Calendar

Calendar

Seminar Series: Spring 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, February 5, 2010
Ariele Hanek '03, Industrial Postdoc at New England Biolabs
Chemical-Scale Studies of Neuroreceptors via Unnatural Amino Acid Incorportation
Understanding the underlying function of Cys-loop neurotransmitter gated ion channels constitutes a significant challenge in chemical neurobiology. Utilizing nonsense suppression methodology we have evaluated structural interactions proposed to be functionally important in this important class of neuroreceptors.  The incorporation of unnatural amino acids allows us to precisely determine the nature of side chain/side chain and specific backbone interactions that cannot be studied by conventional mutagenesis.  The broad impact of this methodology will be discussed in the context of two studies (1) the geometrical and hydrophobic requirements of αVal46 of the nicotinic acetylcholine receptor and (2) photo-induced chemical proteolysis of the γ-aminobutryic type A receptor.

Friday, February 12, 2010
Kurt Deshayes, Senior Scientist, Genetech
Is Cell Suicide a Better Way to Treat Cancer?kurt deshayes photo
Abstract:  An important mechanism for maintaining health in metazoan is the removal of damaged or infected cells by the highly controlled process of programmed cell death, referred to as apoptosis.  One of the primary characteristics of cancer cells is their ability to avoid cellular suicide and continue to proliferate under extreme conditions.  The process of programmed cell death will be described along with the development of molecules that are useful for manipulating programmed cell death and probing the networks that control the lifecycle of the cell.

Friday, February 19, 2010
Elizabeth Jarvo, Assistant Professor of Chemistry, University of California, Irvineliz jarvo photo
Design and Development of Catalytic Reactions Involving Organometallic Nucleophiles

Our long-term goal is to develop a suite of catalyst-controlled allylation and alkylation reactions for a wide variety of electrophiles. The development of these transformations using mechanism-based design of new nucleophilic organometallic intermediates will be presented.  We have described a new class of nucleophilic allylpalladium complexes with bidentate neutral N-heterocyclic carbene (NHC) ligands.  We have used these catalysts to develop catalytic allylation reactions of imines and conjugate acceptors including N-acylpyrroles.  Related studies involving highly nucleophilic allyliridium(I) catalysts provide catalysts for ketone allylation.  An umpolung approach to amination reactions will also be presented.  We hypothesized that N-Cl bonds would undergo oxidative addition with nickel catalysts according to a single-electron transfer mechanism, providing access to nickel amido complexes, and that this elementary step would initiate cross-coupling with organometallic reagents. We have developed a nickel-catalyzed, NCS-mediated coupling of amines with organozinc reagents.

Application Deadline: March 2, 2010: Clare Boothe Luce Research Scholars

Bowdoin is soliciting applications for the first group of Clare Booth Luce Scholars. These scholars will be female students who are interested in mathematics, chemistry, physics or computer science who are interested in embarking on a multi-year research project with a faculty mentor (or a pair of faculty mentors).
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Friday, April 2, 2010
Sarah Delaney, Assistant Professor of Chemistry, Brown Universitysarah delaney photo
The Role of DNA Damange and Repair in Dynamic Mutations
The primary pathogenic element of several neurodegenerative disorders has been pinpointed as a dynamic DNA mutation.  Dynamic mutations are characterized by expansion of a triplet repeat sequence such as (CAG)n/(CTG)n.  As part of the expansion process the formation of non-B DNA conformations by the repeat sequence has previously been proposed.  Furthermore, the base excision repair enzyme 7,8-dihydro-8-oxoguanine glycosylase (OGG1) has recently been implicated in the repeat expansion [Kovtun, I. V., Liu, Y., Bjoras, M., Klugland, A., Wilson, S. H., and McMurray, C. T. (2007) Nature 447, 447-452].  We have found that the non-B conformation adopted by (CAG)10, a hairpin, is hyper-susceptible to DNA damage relative to (CAG)10/(CTG)10 duplex and, in particular, that a hot spot for DNA damage exists.  Specifically, we find that a single guanine in the loop of the hairpin is susceptible to modification by peroxynitrite.  Interestingly, we find that human OGG1 (hOGG1) is able to excise 7,8-dihydro-8-oxoguanine (8-oxoG) from the loop of a hairpin substrate, albeit with a marked decrease in efficiency relative to duplex substrates; the hOGG1 enzyme removes 8-oxoG from the loop of a hairpin with a rate that is ~700-fold slower than that observed for DNA duplex.  Thus, while damage is preferentially generated in the loop of the hairpin, DNA repair is less efficient.  These observed structure-dependent patterns of DNA damage and repair may contribute to the OGG1-dependent mechanism of dynamic mutation.

Friday, April 16, 2009 - CANCELLED
Drew Shindell, NASA Goddard Institute for Space Studies


Friday, April 30, 2010
Jesse Kroll, Assistant Professor, Department of Civil & Environmental Engineering, MITjesse kroll
Oxidative evolution of organic particulate matter in the atmosphere
Organic aerosol (OA) constitutes a large (often dominant) fraction of the total fine particulate matter in the lower atmosphere, and as such has important implications for visibility, human health, and the earth's climate.  However, state-of-the-art models do not predict OA loadings or properties with any accuracy, indicating large gaps in our understanding of the chemistry underlying OA formation and evolution.  Here we present experiments aimed at probing the multi-generational oxidative processing ("aging") of OA, reactions that are likely to be important in the atmosphere but that are rarely accessed in the laboratory or included in models.  Results are presented within the context of a new framework for describing the chemistry of atmospheric organic species, using average carbon oxidation state as a metric for describing the degree of photochemical aging.

USA Science & Engineering Festival

USA Science & Engineering FestivalBowdoin College is proud to be an Official Partner of the inaugural USA Science & Engineering Festival to be held in the greater Washington, D.C. area in October, 2010.