Carotenoids in light harvesting

Ruban, A.V., Pascal, A.A., Robert, B., and Horton, P. 2001. Configuration and dynamics of carotenoids in light-harvesting antennae of the thylakoid membrane. J. Biol. Chem. 276 24862-24870. 

On the other hand, carotenoids in light-harvesting complexes of photosynthetic bacteria assume an all-trans configuration, either twisted (as in Rs. rubrum, Chromatium vinosum, md Rp. palustris) or planar (as in Rb. sphaeroides and Rp. capsulata). Note that chain twisting is not ascribed to the type of carotenoid, but rather to some specific interaction between the carotenoid and the protein environment and apparently affects the efficiency of singlet energy transfer. 

III. Singlet-Singlet Energy Transfer Dynamics involving Carotenoids in Light-Harvesting... 

Iwata K, Hayashi H and Tasumi M (1985) Resonance Raman studies ofthe conformations of all-trans carotenoids in light-harvesting systems of photosynthetic bacteria. Biochim Biophys Acta 810 269-273... 

Naqvi KR, Mela TB, Raju BB, Jovrofi T, Simidjiev 1 and Garab G (1987) Quenching of chlorophyll a singlets and triplets by carotenoids in light-harvesting complex of Photosystem II Comparison of aggregates with trimers. Proc Natl Acad Sci USA 84 109-112... 

Although it is widely agreed that p-carotene is abundant in reacticxi center I- and II-ccmplexes whereas xanthpidiylls are the major carotenoids in light harvesting proteins (8), there are some reports about the presence of lutein in the pigment-proteins of the... 

Carotenoids are essential to plants for photosynthesis, acting in light harvesting and especially in protection against destructive photooxidation. Without carotenoids, photosynthesis in an oxygenic atmosphere would be impossible. Some animals use carotenoids for coloration, especially birds (yellow and red feathers), fish and a wide variety of invertebrate animals, where complexation with protein may modify then-colors to blue, green or purple. ... 

Eukaryotic plants and cyanobacteria. Photosynthetic dinoflagellates, which make up much of the marine plankton, use both carotenoids and chlorophyll in light-harvesting complexes. The carotenoid peridinin (Fig. 23-29), which absorbs blue-green in the 470- to 550-nm range, predominates. The LH complex of Amphidinium carterae consists of a 30.2-kDA protein that forms a cavity into which eight molecules of peridinin but only two of chlorophyll a (Chi a) and two molecules of a galactolipid are bound (Fig. 23-29).268... 

The allenic carotenoid fucoxanthin (Fig. 22-5), which is absent in higher plants, predominates in brown algae, where it occurs in light-harvesting complexes along with Chi a and Chi c.306 307... 

Carotenoids 120 Most in light-harvesting antennae of Photosystem II... 

Singlet-Singlet Energy-Transfer Dynamics in Light-Harvesting Carotenoids.240... 

In this chapter we shall summarize the structure of the LH2 (B800-850) antenna complex from the purple non-sulfur photosynthetic bacterium Rhodopseudomonas acidophila strain 10050, placing special emphasis on the carotenoids. We will then review what is currently known about the details of the carotenoid s light-harvesting role in this system. 

Fig. I. Structures of some carotenoids known to play a major role in light-harvesting in eukaryotic algae a) peridinin b) fuco-xanthin c) siphonaxanthin d) prasinoxanthin.

Fig. (7). Examples of carotenoids present in light harvesting complexes of phototropic bacteria and dinoflagellates.

Carotenoids are constituents of the photosynthetic reaction centers and the lightharvesting complexes of the antennae [13], playing their role as redox intermediates in electron transfer processes of photosystem II [14] and as accessory pigments in light harvesting [5, 15]. 

Another example is the femtosecond-transient absorption and fluorescence after two-photon excitation of carotenoids. The excited /3-carotene decays with a time constant of 9 0.2 ps. The energy transfer process from the excited Si state in light-harvesting proteins can be monitored by the observed chlorophyl fluorescence [1537]. 

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