Bioassay Strategy For Medicinal Plants: In Vitro Antidiabetic Activity And 13c Nmr Profiling Of Extracts From Vitex Negundo L, Fabian M. Dayrit, Myrnille Joy B. Zabala, Lolita G. Lagurin Apr 2018

Untargeted Bioassay Strategy For Medicinal Plants: In Vitro Antidiabetic Activity And 13c Nmr Profiling Of Extracts From Vitex Negundo L, Fabian M. Dayrit, Myrnille Joy B. Zabala, Lolita G. Lagurin

Chemistry Faculty Publications

Bioassay-guided fractionation is the principal method for the identification of active constituents in medicinal plants. By design, this method aims to identify the most active compound in a complex mixture with the objective of discovering novel drug candidates. Described here is a complementary method for the identification of known bioactive compounds in medicinal plants which is untargeted and which takes advantage of the large NMR database of known natural products and availability of statistical software. This untargeted bioassay strategy is demonstrated as a proof of principle in the determination of the antidiabetic compounds in Vitex negundo L. Crude methanol and …


Magnetic Properties Of Acenes And Their O-Quinone Derivatives: Computer Simulation, A. A. Starikova, A. G. Starikov, R. M. Minyaev, Alexander I. Boldyrev, V. I. Minkin Apr 2018

Magnetic Properties Of Acenes And Their O-Quinone Derivatives: Computer Simulation, A. A. Starikova, A. G. Starikov, R. M. Minyaev, Alexander I. Boldyrev, V. I. Minkin

Chemistry and Biochemistry Faculty Publications

Quantum chemical study (DFT UB3LYP/6-311++G(d,p)) of the structure and properties of acenes functionalized with two o-benzoquinone groups and their complexes with sodium cations has been performed. An increase in the number of fused rings has been shown to result in the stabilization of biradicaloid state of acenes and the switching of the character of exchange interactions between redox-active moieties from antiferromagnetic to ferromagnetic. The obtained results allow one to consider o-quinone acene derivatives as a basis for designing magnetoactive compounds.


Detection Of Amyloid Beta (Aβ) Oligomeric Composition Using Matrix-Assisted Laser Desorption Ionization Mass Spectrometry (Maldi Ms)., Jasmine S-H Wang, Shawn N Whitehead, Ken K-C Yeung Apr 2018

Detection Of Amyloid Beta (Aβ) Oligomeric Composition Using Matrix-Assisted Laser Desorption Ionization Mass Spectrometry (Maldi Ms)., Jasmine S-H Wang, Shawn N Whitehead, Ken K-C Yeung

Chemistry Publications

The use of MALDI MS as a fast and direct method to detect the Aβ oligomers of different masses is examined in this paper. Experimental results suggest that Aβ oligomers are ionized and detected as singly charged ions, and thus, the resulting mass spectrum directly reports the oligomer size distribution. Validation experiments were performed to verify the MS data against artifacts. Mass spectra collected from modified Aβ peptides with different propensities for aggregation were compared. Generally, the relative intensities of multimers were higher from samples where oligomerization was expected to be more favorable, and vice versa. MALDI MS was also …


Advancing Professional Development Strategies For Chemistry And Biochemistry Undergraduates, Christian A. Brown Apr 2018

Advancing Professional Development Strategies For Chemistry And Biochemistry Undergraduates, Christian A. Brown

Senior Theses

In the Department of Chemistry and Biochemistry at the University of South Carolina (the Department), most curriculum-driven professional development is reserved for third- and fourth-year students. Classroom learning occurs at all levels, but the context comes late. Early exposure to career options and hands-on training is imperative for undergraduates to obtain maximum experiential learning. The purpose of this project is to advance the current professional development strategies of the Department, specifically targeting second- and third-year students. The study surveyed students' current involvement in professional development activities. The data on extracurricular experience and post-graduation interest was used to design a workshop …


Mxin Differentially Regulates Monomeric And Oligomeric Species Of The Shigella Type Three Secretion System Atpase Spa47, Heather B. Case, Nicholas E. Dickenson Mar 2018

Mxin Differentially Regulates Monomeric And Oligomeric Species Of The Shigella Type Three Secretion System Atpase Spa47, Heather B. Case, Nicholas E. Dickenson

Chemistry and Biochemistry Faculty Publications

Shigella rely entirely on the action of a single type three secretion system (T3SS) to support cellular invasion of colonic epithelial cells and to circumvent host immune responses. The ATPase Spa47 resides at the base of the Shigella needle-like type three secretion apparatus (T3SA), supporting protein secretion through the apparatus and providing a likely means for native virulence regulation by Shigella and a much needed target for non-antibiotic therapeutics to treat Shigella infections. Here, we show that MxiN is a differential regulator of Spa47 and that its regulatory impact is determined by the oligomeric state of the Spa47 ATPase, with …


Progress Toward Synthetically Simplified Natural Anticancer Peptide, David W. Kastner, Steven L. Castle Mar 2018

Progress Toward Synthetically Simplified Natural Anticancer Peptide, David W. Kastner, Steven L. Castle

Library/Life Sciences Undergraduate Poster Competition 2018

Yaku’amide A was isolated in late 2010 from the deep-sea sponge Ceratopsion sp. and exhibits potent inhibitory activity against 39 human cancer cell lines via a potentially novel mode of action. However, the total synthesis requires many steps and produces low yields. In this study, we determined two simpler YA analogues that may retain its anticancer properties and can be synthesized in larger quantities. The analogues replace dehydroisoleucine with either dehydroethylnorvaline or dehydrovaline.


Design, Synthesis, Application Of Biodegradable Polymers, Mussie Gide Mar 2018

Design, Synthesis, Application Of Biodegradable Polymers, Mussie Gide

USF Tampa Graduate Theses and Dissertations

Bacterial infections have posed a serious threat to the public health due to the significant rise of the infections caused by antibiotic-resistant bacteria. There has been considerable interest in the development of antimicrobial agents which mimic the natural HDPs, and among them biodegradable polymers are newly discovered drug candidates with ease of synthesis and low manufacture cost compared to synthetic host defense peptides. Herein, we present the synthesis of biocompatible and biodegradable polymers including polycarbonate polymers, unimolecular micelle hyperbranched polymers and dendrimers that mimic the antibacterial mechanism of HDPs by compromising bacterial cell membranes. The developed amphiphilic polycarbonates are highly …


Investigating The Synthesis Of 1,3,4-Oxadiazoles Via A Novel Two-Step-One-Pot Cyclodehydration Reaction, Brittney Sowers Mar 2018

Investigating The Synthesis Of 1,3,4-Oxadiazoles Via A Novel Two-Step-One-Pot Cyclodehydration Reaction, Brittney Sowers

Undergraduate Honors Thesis Projects

The given research will investigate synthetic strategies and differential functionalization of 1,3,4- oxadiazoles in hopes of obtaining moderate to high yields. Particularly, the effects of electron withdrawing on oxadiazoles will reveal more information about possible mechanistic details and reaction optimization.

The research in this report is a part of a lager research effort being investigated by Dr. Robin Grote. This research is ongoing and has evolved from its start in the Grote Lab. Previously, the Grote Lab has focused on the formation of a patented heterocycle that contained an amino-pyrazine functional group. Currently, our research has shifted focus to the …


A Chimeric Nucleobase - Phenylazo Derivative As An Intrinsic Nucleobase Quencher, Gyeongsu Park, Timothy Martin-Chan, Amer El Samm, Robert H.E. Hudson Mar 2018

A Chimeric Nucleobase - Phenylazo Derivative As An Intrinsic Nucleobase Quencher, Gyeongsu Park, Timothy Martin-Chan, Amer El Samm, Robert H.E. Hudson

Western Research Forum

Molecular beacons are important bioanalytical probes which are most often

constructed from a single-stranded oligonucleotide which has been labeled at

opposite termini with a fluorophore and a quencher. When the fluorophore and

quencher are in close proximity, no fluorescence is observed due to FRET

(Fluorescence Resonance Energy Transfer). DABCYL (4-dimethylaminoazobenzene-

4'-carboxylic acid) has been used as a quencher in the molecular beacon to absorbs

excitation energy from a fluorophore and to dissipate the energy as heat. However,

DABCYL is unable to form a base-pair and is conventionally placed as an overhanging

residue. This produces a derivative wherein the chromophore has …


Non-Methane Organic Gas Emissions From Biomass Burning: Identification, Quantification, And Emission Factors From Ptr-Tof During The Firex 2016 Laboratory Experiment, Abigail R. Koss, Kanako Sekimoto, Jessica B. Gilman, Vanessa Selimovic, Matthew M. Coggon, Kyle J. Zarzana, Bin Yuan, Brian M. Lerner, Steven S. Brown, Jose L. Jimenez, Jordan Krechmer, James M. Roberts, Carsten Warneke, Robert J. Yokelson, Joost De Gouw Mar 2018

Non-Methane Organic Gas Emissions From Biomass Burning: Identification, Quantification, And Emission Factors From Ptr-Tof During The Firex 2016 Laboratory Experiment, Abigail R. Koss, Kanako Sekimoto, Jessica B. Gilman, Vanessa Selimovic, Matthew M. Coggon, Kyle J. Zarzana, Bin Yuan, Brian M. Lerner, Steven S. Brown, Jose L. Jimenez, Jordan Krechmer, James M. Roberts, Carsten Warneke, Robert J. Yokelson, Joost De Gouw

Chemistry and Biochemistry Faculty Publications

Volatile and intermediate-volatility non-methane organic gases (NMOGs) released from biomass burning were measured during laboratory-simulated wildfires by proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF). We identified NMOG contributors to more than 150 PTR ion masses using gas chromatography (GC) pre-separation with electron ionization, H3O+ chemical ionization, and NO+ chemical ionization, an extensive literature review, and time series correlation, providing higher certainty for ion identifications than has been previously available. Our interpretation of the PTR-ToF mass spectrum accounts for nearly 90ĝ€-% of NMOG mass detected by PTR-ToF across all fuel types. The relative contributions of different NMOGs to individual exact ion masses are …


Aerosol Optical Properties And Trace Gas Emissions By Pax And Op-Ftir For Laboratory-Simulated Western Us Wildfires During Firex, Vanessa Selimovic, Robert J. Yokelson, Carsten Warneke, James M. Roberts, Joost De Gouw, James Reardon, David W.T. Griffith Mar 2018

Aerosol Optical Properties And Trace Gas Emissions By Pax And Op-Ftir For Laboratory-Simulated Western Us Wildfires During Firex, Vanessa Selimovic, Robert J. Yokelson, Carsten Warneke, James M. Roberts, Joost De Gouw, James Reardon, David W.T. Griffith

Chemistry and Biochemistry Faculty Publications

Western wildfires have a major impact on air quality in the US. In the fall of 2016, 107 test fires were burned in the large-scale combustion facility at the US Forest Service Missoula Fire Sciences Laboratory as part of the Fire Influence on Regional and Global Environments Experiment (FIREX). Canopy, litter, duff, dead wood, and other fuel components were burned in combinations that represented realistic fuel complexes for several important western US coniferous and chaparral ecosystems including ponderosa pine, Douglas fir, Engelmann spruce, lodgepole pine, subalpine fir, chamise, and manzanita. In addition, dung, Indonesian peat, and individual coniferous ecosystem fuel …


In Vitro Label Free Screening Of Chemotherapeutic Drugs Using Raman Micro-Spectroscopy: Towards A New Paradigm Of Spectralomics., Zeineb Farhane, Haq Nawaz, Franck Bonnier, Hugh Byrne Mar 2018

In Vitro Label Free Screening Of Chemotherapeutic Drugs Using Raman Micro-Spectroscopy: Towards A New Paradigm Of Spectralomics., Zeineb Farhane, Haq Nawaz, Franck Bonnier, Hugh Byrne

Articles

This overview groups some of the recent studies highlighting the potential application of Raman micro-spectroscopy as an analytical technique in preclinical development to predict drug mechanism of action and in clinical application as a companion diagnostic and in personalised therapy due to its capacity to predict cellular resistance and therefore to optimise chemotherapeutic treatment efficacy.

Notably, the anthracyclines, Doxorubicin and Actinomycin D, elicit similar spectroscopic signatures of subcellular interaction characteristic of the mode of action of intercalation. Although Cisplatin and Vincristine show markedly different signatures, at low exposure doses, their signatures at higher doses show marked similarities to those elicited …


Contribution Of Bulky <&Alpha>,<&Beta>-Dehydroamino Acids To The Proteolytic Stability Andenhanced Folding Of <&Beta>-Hairpins And Progress Towards The Total Synthesis Of Yaku<'>Amide A, Ankur Jalan Mar 2018

Contribution Of Bulky <&Alpha>,<&Beta>-Dehydroamino Acids To The Proteolytic Stability Andenhanced Folding Of <&Beta>-Hairpins And Progress Towards The Total Synthesis Of Yaku<'>Amide A, Ankur Jalan

Theses and Dissertations

This dissertation primarily covers the impact of bulky ,-dehydroamino acids on the proteolytic stability and enhanced folding of -hairpins. It partly describes the progress towards the total synthesis of yakuamide A, a potent anticancer peptide with an IC50 value of 14 ng/mL against leukemia cells. Proteins and peptides are a very attractive source of potential medicinal agents as they can target various protein“protein interactions that are implicated in several diseases and disorders. The global sales of peptide drugs in 2013 were estimated to be about $28 billion and are constantly rising at an appreciable rate. However, peptide drugs have a …


Electron Transfer To Nitrogenase In Different Genomic And Metabolic Backgrounds, Saroj Poudel, Daniel R. Colman, Kathryn R. Fixen, Rhesa N. Ledbetter, Yanning Zheng, Natasha Pence, Lance C. Seefeldt, John W. Peters, Caroline S. Harwood, Eric S. Boyd Feb 2018

Electron Transfer To Nitrogenase In Different Genomic And Metabolic Backgrounds, Saroj Poudel, Daniel R. Colman, Kathryn R. Fixen, Rhesa N. Ledbetter, Yanning Zheng, Natasha Pence, Lance C. Seefeldt, John W. Peters, Caroline S. Harwood, Eric S. Boyd

Chemistry and Biochemistry Faculty Publications

Nitrogenase catalyzes the reduction of dinitrogen (N2) using low-potential electrons from ferredoxin (Fd) or flavodoxin (Fld) through an ATP-dependent process. Since its emergence in an anaerobic chemoautotroph, this oxygen (O2)-sensitive enzyme complex has evolved to operate in a variety of genomic and metabolic backgrounds, including those of aerobes, anaerobes, chemotrophs, and phototrophs. However, whether pathways of electron delivery to nitrogenase are influenced by these different metabolic backgrounds is not well understood. Here, we report the distribution of homologs of Fds, Flds, and Fd-/Fld-reducing enzymes in 359 genomes of putative N2 fixers (diazotrophs). Six distinct lineages …


Implications Of Monomer Deformation For Tetrel And Pnicogen Bonds, Wiktor Zierkiewicz, Mariusz Michalczyk, Steve Scheiner Feb 2018

Implications Of Monomer Deformation For Tetrel And Pnicogen Bonds, Wiktor Zierkiewicz, Mariusz Michalczyk, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

A series of TF4 and ZF5 molecules (T = Si, Ge, Sn and Z = P, As, Sb) were allowed to engage in tetrel and pnicogen bonds, respectively, with NH3, pyrazine, and HCN. The interaction energies are quite large, approaching 50 kcal mol-1 in some cases. The formation of each complex is accompanied by substantial geometrical deformation of the Lewis acid to accommodate the approaching base. The energy associated with this monomer rearrangement is the largest for the smaller central atoms Si and P, where it exceeds 20 kcal mol-1. The total reaction …


Chemical Characterization Of Fine Particulate Matter Emitted By Peat Fires In Central Kalimantan, Indonesia, During The 2015 El Niño, Thilina Jayarathne, Chelsea E. Stockwell, Ashley A. Gilbert, Kaitlyn Daugherty, Mark A. Cochrane, Kevin C. Ryan, Erianto I. Putra, Bambang H. Saharjo, Ati D. Nurhayati, Israr Albar, Robert J. Yokelson, Elizabeth A. Stone Feb 2018

Chemical Characterization Of Fine Particulate Matter Emitted By Peat Fires In Central Kalimantan, Indonesia, During The 2015 El Niño, Thilina Jayarathne, Chelsea E. Stockwell, Ashley A. Gilbert, Kaitlyn Daugherty, Mark A. Cochrane, Kevin C. Ryan, Erianto I. Putra, Bambang H. Saharjo, Ati D. Nurhayati, Israr Albar, Robert J. Yokelson, Elizabeth A. Stone

Chemistry and Biochemistry Faculty Publications

Fine particulate matter (PM2:5) was collected in situ from peat smoke during the 2015 El Niño peat fire episode in Central Kalimantan, Indonesia. Twenty-one PM samples were collected from 18 peat fire plumes that were primarily smoldering with modified combustion efficiency (MCE) values of 0.725-0.833. PM emissions were determined and chemically characterized for elemental carbon (EC), organic carbon (OC), water-soluble OC, water-soluble ions, metals, and organic species. Fuel-based PM2:5 mass emission factors (EFs) ranged from 6.0 to 29.6 g kg1 with an average of 17:36:0 g kg1. EC was detected only in 15 plumes and comprised 1% of PM mass. …


Nepal Ambient Monitoring And Source Testing Experiment (Namaste): Emissions Of Particulate Matter From Wood-And Dung-Fueled Cooking Fires, Garbage And Crop Residue Burning, Brick Kilns, And Other Sources, Thilina Jayarathne, Chelsea E. Stockwell, Prakash V. Bhave, Puppala S. Praveen, Chathurika M. Rathnayake, Robiul Md Islam, Arnico K. Panday, Sagar Adhikari, Rashmi Maharjan, J. Douglas Goetz, Peter F. Decarlo, Eri Saikawa, Robert J. Yokelson, Elizabeth A. Stone Feb 2018

Nepal Ambient Monitoring And Source Testing Experiment (Namaste): Emissions Of Particulate Matter From Wood-And Dung-Fueled Cooking Fires, Garbage And Crop Residue Burning, Brick Kilns, And Other Sources, Thilina Jayarathne, Chelsea E. Stockwell, Prakash V. Bhave, Puppala S. Praveen, Chathurika M. Rathnayake, Robiul Md Islam, Arnico K. Panday, Sagar Adhikari, Rashmi Maharjan, J. Douglas Goetz, Peter F. Decarlo, Eri Saikawa, Robert J. Yokelson, Elizabeth A. Stone

Chemistry and Biochemistry Faculty Publications

The Nepal Ambient Monitoring and Source Testing Experiment (NAMaSTE) characterized widespread and under-sampled combustion sources common to South Asia, including brick kilns, garbage burning, diesel and gasoline generators, diesel groundwater pumps, idling motorcycles, traditional and modern cooking stoves and fires, crop residue burning, and heating fire. Fuel-based emission factors (EFs; with units of pollutant mass emitted per kilogram of fuel combusted) were determined for fine particulate matter (PM2.5), organic carbon (OC), elemental carbon (EC), inorganic ions, trace metals, and organic species. For the forced-draft zigzag brick kiln, EFPM2.5 ranged from 12 to 19gkg-1 with major contributions from OC (7%), sulfate …