Carotenoid pigments, function

Mathews-Roth M. M. and Krinsky N. I. (1970). Studies on the protective function of the carotenoid pigments of Sarcina lutea. Photochem Photobiol 11(6) 419 -28. 

To enable the utilization of the full spectral range for classification also in carotenoid-rich species, we propose a method for photodestruction of carotenoid pigments in pollen using 633 nm light. In initial experiments that were conducted at 633 nm excitation, we observed that the bands ascribed to carotenoid molecules were not stable but diminished steadily, even at relatively low excitation intensities of 10 mW. Figure 4.6 displays spectra of horse-chestnut pollen excited with 633 nm as a function of exposure time to the laser. The irreversible decrease of the intensities of the typical carotenoid bands suggests the photodestruction of these molecules (see arrows in Fig. 4.6) [72-74]. With excitation at 785 nm, the spectra of the pollen remained unal-... 

Carotenoids are found in all native photosynfhetic organisms. They serve a dual function, as both accessory antenna pigment and also are essential in photoprotection of photosynfhetic systems from the effects of excess light, especially in the presence of oxygen. Bilins are open-chain tetrapyrroles that are present in antenna complexes called phycobilisomes. These complexes are found in cyanobacteria and red algae. Structures of representative carotenoid pigments are shown in Figure 3. 

The molecules that are produced are called isoprenoids, or terpenes (Figure 12.3). Terpenes include the steroids chlorophyll and carotenoid pigments that function in photosynthesis, and the lipid soluble vitamins A, D, and K (Figure 12.1). 

Stanier RY (1960) Carotenoid pigments Problems of synthesis and function. The Harvey Lectures 54 219- 255 Strehler BL (1957) Some energy transduction problems in photosynthesis. In RudnickD (ed) Rhythmic and Synthetic Processes in Growth, pp 171-199. Princeton University Press, Princeton... 

Moore TA, Gust D and Moore AL (1990) The function of carotenoid pigments in photosynthesis and their possible involvement in the evolution of higher plants. In Krinsky NI, Mathews-Roth MM and Taylor RF, (eds) Carotenoids Chemistry and Biology, pp. 223-228. Plenum Press, New York... 

In addition, the accessory pigment function of carotenoid is depicted by the direct excitation of CAR by light and the transfer of this radiant energy to SENS [reprinted, with permission, from N. I. Krinsky in Carotenoids (0. Isler, Ed.), Birkhauser Verlag, Basel, 1971, p. 684]. 

For carotenoids to function properly they may exist as a protein-pigment complex imbedded within the hydrophobic matrix of cell membranes. The involvement of this complex is partly based on the difficulty in demonstrating carotenoid fluorescence ( ). One of the functions of carotenoids in photosynthesis is the transfer of energy to chlorophylls. Perhaps, DPE s directly or indirectly intercept the electron or energy transfers normally occurring between carotenoids and chlorophylls (, 40). 

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