[MOS] Dewey Holton, Washington University, Tuesday, 10/26/04

[Vinnie Russo]

Dear Colleagues,

The G.R. Harrison Spectroscopy Laboratory and the Department of Electrical 
Engineering and Computer Science would like to invite you to the next 
seminar in our series on Modern Optics and Spectroscopy.

Date & Time:            Tuesday, October 26, 12 noon - 1 PM
Location:               Grier Room (34-401)
Speaker:                Dewey Holten, Washington University
Title:                  Ultrafast electron transfer in photosynthetic 
reaction centers

Refreshments will be served following the talk.

Abstract
Dewey Holten, Washington University
Ultrafast electron transfer in photosynthetic reaction centers
The primary photochemical steps in the energy conversion process in 
photosynthesis occur in pigment-protein complexes called reaction centers 
(RCs).  In the bacterial RC, membrane-spanning multi-step charge separation 
process takes place within 1 ns of with a quantum yield of ~1, and utilizes 
only one of two parallel electron-transport chains (the A branch).  We have 
prepared and investigated a number of mutant RCs that afford electron 
transfer down the normally inactive cofactor chain (the B branch).  The 
penultimate charge-separated state formed via the B branch differs in 
charge-recombination pathway and rate compared to the same state formed via 
the standard route involving the A branch.  This "memory effect" is being 
studied to give insights into functionally significant gating events such 
as proton uptake or pigment-protein relaxations that accompany the overall 
charge-separation process.



Vinnie Russo * vrusso at mit.edu  *  Office Manager
MIT; G.R. Harrison  Spectroscopy Laboratory
77 Mass. Ave., 6-014  *  Cambridge, MA  02139
(v) 617-253-9774  *  (f) 617-253-4513 
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