Excitation-energy transport in the bacteriochlorophyll antenna systems of Rhodospirillum rubrum and Rhodobacter sphaeroides, studied by low-intensity picosecond absorption spectroscopy

Sundström, Villy; Grondelle, Rienk van; Bergström, Hans; Åkesson, Eva; Gillbro, Tomas

doi:10.1016/0005-2728(86)90080-0

Cited by 144 publications

(110 citation statements)

References 37 publications

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“…Later picosecond absorption [47,48, 501 and spectral hole-burning experiments [18-21, 541 gave a 2.2-2.5 ps energy transfer at liquid helium temperature, suggesting a B800 -B850 distance of about 1.7 nm [54], close to the value obtained from the structure. With increasing temperature the rate of transfer speeds up, to about 1 .I ps at 77 K [50] and to 0.6 -0.7 ps at room temperature [50, 51,521.…”

Section: Excitation Transfermentioning

confidence: 59%

Photosynthetic antennae. Photosynthetic light‐harvesting

Grondelle

Monshouwer

Valkūnas

1996

Ber Bunsenges Phys Chem

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The peripheral light-harvesting complex of the photosynthetic bacterium Rhodopseudomonas acidophila (LH2) and the major plant light-harvesting complex LHCII have a very similar function: to absorb solar photons and to transfer the electronic excitation to the pigments surrounding the reaction center, the so-called 'core'. Nevertheless, their structures exhibit a dramatically different arrangement of the pigments. In LH2 the bacteriochlorophyll molecules are arranged in a highly symmetric ring, while in LHCII the positioning of the chlorophylls is very irregular. In both complexes the average distance between the pigments is 1 nm or less and, as a consequence, the electronic interaction between the pigments is strong (> 100 cm-I). Therefore, the excitation transport in these photosynthetic light-harvesting systems can not be described by a simple Fdrster type transfer mechanism, but new or other transfer mechanisms may be operative, for instance a mechanism in which the excitation is to some extent delocalized. Crucial parameters are the strength of the electronic coupling, the amount of energetic disorder and/or heterogeneity and the nature and strength of the interactions of the pigments with the protein. Here we will discuss the current status of the field of photosynthetic energy transfer in particular for LH2. We will evaluate a few simple models that contain some of the essential ingredients to describe the process of energy transfer and finally we will discuss some of the perspectives in this scientific field.

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Section: Excitation Transfermentioning

confidence: 59%

Photosynthetic antennae. Photosynthetic light‐harvesting

Grondelle

Monshouwer

Valkūnas

1996

Ber Bunsenges Phys Chem

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“…2A, (48,49), this implies that the rate of excitation transfer between the two LH1 C rings is faster than (25 ps) Ϫ1 . It is also interesting to note that the curvature found for the ⌽(c) relationship in dimeric particles is too pronounced (29), the average turnover rate per electron is (800 s) Ϫ1 .)…”

Section: Excitonic Connectivity In Rc⅐lh1mentioning

confidence: 95%

Functional Consequences of the Organization of the Photosynthetic Apparatus in Rhodobacter sphaeroides

Comayras

Jungas

Lavergne

2005

Journal of Biological Chemistry

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The purpose of this study was to gain information on the functional consequences of the supramolecular organization of the photosynthetic apparatus in the bacterium Rhodobacter sphaeroides. Isolated complexes of the reaction center (RC) with its core antenna ring (light-harvesting complex 1 (LH1)) were studied in their dimeric (native) form or as monomers with respect to excitation transfer and distribution of the quinone pool. Similar issues were examined in chromatophore membranes. The relationship between the fluorescence yield and the amount of closed centers is indicative of a very efficient excitation transfer between the two monomers in isolated dimeric complexes. A similar dependence was observed in chromatophores, suggesting that excitation transfer in vivo from a closed RC⅐LH1 unit is also essentially directed to its partner in the dimer. The isolated complexes were found to retain 25-30% of the endogenous quinone acceptor pool, and the distribution of this pool among the complexes suggests a cooperative character for the association of quinones with the protein complexes. In chromatophores, the decrease in the amount of photoreducible quinones when inhibiting a fraction of the centers implies a confinement of the quinone pool over small domains, including one to six reaction centers. We suggest that the crowding of membrane proteins may not be the sole reason for quinone confinement and that a quinone-rich region is formed around the RC⅐LH1 complexes.

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“…This number is about an order of magnitude higher than the value obtained from our model. However, the pairwise energy transfer is about 1ps according to our calculation [9]. On the other hand, from the value of k obtained here, by fitting the 200ps decay as well as the τ F , we estimated the Föster radius to be 26.8Å.…”

Section: Spectrometry Comparisonmentioning

confidence: 46%

“…Therefore we have taken k and k ′ as parameters and fit the slow mode of fluorescence decay of excited population observed, i.e. 200ps [6,7,9]. Thus, the absolute value of the largest eigenvalue should be about 3/200ps = 1.5 × 10 10 s −1 .…”

Section: Spectrometry Comparisonmentioning

confidence: 99%