Calendar

Calendar

Seminar Series: Fall 2010

All seminars are Fridays, 3-4pm in Druckenmiller 20 with a student reception in Druckenmiller 26 prior to the seminar, unless otherwise noted.


Friday, October 1, 2010
Sarah Cosgrove Larsen '86, Professor of Chemistry, University of Iowa
A Chemist's View of Nanotechnology:  Small Science with a Big Impact
Although they did not know it at the time, medieval artisans who crafted stained glass windows using very small gold and silver nanoparticles were the first nanotechnologists.  A nanometer is a billionth of a meter.  Nanomaterials have at least one dimension of approximately 100 nm or less and this small size can lead to unusual size-dependent properties.  For example, the gold nanoparticles used in stain glass windows have a ruby red color despite conventional wisdom that tells us that bulk gold should have a yellow color.  Nanotechnology has come a long way since medieval times and has lead to many new applications for nanomaterials in areas such as medicine, energy, the environment, and electronics, to name a few.   Selected nanomaterials, their properties and applications will be highlighted in this talk.  Specifically, porous nanomaterials, such as zeolites, and their applications in catalysis, environmental protection, and nanomedicine will be discussed.

Friday, October 15, 2010
President's Science Symposium - Summer Research Poster Session
Details TBA.

Friday, October 29, 2010
Laura Wieland-Brown, NIH Postdoctoral Fellow, Clardy Labaratory, Harvard Medical School
Biosynthesis of the thaizolylpeptide antibiotics
The thiazolylpeptides are a family of >50 bactericidal antibiotics that block the initial steps of bacterial protein synthesis.  We recently reported a biosynthetic gene cluster for thiocillin and established that it, and by extension the whole class, is ribosomally synthesized. Remarkably, the C-terminal 14 residues of a 52-residue peptide precursor undergo 13 posttranslational modifications to give rise to thiocillin, making this antibiotic the most heavily posttranslationally-modified peptide known to date.  We have utilized the information that we gathered about the thiocillin biosynthetic gene cluster to search for new members of this class of antibiotics.

Friday, November 5, 2010 - CANCELLED
Douglas Theobald, Assistant Professor of Biochemistry, Brandeis University


Friday, November 12, 2010
Matt Hester, Associate Scientist, IDEXX Laboratories
Experiences in Analysis and Purification of Biologically Relevant Molecules in the Pharma and Biotech Industries
Chromatographic and spectroscopic methods are technologies which are routinely used in the pharmaceutical and biotechnology industries.  The proper use of these techniques often leads to better understanding of chemical and biochemical systems, thus facilitating decision making and overall productivity in research and development environments.  From a more practical point of view (practical as in finding a job!), building a skill set in the use of a variety of analytical instrumentation and techniques can lead to a rewarding career in different research settings.  This presentation will be a survey of some of the analysis and purification techniques I have used during my twelve year career in industry.  Some of the topics which will be discussed are chiral chromatography; high-throughput LC-MS analysis, HPLC analysis of proteins; and FT-IR analysis of protein coated surfaces. 

Friday, November 19, 2010
Lauren Webb '00, Assistant Professor of Chemistry, University of Texas at Austin
Vibrational Spectroscopy as a Probe of Electrostatic Fields in Biological Molecules
Here, we describe the development of vibrational spectroscopy as a probe of electrostatic driving forces in the formation of stable and functional protein-protein interfaces.  Biological function arises from complex interactions between cellular macromolecules, such as the organization of two or more proteins into a functioning assembly.  In the post-genomic era, enhanced understanding of the cooperativity between biological molecules is necessary to explore the complexity of living cells.  The affinity and specificity of macromolecular interactions are the result of both structural and electrostatic interactions, but while the field of structural biology has made great advances in this area, much less is understood about electrostatic influences.  We are approaching this problem using vibrational Stark effect (VSE) spectroscopy, in which spectral transitions of molecular probes that are placed strategically at a protein-protein interface can be related directly to the strength and direction of electrostatic fields in the immediate vicinity of the probe.  Here, we present a vibrational spectroscopic investigation of the electrostatic driving forces that regulate the formation of a stable interface between the oncoprotein Ras and a downstream effector RalGDS.  The experimental electrostatic map of this interface obtained through VSE spectroscopy is connected to kinetic and thermodynamic studies of Ras-effector binding, and to preliminary investigations of the interface formed by mutants of Ras that are known to lead to oncogenic function.

December 3, 2010
Laura MacManus-Spencer, Assistant Professor of Chemistry, Union College
The environmental impacts of sunblock products:  Environmental photochemistry of ultraviolet filter chemicals
In order to make decisions about the regulation and environmental remediation of pharmaceuticals and personal care products (PPCPs) it is important to understand their fate in the environment. One class of PPCPs of current environmental concern comprises ultraviolet (UV) filter chemicals, which are used in sunblock, lip balm, and other personal care products to protect the skin from harmful UV radiation. These chemicals enter the environment via direct (e.g., swimming) and indirect (e.g., showering and washing clothes) routes. In this study, we have investigated the environmental photochemistry of four UV filter chemicals, benzophenone-3 (oxybenzone), octyl methoxycinnamate (octinoxate), octyl dimethyl para-aminobenzoic acid (padimate-O), and homomenthyl salicylate (homosalate). Experiments were conducted under natural and simulated sunlight to determine quantum yields, environmental half-lives, and the relative importance of direct (degradation as a result of absorption of light) and indirect (degradation mediated by photo-generated excited species) photolysis for each chemical. Photolysis products have been identified where possible. Oxybenzone does not degrade by direct or indirect photolysis. Homosalate does not undergo direct photolysis but is susceptible to indirect photolysis. Octinoxate and padimate-O degrade readily by direct photolysis, and several degradation products have been identified for each chemical.