Biochemistry, Biophysics, and Structural Biology Commons^™

Lignin Biopolymers In The Age Of Controlled Polymerization, Mitra S. Ganewatta, Hasala N. Lokupitiya, Chuanbing Tang

Faculty Publications

Polymers made from natural biomass are gaining interest due to the rising environmental concerns and depletion of petrochemical resources. Lignin isolated from lignocellulosic biomass is the second most abundant natural polymer next to cellulose. The paper pulp process produces industrial lignin as a byproduct that is mostly used for energy and has less significant utility in materials applications. High abundance, rich chemical functionalities, CO2 neutrality, reinforcing properties, antioxidant and UV blocking abilities, as well as environmental friendliness, make lignin an interesting substrate for materials and chemical development. However, poor processability, low reactivity, and intrinsic structural heterogeneity limit lignins′ polymeric applications …

Cellular Localization Of Rad51d Mutant Proteins And The Application Of Art To Increase Scientific Literacy In America, Claire L. Chabot

Senior Theses

Ovarian cancers are the leading cause of death from cancer of the female reproductive system. Approximately 50% of ovarian cancers have defects in the homologous recombination (HR) DNA repair pathway that is required for the repair of DNA double-stranded breaks. The status of HR genes, such as BRCA1, BRCA2, and the RAD51 family, contributes to ovarian cancer development as well as treatment decisions regarding chemotherapy, radiation, and immunotherapy. The overarching goal of this project is to identify new insights into HR that can integrate with Precision Medicine Initiatives and align with the goals of the Cancer Moonshot 2020 Program. I …

Generalizing Metallocene Mechanochemistry To Ruthenocene Mechanophores, Ye Sha, Yudi Zhang, Enhua Xu, C Wayne Mcalister, Tianyu Zhu, Stephen L. Craig, Chuanbing Tang

Faculty Publications

Recent reports have shown that ferrocene displays an unexpected combination of force-free stability and mechanochemical activity, as it acts as the preferred site of chain scission along the backbone of highly extended polymer chains. This observation raises the tantalizing question as to whether similar mechanochemical activity might be present in other metallocenes, and, if so, what features of metallocenes dictate their relative ability to act as mechanophores. In this work, we elucidate polymerization methodologies towards main-chain ruthenocene-based polymers and explore the mechanochemistry of ruthenocene. We find that ruthenocene, in analogy to ferrocene, acts as a highly selective site of main …

Synthetic Lectins, A Diagnostic And Prognostic Tool For Detecting Glycans In Breast Cancer, Daniel James Gordon

Theses and Dissertations

Cancer diagnostic tools have been pushed to the forefront of medical research because a person’s chance of survival is directly correlated with how early the tumor is identified and treatment is begun. In searching for the subtle differences between healthy and tumor cells, almost every type of cancer has been shown to under, over, or neo express glycans, and these changes in the glycan fingerprint can continue as the disease progresses. This provides a powerful diagnostic opportunity that’s works by screening for glycoproteins and glycosylation patterns that deviate from normal cells.

Boronic acids have a useful and tunable property in …

Characterizing Aft1/2-Grx3/4 Interaction And The Role Of Bol2 During Iron Regulation In Saccharomyces Cerevisiae, William Rivers

Senior Theses

Iron dysregulation has been linked to a variety of human diseases, such as anemia, Friedreich’s ataxia, X-linked sideroblastic anemia, sideroblastic-like microcytic anemia, and myopathy. Thus, it is vitally important to understand the mechanisms for regulating intracellular iron. Here, we use fluorescence microscopy techniques in live cells to study interactions of the yeast proteins Grx3/4, Aft1/2, and Bol2, which have been shown to be involved in turning off iron import when the cell has adequate iron. Modified versions of genes encoding these proteins have been incorporated into several yeast backgrounds to use fluorescence to monitor interactions under varying iron levels.

Purification Of Ara6, Ara7, And Hopaa1-1 For Enzymatic Activity Study, Alexandra M. Koberlein

Senior Theses

This thesis project details the purification of proteins HopAA1-1, ARA6, and ARA7 for enzymatic analysis via the use of a phosphate detection assay. The results of the purification process and phosphate assay suggest that HopAA1-1 is a novel GAP protein found in plant models that may exhibit GAP activity on RAB GTPase protein ARA6.

A New Multivariate Optical Computing Microelement And Miniature Sensor For Spectroscopic Chemical Sensing In Harsh Environments: Design, Fabrication, And Testing, Christopher M. Jones, Bin Dai, Jimmy Price, Jian Li, Megan Pearl, Bill Soltmann, Michael L. Myrick

Faculty Publications

Multivariate optical computing (MOC) is a compressed sensing technique with the ability to provide accurate spectroscopic compositional analysis in a variety of different applications to multiple industries. Indeed, recent developments have demonstrated the successful deployment of MOC sensors in downhole/well-logging environments to interrogate the composition of hydrocarbon and other chemical constituents in oil and gas reservoirs. However, new challenges have necessitated sensors that operate at high temperatures and pressures (up to 230 °C and 138 MPa) as well as even smaller areas that require the miniaturization of their physical footprint. To this end, this paper details the design, fabrication, and …

Exposure Characterization Of Haloacetic Acids In Humans For Exposure And Risk Assessment Applications: An Exploratory Study, Shahid Parvez, Jeffrey L. Ashby, Susana Y. Kimura, Susan D. Richardson

Faculty Publications

Disinfected water is the major source of haloacetic acids (HAAs) in humans, but their inter- and intra-individual variability for exposure and risk assessment applications is under-researched. Thus, we measured HAAs in cross-sectional and longitudinal urine and water specimens from 17 individuals. Five regulated HAAs—mono-, di-, and trichloroacetic acid (MCAA, DCAA, and TCAA) and mono- and dibromoacetic acid (MBAA and DBAA)—and one unregulated HAA—bromochloroacetic acid (BCAA)—were measured. Urinary DCAA, MBAA, DBAA, and BCAA levels were always below the limits of detection (LOD). Measured levels and interindividual variability of urinary MCAA were higher than urinary TCAA. Longitudinal urinary specimens showed MCAA levels …

Metallo-Polyelectrolytes As A Class Of Ionic Macromolecules For Functional Materials, Tianyu Zhu, Ye Sha, Jing Yan, Parasmani Pageni, Md Anisur Rahman, Yi Yan, Chuanbing Tang

Faculty Publications

The fields of soft polymers and macromolecular sciences have enjoyed a unique combination of metals and organic frameworks in the name of metallopolymers or organometallic polymers. When metallopolymers carry charged groups, they form a class of metal-containing polyelectrolytes or metallo-polyelectrolytes. This review identifies the unique properties and functions of metallo-polyelectrolytes compared with conventional organo-polyelectrolytes, in the hope of shedding light on the formation of functional materials with intriguing applications and potential benefits. It concludes with a critical perspective on the challenges and hurdles for metallo-polyelectrolytes, especially experimental quantitative analysis and theoretical modeling of ionic binding.

Nickel Exposure Reduces Enterobactin Production In Escherichia Coli, Clorissa L. Washington-Hughes, Geoffrey T. Ford, Alsten D. Jones, Kimberly Mcrae, Franklin Wayne Outten

Faculty Publications

Escherichia coli is a well- studied bacterium that can be found in many niches, such as industrial wastewater, where the concentration of nickel can rise to low- millimolar levels. Recent studies show that nickel exposure can repress pyochelin or induce pyo-verdine siderophore production in Pseudomonas aueroginosa. Understanding the mo-lecular cross- talk between siderophore production, metal homeostasis, and metal toxicity in microorganisms is critical for designing bioremediation strategies for metal- contaminated sites. Here, we show that high- nickel exposure prolongs lag phase duration as a result of low- intracellular iron levels in E. coli. Although E. coli cells respond to low- …

Hydrogen Sulfide Gas Detection Via Multivariate Optical Computing, Bin Dai, Christopher Michael Jones, Megan Pearl, Mickey Pelletier, Michael L. Myrick

Faculty Publications

Hydrogen-sulfide gas is a toxic, colorless gas with a pungent odor that occurs naturally as a decomposition by-product. It is critical to monitor the concentration of hydrogen sulfide. Multivariate optical computing (MOC) is a method that can monitor analytes while minimizing responses to interferences. MOC is a technique by which an analogue calculation is performed entirely in the optical domain, which simplifies instrument design, prevents the drift of a calibration, and increases the strength and durability of spectroscopic instrumentation against physical perturbation when used for chemical detection and identification. This paper discusses the detection of hydrogen-sulfide gas in the ultraviolet …

Facially Amphiphilic Polyionene Biocidal Polymers Derived From Lithocholic Acid, Mitra S. Ganewatta, Md Anisur Rahman, Louis Mercado, Tinom Shokfai, Alan W. Decho, Theresa M. Reineke, Chuanbing Tang

Faculty Publications

Bacterial infections have become a global issue that requires urgent attention, particularly regarding to emergence of multidrug resistant bacteria. We developed quaternary amine-containing antimicrobial poly(bile acid)s that contain a hydrophobic core of lithocholic acid in the main-chain. Interestingly, by choosing appropriate monomers, these cationic polymers can form core-shell micelles. These polymers exhibited biocidal activity against both Gram-positive and Gram-negative bacterial species. It is demonstrated that the micelles can deliver hydrophobic antibiotics that functionally have dual antimicrobial activities. Cytotoxicity assays against HeLa cells showed dosage-dependent toxicity for polymers with longer linkers.

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 …

Expansion Of The (Bb)>Ru Metallacycle With Coinage Metal Cations: Formation Of B-M-Ru-B (M= Cu, Ag, Au) Dimetalacyclodiboryls†, Bennett J. Eleazer, Mark D. Smith, Alexey A. Popov, Dmitry V. Peryshkov

Faculty Publications

In this work, we introduce a novel approach for the selective assembly of heterometallic complexes by unprecedented coordination of coinage metal cations to strained single ruthenium–boron bonds on a surface of icosahedral boron clusters. M(I) cations (M ¼ Cu, Ag, and Au) insert into B–Ru bonds of the (BB)–carboryne complex of ruthenium with the formation of four-membered B–M–Ru–B metalacycles. Results of theoretical calculations suggest that bonding within these metalacycles can be best described as unusual three-center-two-electron B–M/Ru interactions that are isolobal to B–H/Ru borane coordination for M ¼ Cu and Ag, or the pairs of two-center-two electron B–Au and Au–Ru …

Hydrogen-Bonding-Directed Ordered Assembly Of Carboxylated Poly(3-Alkylthiophene)S, David W. Bilger, Jose A. Figueroa, Neil D. Redeker, Amrita Sarkar, Morgan Stefik, Shanjuu Zhang

Faculty Publications

Hydrogen-bonding-induced ordered assembly of poly(3-alkylthiophene)s derivatives bearing carboxylic acid groups has been investigated from diluted and concentrated solutions to solid films using ultraviolet–visible absorption spectroscopy, polarized optical microscopy, and four-point probe conductivity measurements. In dilute solutions, the polymer undergoes a spontaneous structural transition from disordered coil-like to ordered rodlike conformations, which is evidenced by time-dependent chromism. Many factors such as alkyl-chain length, types of solvents, and temperature are studied to understand the assembly behavior. Transition kinetics of the assembly process reveals a universal second-order rate law, indicating an intermolecular origin due to hydrogen bonding. When more concentrated, hydrogen bonding drives …

Investigating The Toxicity And Accumulation Of 2,4-Dichlorophenoxyacetic Acid (2,4-D) And Glyphosate In Eisenia Fetida, Caitlin Lazurick, Nicole Lidzbarski, Rachel Owings, Jeff Brotherton, Edna Steele

Journal of the South Carolina Academy of Science

Glyphosate, the main ingredient in Roundup^®, is the most widely used herbicide in the world. It is also used in combination with another effective herbicide, 2,4-D, in the formulation called Enlist Duo^®. The EPA approved the use of Enlist Duo^® on certain crops including those genetically modified to be resistant to both herbicides. The predicted significant increase in the use of these herbicides raised concerns from the general public because both compounds have been classified as possibly or probably carcinogenic. Since herbicides are applied directly to vegetation, the safety of organisms that come in contact …

Rapid Reversible Borane To Boryl Hydride Exchange By Metal Shuttling On The Carborane Cluster Surface, Bennett J. Eleazer, Mark D. Smith, Alexey A. Popov, Dmitry V. Peryshkov

Faculty Publications

In this work, we introduce a novel concept of a borane group vicinal to a metal boryl bond acting as a supporting hemilabile ligand in exohedrally metalated three-dimensional carborane clusters. The (POBOP)Ru(Cl)(PPh3) pincer complex (POBOP ¼ 1,7-OP(i-Pr)2-m-2-carboranyl) features extreme distortion of the two-center-two-electron Ru–B bond due to the presence of a strong three-centertwo-electron B–H/Ru vicinal interaction. Replacement of the chloride ligand with a hydride afforded the (POBOP)Ru(H)(PPh3) pincer complex, which possesses B–Ru, B–H/Ru, and Ru–H bonds. This complex was found to exhibit a rapid exchange between hydrogen atoms of the borane and the terminal hydride through metal center shuttling between …

Epigenetic Regulation Of Salicylic Acid-Mediated Plant Defense, Phillip Key

Senior Theses

Plant pathogens remain a significant threat to the stability of modern agricultural systems, and the investigation of mechanisms to improve the security of food resources has led to the partial characterization of plant immune response. With this progress, there is a newfound ability to analyze the relative pathogen resistance capability of specifically modified organisms, and in doing so, it is possible to identify individual alterations that might play a role in creating a more robust immune response. In this study, ten Arabidopsis thaliana mutants were infiltrated with Pseudomonas syringae pv. morsprunorum alongside positive and negative control Col-0 Wild-Type and npr1-2. …

Hierarchical Corannulene-Based Materials: Energy Transfer And Solid-State Photophysics, Allison M. Rice, W. Brett Fellows, Ekaterina A. Dolgopolova, Andrew B. Greytak, Aaron K. Vannucci, Mark D. Smith, Stavros G. Karakalos, Jeanette A. Krause, Stanislav M. Avdoshenko, Alexey A. Popov, Natalia B. Shustova Prof. Dr.

Faculty Publications

We report the first example of a donor–acceptor corannulene-containing hybrid material with rapid ligand-to-ligand energy transfer (ET). Additionally, we provide the first time-resolved photoluminescence (PL) data for any corannulene-based compounds in the solid state. Comprehensive analysis of PL data in combination with theoretical calculations of donor–acceptor exciton coupling was employed to estimate ET rate and efficiency in the prepared material. The ligand-to-ligand ET rate calculated using two models is comparable with that observed in fullerene-containing materials, which are generally considered for molecular electronics development. Thus, the presented studies not only demonstrate the possibility of merging the intrinsic properties of π-bowls, …

Fulleretic Well-Defined Scaffolds: Donor–Fullerene Alignment Through Metal Coordination And Its Effect On Photophysics, Derek E. Williams, Ekaterina A. Dolgopolova, Danielle C. Godfrey, Evgeniya D. Ermolaeva, Perry J. Pellechia Dr., Andrew B. Greytak Prof. Dr., Mark Smith Dr., Stanislav M. Avdoshenko, Dr., Alexey A. Popov Dr., Natalia B. Shustova Prof. Dr.

Faculty Publications

Herein, we report the first example of a crystalline metal–donor–fullerene framework, in which control of the donor–fullerene mutual orientation was achieved through chemical bond formation, in particular, by metal coordination. The 13C cross-polarization magic-angle spinning NMR spectroscopy, X-ray diffraction, and time-resolved fluorescence spectroscopy were performed for comprehensive structural analysis and energy-transfer (ET) studies of the fulleretic donor–acceptor scaffold. Furthermore, in combination with photoluminescence measurements, the theoretical calculations of the spectral overlap function, Förster radius, excitation energies, and band structure were employed to elucidate the photophysical and ET processes in the prepared fulleretic material. We envision that the well-defined fulleretic donor–acceptor …

Measuring The Impact: An Evaluation Of Communities In Harmony, Michael Carl Owens

Senior Theses

In the study reported below, a program evaluation was performed for the student organization Communities in Harmony, a music-based community service organization at the University of South Carolina that works with homeless and socioeconomically disadvantaged children and young adults. This organization is about to enter its fifth year and is in the process of transitioning between leadership teams at the time of publication. The purpose of this study is to evaluate the strengths and weaknesses of the organization so that it can continue to grow and effectively serve its target populations. This study has found that the organization excels at …

Investigating The Function Of Aintegumenta-Like6 (Ail6) In Arabidopsis Flower Development, Han Han

Theses and Dissertations

AINTEGUMENTA (ANT) and AINTEGUMENTA-LIKE6 (AIL6) encode related transcription factors with partially overlapping roles in floral organ development in the model plant Arabidopsis thaliana. ANT and AIL6 do not make equivalent contributions to these processes. Loss of ANT function by itself results in smaller flowers, demonstrating that the role of ANT in organ size control cannot be provided by AIL6. Loss of AIL6 function on its own has no phenotypic consequences indicating that all of its roles in flower development can be provided by ANT or some other genes. To further probe the function of AIL6 in flower development, we investigated …

Reactive Oxygen Species-Mediated Neurodegeneration Is Independent Of The Ryanodine Receptor In Caenorhabditis Elegans, Lyndsay E.A. Young, Daniel C. Williams

Journal of the South Carolina Academy of Science

Despite the significant impacts on human health caused by neurodegeneration, our understanding of the degeneration process is incomplete. The nematode Caenorhabditis elegans is emerging as a genetic model organism well suited for identification of conserved cellular mechanisms and molecular pathways of neurodegeneration. Studies in the worm have identified factors that contribute to neurodegeneration, including excitotoxicity and stress due to reactive oxygen species (ROS). Disruption of the gene unc-68, which encodes the ryanodine receptor, abolishes excitotoxic cell death, indicating a role for calcium (Ca²⁺) signaling in neurodegeneration. We tested the requirement for unc-68 in ROS-mediated neurodegeneration using the …

Precise Repair Of Mping Excision Sites Is Facilitated By Target Site Duplication Derived Microhomology, David M. Gilbert, M. Catherine Bridges, Ashley E. Strother, Courtney E. Burckhalter, James M. Burnette Iii, C. Nathan Hancock

Faculty Publications

A key difference between the Tourist and Stowaway families of miniature inverted repeat transposable elements (MITEs) is the manner in which their excision alters the genome. Upon excision, Stowaway-like MITEs and the associated Mariner elements usually leave behind a small duplication and short sequences from the end of the element. These small insertions or deletions known as “footprints” can potentially disrupt coding or regulatory sequences. In contrast, Tourist-like MITEs and the associated PIF/Pong/Harbinger elements generally excise precisely, returning the genome to its original state. The purpose of this study was to determine the mechanisms underlying these …

Characterization Of The Sufc Atpase During Fe-S Cluster Assembly By The Suf Pathway In Escherichia Coli, Khaleh Mykel Thomas

Theses and Dissertations

The gram-negative bacterium E. coli encodes the Suf pathway to assemble iron-sulfur (Fe-S) clusters under iron starvation and oxidative stress conditions. The ATPase activity of SufC is critical for in vivo Fe-S cluster assembly by the Suf pathway. SufC shares homology with the nucleotide binding domain (NBD) of ATP-binding cassette (ABC) transporters and belongs to the AAA+ (ATPases Associated with diverse cellular Activities) ATPase superfamily, a family of proteins that utilizes energy from ATP hydrolysis to perform a variety of cellular functions. SufC forms a stable SufBC2D complex with partner proteins SufB and SufD. The SufBC2D complex serves as a …

Effects Of Individual Phenotypic Variation On Predator-Prey Relationships Of Xanthid Crabs In North Inlet Estuary, South Carolina, Benjamin J. Toscano

Theses and Dissertations

Ecological communities and the biological interactions that regulate community structure are notoriously complex. To make these systems more tractable, ecologists traditionally measure and model communities at the population level, treating individuals as functionally equivalent. While this approach has yielded tremendous insight into the factors governing communities, it remains unclear whether accounting for individual-level variation could improve our capacity to predict the responses of communities to perturbation, a major goal in the midst of unprecedented rates of environmental change.

The objective of this study was to examine the magnitude of individual-level phenotypic variation in predatory crabs (family Xanthidae), and the effects …

A Comparison Of Angiography Versus Intravascular Ultrasound In The Treatment Of Peripheral Arterial Disease, Michael Pompliano

Senior Theses

Peripheral Arterial Disease is a growing epidemic throughout the United States. It is estimated that 8 to 12 million Americans currently suffer from PAD, a disease of the circulatory system that limits blood flow to your hands and feet. This limited blood flow is due to the narrowing of the arteries that supply blood throughout your body and can disrupt the balance of the nerves and tissues that make up your extremities. If left untreated, it can cause irreparable, life- threatening damage that may result in amputation of the diseased limb. Although the mechanism of PAD is known and well …

Population Analysis And Protein Stability Assays Illustrate Xenobiotic Metabolizing Enzymes Have No Detectable Effect On Breast Cancer Development And Progression, Thomas Daniel Crowder

Theses and Dissertations

Xenobiotic Metabolizing Pathway works to detoxify the cell from numerous carcinogenic, mutagenic, and toxic hydrophobic compounds. As a member of the phase I enzymes (the first phase in the Xenobiotic Metabolizing Pathway) the Cytochrome P-450 Family 1 Sub-family B Protein 1 (Cyp1B1) works to attach an oxygen molecule to its hydrophobic substrate. In performing this reaction, Cyp1B1 often increases the reactivity of the xenobiotic compound. If these reactive Cyp1B1 products migrate into the nucleus and they can cause damage by reacting with DNA. However, the Glutathione S-Transferase Theta 1 (GSTT1) and Glutathione S-Transferase Mu 1 (GSTM1), members of the phase …

The Effects Of Snmp-2 Gene Expression On Mating Discrimination In Male Drosophila Melanogaster, Kristen Taylor Ashourian

Theses and Dissertations

In order to distinguish between relevant and extraneous stimuli, insects have adapted specialized processes to perceive cues that are beneficial for survival and proliferation. Volatile molecules in the environment can stimulate olfactory receptors (ORs) and gustatory receptors (GRs) in chemosensory organs called sensilla. Specialized proteins located within these sensilla guide and assist chemosensory molecules to the receptors, which then trigger a transduction pathway that elicits behavioral responses. Sensory Neuron Membrane Proteins (SNMPs) are transmembrane proteins found on both gustatory and olfactory sensory organs in insects. There are two forms of these proteins, SNMP-1 and SNMP-2. InDrosophila melanogaster, the function of …

Methanol And Ethanol Modulate Responses To Danger- And Microbe- Associated Molecular Patterns In Tomato, Tobacco And Arabidopsis, Claire Teresa Hann

Theses and Dissertations

Methanol is a byproduct of cell wall modification. It is released through the action of pectin methylesterases (PMEs), which demethylate cell wall pectins. Plant PMEs play not only a role in developmental processes but also in responses to herbivory and infection by fungal or microbial pathogens, resulting in increased methanol release. To break down the cell wall barrier, pathogens employ their own PMEs. Interestingly, the infection process also regulates the expression of certain plant PMEs. Methanol is toxic to a number of herbivores and reduces their fitness. At high concentrations, it upregulates signaling and defense genes. However, molecular mechanisms that …