Theory of Multiple Exciton Effects in the Photosynthetic Antenna Complex LHC-II

Renger, Thomas; May, Volkhard

doi:10.1021/jp963372w

Cited by 49 publications

(38 citation statements)

References 19 publications

(51 reference statements)

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“…They reported for both carotenoid to chlorophyll and chlorophyll to chlorophyll similar transfer times and efficiencies to those of native LHC II complexes. Modeling of the energytransfer dynamics in LHC II has also been attempted in the past few years (Renger and May, 1997;Gradinaru et al 1998;Valkunas et al 1999;Iseri and Gu¨len 2001;Novoderezhkin et al 2003). An improvement in the description of the observed rate constants was achieved with a modified Redfield approach, including a strong electronphonon coupling.…”

Section: Introductionmentioning

confidence: 99%

A comparison of the three isoforms of the light-harvesting complex II using transient absorption and time-resolved fluorescence measurements

et al. 2006

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In this article we report the characterization of the energy transfer process in the reconstituted isoforms of the plant light-harvesting complex II. Homotrimers of recombinant Lhcb1 and Lhcb2 and monomers of Lhcb3 were compared to native trimeric complexes. We used low-intensity femtosecond transient absorption (TA) and time-resolved fluorescence measurements at 77 K and at room temperature, respectively, to excite the complexes selectively in the chlorophyll b absorption band at 650 nm with 80 fs pulses and on the high-energy side of the chlorophyll a absorption band at 662 nm with 180 fs pulses. The subsequent kinetics was probed at 30-35 different wavelengths in the region from 635 to 700 nm. The rate constants for energy transfer were very similar, indicating that structurally the three isoforms are highly homologous and that probably none of them play a more significant role in light-harvesting and energy transfer. No signature has been found in the transient absorption measurements at 77 K for Lhcb3 which might suggest that this protein acts as a relative energy sink of the excitations in heterotrimers of Lhcb1/Lhcb2/Lhcb3. Minor differences in the amplitudes of some of the rate constants and in the absorption and fluorescence properties of some pigments were observed, which are ascribed to slight variations in the environment surrounding some of the chromophores depending on the isoform. The decay of the fluorescence was also similar for the three isoforms and multi-exponential, characterized by two major components in the ns regime and a minor one in the ps regime. In agreement with previous transient absorption measurements on native LHC II complexes, Chl b fi Chl a energy transfer exhibited very fast channels but at the same time a slow component (ps). The Chls absorbing at around 660 nm exhibited both fast energy transfer which we ascribe to transfer from 'red' Chl b towards 'red' Chl a and slow transfer from 'blue' Chl a towards 'red' Chl a. The results are discussed in the context of the new available atomic models for LHC II.

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Section: Introductionmentioning

confidence: 99%

A comparison of the three isoforms of the light-harvesting complex II using transient absorption and time-resolved fluorescence measurements

et al. 2006

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“…17 In biological systems such as bacteria and higher plants, light energy is absorbed by special chlorophyll (or bacteriochlorophyll) pigments assembled in protein matrixes in so-called antenna complexes and is transferred via an exciton mechanism to the reaction centre. 18 Recently, considerable attention has been focused on creating artificial mimics of the light-harvesting complexes for nanoarchitectures in molecular-scale electronics, sensors and other optical electronic devices.…”

Section: Introductionmentioning

confidence: 99%

Raman excitation wavelength investigation of single red blood cells in vivo

Wood

McNaughton

2002

J Raman Spectroscopy

169

170

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Raman spectra are reported for oxygenated and deoxygenated haemoglobin contained within a single red blood cell in vivo using excitation wavelengths of 488, 514, 568 and 632.8 nm. The peak assigned in previous work to n 4 is observed at 1376 cm −1 in oxygenated cells and 1356 cm −1 in deoxygenated cells with the results from 488 nm excitation consistent with earlier Raman studies on isolated haem proteins. Exciting the cells with 514 nm radiation revealed two bands appearing in this region at 1372 and 1356 cm −1 in the oxygenated state, whereas in the deoxygenated state only one band at 1356 cm −1 is observed. At 632.8 nm excitation bands in the n 4 region appeared at 1367 and 1365 cm −1 in the oxygenated and deoxygenated states, respectively. Our results clearly show that the enhancement of bands in the vicinity of n 4 within single erythrocytes is influenced by the excitation wavelength. Furthermore, many other bands observed in oxygenated erythrocytes using 632.8 nm excitation were dramatically enhanced compared with the bands observed with other excitation wavelengths. Ruling out other explanations, it is hypothesized that the enhancement observed at 632.8 nm results from excitonic coupling between aligned porphyrins. The high concentration of haemoglobin in a single cell enables the porphyrins to be in close proximity to permit charge transfer between the haem moieties. The high signal-to-noise ratio and excellent reproducibility obtained using Raman water immersion microspectroscopy on single erythrocytes in vivo shows potential as a diagnostic tool for a variety of haemopathies. However, judicious choice of the excitation wavelength is a prerequisite especially if the technique is applied to diagnose oxidation status within erythrocytes.

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“…In such a system the relaxation dynamics can be described more accurately by using Redfield theory on the basis of electron-vibrational eigenstates [60][61][62].…”

Section: Mixing Of Excited and Charge-transfer Statesmentioning

confidence: 99%

Photosynthetic Energy Transfer and Charge Separation in Higher Plants

Krüger

Novoderezhkin

Romero

et al. 2014

The Biophysics of Photosynthesis

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In this chapter we introduce the physical models at the basis of photosynthetic light harvesting and energy conversion (charge separation). We discuss experiments that demonstrate the processes of light harvesting in the major plant light-harvesting complex (LHCII) and charge separation in the photosystem II reaction center (PSII RC) and how these processes can be modeled at a quantitative level. This is only possible by taking into account the exciton structure of the chromophores in the pigment-protein complexes, static (conformational) disorder, and coupling of electronic excitations and charge-transfer (CT) states to fast nuclear motions. We give examples of simultaneous fitting of linear and nonlinear (timedependent) spectral responses based on modified Redfield theory that resulted in a consistent physical picture of the energy-and electron-transfer reactions. This picture, which includes the time scales and pathways of energy and charge transfer, allows for a visualization of the excitation dynamics, thus leading to a deeper understanding of how photosynthetic pigment-proteins perform their function in the harvesting and efficient conversion of solar energy. We show that LHCII has the intrinsic capacity to switch between different light-harvesting and energydissipating (quenched) states. We introduce the conformational "switching" model

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Theory of Multiple Exciton Effects in the Photosynthetic Antenna Complex LHC-II

Cited by 49 publications

References 19 publications

A comparison of the three isoforms of the light-harvesting complex II using transient absorption and time-resolved fluorescence measurements

A comparison of the three isoforms of the light-harvesting complex II using transient absorption and time-resolved fluorescence measurements

Raman excitation wavelength investigation of single red blood cells in vivo

Photosynthetic Energy Transfer and Charge Separation in Higher Plants

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