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Issue 49, 2014
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Terahertz absorption of illuminated photosynthetic reaction center solution: a signature of photoactivation?

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Abstract

Photosynthetic reaction centers develop a stable charge separated state upon illumination. To investigate the molecular vibrations associated with the illuminated state of a reaction center we recorded terahertz absorption spectra of the photosynthetic reaction center from Rhodobacter sphaeroides in the dark and upon illumination and observed a small, but significant THz absorption increase in the 20 to 130 cm−1 spectral region. Reaction centers show very similar terahertz absorption increase when solubilized in detergents and in a lipidic sponge phase indicating that the nature of the bulk solvent has limited influence on the vibrational spectrum. The absorption change of the isolated LM subunit is very similar to that of the intact reaction center. Through temperature control experiments we show that 89% of the absorption change is likely attributed to the non-thermal activation of the protein molecules. These results indicate that picosecond molecular vibrations change primarily in the cofactors and/or in the evolutionary conserved core of the reaction center upon illumination, whereas the nuclear motions of the H-subunit and the bulk solvent have limited impact on the terahertz spectral changes.

Graphical abstract: Terahertz absorption of illuminated photosynthetic reaction center solution: a signature of photoactivation?

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Publication details

The article was received on 25 Apr 2014, accepted on 27 May 2014 and first published on 29 May 2014


Article type: Paper
DOI: 10.1039/C4RA03787A
RSC Adv., 2014,4, 25502-25509

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    Terahertz absorption of illuminated photosynthetic reaction center solution: a signature of photoactivation?

    I. Lundholm, W. Y. Wahlgren, F. Piccirilli, P. Di Pietro, A. Duelli, O. Berntsson, S. Lupi, A. Perucchi and G. Katona, RSC Adv., 2014, 4, 25502
    DOI: 10.1039/C4RA03787A

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