chemistry

Chemistry Department Seminar

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Dr. Tae-Hee Lee of Penn State University will be presenting a seminar titled Single Molecule Studies of Nucleosome Structure and Dynamics.

Abstract: The nucleosome is the fundamental packing unit of the eukaryotic genome. The structure and structural dynamics of the nucleosome are at the core of the mechanisms of gene regulation and maintenance. We studied the structure, structural dynamics, and assembly of nucleosome core particles and how these properties are altered by various epigenetic modifications based on single molecule fluorescence measurements. Our study revealed that these modifications induce changes in the nucleosome core particles that may directly or indirectly contribute to gene regulation activities. Our study demonstrates how single molecule methods can fill the niche not covered by the conventional structural biology tools.

Refreshments will be served at this event.

Faculty Host:  Dr. Chris Richards

Date: 
Friday, October 10, 2014 - 4:00pm to 5:00pm
Location: 
CP-114
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Chemistry Department Seminar

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Bidhya Maharjan of the University of Kentucky will be presenting a seminar titled Ferrocene-Fused Derivatives of Polyacenes, Tropones and Thiepin.

Faculty Advisor: Dr. John Selegue

Date: 
Friday, October 3, 2014 - 4:00pm to 5:00pm
Location: 
CP-114
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Chemistry Department Seminar

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Dr. Rajeev Misra of Arizona State University will be presenting a seminar titled In vivo Investigation of Bacterial Multidrug Efflux Pumps

Abstract: Multidrug resistance among human bacterial pathogens remains a grave social concern. A common cellular mechanism bacteria frequently employ is the efflux of antibiotics from the cell; resistance develops when the rate of drug efflux across the membrane exceeds that of drug influx. One of the most extensively studied multidrug efflux systems of the Resistance-Nodulation-Division (RND) family comprises of the AcrA, AcrB and TolC proteins of Escherichia coli. Fine structural analyses have provided deeper understanding of how drugs are captured and pushed through the AcrB pump protein. However, much remains to be learned as to how the tripartite pump assembles to extrude drugs from AcrB to outside the cell. I will discuss our efforts to gain a better understanding of the AcrAB-TolC pump assembly in vivo.

Due to their high clinical relevance, inhibitors have been sought to reduce or abolish the activity of multidrug resistant efflux pumps. Phenylalanine arginine β-naphthylamide (PAβN) was one of the first lead compounds that showed a potent inhibitory activity against a number of RND pumps, including AcrB. However, the conclusion that PAβN acts principally as an efflux pump inhibitor was questioned by several recent publications. We have attempted to resolve this controversy by employing strains constitutively expressing AcrAB or a homologous AcrEF efflux pumps. The employment of a modified real-time efflux assay allowed for the first time a clear distinction between the efflux pump-inhibiting activity of PAβN and membrane-permeabilizing action of polymyxin B nonapeptide (PMBN). It was determined that at low concentrations, PAβN acts mainly as an inhibitor of the AcrAB and AcrEF efflux pumps. However, at high concentrations, PAβN in the efflux-proficient background not only inhibited the efflux pump activity but also destabilized the membrane. The effects of PAβN on membrane integrity are compounded in cells unable to extrude PAβN.

Refreshments will be served at this event.

Faculty Host: Dr. Yinan Wei

 

Date: 
Friday, September 26, 2014 - 4:00pm to 5:00pm
Location: 
CP-220 (refreshments will be available in CP-114 at 3:30pm)
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Chemistry Department Seminar

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The seminar has moved to CP-220.  

Dr. Franz Geiger of Northwestern University will be presenting a seminar titled Direct Views of the Nano-Bio Interface.

Abstract:  The tendency of proteins, lipids, and other biological species to form coronas around nanoparticles has been put to great use for promoting or inhibiting cellular uptake of engineered nanomaterials. This situation raises the question whether lipid coronas can form spontaneously at the interfacial region between a nanomaterial and a biological membrane, i.e. the nano nano-bio interface, and thereby regulate cellular uptake. Here, we describe the interaction of a well-characterized set of ligand-coated nanoparticles with lipid bilayers of varying chemical composition, the gram-negative bacterium Shewanella oneidensis, and a multicellular organism, the water flea Daphnia magna. Using nanoparticle- and membrane-specific data from microscopy, spectroscopy, and mass measurements, we determine that particles coated with cationic polyelectrolytes disrupt largely zwitterionic bilayers under electrostatically attractive conditions while all other particle-ligand combinations surveyed leave the bilayers intact. Moreover, we report that bilayer disruption coincides with lipid corona formation around the particles and propose this mechanism as the molecular basis for a nanoparticle-specific effect that lowers the survival rate of D. magna when they are exposed to particles wrapped in cationic polyelectrolyte.  Finally, we demonstrate the key role of lipopolysaccharides in protecting S. oneidensis from nanoparticle uptake.

Refreshments will be served at this event.

Faculty Host: Dr. Marcelo Guzman

Date: 
Friday, September 19, 2014 - 4:00pm to 5:00pm
Location: 
CP-114 / CP-220
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Chemistry Department Seminar

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Location Update: The seminar will be held in CP-220, but refreshments will still be available before the event in CP-114.

Dr. Renã Robinson of the University of Pittsburgh will be presenting this week's seminar, titled Increasing Throughput in Proteomics to Study Aging and Alzheimer's Disease

Refreshments will be served at this event.

Faculty Host: Dr. D. Allan Butterfield

Date: 
Friday, September 12, 2014 - 4:00pm to 5:00pm
Location: 
CP-114/CP-220
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Naff Symposium 2014: Todd Yeates, "Giant Protein Cages and Assemblies in Nature and by Design"

40th Annual Naff Symposium chem.as.uky.edu/naff-symposium University of Kentucky College of Arts & Sciences

Dr. Todd Yeates, Department of Chemistry and Biochemistry at UCLA

Abstract: Nature has evolved myriad sophisticated structures based on the assembly of protein subunits. Many types of natural protein assemblies (such as virus capsids) have been studied extensively, while a number of equally sophisticated natural protein assemblies are only beginning to be appreciated. Among the latter group is a broad class of giant, capsid-like assemblies referred to as bacterial microcompartments. They serve as primitive metabolic organelles in many bacteria by encapsulating sequentially acting enzymes within a selectively permeable protein shell. Our laboratory has elucidated key mechanisms of these protein-based bacterial organelles through structural studies. On the engineering side, sophisticated natural protein assemblies like these have for many years represented an ultimate goal in protein design. By exploiting principles of symmetry that are shared by nearly all natural self-assembling structures, we have developed methods for engineering novel proteins that assemble to form a variety of complex, symmetric architectures. Recent successful designs include hollow protein cages composed of 12 or 24 identical subunits in cubic arrangements. Symmetric materials that extend by growth in two or three dimensions are also possible. Natural and engineered protein assemblies will be discussed, along with their future prospects for synthetic biology and biomedical applications.

Naff Symposium 2014: Donald E. Ingber, "From Cellular Mechanotransduction to Biologically Inspired Engineering"

 

 

40th Annual Naff Symposium chem.as.uky.edu/naff-symposium University of Kentucky College of Arts & Sciences

Dr. Donald E. Ingber Director, Wyss Institute for Biologically Inspired Engineering at Harvard University

Abstract: The newly emerging field of Biologically Inspired Engineering centers on understanding the fundamental principles that Nature uses to build and control living systems, and on applying this knowledge to engineer biologically inspired materials and devices for medicine, industry and the environment. A central challenge in this field is to understand of how living cells and tissues are constructed so that they exhibit their incredible organic properties, including their ability to change shape, move, grow, and self-heal. These are properties we strive to mimic, but we cannot yet build manmade devices that exhibit or selectively control these behaviors. To accomplish this, we must uncover the underlying design principles that govern how cells and tissues form and function as hierarchical assemblies of nanometer scale components. In this lecture, I will review work that has begun to reveal these design principles that guide self-assembly of living 3D structures with great robustness, mechanical strength and biochemical efficiency, even though they are composed of many thousands of flexible molecular scale components. Key to this process is that the molecular frameworks of our cells, tissues and organs are stabilized using a tension-dependent architectural system, known as ‘tensegrity’, and these tensed molecular scaffolds combine mechanical load-bearing functions with solid-phase biochemical processing activities. I will describe how this structural perspective has led to new insights into the molecular basis of cellular mechanotransduction – the process by which living cells sense mechanical forces and convert them into changes in intracellular biochemistry, gene expression and thereby influence cell fate decisions during tissue and organ development. In addition, I will present how these scientific advances have been facilitated by development of new micro- and nano-technologies, including engineering of novel human organ-on-a-chip microdevices that also have great potential value as replacements for animal testing in drug development and discovery research. Understanding of these design principles that govern biological organization, and how scientific discovery and technology development can be facilitated by equally melding fundamental science and applied engineering, are critical for anyone who wants to fully harness the power of biology.

 

 

Naff Symposium 2014: Hao Yan, "Designer Architectures for Programmable Self-Assembly"

40th Annual Naff Symposium chem.as.uky.edu/naff-symposium University of Kentucky College of Arts & Sciences

Dr. Hao Yan, Department of Chemistry and Biochemistry & The Biodesign Institute, Arizona State University

Abstract: The central task of nanotechnology is to control motions and organize matter with nanometer precision. To achieve this, scientists have investigated a large variety of materials including inorganic materials, organic molecules, and biological polymers as well as different methods that can be sorted into so-called “bottom-up” and “top-down” approaches. Among all of the remarkable achievements made, the success of DNA self-assembly in building programmable nanopatterns has attracted broad attention. In this talk I will present our efforts in using DNA as an information-coding polymer to program and construct DNA nano-architectures with complex geometrical features. Use of designer DNA architectures as molecular sensor, actuator and scaffolds will also be discussed.

Learning a Hard Science: The Chemistry Learning Center with Lisa Blue

Introductory Chemistry can be a challenge, but Lisa Blue, a professor within the Department of Chemistryeases students' transition to college chemistry with the Chemistry Learning Center. It will serve students of General and Organic Chemistry: answer their questions, provide tutoring, and help students become more confident in their understanding of chemistry.

Visit their website to find information about the General and Organic Chemistry Learning Centers. 

This podcast was produced by Casey Hibbard

Creative Commons License
http://www.as.uky.edu/podcasts/learning-hard-science-chemistry-learning-... by College of Arts and Sciences is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Based on a work at http://www.as.uky.edu/podcasts/learning-hard-science-chemistry-learning-center-lisa-blue.

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