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NSF PR 95-52 - August 17, 1995
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Primary Events in Photosynthesis Revealed
Photosynthesis is the process by which the energy
of sunlight is used by plants and bacteria to produce
substances necessary to sustain life. The earliest
events in this process in bacteria occur in less than
a billionth of a second in pigmentprotein complexes
called reaction centers (RCs). Two National Science
Foundation (NSF)supported researchers at Washington
University in St. Louis, Dewey Holten and Christine
Kirmaier, have made a breakthrough in understanding
these events at the molecular level.
"An understanding of the molecular mechanism of photosynthesis
may enable scientists to mimic these processes in
synthetic non-biological systems to transform light
energy into chemical energy," says Stewart Hendrickson,
program director of the molecular biophysics program
at NSF, which supported the research.
In response to sunlight, electrons are transferred
across the RC and thus across a membrane. This process
occurs by way of only one of two pathways with very
high efficiency. Although there is a similar arrangement
of pigments in both pathways, it has been puzzling
why one pathway is active while the other is inactive.
Holten and Kirmaier have genetically engineered an
RC in which only two amino acids of the protein subunits
have been changed. These changes have resulted in
new properties of the RC. The results of their work
are published in this week's issue of the journal
Science.
The results shed light on the molecular mechanisms
by which the initial events of photosynthesis occur.
They represent an important breakthrough that will
stimulate further experimental and theoretical studies.
"Our recent findings should have a major impact on
photosynthesis research, and should be of general
interest in the important area of electron transfer
processes," says Holten.
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