Events & Seminars > Upcoming Events & Seminars

Fluorescence Polarization and Fluctuation Analysis (FPFA): A method for simultaneously measuring fluorescence lifetime, time-resolved anisotropy, fluorophore concentration, molecular brightness, and lateral diffusion times

Both Förster resonance energy transfer (FRET) and fluorescence correlation spectroscopy (FCS) can be used to study protein interactions and protein-complex conformational changes in living cells. FRET can detect the proximity between two fluorophores on a 1-10 nm scale. It can be measured by monitoring a change in the fluorescence lifetime of a FRET donor for […]

Unpacking the Symmetric Stretch of CCl4: The Confluence of Undergraduate Research and Pedagogical Advancement in Physical Chemistry Lab

When developing a research program at a predominately undergraduate institution, one must carefully select projects that have potential to contribute to the body of scientific knowledge, yet can be performed by undergraduates. Our most recent work from the summer of 2014 was an investigation of the Raman spectrum of the symmetric stretching vibration (ν1) of […]

A hole on the membrane: using pore-forming proteins to attack and sense

Pore-forming toxins (PFTs) represent the largest family of bacterial protein toxins and constitute important bacterial virulence factors. Their cytolytic function operates by introducing a large, water-filled pore into target cell membranes. We recently found out that E. coli ClyA PFT assembles into an oligomeric structure in solution in the absence of either bilayer membranes or […]

Design of Molecular Electrocatalysts for the Production and Oxidation of Hydrogen: Shoving Protons Around With Proton Relays

Solar and wind are carbon-neutral, sustainable energy sources, but their intermittent nature requires reliable energy storage. Catalysts that efficiently interconvert between electrical energy and chemical bonds (fuels) are needed for sustainable, secure energy in the future.  Hydrogenase enzymes in nature based on iron and/or nickel catalyze the oxidation of H2 and the reverse, production of […]

Anticancer Discovery from Simple and Complex Compounds

 Natural products and their derivatives have long been used as medicinal agents, and they still make up a significant fraction of clinically approved drugs. Recently, the trend in drug discovery is toward compounds that are much simpler than natural products, typically synthetic compounds that have few sp3-hybridized carbons and few stereogenic centers.  While such compounds have value for certain […]

Effect of surfaces in modulating protein folding and aggregation mechanisms

Protein-surface interactions are ubiquitous in the crowded cytosol, where proteins encounter a variety of surfaces, ranging from membranes surfaces, to the surfaces presented by chaperone molecules. Protein-surface interactions are also at the heart of a number of emerging technologies, including protein micro-arrays, biosensors and biomaterials. The effect of surfaces on protein structure and stability can […]

The Role of Low-Energy (< 20 eV) Electrons in Astrochemistry

In the interstellar medium, UV photolysis of ice mantles surrounding dust grains is thought to be the mechanism that drives the formation of “complex” molecules. The source of this reaction-initiating UV light is assumed to be local because externally sourced UV radiation cannot penetrate the ice-containing dark, dense molecular clouds. Specifically, exceedingly penetrative high-energy cosmic […]

Microfluidics for Biology and Medicine

The Eddington lab develops simple microfabricated tools which yield unique advantages over current experimental methods. By simplifying device design it is far easier to integrate into other research labs, which is the true test of innovativeness. Specifically, we have projects investigating chemotropic signaling in yeast, developmental biology and stem cell differentiation, oxygen and wound healing, […]

Metal-mediated C-N bond coupling in the gas phase: Experiment and computational chemistry in concert

Thermal C−N coupling processes mediated by transition-metal complexes have been investigated in gas-phase experiments combined with computational methods, and mechanistic aspects and elementary steps of these ion/molecule reactions are described. Three mechanistic variants of C-N bond coupling reactions have been identified: i) M(CH3)+ ions of the zinc triad react with ammonia in an SN2 reaction […]

Chemistry with methane: A cold approach to a hot problem

Three seemingly simple transformations related to the chemistry of methane will be addressed from mechanistic and conceptual points of view, i.e.: 1) metal-mediated dehydrogenation to form metal carbene complexes, 2) the hydrogen-atom abstraction step in the oxidative dimerization of methane, and 3) the mechanisms of the CH4  CH3OH conversion. State-of-the-art gas-phase experiments, in conjunction […]

Contributions to Medicine from a hard core Nano-chemical Physicist leading a small, heterogeneous, army of fearless researchers with all kind of college degrees: Chemistry, Physics, Biology, Biotechnology, Material Science and MDs.

I will highlight three areas of Medicine that may benefit from our Nano approach to instrumentation. The first is our answer to the problem of counting tumor cells circulating in the peripheral blood (CTCs) rapidly and at low cost while the second is our solution to the problem of analysing the protein ciontents of a […]

Unexpected Strength of Protein Quinary Interactions

Protein quinary interactions organize the cellular interior and its metabolism. Although the interactions stabilizing secondary, tertiary and quaternary protein structure are well defined, details about the protein-matrix contacts that comprise quinary structure remain elusive. This gap exists because proteins function in the crowded cellular environment, but are traditionally studied in simple buffered solutions. We employ […]

Anion Photoelectron Spectroscopy: From radicals and transition states to the reaction co-ordinate

Anion photoelectron spectroscopy has proven to be a remarkably tool to obtain fundamental thermochemical information and structural information for stable and transient species. This approach has proven especially useful when coupled with high-level theoretical analyses. I review briefly the experimental methodology and discuss several examples that illustrate the possibilities. These include peroxyl radicals, dichlorocarbene, halomethyl […]

Polarizable Empirical Force Field for Macromolecules based on the Classical Drude Oscillator

Explicit treatment of electronic polarizability in empirical force fields offers the potential to significantly improve the accuracy of molecular simulations of macromolecules in condensed phases.  Towards achieving this we have developed a polarizable force field based on the classical Drude oscillator model.  An overview of the model and the parameter optimization approach will be presented.  […]

Molecular Astronomy: Cool stars, brown dwarfs and exoplanets

The spectral energy distributions of “cool” astronomical objects such as low mass stars, brown dwarfs and exoplanets are dominated by molecular absorption features. Of particular interest are methane, water, ammonia and metal hydrides at high temperatures. An overview of this area of molecular astronomy will be presented from a spectroscopic perspective. The talk will concentrate […]

Recycling CO2

Abstract Controlling the atmospheric CO2 concentration may ultimately require recycling CO2 into liquid fuels and commodity chemicals using renewable energy as the power source. Arguably the greatest challenge for this vision is to develop efficient catalysts that reduce CO2 and its derivatives to a fuel of choice. This talk will describe our development of “oxide-derived” […]

The Structure of Atmospheric Particles & Impacts on Atmospheric Chemistry and Climate

The interactions of aerosol particles with light and clouds are the leading uncertainties in our understanding of the climate system.  These interactions are determined in part by the structure of atmospheric particles.  In this talk, I will give an overview of research in my laboratory that focuses on characterizing the structure of particles and how […]

Advances in α Elimination: Catalytic Organoelement Synthesis

After observation of α-arsinidene elimination from triamidoamine-supported zirconium complexes and reports of α-stannylene and -stibinidene elimination from group 4 metallocenes by Tilley, an expansion of the elements that participate in this rare class of deinsertion reactions has been sought. Triamidoamine-supported zirconium complexes have been limited in effecting α elimination for lighter elements using, for example, silanes […]

The Nature of the Halogen Bond and Other Single-Hole Interactions

Abstract: The halogen bond is the best known incarnation of the set of so called sigma-hole interactions. The sensitivity of the size and strength of sigma holes (localized regions of positive potential) on terminal halides (X) bonded to sufficiently electron withdrawing groups has been investigated at the MP2(full) level of theory. We focus in particular […]

Water (liquid, ice, clusters): Structure, dynamics, hydrogen-bonding, and vibrational spectroscopy

Water is a remarkable substance, with its high boiling point and complex phase diagram.  Many of the usual properties of water are attributed to hydrogen bonding.   Vibrational spectroscopy of various kinds (IR, Raman, 2DIR, SFG, 2DSFG) is an excellent probe of hydrogen bonding as vibrational frequencies are exquisitely sensitive to local environments.   In […]

NMR of conditional peripheral membrane domains

Conditional membrane proteins associate with membranes in response to binding specific ligands. We report the application of NMR techniques to gain insight into the structure, dynamics, and protein-membrane interactions of two fundamentally different conditional membrane modules, C1 and C2 domains from Protein Kinase C. Using NMR relaxation dispersion techniques, paramagnetic relaxation enhancement experiments, and NMR-detected […]

Educating and empowering environmental justice communities to identify and address chemical exposure and human health impacts associated with industrial facility operations

Wilma Subra provides technical assistance to citizens, across the United States and some foreign countries concerned with their environment by combining technical research and evaluation.  This information is then presented to community members so that strategies may be developed to address their local struggles. Committed to protecting the environment and the health and safety of […]

Metalloporphyrins in Chemical and Biological Catalysis – From C-H Hydroxylation to Fluorination

In this lecture I will discuss recent developments from our lab in the areas of synthetic, biomimetic metalloporphyrin catalysts and those of novel, heme-thiolate APO biocatalysts with an active site similar to that of cytochrome P450. These extracellular enzymes are capable of catalyzing the monooxygenation of a variety of substrates using H2O2 as a terminal […]

Water Dynamics in Nanoconfined Systems

Molecular Recognition of DNA by Small Molecules: Fundamentals to Applications

Many human diseases are caused by dysregulated gene expression.  The oversupply or overactivity of one or more transcription factors may be required for the survival, growth, and metastatic behavior of human cancers.  Pyrrole-imidazole polyamides are small molecules programmed to read the DNA double helix by a set of simple chemical principles.  These oligomers achieve affinities […]

Caught in the act: Direct observation and quantitation of molecular transport across membranes

We introduce a new method for monitoring and quantitating the transport of materials across a model cell membrane.  As a proof of concept, we investigate how a small cell-penetrating peptide called Pep-1 is able to carry a large object, such as a protein, across a lipid bilayer.  To create a membrane, two sub-microliter, lipid-encased aqueous […]

Trianionic pincer ligands and their role in creating highly active transition metal catalysts.

To catalyze alkyne polymerization one approach is to create a coordinatively unsaturated metal complex using an OCO3- ligand. Our recent discovery of the highly active (8,000 kg/molCat/h) precatalyst [tBuOCO]W≡CtBu (1) supports this contention. However, the high activity is not derived from the presence of a trianionic pincer ligand, but rather the in situ formation of […]

Membrane proteins and their complexes – insights from mass spectrometry

What can we learn from the study of membrane protein complexes in the gas phase of the mass spectrometer? Aside from the compositional information that is available from obtaining the molecular mass, many additional properties can be deduced. These include polydispersity and heterogeneity, both of which are extremely challenging to capture for membrane protein complexes. […]

Immunity and fertility in Anopheles gambiae: new molecular targets for malaria control

Malaria is the world’s most devastating parasitic disease with close to 1 million deaths per annum, mostly children under the age of 5 in Sub-Saharan Africa. Malaria is transmitted by Anopheles mosquitoes and a single species complex, Anopheles gambiae, is the principal vector for malaria in this region. Historically and still today, vector control by […]

Exposing the Moving Parts of Proteins using NMR Spectroscopy

A common metaphor for protein molecules is that they are Nature’s nanomachines.  Importantly, many of these natural nanomachines have internal moving parts – they are dynamic. Hence, whether and how intrinsic protein mobility contributes to protein mechanism are persistent questions in biology.  Nuclear magnetic resonance (NMR) spectroscopy can characterize molecular dynamics site-specifically, and over a […]