chemistry seminar

Departmental Seminar

Date: 
Friday, December 7, 2018 - 12:00pm to 12:50pm
Location: 
CP-114
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Departmental Seminar

Date: 
Friday, November 30, 2018 - 12:00pm to 12:50pm
Location: 
CP-114
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Departmental Seminar

Date: 
Friday, November 16, 2018 - 12:00pm to 12:50pm
Location: 
CP-114
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Departmental Seminar

Date: 
Friday, November 9, 2018 - 12:00pm to 12:50pm
Location: 
CP-114
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Departmental Seminar

Date: 
Friday, November 2, 2018 - 12:00pm to 12:50pm
Location: 
CP-114
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Departmental Seminar

Date: 
Friday, October 26, 2018 - 12:00pm to 12:50pm
Location: 
CP-114
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Driving forces of greasy protein association in greasy membranes

ABSTRACT: What are the thermodynamic driving forces that influence the free energy of membrane protein folding and association in lipid bilayers? For soluble proteins, the burial of hydrophobic groups away from aqueous interfaces is a major driving force, but membrane-embedded proteins cannot experience hydrophobic forces, as the lipid bilayer lacks water. A fundamental conundrum thus arises: how does a greasy protein surface find its greasy protein partner in the greasy lipid bilayer to fold faithfully into its native structure? Recently, a structurally stable and functional monomeric form of the normally homodimeric Cl-/H+ antiporter CLC-ec1 was designed by introducing tryptophan mutations at the dimer interface. We have used this to develop a new model system for studying reversible dimerization in membranes for free energy measurements, which encompasses the thermodynamic properties of protein interactions in the membrane environment. To quantify monomer vs. dimer populations across a wide range of protein densities, we developed a method that quantifies the capture of subunits into liposomes from large equilibrium membranes single-molecule photobleaching by total internal reflection microscopy.  With this, we are able to determine that CLC-ec1 has a free energy of dimerization of -11 kcal/mole in 2:1 POPE/POPG membranes.  We are now investigating why this complex is so stable, dissecting the changes in enthalpy and entropy while varying protein interactions or the composition of the lipid solvent.  The results from this study will provide a physical foundation for the development of informed strategies aimed at correcting protein mis-folding or regulating protein interactions in membranes in physiologically and pathological situations.

Date: 
Friday, October 19, 2018 - 12:00pm to 12:50pm
Location: 
CP-114
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Dawson Lecture

Date: 
Friday, October 12, 2018 - 12:00pm to 12:50pm
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Electrospray Ionization Photoelectron Spectroscopy: From Multiply-Charged Anions, Transition State Spectroscopy, to Aerosol Related Clusters

Abstract:

Size-selective cryogenic photoelectron spectroscopy (cryoPES) coupled with electrospray ionization source (ESI) has been demonstrated to be a powerful experimental technique to investigate electronic structures and energetics of a wide variety of solution phase species and chemistry in the gas phase. In this talk, I will present the latest results probing various novel molecular clusters ranged from closo-dodecaborate dianions [B12X12]2- to atmospherically relevant species by employing this technique. Transition state dynamics of unimolecular isomerization and chemical reactions via photodetachment of corresponding precursor anions will be reported as well. Future directions of ESI-cryoPES, leading to high resolution photoelectron imaging spectroscopy and time-resolved pump-probe experiments will also be briefly discussed.

Date: 
Friday, October 5, 2018 - 12:00pm to 12:50pm
Location: 
CP-114
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Magnetic Particle Imaging: Tracer Development and Emerging Applications

Abstract:

Magnetic particle imaging (MPI) is an emerging imaging modality that enables the direct mapping of iron oxide nanoparticle tracers.  In MPI, the development of tailored magnetic nanoparticle tracers is paramount to achieving high sensitivity and good spatial resolution. This talk will provide a general overview of the progress in MPI tracer development over the past decade, and will also focus on emerging directions and new opportunities for iron oxide-based tracer design and applications. The presentation will cover magnetic nanoparticle relaxation in MPI and discuss key aspects to consider in tailoring tracers for MPI applications. Emphasis will be given on how structural changes (size, composition, shape, surface chemistry) and inter-particle interactions affect the MPI signal generation process. Moreover, the presentation will discuss emerging research directions in color-MPI (cMPI) and MPI-guided hyperthermia (hMPI).

Date: 
Friday, September 21, 2018 - 12:00pm to 12:50pm
Location: 
CP-114
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