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2016

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Articles 31 - 60 of 82

Full-Text Articles in Medicinal-Pharmaceutical Chemistry

Staphylococcal Nuclease And Ubiquitin Local Folding Energies And Rates Using Peps-Hdx-Esi-Ms, Julie Rhee May 2016

Staphylococcal Nuclease And Ubiquitin Local Folding Energies And Rates Using Peps-Hdx-Esi-Ms, Julie Rhee

Chemistry & Biochemistry Undergraduate Honors Theses

In this study, Protein Equilibrium Population Snapshot Hydrogen-Deuterium Exchange Electrospray Ionization Mass Spectrometry (PEPS-HDX-ESI-MS) was applied to study the local regions of model proteins, staphylococcal nuclease and ubiquitin. The hydrogen deuterium exchange (HDX) has become a key technique for studying the structural and dynamic aspects of proteins in solution. This technique creates a rapid exchange between all of the exchangeable hydrogen ions with deuterium when the protein is exposed to a solvent. The PEPS method is an equilibrium-based method used to determine the populations of the closed native and open denatured states of a protein. By combining the applications of ...


Synthesis Of A Novel Cox-2 Inhibitor Analog For Pet Scan Imaging, Rebecca Neighbor May 2016

Synthesis Of A Novel Cox-2 Inhibitor Analog For Pet Scan Imaging, Rebecca Neighbor

Chancellor’s Honors Program Projects

No abstract provided.


Catalytic Transfer Hydrogenation Of Nitroalkenes To Primary Amines, Brendan Phillips Apr 2016

Catalytic Transfer Hydrogenation Of Nitroalkenes To Primary Amines, Brendan Phillips

Chemistry Honors Papers

This work describes synthetic methodology development in organic chemistry. The goal of this work is to demonstrate new ways of making biologically-relevant molecules that are in line with the principles of green chemistry (chemical practices which seek to be, regarding human and environmental health, benign by design). To this end, a new method has been developed toward the introduction of primary amine functionalities into organic molecules from readily-available aldehydes, via reduction of nitroalkene intermediates. Traditional methods of reducing nitroalkenes to primary amines require harsh conditions, often produce stoichiometric amounts of metal salt waste, and present significant safety challenges to the ...


Agonist-Mediated Activation Of Sting Induces Apoptosis In Malignant B Cells, Chih-Hang Anthony Tang, Joseph A. Zundell, Sujeewa Ranatunga, Cindy Lin, Yulia Nefedova, Juan R. Del Valle, Chih-Chi Andrew Hu Apr 2016

Agonist-Mediated Activation Of Sting Induces Apoptosis In Malignant B Cells, Chih-Hang Anthony Tang, Joseph A. Zundell, Sujeewa Ranatunga, Cindy Lin, Yulia Nefedova, Juan R. Del Valle, Chih-Chi Andrew Hu

Chemistry Faculty Publications

Endoplasmic reticulum (ER) stress responses through the IRE-1/XBP-1 pathway are required for the function of STING (TMEM173), an ER-resident transmembrane protein critical for cytoplasmic DNA sensing, IFN production, and cancer control. Here we show that the IRE-1/XBP-1 pathway functions downstream of STING and that STING agonists selectively trigger mitochondria-mediated apoptosis in normal and malignant B cells. Upon stimulation, STING was degraded less efficiently in B cells, implying that prolonged activation of STING can lead to apoptosis. Transient activation of the IRE-1/XBP-1 pathway partially protected agonist-stimulated malignant B cells from undergoing apoptosis. In Eμ-TCL1 mice with chronic lymphocytic ...


Comparison Of Conventional And Microwave-Assisted Synthesis Of Chemokine Receptor Type 4 (Cxcr4) Antagonists, Saniya Virani, Damilola Gbadebo, Theresa D. Gaines, Francisco Javier Garcia Apr 2016

Comparison Of Conventional And Microwave-Assisted Synthesis Of Chemokine Receptor Type 4 (Cxcr4) Antagonists, Saniya Virani, Damilola Gbadebo, Theresa D. Gaines, Francisco Javier Garcia

Georgia State Undergraduate Research Conference

No abstract provided.


Analysis Of New Hiv-1 Inhibitors As Potential Antiviral Agents For Hiv-2, Rowan Brothers Apr 2016

Analysis Of New Hiv-1 Inhibitors As Potential Antiviral Agents For Hiv-2, Rowan Brothers

Georgia State Undergraduate Research Conference

No abstract provided.


Ruthenium-Catalyzed Amination Of Secondary Alcohols Using Borrowing Hydrogen Methodology, Kostiantyn O. Marichev, James M. Takacs Apr 2016

Ruthenium-Catalyzed Amination Of Secondary Alcohols Using Borrowing Hydrogen Methodology, Kostiantyn O. Marichev, James M. Takacs

Faculty Publications -- Chemistry Department

A new ruthenium complex catalyzes the amination of primary and secondary alcohols and the regioselective mono- and sequential diamination of diols via the borrowing hydrogen pathway. Several variations on new intra- and intermolecular cyclizations of aminoalcohols, diols and diamines lead to heterocyclic ring systems.


Binding Of Oxaliplatin And Its Analogs With Dna Nucleotides At Variable Ph And Concentration Levels, Rippa Sehgal Apr 2016

Binding Of Oxaliplatin And Its Analogs With Dna Nucleotides At Variable Ph And Concentration Levels, Rippa Sehgal

Masters Theses & Specialist Projects

Oxaliplatin is one of the three FDA-approved platinum anticancer drugs and considered a third generation drug, discovered after the first generation drug cisplatin and second generation drug carboplatin. It is known to react with proteins and DNA nucleotides in the body. Reaction with DNA occurs primarily at guanosine residues and secondarily at adenine residues for oxaliplatin and other platinum drugs. We have previously studied oxaliplatin and an analog with additional steric hindrance in the amine ligand and found that the analog had different reactivity with methionine. Now, we have prepared oxaliplatin and its three analogs Pt(Me2dach)(ox), Pt(en ...


One Year Later: The Politics And Stories Of Post-Earthquake Nepal, Boyer Andrew Apr 2016

One Year Later: The Politics And Stories Of Post-Earthquake Nepal, Boyer Andrew

Independent Study Project (ISP) Collection

A 7.8 magnitude earthquake struck Nepal on April 25th, 2015. This was followed by a second major earthquake of magnitude 7.3 on May 12th , 2015. These disasters took the lives of thousands of Nepali people, destroyed hundreds of thousands of structures, and displaced an estimated two million people. Immediately following the disaster, there was an outpouring of humanitarian aid from around the world. This lead to a conference where $4.1 billion USD of reconstruction funds were pledged to Nepal by international donors. Five months later, a new constitution passed into law and an informal blockade ...


Electronic Cigarettes: Truth Or Toxic?, Timothy S. Turner, Alyx S. Frantzen Mar 2016

Electronic Cigarettes: Truth Or Toxic?, Timothy S. Turner, Alyx S. Frantzen

Undergraduate Research Conference

With the increasing research on the hazards of cigareDes, people are looking for a safer alterna>ve to smoking. Electronic CigareDes were introduced in the early 2000’s to serve this purpose, and they are gaining increasing popularity. Many e-cigareDe companies claim that the use of e-cigareDes is completely harmless because of combus>on of the organic liquids would cause the inhala>on of only water vapor and carbon dioxide along with the flavors and nico>ne. Companies also adver>se their products to help smokers quit smoking. Recently, “vaping” has grown increasingly popular especially with minors since several states ...


Fabrication Of A Gma-Co-Edma Monolith In A 2.0 Mm I.D. Polypropylene Housing., Marcello Iacono, Damian Connolly, Andreas Heise Mar 2016

Fabrication Of A Gma-Co-Edma Monolith In A 2.0 Mm I.D. Polypropylene Housing., Marcello Iacono, Damian Connolly, Andreas Heise

Chemistry Articles

Polymers are interesting housing materials for the fabrication of inexpensive monolithic chromatography and solid phase extraction (SPE) devices. Challenges arise when polymeric monoliths are formed in non-conical, cylindrical tubes of larger diameter due to potential monolith detachment from the housing wall resulting in loss of separation performance and mechanical stability. Here, a two-step protocol is applied to ensure formation of robust homogeneous methacrylate monolith in polypropylene (PP) tubing with a diameter of 2.0 mm. Detailed Fourier-transform infrared (FTIR) spectroscopic analysis and Scanning Electron Microscopy (SEM) imaging confirm the successful pre-modification of the tubing wall with an anchoring layer of ...


A Sodium Salt Of The Dimer Of Boronoterephthalic Acid Anhydride, Scott Simmons, Albert Fratini, Vladimir Benin Mar 2016

A Sodium Salt Of The Dimer Of Boronoterephthalic Acid Anhydride, Scott Simmons, Albert Fratini, Vladimir Benin

Albert Fratini

The title compound, sodium bis­(6-carb­oxy-1-hy­droxy-3-oxo-1,3-dihydro-2,1-benzoxaborol-1-yl)oxidanium, Na+·C16H15B2O13-, was prepared in two steps from 2-bromo-p-xylene. Its crystal structure was determined at 140 K and has triclinic (P) symmetry. The compound presents a unique structural motif, including two units of the cyclic anhydride of boronoterephthalic acid, joined by a protonated, and thereby trivalent, oxonium center. Association in the crystal is realized by complementary hydrogen bonding of the carboxyl groups, as well as by coordination of the sodium cations to the oxygen centers on the five-membered rings.


Protein Arginine Methylation And Citrullination In Epigenetic Regulation, Jakob Fuhrmann, Paul R. Thompson Mar 2016

Protein Arginine Methylation And Citrullination In Epigenetic Regulation, Jakob Fuhrmann, Paul R. Thompson

Thompson Lab Publications

The post-translational modification of arginine residues represents a key mechanism for the epigenetic control of gene expression. Aberrant levels of histone arginine modifications have been linked to the development of several diseases including cancer. In recent years, great progress has been made in understanding the physiological role of individual arginine modifications and their effects on chromatin function. The present review aims to summarize the structural and functional aspects of histone arginine modifying enzymes and their impact on gene transcription. We will discuss the potential for targeting these proteins with small molecules in a variety of disease states.


“Zipped Synthesis” By Cross-Metathesis Provides A Cystathionine Β‑Synthase Inhibitor That Attenuates Cellular H2S Levels And Reduces Neuronal Infarction In A Rat Ischemic Stroke Model, Christopher D. Mccune, Su Jing Chan, Matthew L. Beio, Weijun Shen, Woo Jin Chung, Laura M. Szczesniak, Chou Chai, Shu Qing Koh, Peter T.-H. Wong, David B. Berkowitz Mar 2016

“Zipped Synthesis” By Cross-Metathesis Provides A Cystathionine Β‑Synthase Inhibitor That Attenuates Cellular H2S Levels And Reduces Neuronal Infarction In A Rat Ischemic Stroke Model, Christopher D. Mccune, Su Jing Chan, Matthew L. Beio, Weijun Shen, Woo Jin Chung, Laura M. Szczesniak, Chou Chai, Shu Qing Koh, Peter T.-H. Wong, David B. Berkowitz

David Berkowitz Publications

The gaseous neuromodulator H2S is associated with neuronal cell death pursuant to cerebral ischemia. As cystathionine β-synthase (CBS) is the primary mediator of H2S biogenesis in the brain, it has emerged as a potential target for the treatment of stroke. Herein, a “zipped” approach by alkene cross-metathesis into CBS inhibitor candidate synthesis is demonstrated. The inhibitors are modeled after the pseudo-C2-symmetric CBS product (L,L)-cystathionine. The “zipped” concept means only half of the inhibitor needs be constructed; the two halves are then fused by olefin cross-metathesis. Inhibitor design is also mechanism-based, exploiting the favorable kinetics ...


Lysosome Triggered Near-Infrared Fluorescence Imaging Of Cellular Trafficking Processes In Real Time., Marco Grossi, Marina Morgunova, Shane Cheung, Dimitri Scholz, Emer Conroy, Marta Terrile, Angela Panarella, Jeremy C. Simpson, William M. Gallagher, Donal F. O'Shea Mar 2016

Lysosome Triggered Near-Infrared Fluorescence Imaging Of Cellular Trafficking Processes In Real Time., Marco Grossi, Marina Morgunova, Shane Cheung, Dimitri Scholz, Emer Conroy, Marta Terrile, Angela Panarella, Jeremy C. Simpson, William M. Gallagher, Donal F. O'Shea

Chemistry Articles

Bioresponsive NIR-fluorophores offer the possibility for continual visualization of dynamic cellular processes with added potential for direct translation to in vivo imaging. Here we show the design, synthesis and lysosome-responsive emission properties of a new NIR fluorophore. The NIR fluorescent probe design differs from typical amine functionalized lysosomotropic stains with off/on fluorescence switching controlled by a reversible phenol/phenolate interconversion. Emission from the probe is shown to be highly selective for the lysosomes in co-imaging experiments using a HeLa cell line expressing the lysosomal-associated membrane protein 1 fused to green fluorescent protein. The responsive probe is capable of real-time ...


The Design And Synthesis Of Ghrelin Analogues As Non‐Invasive Ghs‐R1a Imaging Probes, Carlie L. Charlton Feb 2016

The Design And Synthesis Of Ghrelin Analogues As Non‐Invasive Ghs‐R1a Imaging Probes, Carlie L. Charlton

Electronic Thesis and Dissertation Repository

The field of molecular imaging is constantly growing and evolving in order to provide the best possible healthcare for patients in various stages of disease and therapy. Molecular imaging aims to locate specific markers of disease by selectively targeting the markers of interest with high selectivity and visualizing the accumulation using external detection. The growth hormone secretagogue receptor-1a (GHS-R1a) has been shown to be involved in various important biological functions such as energy homeostasis and cardiac contractility. GHS-R1a has shown involvement in proliferation, migration and cell invasion of specific cancer subtypes. Therefore, targeting GHS-R1a is an important marker of different ...


Development And Validation Of A Sensitive Uplc-Ms/Ms Method For The Quantitation Of [13c]Sucrose In Rat Plasma, Blood, And Brain: Its Application To The Measurement Of Blood-Brain Barrier Permeability, Mohammad K. Miah, Ulrich Bickel, Reza Mehvar Feb 2016

Development And Validation Of A Sensitive Uplc-Ms/Ms Method For The Quantitation Of [13c]Sucrose In Rat Plasma, Blood, And Brain: Its Application To The Measurement Of Blood-Brain Barrier Permeability, Mohammad K. Miah, Ulrich Bickel, Reza Mehvar

Pharmacy Faculty Articles and Research

Accurate and reproducible measurement of blood-brain barrier (BBB) integrity is critical in the assessment of the pathophysiology of the central nervous system disorders and in monitoring therapeutic effects. The widely-used low molecular weight marker [14C]sucrose is non-specific in the absence of chromatographic separation. The purpose of this study was to develop and validate a sensitive and reproducible LC-MS/MS method for the analysis of stable isotopemodified [13C12]sucrose in brain, plasma, and blood to determine BBB permeability to sucrose. After addition of internal standard (IS, [13C6]sucrose), the marker and IS were recovered from diluted rat blood, plasma, and ...


Citrullination-Acetylation Interplay Guides E2f-1 Activity During The Inflammatory Response, Fatemeh Ghari, Anne-Marie Quirke, Shonagh Munro, Joanna Kawalkowska, Sarah Picaud, Joanna Mcgouran, Venkataraman Subramanian, Aaron Muth, Richard Williams, Benedikt Kessler, Paul R. Thompson, Panagis Fillipakopoulos, Stefan Knapp, Patrick J. Venables, Nicholas B. La Thangue Feb 2016

Citrullination-Acetylation Interplay Guides E2f-1 Activity During The Inflammatory Response, Fatemeh Ghari, Anne-Marie Quirke, Shonagh Munro, Joanna Kawalkowska, Sarah Picaud, Joanna Mcgouran, Venkataraman Subramanian, Aaron Muth, Richard Williams, Benedikt Kessler, Paul R. Thompson, Panagis Fillipakopoulos, Stefan Knapp, Patrick J. Venables, Nicholas B. La Thangue

Thompson Lab Publications

Peptidyl arginine deiminase 4 (PAD4) is a nuclear enzyme that converts arginine residues to citrulline. Although increasingly implicated in inflammatory disease and cancer, the mechanism of action of PAD4 and its functionally relevant pathways remains unclear. E2F transcription factors are a family of master regulators that coordinate gene expression during cellular proliferation and diverse cell fates. We show that E2F-1 is citrullinated by PAD4 in inflammatory cells. Citrullination of E2F-1 assists its chromatin association, specifically to cytokine genes in granulocyte cells. Mechanistically, citrullination augments binding of the BET (bromodomain and extra-terminal domain) family bromodomain reader BRD4 (bromodomain-containing protein 4) to ...


Synthesis Of Novel Aporphine-Inspired Neuroreceptor Ligands, Nirav R. Kapadia Feb 2016

Synthesis Of Novel Aporphine-Inspired Neuroreceptor Ligands, Nirav R. Kapadia

All Dissertations, Theses, and Capstone Projects

Aporphines are a group of tetracyclic alkaloids that belong to the ubiquitous tetrahydroisoquinoline family. The aporphine template is known to be associated with a range of biological activities. Aporphines have been explored as antioxidants, anti-tuberculosis, antimicrobial and anticancer agents. Within the Central Nervous Systems (CNS), aporphine alkaloids are known to possess high affinity for several clinically valuable targets including dopamine receptors (predominantly D1 and D2), serotonin receptors (5-HT1A and 5-HT7) and α adrenergic receptors. Aporphines are also inhibitors of the acetylcholinesterase enzyme – a clinical target for the treatment of Alzheimer’s disease. Considering the diverse profile ...


Structural Dependence Of The In Vitro Cytotoxicity, Oxidative Stress And Uptake Mechanisms Of Poly(Propylene Imine) Dendritic Nanoparticles, Humza Khalid, Sourav Prasanna Mukherjee, Luke O'Neill, Hugh Byrne Feb 2016

Structural Dependence Of The In Vitro Cytotoxicity, Oxidative Stress And Uptake Mechanisms Of Poly(Propylene Imine) Dendritic Nanoparticles, Humza Khalid, Sourav Prasanna Mukherjee, Luke O'Neill, Hugh Byrne

Articles

The in vitro cytotoxic and intracellular oxidative stress responses to exposure to poly (propylene imine) (PPI) dendritic nanoparticles of increasing generation (number of repeated branching cycles) (G0-G4) were assessed in an immortal non-cancerous human keratinocyte cell-line (HaCaT). Confocal fluorescence microscopy with organelle staining was used to explore the uptake and intracellular trafficking mechanisms. A generation and dose dependent cytotoxic response was observed, increasing according to generation and therefore number of surface amino groups. A comparison of the cytotoxic response of G4 PPI and the related G4 Poly (amido amine) dendrimer indicates that the PPI with the same number of surface ...


The Ssdna Mutator Apobec3a Is Regulated By Cooperative Dimerization, Markus-Frederik Bohn, Shivender Shandilya, Tania Silvas, Ellen Nalivaika, Takahide Kouno, Brian Kelch, Sean Ryder, Nese Yilmaz, Mohan Somasundaran, Celia Schiffer Jan 2016

The Ssdna Mutator Apobec3a Is Regulated By Cooperative Dimerization, Markus-Frederik Bohn, Shivender Shandilya, Tania Silvas, Ellen Nalivaika, Takahide Kouno, Brian Kelch, Sean Ryder, Nese Yilmaz, Mohan Somasundaran, Celia Schiffer

Celia A. Schiffer

Deaminase activity mediated by the human APOBEC3 family of proteins contributes to genomic instability and cancer. APOBEC3A is by far the most active in this family and can cause rapid cell death when overexpressed, but in general how the activity of APOBEC3s is regulated on a molecular level is unclear. In this study, the biochemical and structural basis of APOBEC3A substrate binding and specificity is elucidated. We find that specific binding of single-stranded DNA is regulated by the cooperative dimerization of APOBEC3A. The crystal structure elucidates this homodimer as a symmetric domain swap of the N-terminal residues. This dimer interface ...


Structure Of The Vif-Binding Domain Of The Antiviral Enzyme Apobec3g, Takahide Kouno, Elizabeth Luengas, Megumi Shigematsu, Shivender Shandilya, Jingying Zhang, Luan Chen, Mayuko Hara, Celia Schiffer, Reuben Harris, Hiroshi Matsuo Jan 2016

Structure Of The Vif-Binding Domain Of The Antiviral Enzyme Apobec3g, Takahide Kouno, Elizabeth Luengas, Megumi Shigematsu, Shivender Shandilya, Jingying Zhang, Luan Chen, Mayuko Hara, Celia Schiffer, Reuben Harris, Hiroshi Matsuo

Celia A. Schiffer

The human APOBEC3G (A3G) DNA cytosine deaminase restricts and hypermutates DNA-based parasites including HIV-1. The viral infectivity factor (Vif) prevents restriction by triggering A3G degradation. Although the structure of the A3G catalytic domain is known, the structure of the N-terminal Vif-binding domain has proven more elusive. Here, we used evolution- and structure-guided mutagenesis to solubilize the Vif-binding domain of A3G, thus permitting structural determination by NMR spectroscopy. A smaller zinc-coordinating pocket and altered helical packing distinguish the structure from previous catalytic-domain structures and help to explain the reported inactivity of this domain. This soluble A3G N-terminal domain is bound by ...


Simultaneously Targeting The Ns3 Protease And Helicase Activities For More Effective Hepatitis C Virus Therapy, Jean Ndjomou, M Corby, Noreena Sweeney, Alicia Hanson, Cihan Aydin, Akbar Ali, Celia Schiffer, Kelin Li, Kevin Frankowski, Frank Schoenen, David Frick Jan 2016

Simultaneously Targeting The Ns3 Protease And Helicase Activities For More Effective Hepatitis C Virus Therapy, Jean Ndjomou, M Corby, Noreena Sweeney, Alicia Hanson, Cihan Aydin, Akbar Ali, Celia Schiffer, Kelin Li, Kevin Frankowski, Frank Schoenen, David Frick

Celia A. Schiffer

This study examines the specificity and mechanism of action of a recently reported hepatitis C virus (HCV) nonstructural protein 3 (NS3) helicase-protease inhibitor (HPI), and the interaction of HPI with the NS3 protease inhibitors telaprevir, boceprevir, danoprevir, and grazoprevir. HPI most effectively reduced cellular levels of subgenomic genotype 4a replicons, followed by genotypes 3a and 1b replicons. HPI had no effect on HCV genotype 2a or dengue virus replicon levels. Resistance evolved more slowly to HPI than telaprevir, and HPI inhibited telaprevir-resistant replicons. Molecular modeling and analysis of the ability of HPI to inhibit peptide hydrolysis catalyzed by a variety ...


Structural Basis For Mutation-Induced Destabilization Of Profilin 1 In Als, Sivakumar Boopathy, Tania Silvas, Maeve Tischbein, Silvia Jansen, Shivender Shandilya, Jill Zitzewitz, John Landers, Bruce Goode, Celia Schiffer, Daryl Bosco Jan 2016

Structural Basis For Mutation-Induced Destabilization Of Profilin 1 In Als, Sivakumar Boopathy, Tania Silvas, Maeve Tischbein, Silvia Jansen, Shivender Shandilya, Jill Zitzewitz, John Landers, Bruce Goode, Celia Schiffer, Daryl Bosco

Celia A. Schiffer

Mutations in profilin 1 (PFN1) are associated with amyotrophic lateral sclerosis (ALS); however, the pathological mechanism of PFN1 in this fatal disease is unknown. We demonstrate that ALS-linked mutations severely destabilize the native conformation of PFN1 in vitro and cause accelerated turnover of the PFN1 protein in cells. This mutation-induced destabilization can account for the high propensity of ALS-linked variants to aggregate and also provides rationale for their reported loss-of-function phenotypes in cell-based assays. The source of this destabilization is illuminated by the X-ray crystal structures of several PFN1 proteins, revealing an expanded cavity near the protein core of the ...


Inhibition Of Apobec3g Activity Impedes Double-Stranded Dna Repair, Ponnandy Prabhu, Shivender Shandilya, Elena Britan-Rosich, Adi Nagler, Celia Schiffer, Moshe Kotler Jan 2016

Inhibition Of Apobec3g Activity Impedes Double-Stranded Dna Repair, Ponnandy Prabhu, Shivender Shandilya, Elena Britan-Rosich, Adi Nagler, Celia Schiffer, Moshe Kotler

Celia A. Schiffer

The cellular cytidine deaminase APOBEC3G (A3G) was first described as an anti-HIV-1 restriction factor, acting by directly deaminating reverse transcripts of the viral genome. HIV-1 Vif neutralizes the activity of A3G, primarily by mediating degradation of A3G to establish effective infection in host target cells. Lymphoma cells, which express high amounts of A3G, can restrict Vif-deficient HIV-1. Interestingly, these cells are more stable in the face of treatments that result in double-stranded DNA damage, such as ionizing radiation and chemotherapies. Previously, we showed that the Vif-derived peptide (Vif25-39) efficiently inhibits A3G deamination, and increases the sensitivity of lymphoma cells to ...


Rediii: A Pipeline For Automated Structure Solution, Markus-Frederik Bohn, Celia Schiffer Jan 2016

Rediii: A Pipeline For Automated Structure Solution, Markus-Frederik Bohn, Celia Schiffer

Celia A. Schiffer

High-throughput crystallographic approaches require integrated software solutions to minimize the need for manual effort. REdiii is a system that allows fully automated crystallographic structure solution by integrating existing crystallographic software into an adaptive and partly autonomous workflow engine. The program can be initiated after collecting the first frame of diffraction data and is able to perform processing, molecular-replacement phasing, chain tracing, ligand fitting and refinement without further user intervention. Preset values for each software component allow efficient progress with high-quality data and known parameters. The adaptive workflow engine can determine whether some parameters require modifications and choose alternative software strategies ...


Modulation Of Hiv Protease Flexibility By The T80n Mutation, Hao Zhou, Shangyang Li, John Badger, Ellen Nalivaika, Yufeng Cai, Jennifer Foulkes-Murzycki, Celia Schiffer, Lee Makowski Jan 2016

Modulation Of Hiv Protease Flexibility By The T80n Mutation, Hao Zhou, Shangyang Li, John Badger, Ellen Nalivaika, Yufeng Cai, Jennifer Foulkes-Murzycki, Celia Schiffer, Lee Makowski

Celia A. Schiffer

The flexibility of HIV protease (HIVp) plays a critical role in enabling enzymatic activity and is required for substrate access to the active site. While the importance of flexibility in the flaps that cover the active site is well known, flexibility in other parts of the enzyme is also critical for function. One key region is a loop containing Thr 80, which forms the walls of the active site. Although not situated within the active site, amino acid Thr80 is absolutely conserved. The mutation T80N preserves the structure of the enzyme but catalytic activity is completely lost. To investigate the ...


A Direct Interaction With Rna Dramatically Enhances The Catalytic Activity Of The Hiv-1 Protease In Vitro, Marc Potempa, Ellen Nalivaika, Debra Ragland, Sook-Kyung Lee, Celia Schiffer, Ronald Swanstrom Jan 2016

A Direct Interaction With Rna Dramatically Enhances The Catalytic Activity Of The Hiv-1 Protease In Vitro, Marc Potempa, Ellen Nalivaika, Debra Ragland, Sook-Kyung Lee, Celia Schiffer, Ronald Swanstrom

Celia A. Schiffer

Though the steps of human immunodeficiency virus type 1 (HIV-1) virion maturation are well documented, the mechanisms regulating the proteolysis of the Gag and Gag-Pro-Pol polyproteins by the HIV-1 protease (PR) remain obscure. One proposed mechanism argues that the maturation intermediate p15NC must interact with RNA for efficient cleavage by the PR. We investigated this phenomenon and found that processing of multiple substrates by the HIV-1 PR was enhanced in the presence of RNA. The acceleration of proteolysis occurred independently from the substrate's ability to interact with nucleic acid, indicating that a direct interaction between substrate and RNA is ...


A Balance Between Inhibitor Binding And Substrate Processing Confers Influenza Drug Resistance, Li Jiang, Ping Liu, Claudia Bank, Nicholas Renzette, Kristina Prachanronarong, L. Yilmaz, Daniel Caffrey, Konstantin Zeldovich, Celia Schiffer, Timothy Kowalik, Jeffrey Jensen, Robert Finberg, Jennifer Wang, Daniel Bolon Jan 2016

A Balance Between Inhibitor Binding And Substrate Processing Confers Influenza Drug Resistance, Li Jiang, Ping Liu, Claudia Bank, Nicholas Renzette, Kristina Prachanronarong, L. Yilmaz, Daniel Caffrey, Konstantin Zeldovich, Celia Schiffer, Timothy Kowalik, Jeffrey Jensen, Robert Finberg, Jennifer Wang, Daniel Bolon

Celia A. Schiffer

The therapeutic benefits of the neuraminidase (NA) inhibitor oseltamivir are dampened by the emergence of drug resistance mutations in influenza A virus (IAV). To investigate the mechanistic features that underlie resistance, we developed an approach to quantify the effects of all possible single-nucleotide substitutions introduced into important regions of NA. We determined the experimental fitness effects of 450 nucleotide mutations encoding positions both surrounding the active site and at more distant sites in an N1 strain of IAV in the presence and absence of oseltamivir. NA mutations previously known to confer oseltamivir resistance in N1 strains, including H275Y and N295S ...


Structural And Thermodynamic Effects Of Macrocyclization In Hcv Ns3/4a Inhibitor Mk-5172, Djade Soumana, Nese Yilmaz, Kristina Prachanronarong, Cihan Aydin, Akbar Ali, Celia Schiffer Jan 2016

Structural And Thermodynamic Effects Of Macrocyclization In Hcv Ns3/4a Inhibitor Mk-5172, Djade Soumana, Nese Yilmaz, Kristina Prachanronarong, Cihan Aydin, Akbar Ali, Celia Schiffer

Celia A. Schiffer

Recent advances in direct-acting antivirals against Hepatitis C Virus (HCV) have led to the development of potent inhibitors, including MK-5172, that target the viral NS3/4A protease with relatively low susceptibility to resistance. MK-5172 has a P2-P4 macrocycle and a unique binding mode among current protease inhibitors where the P2 quinoxaline packs against the catalytic residues H57 and D81. However, the effect of macrocyclization on this binding mode is not clear, as is the relation between macrocyclization, thermodynamic stabilization, and susceptibility to the resistance mutation A156T. We have determined high-resolution crystal structures of linear and P1-P3 macrocyclic analogs of MK-5172 ...