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Medicinal Chemistry and Pharmaceutics

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Full-Text Articles in Medicinal-Pharmaceutical Chemistry

Thioredoxin Modulates Protein Arginine Deiminase 4 (Pad4)-Catalyzed Citrullination, Mitesh Nagar, Ronak Tilvawala, Paul R. Thompson Feb 2019

Thioredoxin Modulates Protein Arginine Deiminase 4 (Pad4)-Catalyzed Citrullination, Mitesh Nagar, Ronak Tilvawala, Paul R. Thompson

Open Access Articles

Protein citrullination is a post-translational modification catalyzed by the protein arginine deiminases (PADs). This modification plays a crucial role in the pathophysiology of numerous autoimmune disorders including RA. Recently, there has been a growing interest in investigating physiological regulators of PAD activity to understand the primary cause of the associated disorders. Apart from calcium, it is well-documented that a reducing environment activates the PADs. Although the concentration of thioredoxin (hTRX), an oxidoreductase that maintains the cellular reducing environment, is elevated in RA patients, its contribution toward RA progression or PAD activity has not been explored. Herein, we demonstrate that hTRX ...


T Cell Epitope Engineering: An Avian H7n9 Influenza Vaccine Strategy For Pandemic Preparedness And Response, Leonard Moise, Bethany M. Biron, Christine M. Boyle, Nese Kurt Yilmaz, Hyesun Jang, Celia A. Schiffer, Ted M. Ross, William D. Martin, Anne S. De Groot Sep 2018

T Cell Epitope Engineering: An Avian H7n9 Influenza Vaccine Strategy For Pandemic Preparedness And Response, Leonard Moise, Bethany M. Biron, Christine M. Boyle, Nese Kurt Yilmaz, Hyesun Jang, Celia A. Schiffer, Ted M. Ross, William D. Martin, Anne S. De Groot

Schiffer Lab Publications

The delayed availability of vaccine during the 2009 H1N1 influenza pandemic created a sense of urgency to better prepare for the next influenza pandemic. Advancements in manufacturing technology, speed and capacity have been achieved but vaccine effectiveness remains a significant challenge. Here, we describe a novel vaccine design strategy called immune engineering in the context of H7N9 influenza vaccine development. The approach combines immunoinformatic and structure modeling methods to promote protective antibody responses against H7N9 hemagglutinin (HA) by engineering whole antigens to carry seasonal influenza HA memory CD4(+) T cell epitopes - without perturbing native antigen structure - by galvanizing HA-specific memory ...


Assembly Of Human C-Terminal Binding Protein (Ctbp) Into Tetramers, Andrew G. Bellesis, Anne M. Jecrois, Janelle A. Hayes, Celia A. Schiffer, William E. Royer Jun 2018

Assembly Of Human C-Terminal Binding Protein (Ctbp) Into Tetramers, Andrew G. Bellesis, Anne M. Jecrois, Janelle A. Hayes, Celia A. Schiffer, William E. Royer

Schiffer Lab Publications

C-terminal binding protein 1 (CtBP1) and CtBP2 are transcriptional coregulators that repress numerous cellular processes, such as apoptosis, by binding transcription factors and recruiting chromatin-remodeling enzymes to gene promoters. The NAD(H)-linked oligomerization of human CtBP is coupled to its co-transcriptional activity, which is implicated in cancer progression. However, the biologically relevant level of CtBP assembly has not been firmly established; nor has the stereochemical arrangement of the subunits above that of a dimer. Here, multi-angle light scattering (MALS) data established the NAD(+)- and NADH-dependent assembly of CtBP1 and CtBP2 into tetramers. An examination of subunit interactions within CtBP1 ...


Characterization Of Pharmaceutical Cocrystals And Salts By Dynamic Nuclear Polarization-Enhanced Solid-State Nmr Spectroscopy, Li Zhao, Michael P. Hanrahan, Genetech, Inc., Aaron J. Rossini Feb 2018

Characterization Of Pharmaceutical Cocrystals And Salts By Dynamic Nuclear Polarization-Enhanced Solid-State Nmr Spectroscopy, Li Zhao, Michael P. Hanrahan, Genetech, Inc., Aaron J. Rossini

Ames Laboratory Accepted Manuscripts

Multicomponent solids such as cocrystals have emerged as a way to control and engineer the stability, solubility, and manufacturability of solid active pharmaceutical ingredients (APIs). Cocrystals are typically formed by solution- or solid-phase reactions of APIs with suitable cocrystal coformers, which are often weak acids. One key structural question about a given multicomponent solid is whether it should be classified as a salt, where the basic API is protonated by the acid, or as a cocrystal, where the API and coformer remain neutral and engage in hydrogen bonding interactions. It has previously been demonstrated that solid-state NMR spectroscopy is a ...


The Forensic Characterization Of Bacterial And Fungal Organisms In Traditional Chinese Medicine, Julia Grzymkowski, Christopher J. Ehrhardt, Justin L. Poklis, Michelle R. Peace Jan 2018

The Forensic Characterization Of Bacterial And Fungal Organisms In Traditional Chinese Medicine, Julia Grzymkowski, Christopher J. Ehrhardt, Justin L. Poklis, Michelle R. Peace

Undergraduate Research Posters

There has been an increase in use of Traditional Chinese Medicine (TCM) in the United States because they are less expensive and believed to be more effective with less adverse effects in comparison to traditional pharmaceutics. Therefore, sales have increased in the US, despite articles and case studies demonstrating the dangers, such as injury and death, related to TCM, stemming from improper labelling, toxic contaminants, and, in some cases, the presence of pathogenic bacteria. The aim of this study was to perform a survival experiment to demonstrate the importance of proper herbal brewing technique and to conduct a molecular and ...


Structural Determination Of The Broadly Reactive Anti-Ighv1-69 Anti-Idiotypic Antibody G6 And Its Idiotope, Yuval Avnir, Kristina L. Prachanronarong, Shurong Hou, Brendan J. Hilbert, Markus-Frederik Bohn, Timothy F. Kowalik, Robert W. Finberg, Jennifer P. Wang, Nese Kurt Yilmaz, Celia A. Schiffer, Wayne A. Marasco Dec 2017

Structural Determination Of The Broadly Reactive Anti-Ighv1-69 Anti-Idiotypic Antibody G6 And Its Idiotope, Yuval Avnir, Kristina L. Prachanronarong, Shurong Hou, Brendan J. Hilbert, Markus-Frederik Bohn, Timothy F. Kowalik, Robert W. Finberg, Jennifer P. Wang, Nese Kurt Yilmaz, Celia A. Schiffer, Wayne A. Marasco

Schiffer Lab Publications

The heavy chain IGHV1-69 germline gene exhibits a high level of polymorphism and shows biased use in protective antibody (Ab) responses to infections and vaccines. It is also highly expressed in several B cell malignancies and autoimmune diseases. G6 is an anti-idiotypic monoclonal Ab that selectively binds to IGHV1-69 heavy chain germline gene 51p1 alleles that have been implicated in these Ab responses and disease processes. Here, we determine the co-crystal structure of humanized G6 (hG6.3) in complex with anti-influenza hemagglutinin stem-directed broadly neutralizing Ab D80. The core of the hG6.3 idiotope is a continuous string of CDR-H2 ...


Development Of Neurotensin-Based Radiopharmaceuticals For Neurotensin-Receptor-1-Positive Tumors Targeting, Yinnong Jia May 2017

Development Of Neurotensin-Based Radiopharmaceuticals For Neurotensin-Receptor-1-Positive Tumors Targeting, Yinnong Jia

Theses & Dissertations

The neurotensin receptor 1 (NTR1) is overexpressed in many cancers, due to its role as a growth pathway. These NTR1-positive cancers include pancreatic, colon, prostate and breast cancers. In the radiopharmaceutical field, the overexpression of NTR1 in cancer has prompted the development of NTR1-targeted diagnostics and therapeutics. The neurotensin (NT) peptide exhibits low nanomolar affinity for NTR1 and has been the paradigm for NTR1-targeted agents. Since the 1980’s, radiolabeled NT analogs have been developed and evaluated for targeting NTR1-positive cancers. Since native NT is rapidly degraded in vivo by a variety of peptidases, a tremendous amount of effort has ...


Structural Activity Relationship Study On Dual Plk1 /Brd4 Inhibitor, Bi- 2536, Hailemichael Yosief, Shuai Liu, Dennis L. Buckley, Justin M. Roberts, Alex M. Muthengi, Francesca M. Corsini, James E. Bradner, Wei Zhang May 2016

Structural Activity Relationship Study On Dual Plk1 /Brd4 Inhibitor, Bi- 2536, Hailemichael Yosief, Shuai Liu, Dennis L. Buckley, Justin M. Roberts, Alex M. Muthengi, Francesca M. Corsini, James E. Bradner, Wei Zhang

UMass Center for Clinical and Translational Science Research Retreat

Polo-like kinase 1 (PLK1) and BRD4 are two different therapeutic targets in cancer drug discovery. Recently it has been reported that PLK1 inhibitor, BI-2536, is also a potent inhibitor of BRD4. The simultaneous inhibition of PLK1 and BRD4 by a single drug molecule is interesting because this could lead to the development of effective therapeutic strategy for different types of disease conditions in which PLK1 and BRD4 are implicated. Structural activity relationship studies has been carried out on BI-2536 to generate analogs with enhanced dual inhibitory activity against BRD4 and PLK1 as well as to render the molecule selective to ...


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 ...


Structural Basis For Mutation-Induced Destabilization Of Profilin 1 In Als, Sivakumar Boopathy, Tania V. Silvas, Maeve Tischbein, Silvia Jansen, Shivender Shandilya, Jill A. Zitzewitz, John E. Landers, Bruce L. Goode, Celia A. Schiffer, Daryl A. Bosco Jun 2015

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

Schiffer Lab Publications

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 ...


Rediii: A Pipeline For Automated Structure Solution, Markus-Frederik Bohn, Celia A. Schiffer May 2015

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

Schiffer Lab Publications

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 ...


Development Of A Novel Screening Strategy Designed To Discover A New Class Of Hiv Drugs, Nancy Cheng, Sook-Kyung Lee, P. Donover, Mel Reichman, Celia Schiffer, Emily Hull-Ryde, Ronald Swanstrom, William Janzen Jan 2015

Development Of A Novel Screening Strategy Designed To Discover A New Class Of Hiv Drugs, Nancy Cheng, Sook-Kyung Lee, P. Donover, Mel Reichman, Celia Schiffer, Emily Hull-Ryde, Ronald Swanstrom, William Janzen

Celia A. Schiffer

Current antiretroviral treatments target multiple pathways important for human immunodeficiency virus (HIV) multiplication, including viral entry, synthesis and integration of the DNA provirus, and the processing of viral polyprotein precursors. However, HIV is becoming increasingly resistant to these "combination therapies." Recent findings show that inhibition of HIV Gag protein cleavage into its two structural proteins, matrix (MA) and capsid (CA), has a devastating effect on viral production, revealing a potential new target class for HIV treatment. Unlike the widely used HIV protease inhibitors, this new class of inhibitor would target the substrate, not the protease enzyme itself. This approach offers ...


Ligand-Receptor Interactions For Supramolecular Disassembly With Applications In Screening And Drug Delivery, Diego Amado Torres Jan 2014

Ligand-Receptor Interactions For Supramolecular Disassembly With Applications In Screening And Drug Delivery, Diego Amado Torres

Doctoral Dissertations

Proteins have the capacity to bind specific sets of compounds known as ligands, these are small molecules with a recurrent theme in their molecular design that is a characteristic exploited here to (i) identify particular affinities of small molecules for proteins with the aim of using them as ligands, inhibitors, or targeting moieties in more complex systems by means of a methodology that screens small molecules based on protein affinity; (ii) decorate a self-assembling supramolecular system at different positions, making it responsive to a complementary protein with the aim of exploring differences in disassembly and sensitivity of the release of ...


Promise Of Advances In Simulation Methods For Protein Crystallography: Implicit Solvent Models, Time-Averaging Refinement, And Quantum Mechanical Modeling, Celia Schiffer, Jan Hermans Nov 2011

Promise Of Advances In Simulation Methods For Protein Crystallography: Implicit Solvent Models, Time-Averaging Refinement, And Quantum Mechanical Modeling, Celia Schiffer, Jan Hermans

Celia A. Schiffer

No abstract provided.


Competition Between Ski And Creb-Binding Protein For Binding To Smad Proteins In Transforming Growth Factor-Beta Signaling, Weijun Chen, Suvana Lam, Hema Srinath, Celia Schiffer, William Royer, Kai Lin Nov 2011

Competition Between Ski And Creb-Binding Protein For Binding To Smad Proteins In Transforming Growth Factor-Beta Signaling, Weijun Chen, Suvana Lam, Hema Srinath, Celia Schiffer, William Royer, Kai Lin

Celia A. Schiffer

The family of Smad proteins mediates transforming growth factor-beta (TGF-beta) signaling in cell growth and differentiation. Smads repress or activate TGF-beta signaling by interacting with corepressors (e.g. Ski) or coactivators (e.g. CREB-binding protein (CBP)), respectively. Specifically, Ski has been shown to interfere with the interaction between Smad3 and CBP. However, it is unclear whether Ski competes with CBP for binding to Smads and whether they can interact with Smad3 at the same binding surface on Smad3. We investigated the interactions among purified constructs of Smad, Ski, and CBP in vitro by size-exclusion chromatography, isothermal titration calorimetry, and mutational ...


Mass Spectrometry Analysis Of Hiv-1 Vif Reveals An Increase In Ordered Structure Upon Oligomerization In Regions Necessary For Viral Infectivity, Jared Auclair, Karin Green, Shivender Shandilya, James Evans, Mohan Somasundaran, Celia Schiffer Nov 2011

Mass Spectrometry Analysis Of Hiv-1 Vif Reveals An Increase In Ordered Structure Upon Oligomerization In Regions Necessary For Viral Infectivity, Jared Auclair, Karin Green, Shivender Shandilya, James Evans, Mohan Somasundaran, Celia Schiffer

Celia A. Schiffer

HIV-1 Vif, an accessory protein in the viral genome, performs an important role in viral pathogenesis by facilitating the degradation of APOBEC3G, an endogenous cellular inhibitor of HIV-1 replication. In this study, intrinsically disordered regions are predicted in HIV-1 Vif using sequence-based algorithms. Intrinsic disorder may explain why traditional structure determination of HIV-1 Vif has been elusive, making structure-based drug design impossible. To characterize HIV-1 Vif's structural topology and to map the domains involved in oligomerization we used chemical cross-linking, proteolysis, and mass spectrometry. Cross-linking showed evidence of monomer, dimer, and trimer species via denaturing gel analysis and an ...


Viral Protease Inhibitors, Jeffrey Anderson, Celia Schiffer, Sook-Kyung Lee, Ronald Swanstrom Nov 2011

Viral Protease Inhibitors, Jeffrey Anderson, Celia Schiffer, Sook-Kyung Lee, Ronald Swanstrom

Celia A. Schiffer

This review provides an overview of the development of viral protease inhibitors as antiviral drugs. We concentrate on HIV-1 protease inhibitors, as these have made the most significant advances in the recent past. Thus, we discuss the biochemistry of HIV-1 protease, inhibitor development, clinical use of inhibitors, and evolution of resistance. Since many different viruses encode essential proteases, it is possible to envision the development of a potent protease inhibitor for other viruses if the processing site sequence and the catalytic mechanism are known. At this time, interest in developing inhibitors is limited to viruses that cause chronic disease, viruses ...


Mutation Patterns And Structural Correlates In Human Immunodeficiency Virus Type 1 Protease Following Different Protease Inhibitor Treatments, Thomas Wu, Celia Schiffer, Matthew Gonzales, Jonathan Taylor, Rami Kantor, Sunwen Chou, Dennis Israelski, Andrew Zolopa, W. Jeffrey Fessel, Robert Shafer Nov 2011

Mutation Patterns And Structural Correlates In Human Immunodeficiency Virus Type 1 Protease Following Different Protease Inhibitor Treatments, Thomas Wu, Celia Schiffer, Matthew Gonzales, Jonathan Taylor, Rami Kantor, Sunwen Chou, Dennis Israelski, Andrew Zolopa, W. Jeffrey Fessel, Robert Shafer

Celia A. Schiffer

Although many human immunodeficiency virus type 1 (HIV-1)-infected persons are treated with multiple protease inhibitors in combination or in succession, mutation patterns of protease isolates from these persons have not been characterized. We collected and analyzed 2,244 subtype B HIV-1 isolates from 1,919 persons with different protease inhibitor experiences: 1,004 isolates from untreated persons, 637 isolates from persons who received one protease inhibitor, and 603 isolates from persons receiving two or more protease inhibitors. The median number of protease mutations per isolate increased from 4 in untreated persons to 12 in persons who had received four ...


Curling Of Flap Tips In Hiv-1 Protease As A Mechanism For Substrate Entry And Tolerance Of Drug Resistance, Walter Scott, Celia Schiffer Nov 2011

Curling Of Flap Tips In Hiv-1 Protease As A Mechanism For Substrate Entry And Tolerance Of Drug Resistance, Walter Scott, Celia Schiffer

Celia A. Schiffer

BACKGROUND: The human immunodeficiency virus type 1 (HIV-1) protease is an essential viral protein that is a major drug target in the fight against Acquired Immune Deficiency Syndrome (AIDS). Access to the active site of this homodimeric enzyme is gained when two large flaps, one from each monomer, open. The flap movements are therefore central to the function of the enzyme, yet determining how these flaps move at an atomic level has not been experimentally possible.

RESULTS: In the present study, we observe the flaps of HIV-1 protease completely opening during a 10 ns solvated molecular dynamics simulation starting from ...


Exploring The Role Of The Solvent In The Denaturation Of A Protein: A Molecular Dynamics Study Of The Dna Binding Domain Of The 434 Repressor, Celia Schiffer, Volker Dötsch, Kurt Wuthrich, Wilfred Van Gunsteren Nov 2011

Exploring The Role Of The Solvent In The Denaturation Of A Protein: A Molecular Dynamics Study Of The Dna Binding Domain Of The 434 Repressor, Celia Schiffer, Volker Dötsch, Kurt Wuthrich, Wilfred Van Gunsteren

Celia A. Schiffer

Molecular dynamics simulations of the DNA binding domain of 434 repressor are presented which aim at unraveling the role of solvent in protein denaturation. Four altered solvent models, each mimicking various possible aspects of the addition of a denaturant to the aqueous solvent, were used in the simulations to analyze their effects on the stability of the protein. The solvent was altered by selectively changing the Coulombic interaction between water and protein atoms and between different water molecules. The use of a modified solvent model has the advantage of mimicking the presence of denaturant without having denaturant molecules present in ...


Resilience To Resistance Of Hiv-1 Protease Inhibitors: Profile Of Darunavir, Eric Lefebvre, Celia A. Schiffer Nov 2011

Resilience To Resistance Of Hiv-1 Protease Inhibitors: Profile Of Darunavir, Eric Lefebvre, Celia A. Schiffer

Celia A. Schiffer

The current effectiveness of HAART in the management of HIV infection is compromised by the emergence of extensively cross-resistant strains of HIV-1, requiring a significant need for new therapeutic agents. Due to its crucial role in viral maturation and therefore HIV-1 replication and infectivity, the HIV-1 protease continues to be a major development target for antiretroviral therapy. However, new protease inhibitors must have higher thresholds to the development of resistance and cross-resistance. Research has demonstrated that the binding characteristics between a protease inhibitor and the active site of the HIV-1 protease are key factors in the development of resistance. More ...