Abstract
Peridinin-chlorophyll-protein (PCP) is a unique light-harvesting protein that uses carotenoids as its primary light-absorbers. This paper theoretically investigates excitation transfer between carotenoids and chlorophylls in PCP of the dinoflagellate Amphidinium carterae. Calculations based on a description of the electronic states of the participating chromophores and on the atomic level structure of PCP seek to identify the mechanism and pathways of singlet excitation flow. After light absorption the optically allowed states of peridinins share their electronic excitation in excitonic fashion, but are not coupled strongly to chlorophyll residues in PCP. Instead, a gateway to chlorophyll Q(y) excitations is furnished through a low-lying optically forbidden excited state, populated through internal conversion. Carbonyl group and non-hydrogen side groups of peridinin are instrumental in achieving the respective coupling to chlorophyll. Triplet excitation transfer to peridinins, mediated by electron exchange, is found to efficiently protect chlorophylls against photo-oxidation.
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Selected References
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- Hofmann E., Wrench P. M., Sharples F. P., Hiller R. G., Welte W., Diederichs K. Structural basis of light harvesting by carotenoids: peridinin-chlorophyll-protein from Amphidinium carterae. Science. 1996 Jun 21;272(5269):1788–1791. doi: 10.1126/science.272.5269.1788. [DOI] [PubMed] [Google Scholar]
- Hu X., Damjanović A., Ritz T., Schulten K. Architecture and mechanism of the light-harvesting apparatus of purple bacteria. Proc Natl Acad Sci U S A. 1998 May 26;95(11):5935–5941. doi: 10.1073/pnas.95.11.5935. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Humphrey W., Dalke A., Schulten K. VMD: visual molecular dynamics. J Mol Graph. 1996 Feb;14(1):33-8, 27-8. doi: 10.1016/0263-7855(96)00018-5. [DOI] [PubMed] [Google Scholar]
- Kleima F. J., Hofmann E., Gobets B., van Stokkum I. H., van Grondelle R., Diederichs K., van Amerongen H. Förster excitation energy transfer in peridinin-chlorophyll-a-protein. Biophys J. 2000 Jan;78(1):344–353. doi: 10.1016/S0006-3495(00)76597-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kleima F. J., Wendling M., Hofmann E., Peterman E. J., van Grondelle R., van Amerongen H. Peridinin chlorophyll a protein: relating structure and steady-state spectroscopy. Biochemistry. 2000 May 2;39(17):5184–5195. doi: 10.1021/bi992427s. [DOI] [PubMed] [Google Scholar]
- Kühlbrandt W., Wang D. N., Fujiyoshi Y. Atomic model of plant light-harvesting complex by electron crystallography. Nature. 1994 Feb 17;367(6464):614–621. doi: 10.1038/367614a0. [DOI] [PubMed] [Google Scholar]
- Norris B. J., Miller D. J. Nucleotide sequence of a cDNA clone encoding the precursor of the peridinin-chlorophyll a-binding protein from the dinoflagellate Symbiodinium sp. Plant Mol Biol. 1994 Feb;24(4):673–677. doi: 10.1007/BF00023563. [DOI] [PubMed] [Google Scholar]
- Song P. S., Koka P., Prézelin B. B., Haxo F. T. Molecular topology of the photosynthetic light-harvesting pigment complex, peridinin-chlorophyll a-protein, from marine dinoflagellates. Biochemistry. 1976 Oct 5;15(20):4422–4427. doi: 10.1021/bi00665a012. [DOI] [PubMed] [Google Scholar]