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B800→B850 energy transfer mechanism in bacterial LH2 complexes investigated by B800 pigment exchange

Herek, J. L. LU ; Fraser, N. J. LU ; Pullerits, T. LU ; Martinsson, P. LU ; Polívka, T. LU ; Scheer, H. ; Cogdell, R. J. and Sundström, V. LU (2000) In Biophysical Journal 78(5). p.2590-2596
Abstract
Femtosecond transient absorption measurements were performed on native and a series of reconstituted LH2 complexes from Rhodopseudomonas acidophila
10050 at room temperature. The reconstituted complexes contain
chemically modified tetrapyrrole pigments in place of the native
bacteriochlorophyll a-B800 molecules. The spectral
characteristics of the modified pigments vary significantly, such that
within the B800 binding sites the B800 Qy absorption maximum can be shifted incrementally from 800 to 670 nm. As the spectral overlap between the B800 and B850 Qy
bands decreases, the rate of energy transfer (as determined by the
time-dependent bleaching of... (More)
Femtosecond transient absorption measurements were performed on native and a series of reconstituted LH2 complexes from Rhodopseudomonas acidophila
10050 at room temperature. The reconstituted complexes contain
chemically modified tetrapyrrole pigments in place of the native
bacteriochlorophyll a-B800 molecules. The spectral
characteristics of the modified pigments vary significantly, such that
within the B800 binding sites the B800 Qy absorption maximum can be shifted incrementally from 800 to 670 nm. As the spectral overlap between the B800 and B850 Qy
bands decreases, the rate of energy transfer (as determined by the
time-dependent bleaching of the B850 absorption band) also decreases;
the measured time constants range from 0.9 ps (bacteriochlorophyll a in the B800 sites, Qy absorption maximum at 800 nm) to 8.3 ps (chlorophyll a in the B800 sites, Qy absorption maximum at 670 nm).
This correlation between energy transfer rate and spectral blue-shift
of the B800 absorption band is in qualitative agreement with the trend
predicted from Förster spectral overlap calculations, although the
experimentally determined rates are ∼5 times faster than those predicted
by simulations. This discrepancy is attributed to an underestimation of
the electronic coupling between the B800 and B850 molecules. (Less)
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author
; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Biophysical Journal
volume
78
issue
5
pages
7 pages
publisher
Cell Press
external identifiers
  • pmid:10777755
  • scopus:0033624917
ISSN
0006-3495
DOI
10.1016/S0006-3495(00)76803-2
language
English
LU publication?
yes
id
863846d8-6e1e-4b34-ac83-bf130431013e
date added to LUP
2025-10-28 17:05:26
date last changed
2025-11-20 12:46:39
@article{863846d8-6e1e-4b34-ac83-bf130431013e,
  abstract     = {{Femtosecond transient absorption measurements were performed on native and a series of reconstituted LH2 complexes from <em>Rhodopseudomonas acidophila</em><br>
 10050 at room temperature. The reconstituted complexes contain <br>
chemically modified tetrapyrrole pigments in place of the native <br>
bacteriochlorophyll <em>a</em>-B800 molecules. The spectral <br>
characteristics of the modified pigments vary significantly, such that <br>
within the B800 binding sites the B800 <em>Q</em><sub>y</sub> absorption maximum can be shifted incrementally from 800 to 670 nm. As the spectral overlap between the B800 and B850 <em>Q</em><sub>y</sub><br>
 bands decreases, the rate of energy transfer (as determined by the <br>
time-dependent bleaching of the B850 absorption band) also decreases; <br>
the measured time constants range from 0.9 ps (bacteriochlorophyll <em>a</em> in the B800 sites, <em>Q</em><sub>y</sub> absorption maximum at 800 nm) to 8.3 ps (chlorophyll <em>a</em> in the B800 sites, <em>Q</em><sub>y</sub> absorption maximum at 670 nm).<br>
 This correlation between energy transfer rate and spectral blue-shift <br>
of the B800 absorption band is in qualitative agreement with the trend <br>
predicted from Förster spectral overlap calculations, although the <br>
experimentally determined rates are ∼5 times faster than those predicted<br>
 by simulations. This discrepancy is attributed to an underestimation of<br>
 the electronic coupling between the B800 and B850 molecules.}},
  author       = {{Herek, J. L. and Fraser, N. J. and Pullerits, T. and Martinsson, P. and Polívka, T. and Scheer, H. and Cogdell, R. J. and Sundström, V.}},
  issn         = {{0006-3495}},
  language     = {{eng}},
  number       = {{5}},
  pages        = {{2590--2596}},
  publisher    = {{Cell Press}},
  series       = {{Biophysical Journal}},
  title        = {{B800→B850 energy transfer mechanism in bacterial LH2 complexes investigated by B800 pigment exchange}},
  url          = {{http://dx.doi.org/10.1016/S0006-3495(00)76803-2}},
  doi          = {{10.1016/S0006-3495(00)76803-2}},
  volume       = {{78}},
  year         = {{2000}},
}