Xanthophylls characteristics

Resonance Raman spectra of all four LHCII xanthophylls reveal differences in the v, frequencies, which normally depends upon the conjugation number (Heyde et al 1971 Rimai et al 1973). In addition, the neoxanthin transition is further upshifted reflecting the m-conformation. The v, region of this xanthophyll possesses additional bands at 1120,1132, and 1203 cm-1 characteristic for the 9-cis configuration (Hu et al., 1997). The v3 band frequency also differs in these xanthophylls. Finally, v4 is small and featureless in all isolated pigments. 

Retinoid-A term undergoing nearly continual modification in order to accurately describe the characteristics of a large family derived from the carotenes and xanthophylls. The family exhibits specific properties required in vision, metabolism and reproduction. Many of these properties are dependent on the stereo-chemistry of the materials. Only some of the stereo-chemical features may be required in a given application. The definition of Spom, et. al. in 1994 is the most widely used. However, it does not stress the visual properties required to form a chromophore in vision. 

Paprika oleoresin (E 160(c)) is an orange-red oil-soluble extract from sweet red peppers Capsicum annum. The major coloring compounds are xanthophylls cap-santhin (Formula 9.8), capsorubin as their dilaurate esters, and P-carotene. The presence of characteristic flavoring and spicy pungency components limits application of this extract in foodstuffs. 

Distributions of carotenoids can be characteristic for various groups of photosynthetic organisms. Fucoxan-thin is characteristic of diatoms (BaciUariophyceae) and peridinin is found in many dinoflagellates (Dinophyceae Fig. 2.23). In contrast, diatoxanthin and diadinoxanthin occur in many phytoplanktonic classes due to their xanthophyll cycle role (Fig. 2.25).Although it is a less specific marker compound, (3-carotene is abundant in cyanobacteria. Photosynthetic bacteria produce acyclic and aromatic carotenoids (e.g. lycopene and okenone, respectively Fig. 2.23). Astaxanthin and its esters are major constituents of marine zooplankton (Fig. 2.23). 

Fraits with a total disappearance of chlorophylls, usually having a characteristic yellow colour due to unmasked carotenes and xanthophylls following the degreening process (i.e., banana, plantain). 

All lutl alleles are recessive mutations (Fig. 3 A) that accumulate an additional carotenoid with an HPLC retention time and UV/visible absorption spectrum characteristic of a monohydroxy / , e-carotenoid (an a-carotene derived xanthophyll). The identification of the accumulating compound as zeinoxanthin ()3,e-caroten-3-ol) was confirmed by mass spectrometry (Pogson et al., 1996). The only difference between lutein and zeinoxanthin is the presence of an hydroxyl group on carbon 3 of the -ring in lutein. The decrease in lutein and its partial replacement by its immediate precursor, zeinoxanthin, defines lutl as a mutation... 

Zeaxanthin, on the other hand, while chemically most similar to lutein, has an S, energy below chlorophyll and binding sites for this xanthophyll may be both weaker and more limited in the photosystems. These combined characteristics may explain why violaxanthin and antheraxanthin accumulate preferentially in the absence of lutein. 

Figures 2 and 3 show diurnal changes in xanthophyll cycle conversion and PS II characteristics for understory leaves experiencing intermittent sunflecks. Growing on the deeply shaded floor of a multilayered subtropical rainforest, leaves of the very shade-tolerant species Alocasia brisbanensis experienced only two sunflecks of low intensity during the whole day (Fig. 2). In contrast, the vine Stephania japonica which can be found in sites ranging from full sun to deep shade was characterized in an understory site where it experienced multiple, high-intensity sunflecks over the course of the day (Fig. 3). Despite these profound differences in sunfleck...

Maxwell C, Griffiths H and Young AJ (1994) Photosynthetic acclimation to light regime and water stress by the C -CAM epiphyte Guzmania monostachia gas-exchange characteristics, photochemical efficiency and the xanthophyll cycle. Frmct... 

The 3-hydroxy-K end group is characteristic of capsorubin (28), and other carotenoids isolated from paprika (Capsicum annuum). All syntheses are based on the Cio + C2o + Cio = C4o strategy, and use crocetindialdehyde (27) as central building block and the aldol condensation as the coupling reaction Scheme 6). The synthesis of optically active capsorubin (28), reported in 1973, was the first synthesis of an enantiomerically pure xanthophyll [11]. For the optically active form of the key building block, the frans-Cio-hydroxyketone 26, two approaches have been reported. In the first reaction sequence, (+)-camphor (143) was converted into camphoric acid (144) by treatment with nitric acid. Camphoric acid (144) was then esterified with dimethyl sulphate... 

In a second set of experiments, chlorophyll fluorescence characteristics were compared between lichen thalli with green or blue-green algal phycobionts. Green algae are known to possess the xanthophyll cycle, whereas blue-green algae lack the xanthophyll cycle, i.e. they lack the epoxide forms violaxanthin (di-epoxide) and antheraxanthin (mono-epoxide) which are the... 

Carotenoids are red and yellow fat-soluble pigments composed of a class of hydrocarbons (carotenes) and their oxygenated derivatives (oxycarotenoids or xanthophylls). The basic structure consists of eight isoprenoid units. A series of conjugated double bonds provides the characteristic chromophore. The basic structure can be modified by hydroxylation, hydrogenation, dehydrogenation, cyclization, or oxidation (Schwieter and Isler, 1967). Bacteria are capable of adding further isoprenoid units. 

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