Seminar Series: Spring 2011

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

Friday, February 18, 2011

Cory Theberge, Assistant Professor, University of New EnglandCory Theberge,
Assistant Professor, University of New England
Novel CGRP Receptor Antagonists for the Treatment of the Migraine
Dr. Theberge's presentation will detail the chemical and pharmacological challenges encountered when developing calcitonin gene-related peptide (CGRP) receptor antagonists for the treatment of migraine headaches.  Dr. Theberge welcomes the discussion of medicinal chemistry subject material and can share his experienced perspective on chemistry careers in the modern pharmaceutical company environment.

Friday, April 8, 2011
Greg Weiss, Professor, UC IrvineGreg Weiss,
Professor, UC Irvine
In Vitro Molecular Evolution with Self-Made and Reactive Peptide Libraries Displayed on Bacteriophage
The Weiss laboratory leverages the power of diverse collections of molecules displayed on the surfaces of bacteria-specific viruses, termed bacteriophage, for biosensors, dissecting molecular recognition, and other applications.  Our laboratory has recently harnessed a new type of bacteriophage capable of synthesizing trillions of different protein variants.  Such diversity in an expedient and readily adapted format opens the door to a myriad of protein engineering applications, provided the significant caveats can be defined and managed.  Separately, the laboratory has sifted through phage-displayed libraries to identify peptides capable of reacting with the hydrazide functionality.  Unexpectedly, peptides selected from the library provide a nucleophile to react with the carbonyl of the hydrazide.  These studies establish a starting point for further studies aimed at controlling the biology and chemistry of proteins inside the cell.

April 15, 2011
Kristen Brownell Kristen Brownell '07,
Inaugural Fellow, Center for Molecular Analaysis and Design, Stanford University
Investigations of Ruthenium Transfer Hydrogenation Catalysts as Efficient and Reversible Electrooxidation Catalysts for Alcohols
The energy-efficient removal of high free energy electrons stored in chemical fuels is a key step in the electron economy.  The electron economy can be described as a complete cycle of the conversion of high free-energy electrons of fuels into work and the subsequent regeneration of the spent fuel when energy is available.  This project aims to develop ruthenium transfer hydrogenation catalysts as electrooxidation catalysts for alcohols, specifically methanol.  We will devise a means to remove 2 electrons and 2 protons from a ruthenium hydride such that one can electrochemically oxidize methanol to carbon dioxide at a low overpotential and catalyze the reverse of this reaction, the electroreduction of carbon dioxide to methanol.  Increased understanding of the fundamental electrochemical and chemical steps required for selective and efficient electrocatalysts on a molecular level should inform the design of improved scalable heterogeneous electrocatalysts.  The ultimate goal of this project is the development of a catalytic system that will enable the efficient reversible oxidation of a non-toxic hydrocarbon liquid fuel.

Friday, April 22, 2011
Mark Levandoski - Grinnell CollegeMark Levandoski, Associate Professor, Grinnell College
Rheostats and Switches:  Allosteric Modulation of Nicotinic Acetylocholine Receptors
We study the pharmacology of neuronal nicotinic acetylcholine receptors, an important class of ligand-gated ion channels that, among other things, mediate the effects of nicotine from tobacco.  We are interested in compounds that modulate the receptor activity:  rather than turning channels strictly on or off, these compounds ramp activity up or down.  We will discuss recent work aimed at understanding specificity and molecular motion underlying modulator activity in this system.

Friday, May 6, 2011
Patricia Maurice, Professor, University of Notre DamePatricia Maurice, Professor, University of Notre Dame
The Role of Siderophores in Fe Acquisition by Aerobic Bacteria:  Fe Oxide Nanoparticles and Natural Organic Matter
Fe is an essential nutrient for nearly all organisms. Yet, dissolved concentrations of Fe in aerobic, circum-neutral environments are typically ~10 orders of magnitude less than biological requirements.  In order to acquire Fe, aerobic bacteria often exude low molecular weight organic ligands known as siderophores, which have extremely high Fe(III) binding affinities.  Siderophores have been shown to play important roles in Fe mobilization from Fe-bearing minerals.
This research investigated Fe acquisition from hematite (α-Fe2O3), nanohematite, and natural organic matter (NOM) by a siderophore-producing Pseudomonas mendocina bacterium and an engineered “gene knock out” siderophore (-) mutant that was incapable of producing and releasing siderophore(s). Microbial growth (population size) under Fe-limited batch conditions was monitored via optical density. In addition, a biosensor assay used siderophore transcriptional output as a measure of cellular Fe status as an independent means of determining how readily Fe was obtained from the various potential sources.
Results of bioassay analysis showed that (1) siderophores work in conjunction with other organic ligands commonly found in soils; (2) in the absence of other organic ligands, siderophores are required for Fe acquisition from hematite particles > 10 nm in size but not for particles < 10 nm; and (3) NOM-bound Fe is highly bioavailable and siderophores are not needed for Fe acquisition from NOM. Preliminary results suggest that a cell-wall-associated reductive mechanism allows for Fe acquisition from nano-scale Fe sources but not from larger particles.  Overall, this research demonstrates that nanomaterials may interact with bacteria through unique pathways and have different bioavailability than other materials.