Light-harvesting pigments

Carotenoids exhibit multiple physiological roles, i.e. as light-harvesting pigments in photosynthesis, as quenching solutes for the triplet state of chlorophyll a to... 

Pullerits T. and Sundstrom V. (1996) Photosynthetic Light-Harvesting Pigment-Protein Complexes Toward Understanding How and Why, Acc. Chem. Res. 29, 381-389. 

Chlorophyll a (Chi a) functions as the primary light harvesting pigment in marine oxygenic phototrophs. Even though the C Chl a ratio of photoautotrophic cells varies considerably as a function of environmental conditions and growth rate (Laws et al., 1983), measurements of Chi a have been used extensively to estimate the biomass of photoautotrophic microorganisms in the sea. 

Finally, carotenoids are the metabolic precursors for three more of the flavor volatiles of the tomato. Although the role of carotenoids, light-harvesting pigments in plants, in human nutrition is the subject of debate, these compounds are antioxidants and P-carotene is the principal source of the visual pigments of the eye. 

A. Imaging Aggregates of the Green Plant Light-Harvesting Pigment-... 

FIGURE 4.5 Aggregates of light-harvesting pigment-protein complex (LHCll) imaged with (a) MPF, (h) SHG, and (c) THG contrasts. The scale har is 3 pm. 

Cyanobacteria and red algae employ phycobilins such as phycoerythrobilin and phycocyanobilin (Fig. 19-40b) as their light-harvesting pigments. These open-chain tetrapyrroles have the extended polyene system found in chlorophylls, but not their cyclic structure or... 

Biological systems Ligand-myoglobin Protein dynamics Bacteriorhodopsin Light harvesting Pigment-protein complexes Photosynthetic reaction centers... 

The photosynthetic apparatus is found in and on membrane structures, which, in plant cells and algae, are located in chloroplasts and are called thylakoids. In bacteria the photosynthetic membrane is derived by complex invagination of the cytoplasmic membrane. The photosynthetic apparatus is made up of antennae, which contain light-harvesting pigment molecules (usually chlorophylls or bacteriochlorophylls) and photochemical reaction centres, which also contain pigments, together with the necessary enzymes and coenzymes. 

Figure 2.13 (a) Spatially-orientated antenna network of light-harvesting pigments. (Reproduced by... 

The unique water-soluble peridinin- Chi a-protein (PCP) complexes are found in many dynoflagellates in addition to intrinsic membrane complexes. [64] It contains Chi a and the unusual carotenoid peridinin in stoichiometric ratio of 1 4. Unlike other families of antennas, the main light-harvesting pigments are carotenoids, not chlorophylls. The structure of the PCP consists of a protein that folds into four domains, each of which embeds four peridinin molecules and a single Chi a. The protein then forms trimers, suggested to be located in the lumen [64] in contact with both LHCI and LHCII [66], allowing efficient EET to occur. 

Bacteriochlorophyll a is the dominant light-harvesting pigment in purple sulfur bacteria (e.g., Chromatiaceae) and where its synthesis is inhibited by the presence of O2. Similarly, bacteriochlorophyll e has been shown to be indicative of green sulfur bacteria (e.g., Chlorobium phaeovibroides and... 

Cogdell, R.J. and Thomber, J.P. 1979. The preparation and characterization of different types of light-harvesting pigment-protein complexes. In Chlorophyll organization and Energy Transfer in Photosynthesis . (CIBA Foundation Symposium 61, new series). (Excerpta Medica, Amsterdam), pp. 61-79. 

Pullerits T, Sundstrom V. Photosynthetic light-harvesting pigment-protein complexes toward understanding how and why. Acc Chem Res 1996 29 381-9. 

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