Chemistry & Biochemistry
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Item Aspartate 458 and the glycine triad of human glutathione synthetase(2011-08) Brown, Teresa Rae; Anderson, Mary; Sheardy, Richard Dean; Britt, MarkHuman glutathione synthetase (hGS) catalyzes the second ATP-dependent step in the biosynthesis of glutathione (GSH). Human GS displays negative cooperative to the γ-glutamyl substrate (GAB). The hGS active site has three highly conserved catalytic loops, notably the G- and A-loop. Herein, with experimental and computational investigations, we report the impact of mutation of A-loop residue Asp458 and the glycine triad (Gly369, Gly370 and Gly371) on hGS structure, activity, cooperativity and stability. The Michaelis-Menten constant (Km) was determined for all three substrates (Glycine, GAB, ATP). For Asp458 mutant hGS, ATP Km was unchanged, glycine Km increased, and GAB Km decreased along with a change in cooperativity (negative- to non-cooperative). The glycine triad valine mutations (G369V, G370V and G371V) displayed dramatic decreased activity compared to wild-type. These findings indicate that Asp458 and the glycine triad are essential for hGS catalysis and that mutation of Asp458 directly impacts the allostery of this enzyme.Item Cadmium distribution and selected tissue histology in rats following administration of cadmium chloride and/or gamma radiation(12/31/1981) Kundomal, Yashdev R.; Hupp, Eugene; Erdman, Howard; Aboul-Ela, Mohammad; Fry, Kenneth; Hines, John; Wendel, CarltonItem Cardiopulmonary effects of prolonged morphine-chloralose anesthesia in dogs(5/31/1981) Buchanan, Cheri Kay; Rubal, Bernard J.; Williams, Burl; Fry, KennethItem Characterizing the thermodynamic parameters of anti-cancer drug Carboplatin and DNA through Spectroscopic techniques(6/3/2020) Williams, Sara M; Mirsaleh-Kohan, NasrinSpectroscopic techniques have been employed to understand the interactions and thermodynamic parameters between the anti-cancer drug Carboplatin and the DNA oligomer COTAR 2: ATT AAT GGA TCC ATT AAT. This is a self-complementary sequence that has been previously shown to bind [Co(NH3)2(OH2)2]+3 with high specificity and is of interest because it contains two isolated G-G sites. Both Cisplatin and Carboplatin are known for binding preferentially to G-G sites. These anti-cancer drugs are commonly used in chemotherapeutic treatments and are known to have adverse side effects. In order to improve treatment options, it’s necessary to understand the molecular basis of their interactions with DNA. The binding of Carboplatin with COTAR 2 has been analyzed using Circular Dichroism (CD), Surface−Enhanced Raman Scattering (SERS), and UV-Vis Spectroscopy. The combination of these techniques allows for better understanding of structure and stability of platinum-DNA complexes, as well as binding kinetics. In this thesis, the results of these studies will be presented, and our current understanding of this interaction will be discussed.Item Copper phenanthroline complexes in a new era: Utilizing “green” chemistry in the synthesis of cu-phen coordination complexes(1/30/2019) Wilk, Mikaela; Sheardy, Richard DeanThe purpose of this research was to expand on the knowledge of a well know organometallic system: copper phenanthroline complexes. Copper phenanthroline complexes have been widely studied and are currently being investigated for uses in catalysis, medicine, and solar energy applications. It was the goal of this research to synthesize well known useful complexes using new solventless synthesis methodology as well as to create new materials to study for potential application in these fields. This thesis includes 134 figures, 64 tables, and is 189 pages long. Eight compound have been synthesized and characterized through techniques such as X-ray crystallography, elemental analysis, thermogravimetric analysis, melting point, 1H-NMR, Fourier transform infrared spectroscopy (FTIR), electronic absorption spectroscopy, diffuse reflectance spectroscopy, and photoluminescence spectroscopy. Analysis of the results are discussed and conclusions about potential applications are made.Item Damage mechanisms of anticancer agents: Platinum-based drugs and copper complexes(10/3/2018) Nguyen, Trang Thi Minh; Mirsaleh-Kohan, Nasrin; Rawashdeh-Omary, ManalCisplatin and carboplatin, which belong to the platinum based-drugs family are accustomed to treat various types of cancers. Although they have been used widely in chemotherapy, cisplatin and carboplatin are confronting some issues such as toxicities and drugs resistances. Therefore, designing a new drug without those issues is a challenge. In this study, the technique of Surface-Enhanced Raman Scattering (SERS) is employed in order to research the modification to guanine when cisplatin or carboplatin bound. The success in clinical use of cisplatin has put metal-based drugs on the first row for cancer treatment. Other than platinum complexes, copper complexes gain major attraction to many scientists. It has been proposed that copper carries less toxic, so copper complexes are potential anticancer agents. Infrared and Raman spectroscopic techniques are engaged to obtain vibrational spectra of copper complexes. Also, SERS technique is utilized to explore the interaction of four new copper complexes with guanine or adenine. The findings show that when either cisplatin or carboplatin is added to guanine, the guanine spectral changes within the range of 400 and 1800 frequencies. Moreover, new copper complexes also express the guanine or adenine spectral changes in the same range.Item Design and photophysical characterizations of new copper(I) and silver(I) mixed ligand complexes with “green chemistry” incorporation(1/25/2022) Jawaid, Ramsha; Rawashdeh-Omary, ManalThis thesis is a study of mixed ligand coinage metal complexes. It has 122 pages, 68 figures, 14 tables, and the references. It discusses one main project divided by three chapters describing in general the synthesis, structure and spectroscopic studies of silver (I) and copper (I) complexes. Chapter I discusses the introduction to trinculear pyrazolate complexes of d10 coinage metals, N-donor heterocyclic ligands, polycyclic aromatic hydrocarbon ligand, mixed-metal and mixed-ligand complexes. It also investigates the impact of structural factors and various synthetic conditions on photophysical properties as well as the potential applications including sensors for (VOCs), metal-organic frameworks (MOFs), solar cells and organic light emitting diodes (OLEDs). Chapter II involves both solvent-mediated and solvent-less synthetic routes of silver (I) and copper (I) complexes and mixed-metal and mixed-ligand complexes and their characterization through elemental analysis, x-ray crystallography, melting point, photoluminescence, 1H NMR, FT-IR, absorption spectroscopy and thermogravimetric analysis. Chapter III summarizes the conclusion of the results obtained in chapter II and the expected applications of similar compounds in the industry.Item The dimer loop and electrostatic interactions at the dimer interface of human glutathione synthetase(2012-12) De Jesus, Margarita; Anderson, Mary; Britt, Mark; Sheardy, Richard DeanHuman glutathione synthetase (hGS) is homodimeric and negatively cooperative toward its γ-glutamyl substrate making it a good model to study protein-protein interactions. The allosteric pathway between hGS active sites is hypothesized to travel through the dimer interface. To better understand the allostery of hGS and interactions at the dimer interface, two regions, the dimer loop [35-TSQEPTSSE-43] and key amino acid residues (Serine42, Arginine221 and Aspartate24) were studied using site-directed mutagenesis and analyzed for effects on cooperativity, activity and stability. Alanine mutant enzymes of dimer loop residues did not greatly affect activity or stability of hGS, nor change the cooperativity of hGS, but did affect γ-glutamyl substrate affinity, while alanine mutant enzymes of residues Ser42, Arg221 and Asp24 did not change cooperativity, but did decrease in activity and stability, and increase in γ-glutamyl affinity, with Asp24 having the greatest loss in activity and stability, followed by Arg221, and then Ser42.Item Echocardiographic evaluation of a group of obese women(12/31/1981) Elmesallamy, Fatma H.; Rubal, Bernard J.; Fry, Kenneth A.; Aboul-Ela, M. M.Item The effects of the Sea World Talented and Gifted Endangered Species Program on the knowledge of seventh graders(1997-12) Braun, Sharron; Jones, Richard; Wendel, CarltonThis study was conducted to determine if cognitive gains were made by seventh graders after participation in an endangered species program conducted by Sea World. Fifty-seven students attending a private school participated in the study. After pre-instruction with materials provided by Sea World, the students participated in a four-hour instructional tour of Sea World conducted by Sea World personnel. Data analysis of pre- and post tests included mean, standard deviation, and ANOVA. Post test scores showed a significant difference between the means of the pre test and post test. Results in the standard deviation show more consistency in student scores on the post test.Item The element effect in methoxide ion substitution of the (Z) and (E) isomers of O-methyl-4-methoxybenzohydroximoyl halides(1997-08) Dolliver, Debra; Johnson, James E.; Ni, J.The (Z) and (E) isomers ofO-methyl-4-methoxybenzohydroximoyl chloride [p-OCH3ArC( Cl )=NOCH3] and 0-methyl-4-methoxybenzohyd roximoyl bromide [p-OCH3ArC(Br)=NOCH3] were synthesized, and the rates of methoxide substitution were measured (90% dimethyl sulfoxide and 10% methanol at 44.6° C). Kinetic measurements demonstrated the reaction to be first order in methoxide and first order in the hydroximoyl halide. Two mechanisms were considered for this reaction: a multistep addition-elimination mechanism (AN+ ON) and a concerted (SN2-like) mechanism (ANON)- The element effect (k8r11Item Employing chromatographic and spectroscopic methodologies to monitor DNA response to platinum-based chemotherapeutic drugs(6/16/2020) Wappes, Skylar C; Mirsaleh-Kohan, NasrinIn order to design platinum-based chemotherapeutic drugs that express low toxicity and high efficiency, their nature of interaction with DNA, effectiveness, as well as their mechanisms need to be better understood. This research investigates how Cisplatin, cis-diamminedichloroplatinum (II) and its derivatives, Carboplatin, Nedaplatin, and Oxaliplatin, effect DNA stability and structure. Two sensitive and selective analytical methodologies - Surface-Enhanced Raman Scattering (SERS) and High-Performance Liquid Chromatography (HPLC)- were applied to monitor the key concepts stated above. In this project, it was found that of all the drugs, Carboplatin did not significantly modify the DNA. Even though Carboplatin complexes were made at a 1:2 volume ratio it left more DNA unbound (5% unbound) compared to the other drug complexes which were ran at a 1:1 ratio (<2% unbound). Averaging the drug interactions, Cisplatin and Oxaliplatin left less DNA unbound than Nedaplatin did, but Carboplatin in all HPLC experiments left significantly more DNA unbound. In both SERS and HPLC experiments, Carboplatin modified each DNA less than Cisplatin.Item Fine and coarse tuning of the photophysical and chemical properties of cuprous iodide complexes with various imine based ligands(1/9/2018) Scoggins, Laura E; Sheardy, Richard Dean; Mirsaleh-Kohan, Nasrin; Rawashdeh-Omary, ManalThis thesis is a study of copper iodide complexes with various imine based ligands. It has 150pp, 17 tables, 112 figures and the references for the study of these CuI complexes. The one main project is discussed over four chapters unfolding the synthesis, structure and spectroscopic studies of the copper iodide complexes. Chapter I introduces the background of copper halide complexes, physical and photophysical properties of these complexes, and their potential applications. Chapter II discusses the synthesis of each copper iodide complex. Chapter III covers the characterization of the synthesized compounds including x-ray crystallography, elemental analysis, photoluminescence, lifetime, 1HMNR, FT-IR, absorption spectroscopy and thermogravimetric analysis. Chapter IV concludes and summarizes the results obtained in chapters II and III and the expected applicationsItem Glutathione synthetase: Conserved residues of the substrate loop(2013-05) Shrestha, Bisesh; Anderson, Mary; Britt, Mark; Anderson, Mary E.; Sheardy, Richard DeanThe important antioxidant tripeptide glutathione (GSH) is synthesized in two ATP-dependent steps; the second enzyme in the biosynthetic pathway, glutathione synthetase (GS), ligates glycine to γ-glutamylcysteine (γ-GC). Human glutathione synthetase (hGS) deficiency causes hemolytic anemia, metabolic acidosis, 5-oxprolinuria and a total deficiency may be lethal. Three flexible loops (A, G and S) surround the substrates (ATP, glycine and γ-GC). Human glutathione synthetase is negatively cooperative to one substrate, γ-GC. The Substrate- or S-loop is proximal to γ-GC and thought to participate in γ-GC binding. The S-loop (266-FRDGYMPRQYS-276) contains 11 residues, some of which are highly conserved (F266, R267, G269, Y270, P272 and Y275). Site directed mutagenesis was used to change these highly conserved S-loop residues, and then their roles in substrate binding, enzyme activity and stability were assessed.Item HPLC analysis to assess efficacy of cisplatin, nedaplatin, and oxaliplatin(Dec-23) Hernandez, Jessica 1990-; Mirsaleh-Kohan, Nasrin; Beatty, John; Salazar, GustavoPlatinum drugs are one of the most widely used agents against cancerous cells. Cisplatin’s chemotherapeutic efficacy is limited by the increase of tumor resistivity and unwanted side effects. Cisplatin’s cytotoxicity is linked to its ability of forming 1,2-intrastrand adducts with adjacent guanine (G) bases. An analytical method to detect and quantify the amount of platinum bound to DNA is necessary to enhance and develop anticancer drugs. In this work, High Performance Liquid Chromatography (HPLC) analysis was performed to assess the binding of cisplatin, nedaplatin, and oxaliplatin to the dinucleotide dGpdG. By examining the concentration ratios and incubation periods at 37 °C, we measured the amount of platinum drug reacted with DNA (platination rates) indicating the percentage of Platinum-DNA (Pt-DNA) adducts. Cisplatin proved to be the most effective, followed by nedaplatin, and then oxaliplatin. This research has implications in designing more efficient anticancer drugs.Item Human glutathione synthetase reaction order and kinetics examined using spectroscopic and calorimeteric techniques(3/4/2019) Stopper, Anna Rachel; Anderson, Mary EGlutathione (GSH) is a tripeptide important in preventing cellular oxidative damage. Human glutathione synthetase (hGS) catalyzes the second stage of GSH biosynthesis. Homodimeric human glutathione synthetase is negatively cooperative with respect to its L-γ-Glu-Cys substrate. Although the allosteric effects of substrates binding to hGS have been studied, the order of substrate binding has not. GS in plants and prokaryotes are reported to exhibit opposing random ter and ordered ter ter reaction orders respectively; currently little is known about the reaction order in humans. Knowledge of the mechanism and reaction order of hGS is vital to understand how it contributes to the regulation of the levels of the limiting amino acid cysteine and of glutathione. Using ITC binding studies the mechanism of action and reaction order of hGS has been evaluated and suggests a semi-ordered reaction in human GS.Item Human glutathione synthetase residues Valine 44 and Valine 45 are required for subunit stability and negative cooperativity(2011-08) Slavens, Kerri; Anderson, Mary; Britt, Mark; Sheardy, Richard DeanValine 44 and Valine 45 serve as important residues for human glutathione synthetase (hGS) function and stability given their location at the dimer interface of this enzyme. Computational studies suggest Val45 has more impact on the structure and stability of hGS than Val44. Experimentally, enzymes with mutations at the 44 and/or 45 positions were prepared, purified and assayed for initial activity. The Val45 position mutations have a greater impact on enzyme activity than mutations at Val44. Differential scanning calorimetry experiments reveal a stability loss in all mutant enzymes. The γ-GluABA substrate affinity remains unaltered in V44A and V45A mutant enzymes, but increases with tryptophan introduction. Hill coefficients trend towards less negative cooperativity except with V45W. These results imply that residues V44 and V45 are located along the allosteric pathway of this negatively cooperative dimeric enzyme and that these residues are integral to the stability of human glutathione synthetase.Item Identifying and correcting misconceptions about the solar system through a constructivist teaching approach(1996-12-30) Acker, Sharron F.; Caswell, Ruth M.; Wendel, CarltonThe purpose of this study was to help students identify and correct, through the constructivist approach, naive conceptions and misconceptions that interfere or prevent learning from taking place. The question was, can naive conceptions and misconceptions be identified and corrected with the constructivist approach to education. Five classes of 114 fifth graders participated in this study. Their naive conceptions and misconceptions were identified through individual and group responses. After the misconceptions were identified, correcting them through the constructivist approach began. Students were given a scenario to perform, and through project based activities and a variety of different resources, the students were able to correct their misconceptions and construct their knowledge about the solar system. Overall, the results from the data collected indicated the constructivist approach to education is effective in identifying and correcting naive conceptions and misconceptions.Item Identifying chlorhexidine and sodium hypochlorite reaction products and the environmental implications of its interaction with cotton fibers(Dec-23) Huynh, Stacy 1997-; Beatty, John; Salazar, Gustavo; Lin, ShiruChlorhexidine is heavily used in the medical and dental field and is prescribed for multiple uses related to healthcare. When in contact with sodium hypochlorite, chlorhexidine breaks down into several toxic compounds that are not fully understood, and these compounds have impacts on the environment and human health, due to its heavy use in the medical field. Chlorhexidine breaks down into compounds that permanently adhere to and damage the cellulose fibers found in cotton fabrics and alter the visible quality of fabric, which leads to re-washing of fabrics or outright disposal of fabric due to the staining and damage. Chlorhexidine is also used in conjunction with sodium hypochlorite in dental procedures, such as root canals, and the toxic nature of this interaction is not fully understood. Previous studies have identified several products of this reaction, one being para-chloroaniline, suggesting that chlorhexidine should not be used in conjunction with chemical oxidizers like bleach until the toxic products are further studied and identified. Understanding how chlorhexidine interacts with textile fibers like cellulose will save water and cotton fabric from being prematurely disposed of and negatively impacting the environment. This project will work to understand the reaction between chlorhexidine and sodium hypochlorite, the toxic products that result from this reaction, and its interactions with cotton fiber textiles to reduce its impact on health and the environment.Item Increasing students' retention of science vocabulary using music(1997-05) Gavin, Andrea; Wendel, CarltonThis study was to see if there will be an increase in the vocabulary retention of fifth grade students by using music in conjunction with hands-on instruction to reinforce meteorology vocabulary. The subjects for this study were two fifth-grade classes of 17 students each. The academic levels of the students were heterogeneous, consisting of high, medium, low abilities, and special education. The same teacher instructed both groups. The site is an elementary school in a large, urban district in North Texas. A multiple choice test was administered as a pre and post assessment. Even though results show no significant differences in mean scores for the groups, the scores of the treatment group showed less of a decrease than scores for the control group after one month.