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Articles 271 - 300 of 397
Full-Text Articles in Chemistry
Synthesis And Evaluation Of Some Steroidal Oximes As Cytotoxic Agents: Structure/Activity Studies (Ii), Jianguo Cui, Lei Fan, Yanmin Huang, Yi Xin, Aimin Zhou
Synthesis And Evaluation Of Some Steroidal Oximes As Cytotoxic Agents: Structure/Activity Studies (Ii), Jianguo Cui, Lei Fan, Yanmin Huang, Yi Xin, Aimin Zhou
Chemistry Faculty Publications
Hydroximinosteroids isolated from marine sponges display a variety of biological functions including cytotoxicity and anti-virus. In this study, we synthesized a series of hydroximinosteroid derivatives with a different functional group on the ring A or B and various side chains at position 17, and analyzed the cytotoxicity of these compounds against sk-Hep-1, H-292, PC-3 and Hey-1B cancer cells. Our results revealed that although a cholesterol-type side chain at position 17 is required for the biological activity of the compounds as we previously confirmed, elimination of the 4,5-double bond augmented the cytotoxic activity for the steroidal oximes. In addition, the presence …
A Cox-2 Inhibitor Nimesulide Analog Selectively Induces Apoptosis In Her2 Overexpressing Breast Cancer Cells Via Cytochrome C Dependent Mechanisms, Bin Chen, Bin Su, Shiuan Chen
A Cox-2 Inhibitor Nimesulide Analog Selectively Induces Apoptosis In Her2 Overexpressing Breast Cancer Cells Via Cytochrome C Dependent Mechanisms, Bin Chen, Bin Su, Shiuan Chen
Chemistry Faculty Publications
Epidemiological and animal model studies have suggested that non-steroidal anti-inflammatory drugs (NSAIDs) can act as chemopreventive agents. The cyclooxygenase-2 (COX-2) inhibitor nimesulide shows anti-cancer effect in different type of cancers. In the current study, five breast carcinoma cell lines were used to explore the anti-cancer mechanisms of a nimesulide derivative compound 76. The compound dose dependently suppressed SKBR-3, BT474 and MDA-MB-453 breast cancer cell proliferation with IC50 of 0.9 μM, 2.2 μM and 4.0 μM, respectively. However, it needs much higher concentrations to inhibit MCF-7 and MDA-MB-231 breast cancer cell growth with IC50 at 22.1 μM and 19.6 μM, respectively. …
Cholesterol Levels And Activity Of Membrane Bound Proteins: Characterization By Thermal And Electrochemical Methods, Noufissa Zanati, Michael Ellen Mathews, Perera N. Indika, John J. Moran, Jean A. Boutros, Alan T. Riga, Mekki Bayachou
Cholesterol Levels And Activity Of Membrane Bound Proteins: Characterization By Thermal And Electrochemical Methods, Noufissa Zanati, Michael Ellen Mathews, Perera N. Indika, John J. Moran, Jean A. Boutros, Alan T. Riga, Mekki Bayachou
Chemistry Faculty Publications
The long-term goal of this investigation is to study the effects of increased cholesterol levels on the molecular activity of membrane-bound enzymes such as nitric oxide synthase, that are critical in the functioning of the cardiovascular system. In this particular investigation, we used differential scanning calorimetry (DSC) and dielectric thermal analysis (DETA) to study the effect of added cholesterol on melting/recrystallization and dielectric behavior, respectively, of phosphatidylcholine (PC) bilayered thin films. We also used electrochemical methods to investigate the effect of added cholesterol on the redox behavior of the oxygenase domain of nitric oxide synthase as a probe embedded in …
Reductive Decomposition Of A Diazonium Intermediate By Dithiothreitol Affects The Determination Of Nos Turnover Rates, Perera N. Indika, Talal Sabbagh, Jean A. Boutros, Mekki Bayachou
Reductive Decomposition Of A Diazonium Intermediate By Dithiothreitol Affects The Determination Of Nos Turnover Rates, Perera N. Indika, Talal Sabbagh, Jean A. Boutros, Mekki Bayachou
Chemistry Faculty Publications
Accurate determination of nitrite either as such or as the breakdown product of nitric oxide (NO) is critical in a host of enzymatic reactions in various settings addressing structure–function relationships, as well as mechanisms and kinetics of molecular operation of enzymes. The most common way to quantify nitrite, for instance in nitric oxide synthase (NOS) mechanistic investigations, is the spectrophotometric assay based on the Griess reaction through external standard calibration. This assay is based on a two-step diazotization reaction, in which a cationic diazonium derivative of sulfanilamide is formed as intermediate before the final absorbing azo-product. We show that this …
Inactivation Of [Fe-Fe]-Hydrogenase By O2. Thermodynamics And Frontier Molecular Orbitals Analyses, Daniela Dogaru, Stefan Motiu, Valentin Gogonea
Inactivation Of [Fe-Fe]-Hydrogenase By O2. Thermodynamics And Frontier Molecular Orbitals Analyses, Daniela Dogaru, Stefan Motiu, Valentin Gogonea
Chemistry Faculty Publications
The oxidation of H-cluster in gas phase, and in aqueous enzyme phase, has been investigated by means of quantum mechanics (QM) and combined quantum mechanics–molecular mechanics (QM/MM). Several potential reaction pathways (in the above-mentioned chemical environments) have been studied, wherein only the aqueous enzyme phase has been found to lead to an inhibited hydroxylated cluster. Specifically, the inhibitory process occurs at the distal iron (Fed) of the catalytic H-cluster (which isalso the atom involved in H2 synthesis). The processes involved in the H-cluster oxidative pathways are O2 binding, e− transfer, protonation, and H2O removal. We found that oxygen binding is …
Isolation And Characterization Of Aromatase Inhibitors From Brassaiopsis Glomerulata (Araliaceae), Marcy J. Balunas, Bin Su, Soedarsono Riswan, Harry H.S. Fong, Robert W. Brueggemeier, John M. Pezzuto, A. Douglas Kinghorn
Isolation And Characterization Of Aromatase Inhibitors From Brassaiopsis Glomerulata (Araliaceae), Marcy J. Balunas, Bin Su, Soedarsono Riswan, Harry H.S. Fong, Robert W. Brueggemeier, John M. Pezzuto, A. Douglas Kinghorn
Chemistry Faculty Publications
The hexane- and ethyl acetate-soluble extracts of the leaves of Brassaiopsis glomerulata (Blume) Regel (Araliaceae), collected in Indonesia, were found to inhibit aromatase, the rate-limiting enzyme in the production of estrogens from androgens, in both enzyme- and cell-based aromatase inhibition (AI) assays. Bioassay-guided fractionation led to the isolation of six known compounds of the steroid and triterpenoid classes (1–6) from the hexane extract, of which 6β-hydroxystimasta-4-en-3-one (5), was moderately active in the cell-based AI assay. Fractionation of the ethyl acetate extract afforded seven pure isolates (7–13) of the modified peptide, fatty acid, monoterpenoid, and benzenoid types, including six known compounds …
Structural Investigation Of The Complex Of Filamin A Repeat 21 With Integrin Αiib And Β3 Cytoplasmic Tails – A Potential “Transmission” To Regulate Cell Migration, Jianmin Liu
ETD Archive
Cell functions in multi-cellular organisms are strongly depend on the dynamic cooperation between cell adhesion and cytoskeleton reorganization. Integrins, the major cell adhesion receptors, bind to extracellular matrix (ECM) and soluble ligands on the cell surface and link to the actin cytoskeleton inside the cell membrane. In this manner, integrins integrate cell adhesion and cytoskeleton reorganization by acting as a mechanical force transducer and a biochemical signaling hub (Zamir and Geiger 2001). Consequently, integrins are vital for development, immune responses, leukocyte traffic and hemostasis, and a variety of other cellular and physiological processes. Integrins are also are the focal point …
Hemeproteins Bathed In Ionic Liquids;Examining The Role Of Water And Protons In Redox Behavior And Catalytic Function, John Joseph Moran
Hemeproteins Bathed In Ionic Liquids;Examining The Role Of Water And Protons In Redox Behavior And Catalytic Function, John Joseph Moran
ETD Archive
We investigate the changing behaviors of myoglobin and nitric oxide synthase (NOS) in the near-absence of bulk water and/or protons by using ionic liquid butyl methyl imidazolium tetrafluoroborate as a non-aqueous milieu. Through direct charge transfer and metalloprotein-mediated catalytic reduction of oxygen and nitric oxide, we shed light on diverging aspects on how the two hemeproteins face the scarcity of water and/or protons in bulk. Isotopic effect investigations using D2O further elucidates kinetic aspects of proton transfer. Finally, in the case of NOS oxygenase, pterin cofactor binding and NOS-mediated catalytic oxidation of L-arginine in ionic liquids interrogates proton and water …
Fabricating New Miniaturized Biosensors For The Detection Of Dna Damage And Dna Mismatches, N. Indika Perera
Fabricating New Miniaturized Biosensors For The Detection Of Dna Damage And Dna Mismatches, N. Indika Perera
ETD Archive
A large number of genetic diseases and genetic disorders are simply caused by base alterations in the genome. Therefore, developing efficient and cost effective techniques for routine detection of these alterations is of great importance. Different methods involving gel electrophoresis and Polymerase Chain Reaction have been widely employed, but majority of these methods are costly, time consuming, and lack throughput, creating a fundamental gap between the current state-of-the-art and desired characteristics of low-cost, high-speed, simplicity, versatility, and potential for miniaturization. In this study, we attempt to bridge this gap by developing new sensing platforms to detect DNA base mismatches and …
Nitric Oxide Synthase In Confined Environments;Detection And Quantification Of Nitric Oxide Released From Cells And Modified Liposomes Using A Sensitive Metal Catalyst-Pedot Modified Carbon Fiber Electrode, P. A. Reshani H. Perera
Nitric Oxide Synthase In Confined Environments;Detection And Quantification Of Nitric Oxide Released From Cells And Modified Liposomes Using A Sensitive Metal Catalyst-Pedot Modified Carbon Fiber Electrode, P. A. Reshani H. Perera
ETD Archive
Nitric oxide (NO) is a freely diffusible, gaseous free radical, associated with many physiological and pathological processes that include neuronal signaling, immune response, and inflammatory response. NO is produced from L-arginine in an NADPH-dependent reaction catalyzed by a family of nitric oxide synthase (NOS) enzymes. A deficiency in NO plays a role in hypertension, hyperglycaemia, and arteriosclerosis, among other pathological states. Conversely, increased NO levels contribute to arthritis, septic shock, and hypotention. Therefore, measuring and quantifying NO production in biological systems and matrices may be vital in elucidating physiological and pathological processes. The goal of this work is to develop …
Development Of Quantitative Bioanalytical Methods For The Measurement Of Pharmaceutical Compounds Via Hplc-Uv And Hplc-Ms/Ms, Melissa A. Mcculloch
Development Of Quantitative Bioanalytical Methods For The Measurement Of Pharmaceutical Compounds Via Hplc-Uv And Hplc-Ms/Ms, Melissa A. Mcculloch
ETD Archive
Research in pharmaceutical treatments for illnesses and disease processes has rapidly grown in the past decade. The field is fueled by advances in our understanding of the molecular mechanics of the human body, coupled with the development of sophisticated scientific instruments which can efficiently generate massive amounts of important data. This has led to an ever-growing need for the development of quantitative bioanalytical methods to measure pharmaceutical compounds. In this work, the theory behind the analytical processes and instruments that make these investigations possible is discussed. Further, the development of two high performance liquid chromatographic (HPLC) methods with both ultra …
New Generation Of Electrochemical Sensors For Nitric Oxide;Ruthenium/Carbon-Based Nanostructures And Colloids As Electrocatalytic Platforms, W. Pubudu M. Peiris
New Generation Of Electrochemical Sensors For Nitric Oxide;Ruthenium/Carbon-Based Nanostructures And Colloids As Electrocatalytic Platforms, W. Pubudu M. Peiris
ETD Archive
Nitric oxide (NO) is an important intercellular messenger that acts in many tissues to regulate a diverse range of physiological and pathological processes. The physiologically implications of NO function are far from being completely understood. The multifaceted reactivity of NO prompted the need for accurate determination of the concentration of this molecule. However, it is difficult to detect nitric oxide, particularly in biological media and near live cells due to its short half-life, a result of its reactivity and the low levels of NO produced in vivo. As a result, the accurate and reliable detection of NO under varying experimental …
Nos-Based Biopolymers: Towards Novel Thromboresistant No-Release Materials, Charbel Abou Diwan
Nos-Based Biopolymers: Towards Novel Thromboresistant No-Release Materials, Charbel Abou Diwan
ETD Archive
Nitric Oxide releasing biopolymers have the potential to prolong vascular graft and stent potency without adverse systemic vasodilation. It was reported in literature that eNOS-overexpressing endothelial cell seeding of synthetic small diameter vascular grafts decreased human platelet aggregation by 46 and bovine aortic smooth muscle cell proliferation by 67.2 in vitro. We hypothesized that incorporating the enzyme nitric oxide synthase (NOS) in biocompatible polymeric matrix will provide a source of NO that utilizes endogenous compounds to maintain an unlimited supply of NO. To test this hypothesis, we have incorporated the enzyme nitric oxide synthase into a polyethyleneimine film using a …
Cofactor Control Of A Vital Enzymatic Reaction;The Effect Of Factor Va On Thrombin Formation During Blood Coagulation, Jamila Hirbawi
Cofactor Control Of A Vital Enzymatic Reaction;The Effect Of Factor Va On Thrombin Formation During Blood Coagulation, Jamila Hirbawi
ETD Archive
The LONG-TERM goal of our research is to study and analyze the structure and function of the factor V molecule in order to understand its regulatory effects on the natural process of hemostasis and its role in the life-threatening development of deep venous thrombosis. The SHORT-TERM goal of our research is to identify the amino acid residue(s) of factor V that interact with prothrombin during the assembly and function of the prothrombinase complex in order to fully understand its particular role in maintaining the integrity of the blood coagulation cascade. The final goal of the coagulation cascade is the formation …
Hemoprotein-Mediated Activation Of Nitroalkanes, Ling Li
Hemoprotein-Mediated Activation Of Nitroalkanes, Ling Li
ETD Archive
Chemicals and drugs are known to be metabolized mostly by Cytochrome P450 xenobiotic metabolizing enzymes. However, the detailed mechanism of nitro-compounds metabolism is still unclear. The activation of nitro-xenobiotics by heme-P450 enzymes is a potential explanation for the origin of nitro-compound carcinogenesis. Investigating the interaction of simple nitro-compounds with redox activity of heme enzymes is therefore critical to explore the mechanism and products of activation. In this study, multiple analytical methods and instrumentations are employed and graphic and simulation software such as Origin┬« and Digisim┬« are utilized to quantitatively derive parameters from experimental raw data. This study shows that myoglobin, …
Development Of A Novel Gradient Chromatofocusing Tandem Mass Spectometry Technique For The Determination Of Cationic Compounds In Biofluids;Identification Of Caspace 3 Cleavage Sites Of Nhe-1 By High Performance Liquid Chromatography- Mass Spectrometry, Jianhua Tang
ETD Archive
In Part I, work was done to develop a novel gradient chromatofocusing liquid chromatography-tandem mass spectrometry (MS/MS) technique for the determination of ionic compounds in biological matrix. The analysis of ionic compounds poses a great challenge to current LC-MS techniques, due to the fact that there is little or no retention. These ionic compounds are eluted at almost the same time as biological matrix, which is normally directed to waste prior to connecting to the mass spectrometer. A review of current LC-MS techniques for ionic compounds is given in Chapter 1. They all have advantages and disadvantages. To retain and …
Plasma Biomarkers For Age-Related Macular Degeneration, Jiaqian Ni
Plasma Biomarkers For Age-Related Macular Degeneration, Jiaqian Ni
ETD Archive
No abstract provided.
Synthesis And Evaluation Of Some Steroidal Oximes As Cytotoxic Agents: Structure/Activity Studies (I), Jianguo Cui, Lei Fan, Li Liang Huang, Hong Li Liu, Aimin Zhou
Synthesis And Evaluation Of Some Steroidal Oximes As Cytotoxic Agents: Structure/Activity Studies (I), Jianguo Cui, Lei Fan, Li Liang Huang, Hong Li Liu, Aimin Zhou
Chemistry Faculty Publications
The side chain of a compound plays an important role in its biological function. In our studies, we have found that hydroximinosteroid derivatives with different side chains and position of hydroximino on ring A and B displayed remarkable distinct cytotoxicities against a diversity of cancer cell types. Presence of an oxime group on ring B and a hydroxy on ring A or B resulted in a higher cytotoxicity than other structural motifs. In addition, a cholesterol-type side chain at position 17 was required for the biological activity. Our findings provide new evidence showing the relationship between the chemical structure and …
Statins Induce Apoptosis In Ovarian Cancer Cells Through Activation Of Jnk And Enhancement Of Bim Expression, Hongli Liu, Shu Ling Liang, Sheetal Kumar, Crystal M. Weyman, Wendy Liu, Aimin Zhou
Statins Induce Apoptosis In Ovarian Cancer Cells Through Activation Of Jnk And Enhancement Of Bim Expression, Hongli Liu, Shu Ling Liang, Sheetal Kumar, Crystal M. Weyman, Wendy Liu, Aimin Zhou
Chemistry Faculty Publications
Purpose:Ovarian cancer is the leading cause of death among all gynecological malignancies in Western countries. Although therapy for ovarian cancer has been greatly improved in the past 20 years, the overall survival for patients with advanced ovarian cancer has not changed significantly. The poor survival rates in patients with advanced ovarian cancer are due both to late diagnosis and to lack of effective drugs for the majority of patients who have a relapse and develop resistance to current chemotherapy agents used for ovarian cancer. Thus, developing and discovering effective novel drugs with different molecular structures from conventional chemotherapy agents have …
Spectroscopy Is Applied Quantum Mechanics. Part 4: Ideal Systems, David W. Ball
Spectroscopy Is Applied Quantum Mechanics. Part 4: Ideal Systems, David W. Ball
Chemistry Faculty Publications
The article features the last and fourth part of the lecture series about the application of quantum mechanics to spectroscopy. It examines ideal systems with wave functions that can be derived from the Schroedinger equation. It likewise follows discourse for failings of classical mechanics, the quantum hypothesis, and the emergence of a new theory called quantum mechanics.
Spectroscopy Is Applied Quantum Mechanics. Part 3: Introduction To Quantum Mechanics, David W. Ball
Spectroscopy Is Applied Quantum Mechanics. Part 3: Introduction To Quantum Mechanics, David W. Ball
Chemistry Faculty Publications
The article discusses the pioneering work of Erwin Schrödinger on wave mechanics that forms the basis of modern understanding in subatomic behavior. Schrödinger introduced a second-order differential equation that had to be solved to explain the nature of the hydrogen atom. He also demonstrated that the matrix mechanics of Heisenberg and Born were mathematically equivalent and developed the concept of perturbation theory to explain the Stark effect.
4-Hydroxyphenylretinamide (4hpr) Derivatives Regulate Aromatase Activity And Expression In Breast Cancer Cells, Bin Su, Serena M. Mershon, Laura A. Stonerock, Robert W. Curley Jr., Robert W. Brueggemeier
4-Hydroxyphenylretinamide (4hpr) Derivatives Regulate Aromatase Activity And Expression In Breast Cancer Cells, Bin Su, Serena M. Mershon, Laura A. Stonerock, Robert W. Curley Jr., Robert W. Brueggemeier
Chemistry Faculty Publications
Recent studies exhibit that 4-hydroxyphenylretinamide (4HPR) decreases aromatase activity in breast and placental cells. The effect of synthetic 4HPR analogs on aromatase and expression was examined in three breast cancer cell lines. Most derivatives did not decrease cellular aromatase activity. Two of the analogs even stimulated aromatase activity at the transcriptional level. Only one derivative significantly decreased aromatase in all three breast cancer cell lines and also suppressed CYP19 gene expression in one of the cell line. Placental microsomal aromatase assay rule out the possibility that this compound directly inhibits the aromatase enzyme. A non-genomic mechanism in suppression of cellular …
Determination Of Endocannabinoid Receptor Antagonist Sr141716 (Rimonabant) In Plasma By Liquid Chromatograph Tandem Mass Spectrometry, Melissa Mcculloch, Xiang Zhou, Yan Xu, Steve Brunell, Linda Spear
Determination Of Endocannabinoid Receptor Antagonist Sr141716 (Rimonabant) In Plasma By Liquid Chromatograph Tandem Mass Spectrometry, Melissa Mcculloch, Xiang Zhou, Yan Xu, Steve Brunell, Linda Spear
Chemistry Faculty Publications
SR141716 (rimonabant) is an endocannabinoid receptor antagonist. Endocannabinoids are a class of chemicals that affect neurotransmission via G-protein coupled CB1 (brain) and CB2 (peripheral tissue) receptors. Numerous animal studies have shown that SR141716 binds with the CB1 receptor in the brain, resulting in several biological consequences including reduced alcohol intake and reward as well as reduced food consumption. In this work, an analytical method based on liquid chromatography and electrospray ionization tandem mass spectrometry (LC–ESI-MS/MS) has been developed and validated for the quantitative measurement of SR141716 in both human and rat plasma to support the investigation of this compound. A …
A Facile And Efficient Synthesis Of Some (6e)-Hydroximino-4-En-3-One Steroids, Steroidal Oximes From Cinachyrella Spp. Sponges, Jianguo Cui, Liliang Huang, Lei Fan, Aimin Zhou
A Facile And Efficient Synthesis Of Some (6e)-Hydroximino-4-En-3-One Steroids, Steroidal Oximes From Cinachyrella Spp. Sponges, Jianguo Cui, Liliang Huang, Lei Fan, Aimin Zhou
Chemistry Faculty Publications
Using β-sitosterol as a starting material, (6E)-hydroximino-24-ethylcholest-4-en-3-one (1), a natural steroidal oxime from Cinachyrella alloclada and C. apion, was synthesized in four steps with a high overall yield. First, β-sitosterol (5a) is transformed into the corresponding 24-ethylcholest-4-en-3,6-dione (6a) via oxidation with pyridinium chlorochromate (PCC). Selective reduction of 6a by NaBH4 in the presence of CoCl2 gives 24-ethylcholest- 4-en-3β-ol-6-one (7a). The reaction of 7a with hydroxylamine hydrochloride offers the oxime 8a and the oxidation of 8a by Jones reagent gives the target steroid 1. (6E)-Hydroximinocholest-4-en-3-one (2) and (6E)-hydroximino-24-ethylcholest-4,22-dien-3-one (4) were synthesized by a similar method. The cytotoxicity of the synthesized compounds …
A Polarizable Force-Field Model For Quantum-Mechanical-Molecular-Mechanical Hamiltonian Using Expansion Of Point Charges Into Orbitals, P. K. Biswas, Valentin Gogonea
A Polarizable Force-Field Model For Quantum-Mechanical-Molecular-Mechanical Hamiltonian Using Expansion Of Point Charges Into Orbitals, P. K. Biswas, Valentin Gogonea
Chemistry Faculty Publications
We present an ab initio polarizable representation of classical molecular mechanics (MM) atoms by employing an angular momentum-based expansion scheme of the point charges into partial wave orbitals. The charge density represented by these orbitals can be fully polarized, and for hybrid quantum-mechanical-molecular-mechanical (QM/MM) calculations, mutual polarization within the QM/MM Hamiltonian can be obtained. We present the mathematical formulation and the analytical expressions for the energy and forces pertaining to the method. We further develop a variational scheme to appropriately determine the expansion coefficients and then validate the method by considering polarizations of ions by the QM system employing the …
Role Of Transcription Factor Mef2a In Development Of Coronary Artery Disease (Cad) And Myocardial Infarction (Mi), Maniragava Sai Bhagavatula
Role Of Transcription Factor Mef2a In Development Of Coronary Artery Disease (Cad) And Myocardial Infarction (Mi), Maniragava Sai Bhagavatula
ETD Archive
Coronary artery disease (CAD) and myocardial infarction (MI) are the leading cause of death in developed countries. Genetic factors play an important role in the pathogenesis of CAD and MI. The revolutionary advances in molecular genetics have provided new insights into the genetic pathways involved in this disease. Recently, our laboratory used linkage analysis to map the first disease-causing gene for CAD and MI to chromosome 15q26 in a large family and subsequently mutation analysis identified a 7-amio acid deletion in MEF2A, a gene encoding a transcription factor. Later we identified three novel mutations N263S, P279L, G283D in four other …
New Insights Into Molecular Mechanisms Of Fludarabine, Alina D. Bulgar
New Insights Into Molecular Mechanisms Of Fludarabine, Alina D. Bulgar
ETD Archive
Nucleotide analogs (e.g. fludarabine) are antimetabolites used in the treatment of a wide variety of hematological malignancies and solid tumors. Upon being metabolized to their active triphosphate form, these agents are incorporated into DNA. Among other molecular targets, their incorporation may lead to activation of base excision repair (BER) pathway. The molecular mechanism of BER recognition and repair of the incorporated fludarabine has not yet been elucidated. The main focus of this research was to study the involvement of BER pathway in the response to fludarabine induced DNA damage. Also, the possibility of enhancing antineoplastic activity of fludarabine by inhibition …
Quadrupole Magnetic Field-Flow Fractionation;A Novel Technique For The Characterization Of Magnetic Particles, Francesca Carpino
Quadrupole Magnetic Field-Flow Fractionation;A Novel Technique For The Characterization Of Magnetic Particles, Francesca Carpino
ETD Archive
In the last few decades, the development and use of nanotechnology has become of increasing importance. Magnetic nanoparticles, because of their unique properties, have been employed in many different areas of application. They are generally made of a core of magnetic material coated with some other material to stabilize them and to help disperse them in suspension. The unique feature of magnetic nanoparticles is their response to a magnetic field. They are generally superparamagnetic, in which case they become magnetized only in a magnetic field and lose their magnetization when the field is removed. It is this feature that makes …
Hydrogenase Inhibition By O2: Density Functional Theory/Molecular Mechanics Investigation, Daniela Dogaru
Hydrogenase Inhibition By O2: Density Functional Theory/Molecular Mechanics Investigation, Daniela Dogaru
ETD Archive
[Fe-Fe]-hydrogenases are enzymes that reversibly catalyze the reduction of protons to molecular hydrogen, which occurs in anaerobic media. In living systems, [Fe-Fe]-hydrogenases shift the reversible reaction towards H2 formation. The [Fe-Fe]-hydrogenase H-cluster is the active site, which contains two iron atoms (Fep-Fed, i.e., proximal and distal iron). Because most experimental and theoretical investigations confirm that the structure of di-iron air inhibited species is FepII-FedII-O-O-H-, O2 has to be prevented from binding to Fed in all di-iron subcluster oxidation states in order to retain a catalytically active enzyme. By understanding the catalytic processes of metalloenzymes, researches are enabled to produce an …
A Theoretical Study For The Reactivation Of O2 Inhibited [Fe-Fe]-Hydrogenase, Stefan Motiu
A Theoretical Study For The Reactivation Of O2 Inhibited [Fe-Fe]-Hydrogenase, Stefan Motiu
ETD Archive
The current investigation presents a reactivation pathway of the exogenously inhibited H-cluster (viz., by O2, or OH-, which metabolizes to H2O), for both vacuum and aqueous enzyme phase. The H-cluster is the catalytic site of [Fe-Fe]-hydrogenase, with the latter extracted from Desulfovibrio desulfuricans (Dd) bacteria. It consists of proximal iron, Fep, and distal Fed subunit, [Fep-Fed], which is bridged by di(thiomethyl)amine (DTMA) ligand, and a proximal cubane subunit, [Fe4-S4]2+p. [Fep-Fed] is coordinated by two cyanides (CN-), two terminal carbonyls (COt), and a bridging carbonyl (COb)*. An Fe atom from [Fe4-S4]2+p connects Fep through a cysteinyl sulfur (of Cys382). Density functional …