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Physical Sciences and Mathematics Commons™

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Chemistry

Western Washington University

2019

Articles 1 - 13 of 13

Full-Text Articles in Physical Sciences and Mathematics

Polycarbodiimides And Polyguanidines : Their Reactivity And Applications In Covalent Adaptable Networks, Alberto Melchor Bañales May 2019

Polycarbodiimides And Polyguanidines : Their Reactivity And Applications In Covalent Adaptable Networks, Alberto Melchor Bañales

Scholars Week

We have recently discovered a new chemical transformation in which N,N’,N’’ tri-substituted guanidines undergo a thermal exchange reaction. Kinetic investigations indicate that the transformation is first order with respect to the guanidine, indicating a dissociative mechanism in which a carbodiimide and amine are formed as intermediates. This new reaction has been applied to polymer systems. Polycarbodiimides were shown to undergo postpolymerization modification with amines to form polyguanidines at room temperature under an hour. Polyguanidines undergo the newly found chemical transformation to form different substituted polyguanidines. This exchange reaction will be applied to the preparation of a covalent adaptable network by …

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Engineering Sortase; Activity And Selectivity Of New Hybrid And Ancestral Variants Of Sortase A, Sarah Struyvenberg May 2019

Engineering Sortase; Activity And Selectivity Of New Hybrid And Ancestral Variants Of Sortase A, Sarah Struyvenberg

Scholars Week

Bacterial sortase enzymes are a beneficial tool in innovative mechanisms of protein engineering. However, important limitations to utilization of sortases for engineered purposes exist; namely, that sortase A (SrtA) is a relatively poor enzyme and very specific for the substrate containing LPATXG motif. Exciting previous work from our collaborators reveals that sortases from different species recognize different sequences and that activity can vary. Therefore, we wanted to create and investigate hybrid sortase enzymes between SrtA from S. aureus and Streptococcus pneumoniae, wherein we swapped a substrate-interacting loop between the beta-E and beta-F strands. Our hypothesis is that these residues are …

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Bottom-Up Shape Engineering Of Organic Molecular Single-Crystals, Griffin Reed May 2019

Bottom-Up Shape Engineering Of Organic Molecular Single-Crystals, Griffin Reed

Scholars Week

The ability to fabricate complex submicron-scale components from inorganic crystalline semiconductor materials such as c-Si enables countless modern technologies, from microelectromechanical systems to integrated circuits. For single-crystal molecular materials on the other hand, comparable approaches to defining micron- and submicron-scale structure are much less well developed, in part because weak intermolecular binding forces make molecular crystals vulnerable to damage by conventional techniques such as reactive ion etching, wet etching, and energetic beam milling. Here we show how the same weak forces that are problematic for top-down patterning of molecular crystals can be exploited to enable controlled bottom-up growth, by leveraging …

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Equity In Stem: Utilizing Student Experience To Better Inform Policy And Practice, Natasha Hessami Apr 2019

Equity In Stem: Utilizing Student Experience To Better Inform Policy And Practice, Natasha Hessami

WWU Honors College Senior Projects

As women and people of color continue to pursue higher education and other advanced degrees, the STEM field consistently lags behind in diverse representation and leadership. There is a critical need to address the structural barriers marginalized groups face to accessing and succeeding in STEM and invest both time and money into innovative student-centered solutions. This project outlines the development of the CSE Student Ambassador program and implementation recommendations, the development and presentation of seminars focused on equity in the Biology and Chemistry departments, and general recommendations for faculty to make classroom and lab spaces more inclusive.

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The Atomic And Electronic Structure And Tunability Of Ruddlesden-Popper Phases For Photovoltaic Applications, Britt A. Tyler Jan 2019

The Atomic And Electronic Structure And Tunability Of Ruddlesden-Popper Phases For Photovoltaic Applications, Britt A. Tyler

WWU Graduate School Collection

There is an increasing need for alternative energy sources that reduce the global reliance on fossil fuels. Since their demonstration in 2009, perovskite solar cells (based on compounds with the formula ABX3, such as CH3NH3PbI3) have become an extremely promising and active research area. Still, there are obstacles to the widespread use of these technologies, including their instability and the environmental impacts of lead. It is therefore important to find ways to modify and tune the structure and properties of perovskites to optimize their stability and photovoltaic performance. This research explores a …

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Surface Modified Gold Nanorods Based Mercury Sensor, Tianqi Luan Jan 2019

Surface Modified Gold Nanorods Based Mercury Sensor, Tianqi Luan

WWU Graduate School Collection

The high toxicity of mercury in the form of inorganic vapor and organic compounds has become a major concern leading scientists to investigate more accurate and effective methods for the quantification of residue mercury in drinking water, aquaculture products and industrial wastes. In this research, we designed a mercury sensor based on the amalgamation between mercury and gold nanorods (AuNRs) which relate the longitudinal surface plasmon resonance (LSPR) peak shift induced by aspect ratio (AR) change after amalgamation. However, most of AuNRs synthesized based on seed mediated methods use either citrate or hexadecyl trimethyl ammonium bromide (CTAB) as surface stabilizing …

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Synthesis Of A Stimulus Responsive Phosphine Ligand And Metal Binding Studies, Gabriel Bourne Jan 2019

Synthesis Of A Stimulus Responsive Phosphine Ligand And Metal Binding Studies, Gabriel Bourne

WWU Graduate School Collection

Cations have been shown to modify a variety of properties of transition metals, including bite angle, isomerization, substrate control, and catalytic activation. Herein describes the synthesis of a novel stimulus responsive phosphine ligand. Ligand binding studies by NMR salt titration show a preference in the order of Na+ > Li+ > K+. Platinum dimethyl and dichloride complexes with the phosphine ligand were also synthesized. Isomerization of the platinum chloride complex between cis and trans is reported.

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Multifunctional Microgels For Nanoparticle-Based Detection Methodologies, Alyson Silva Jan 2019

Multifunctional Microgels For Nanoparticle-Based Detection Methodologies, Alyson Silva

WWU Graduate School Collection

In this study, pH-responsive microgel particles, comprised of 2-vinyl pyridine (P2VP) and styrene (PS), are explored as scaffolds to assemble metallic nanoparticles (NPs) for ultrasensitive detection strategies. Microgel particles serve as size-tunable scaffolds to assemble metal (silver or gold) NPs for surface-enhanced Raman scattering (SERS) vibrational spectroscopy. The high sensitivity of SERS arises from the enormous enhancement of the Raman scattering cross sections of molecules adsorbed to roughened metal surfaces, such as metal NPs. Using a sterically stabilized latex of random copolymers of PS and P2VP (PSxP2VPy), this polymer is capable of transitioning to a microgel state through acid-base titration. …

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Synthesis Of An Archazolid Based Enzyme Inhibitor, Cooper A. Vincent Jan 2019

Synthesis Of An Archazolid Based Enzyme Inhibitor, Cooper A. Vincent

WWU Graduate School Collection

The archazolids are a family of natural products that display powerful growth inhibitory activity against a number of human cancer cell lines. This activity has been linked to inhibition of the vacuolar-type ATPase (V-ATPase) and more recently cyclooxygenase (COX) enzymes. Using the archazolid structure as a starting point, several simplified analogues have been prepared and assayed for their V-ATPase and COX inhibitory activity. These simplified analogues were prepared using a novel Suzuki coupling with yields over 80%. They were assayed to investigate both their V-ATPase and COX inhibitory activity. In our assays there was no COX inhibition, while there was …

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Structural Studies Of Complexes Of Blood Coagulation Factor Viii, Joseph S. Gish Jan 2019

Structural Studies Of Complexes Of Blood Coagulation Factor Viii, Joseph S. Gish

WWU Graduate School Collection

Factor VIII (FVIII) is a 2332 amino acid glycoprotein with domain organization of A1-A2-B-A3-C1-C2 which is a crucial component of the blood coagulation cascade. After secretion, FVIII circulates in the bloodstream at a concentration of one nanomolar bound to von Willebrand Factor (vWF) which protects FVIII from clearance. In the event of an injury to the bloodstream, FVIII is proteolytically cleaved, releases from vWF and binds to both activated platelet surfaces and activated Factor IX with nanomolar affinity. These interactions increase the rate of blood clot formation 100,000 fold. Hemophilia A is an x-linked recessive disease affecting 1 in 5000 …

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Structural Studies On The Mechanism Of Argyrin B And The L12 – L11 Ribosomal Protein Interface, Christopher Swanson Jan 2019

Structural Studies On The Mechanism Of Argyrin B And The L12 – L11 Ribosomal Protein Interface, Christopher Swanson

WWU Graduate School Collection

The mechanism of action of argyrin B and the molecular interactions of L11 and L12 has been undetermined and underrepresented in the research of bacterial translation. This work seeks to examine the mechanism of action of argyrin B by performing in vitro structural studies of its interaction with its specific target protein elongation factor-G. We demonstrate that argyrin B inhibits translation, and allows GTPase activity to proceed, contrary to assumptions made in prior research. We determine that ribosome recycling is the likely step through which argyrin B acts as an antibiotic, since translocation is unaffected by argyrin B and association …

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Progress Towards The Substrate-Bound Structure Of Streptococcus Pneumoniae Sortase A, Nicholas M. Horvath Jan 2019

Progress Towards The Substrate-Bound Structure Of Streptococcus Pneumoniae Sortase A, Nicholas M. Horvath

WWU Graduate School Collection

Sortases are cysteine transpeptidases found primarily on the cell surface of Gram-positive bacteria. Sortase-mediated ligations have become an attractive option for protein modification chemistry, enabling the synthesis of a wide range of non-natural polypeptide derivatives. Attempts at understanding how these enzymes recognize and bind substrates are integral to furthering their usefulness in protein engineering and, potentially, treatment of bacterial diseases. However, the variable substrate specificity and activity between homologs of these enzymes is not yet fully understood. Of specific interest to us is sortase A from Streptococcus pneumoniae (SrtApneu), as it demonstrates a broad substrate tolerance not …

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Isopeptide Ligations Catalyzed By Streptococcus Suis Sortase A, Sarah Bowersox Jan 2019

Isopeptide Ligations Catalyzed By Streptococcus Suis Sortase A, Sarah Bowersox

WWU Graduate School Collection

Chemically modified proteins are critical components of modern therapeutics and basic research. To generate non-natural protein derivatives, bacterial sortase enzymes have been effective due to their ability to catalyze selective ligations between protein targets and functional groups that are uncommon in nature. Thus far, the enzymatic approach using sortase has been limited to modifications at the termini of peptide chains. Here we describe efforts to develop a sortase-mediated strategy for the formation of isopeptide bonds at the side chains of internal lysine residues. To this end, we have identified a sortase A homolog from Streptococcus suis (SrtAsuis) that …

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