Upcoming Events

Peter Woodruff, Chemistry Seminar: "Harnessing Enzymes to Synthesize Probes Against Pathogenic Mycobacteria"

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April 3, 2015 3:00 PM  – 4:00 PM
Druckenmiller Hall, Room 020

Mycobacteria, including the pathogenic Mycobacterium tuberculosis, require the sugar trehalose for construction of their cell wall. Trehalose analogs are emerging as valuable tools for inhibiting Mycobacterium tuberculosis, but progress in this area is slow due to the difficulty in synthesizing these compounds using traditional organic synthesis. 

In this chemistry seminar, Peter Woodruff discusses the invention of a chemoenzymatic method for the synthesis of trehalose analogs that employs the heat-stable enzyme trehalose synthase (TreT) from the hyperthermophile Thermoproteus tenax. He examines how, by using TreT, various trehalose analogues were prepared quickly (one hour) in high yield in a single step from readily available glucose analogues. In addition, he explains data that reveals how several of these analogs are incorporated into the mycobacterial cell wall used to detect the bacteria, laying the groundwork for imaging tuberculosis infections in live patients.

Woodruff is assistant professor of chemistry at the University of Southern Maine. 

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Joe Dinnocenzo "Revised View of Electron Transfer Dependence on Free Energy"

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April 17, 2015 12:00 PM  – 1:00 PM
Druckenmiller Hall, Room 020



In a landmark publication over 40 years ago, Rehm and Weller
used a comprehensive set of data to show that photoinduced
electron transfer (PET) rate constants correlate with excited state energies and ground state redox potentials. The Rehm Weller paper has been cited more than 3000 times and the data contained in it interpreted by a variety of theoretical models. In this talk I will show that the widely accepted Rehm-Weller equation and plot have serious flaws.
Revised measurements obtained in our lab differ significantly from those of Rehm and Weller and are interpreted in terms of a simple Boltzmann-type equation that takes into account not only Coulombic stabilization of contact ion radical pairs produced by PET, but also solvation and desolvation processes. In addition, we found that the mechanism for the PET reactions studied by Rehm and Weller does not involve simple, one?electron transfer, but instead occur by two partial electron transfers via exciplex intermediates. The general implications of our results and a variety of lessons learned will be discussed.


Joseph Dinnocenzo is a Professor of Chemistry at the University of Rochester.



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