Analytical Chemistry Commons^™

Bisthioether Stapled Peptides Targeting Polycomb Repressive Complex 2 Gene Repression, Gan Zhang

Dissertations, Theses, and Capstone Projects

Interactions between proteins play a key role in nearly all cellular process, and therefore, disruption of such interactions may lead to many different types of cellular dysfunctions. Hence, pathologic protein-protein interactions (PPIs) constitute highly attractive drug targets and hold great potential for developing novel therapeutic agents for the treatment of incurable human diseases. Unfortunately, the identification of PPI inhibitors is an extremely challenging task, since traditionally used small molecule ligands are mostly unable to cover and anchor on the extensive flat surfaces that define those binary protein complexes. In contrast, large biomolecules such as proteins or peptides are ideal fits …

Potential Degradation Of Hexabromocyclododecane (Hbcdd) In Sediments: Stereoisomer Specific Reaction Of Hbcdd With Reduced Sulfur Species Or Fe(Ii) Bound To Iron Oxides, Xianmiao Zhang

Dissertations, Theses, and Capstone Projects

The individual degradation rates of the three dominant stereoisomers (alpha, beta, gamma) of hexabromocyclododecane (HBCDD) with bisulfide and polysulfides were investigated at pH 9-10 in methanol/water solutions at two different temperatures (25 °C and 40 °C). alpha-HBCDD reacts significantly slower than beta-HBCDD and gamma-HBCDD. It was also observed that the reaction of HBCDD with polysulfides is faster than with bisulfide. For the reaction of HBCDD with bisulfide, the experiments were performed in 20% water/80% methanol, 50% water/50% methanol and 80% water/20% methanol at 40 °C. It was determined that the solvent polarity affects the reaction and the second-order rate constants …

High Resolution Imaging Of Single Nanoparticles And Two-Dimensional Nano-Material By Scanning Electrochemical Microscopy, Tong Sun

Dissertations, Theses, and Capstone Projects

Electrochemistry at nanostructured interfaces is of significant current interest. Metal nanoparticles (NPs) and two-dimensional semiconductor nanomaterial are particularly important because of their applications in catalysis, energy conversion and storage, sensors, and medicine. Electrocatalytic processes at such nanostructured interfaces are essential for the generation of hydrogen and other types of fuels and photochemical energy conversion. Nanoscale electrochemical experiments require the fabrication and characterization of nanometer-size electrochemical probes. The main advantages of the nanoprobes include very fast mass-transfer rate, high signal-to-noise ratio and extremely fine spatial resolution of electrochemical imaging. During my Ph.D. research, nanoscale disk-type platinum electrochemical probes were developed for …

Characterization And Quantification Of Covalent Modification Of Proteins Using Mass Spectrometry, Pratikkumar N. Rathod

Dissertations, Theses, and Capstone Projects

Identification and characterization of various post-translational modifications of protein is a key to understanding many unknown cellular processes. In the last few decades, mass spectrometry has evolved as an essential and effective analytical tool for qualitative and quantitative analysis of proteins. In this research, we have developed a novel MALDI-MS² based quantification method for Desmosine and Isodesmosine, which served as cross-linking amino acids of elastin, in order to measure the elastin degradation in the body. This is the first quantification method that not only illustrates the potential of MALDI-Ion Trap MS², but also improvement over the current …

An Improved Method For The Analysis Of Fiber Evidence Using Polarized Light Microscopy, Samuel F. Kaplan

Student Theses

Using the basic fundamentals of polarized light microscopy, a new and improved method for identifying synthetic fibers is presented in this thesis. Using the equation of an ellipse in spherical coordinates, an EXCEL™ (Microsoft Inc., Seattle, WA) spreadsheet was developed that generated tables of data that provide a foundation for a new and more efficient method in fiber analysis. Intermediate refractive index values for each subclass of textile fibers were calculated based on the fiber's principal refractive index values. The angles of refractive index matching to known refractive index fluids vary from 0 to 90 degrees upon rotation of the …

The Therapeutic Potential Of Natural Products From Vaccinium Berries For Viral And Lung Diseases Through An Improved Lc-Ms-Based Chemometric Approach, Vanya I. Petrova

Dissertations, Theses, and Capstone Projects

Smoking is a global epidemic that creates serious health and economic burden. It is the primary, preventative factor for the majority of causes of death worldwide. Analysis of publicly available data revealed that smoking prevalence rates among the youth in developing countries, especially in Bulgaria, are alarmingly high. The Bulgarian population has one of the highest percentages of smokers and the second highest rate among teenage girls. Consequently, chronic diseases affected by smoking, such as chronic obstructive pulmonary disorder (COPD), have been increasing there in the last five years. Poland, on the other hand, is an exemplary outlier for the …

Nanoporous Carbon-Based Co2 Reduction Catalysts: Exploring The Combined Effects Of Surface Chemistry And Porosity, Wanlu Li

Dissertations, Theses, and Capstone Projects

For the first-time sulfur-doped, nitrogen-doped and sulfur, nitrogen-codoped nanoporous carbons were systematically studied as catalysts for CO₂ electrochemical reduction reaction (CO₂ERR). The Faradaic efficiencies (FE) of CO and CH₄ formation were calculated to evaluate the performance of these carbons. The best catalysts showed the FE of CO and CH₄ formation of 29% and 0.76%, respectively. It was found that the overall performance in CO₂ERR dramatically increased upon the reduction pretreatment of the carbons in N₂-saturated electrolyte before the CO₂ reduction process. The pretreated carbon showed the maximum FE of CO …

The Study Of The Degradation Of Hexabromocyclododecane In A Heterogeneous System Containing Fe(Ii) Adsorbed To The Iron Oxide Hematite., Kristian K. Roopnarine

Dissertations and Theses

The reaction of hexabromocyclododecane (HBCDD), a widely used brominated flame retardant, was studied in a heterogenous mixture containing reactive Fe(II) adsorbed to the iron oxide hematite. The adsorbed Fe(II)/iron oxide system has shown to be a potent reductant in the transformation of organic contaminants with relatively water soluble organic contaminants. There currently aren’t many studies involving hydrophobic organic contaminants, such as HBCDD, in this reducing Fe(II)/iron oxide system. The results indicate that across the pHs 6.86, 6.95, 7.15 and 7.35 γ and β-HBCDD are degraded within a couple days. The pseudo-first order rate constants at pH 6.95 are 0.049 hr …

Species Identification Of Necrophagous Insect Eggs Based On Amino Acid Profile Differences Revealed By Direct Analysis In Real Time-High Resolution Mass Spectrometry, Justine E. Giffen, Jennifer Y. Rosati, Cameron M. Longo, Rabi A. Musah

Publications and Research

The colonization of decomposing remains by necrophagous insects such as blow flies is of forensic importance because the progression through the various stages of insect development can be correlated to time of death. The ability to infer this information hinges on accurate determination of the fly species that are associated with the entomological evidence collected. This evidence can include eggs, larvae, pupae, and puparial casings. Determination of the egg’s identity is particularly challenging because the eggs of multiple species are morphologically very similar. We report here that the species identity of fly eggs can be determined from their chemical fingerprint …

Detection Of Cathinone And Mephedrone In Plasma By Lc-Ms/Ms Using Standard Addition Quantification Technique, Theron W. Ng-A-Qui

Student Theses

Designer drugs are structural analogs of Drug Enforcement Agency (DEA) Schedule I and II substances. They are synthesized to mimic the effects of illegal drugs of abuse and to bypass the provisions of drug regulations. Despite the increased availability of designer drugs, few studies have focused on specific analytical extraction techniques for their detection and quantification in biological samples. Solid phase extraction (SPE) is the most commonly used technique for sample preparation. The purpose of this study is to evaluate the extraction efficiency of the various SPE columns with different sorbent materials for two designer drugs, cathinone and mephedrone in …

Metabolic Profiling Of Genetically Modified Potato Periderm Tissues, Liqing Jin

Dissertations, Theses, and Capstone Projects

Potato tubers are protected from dehydration and pathogens by a covering peel (periderm) impregnated with suberin, a complex cross-linked biopolymer that contains both polyaliphatic and lignin-like aromatic domains. Current models describing the macromolecular structure of suberin assume that ferulic acid cross-links both domains as it may form carboxyl ester bonds with aliphatic monomers and non-ester radical-coupled bonds with phenolics. Ferulic acid also links by ester bonds to glycans and acts in cross-linking polysaccharides and lignin. Fatty alcohol/ω-hydroxyacid hydroxycinnamoyl transferase (FHT) is a BADH acyltransferase responsible for the synthesis of akyl-ferulates that is necessary for suberin biosynthesis. Periderm from FHT-RNAi …

Electrochemical Nanoprobes For Electron Transfer Kinetics And Electrocatalysis Study, Yun Yu

Dissertations, Theses, and Capstone Projects

The studies of electrochemical processes on the nanoscale have led to a significant progress in understanding of electrochemical mechanisms and characterization of nanomaterials in the fields of energy, catalysis, and biological research. Electrochemical experiments at nanoscale require the fabrication and characterization of nanometer-sized electrochemical probes. The main advantages of the nanoprobes include very fast mass-transfer rate, high signal-to-noise ratio and extremely fine spatial resolution of electrochemical imaging. In the course of my Ph.D. research, different types of electrochemical probes were developed for measuring electron-transfer kinetics, probing single catalytic nanoparticles and sampling ultra-small volume of liquids.

We developed methodologies to fabricate …

Metabolic Profiling And Polymer Formation Of Gene Silenced Potato Periderms, Qing Cai

Dissertations, Theses, and Capstone Projects

Suberin is a biopolyester constituent of specialized plant periderm tissues formed within the phellem cell walls. Suberin and waxes of the periderm layer act to prevent water diffusion, mechanical breakdown and pathogenic invasion in plants. Ferulic esters, ω-hydroxyacids and α,ω-fatty diacids are considered to be the most important linkage between aliphatic and aromatic suberin domains and also linked with cell-wall polysaccharides. The potato gene FHT (fatty ω- hydroxyacid/fatty alcohol hydroxycinnamoyl transferase) esterifies ferulic acid to suberin. Diminished levels of feruloyl transferase activity have been associated with lowered amounts of feruloyl esters of fatty acids in both suberin-associated waxes and suberin …

Specific Binding Affinity Of The Non-Catalytic Domain Of Eukaryotic Like Type Ib Topoisomerase Of Vaccinia Virus, Benjamin R. Reed

Dissertations, Theses, and Capstone Projects

Topoisomerases are ubiquitous proteins that alter supercoiling in double stranded DNA (dsDNA) during transcription and replication and. vaccinia and the closely related poxvirus variola virus, at 314 amino acids in length, encode the smallest of the type I topoisomerases(TopIB). TopIB is a two domain protein that recognizes the sequence 5’-T/CCCTT, cleaves at the 3’-end and relaxes supercoiling through rotation. The C-terminal domain (CTD) alone contains the catalytic activity and specificity. Deletion of the N-terminal domain results in a greatly reduced rate of relaxation and rapid dissociation. Biochemical data suggests that the N-terminal domain (NTD) is important for pre-cleavage binding and …

Supercharging: An Investigation Into The Effects Of External Amino Acid Residue Charge On The Solubility And Internal Electric Character Of Bound Ligands In A Heme-Binding De Novo-Designed Protein, Cooper French

Dissertations and Theses

De novo protein design offers many interesting prospects both as a means to better understand natural protein dynamics and as a potential resource in biomedical and industrial applications. In this work I describe the modification of a simple, well-characterized heme-binding protein by altering side chain residue identities on the hydrophilic surface of the protein to produce variants with a range of net external charges. These charge modifications had a significant impact on nearly every measurable character of the protein. This work establishes the hard limits of supercharging within our experimental protein scaffold system, demonstrating that excessive positive charge increased the …