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Biochimica et Biophysics Ada, 934 (1988) 96-107 Fluorescence induction transients indicate dissociation of Photosystem I1

Summary: Biochimica et Biophysics Ada, 934 (1988) 96-107
BBA 42784
Fluorescence induction transients indicate dissociation of Photosystem I1
from the phycobilisomeduring the State-2 transition
in the cyanobacteriurn Synechococcus 6301
Conrad W. Mullineaux and John F. Alien
Departmentof Pure andApplied Biology, University of Leeds, Leeds (U.K.)
(Received 2 December 1987)
Key words: Photosynthesis; State transition; Chlorophyll fluorescenceinduction; Phycobihsome; Cyanobacterium;
Light harvesting; (Synechococcus sp.)
Cells of Synechococcus 6301 were adapted to State 1or to State 2. Fluorescence induction transients on a
millisecond time-scale were then recorded in the presence of DCMU, using excitation of different
wavelengths primarily in order to excite either the phycobilisome or the chlorophyll a antenna of
Photosystem I1 (PS 11). The transients recorded with the phycobilisome-absorbed light indicate a reduction
in PS I1 absorption cross-section during the transition to State 2. The transients recorded using chlorophyll
a-absorbed light indicate increased energy transfer away from PS I1 in State 2, possibly due to increased
spill-over of energy from PS I1 to PS I in State 2. We suggest that the basis of the State-2 transition in
phycobilisome-containingorganisms is a decreased excitation-energytransfer to PS I1 reaction centres that
results from detachment of PS I1 from the phycobilisome.


Source: Allen, John F. - School of Biological and Chemical Sciences, Queen Mary, University of London


Collections: Renewable Energy; Biology and Medicine