Showing papers on "Neoxanthin published in 1982"

Carotenoid Composition of Chlorophyll-Carotenoid-Proteins from Radish Chloroplasts

Abstract: The uneven distribution of carotenoids and chlorophylls between several chlorophyll- carotenoid-proteins isolated from radish chloroplasts by SDS-polyacrylamide-gel electrophoresis is described. Lutein and neoxanthin are enriched in the light-harvesting chlorophyll a/b-protein LHCP3, which exhibits low chlorophyll a/b ratios (1.1-1.3) and high values for the ratio chlorophyll a/β-carotene (a/c = 60-180). β-carotene is bound not only to the chlorophyll a-protein CPI + CPIa of photosystem I, but also to the chlorophyll a-protein CPa. Both chlorophyll a-proteins are characterized by high values for the ratio a/b and low values for the ratio a/c.

PIGMENT ORGANIZATION IN THE LIGHT‐HARVESTING CHLOROPHYLL‐a/b PROTEIN COMPLEX OF LETTUCE CHLOROPLASTS. EVIDENCE OBTAINED FROM PROTECTION OF THE CHLOROPHYLLS AGAINST PROTON ATTACK and FROM EXCITATION ENERGY TRANSFER

Abstract: — The light-harvesting Chl-a/b protein complex (LHC) of Lactuca sativa L. was examined for pigment content, excitation energy transfer and behavior under acidic conditions: (1) Lettuce LHC contains Chl-a, Chl-b and xanthophylls (lutein, neoxanthin, lactucaxanthin, viola-xanthin) at a molar ratio of 6:4:3; their contribution to the absorbance of the LHC between 390 and 530 nm is estimated to be about 31% (Chl-a), 26% (Chl-h) and 43% (xanthophylls). (2) Energy transfer from xanthophylls and Chl-fe to Chl-a takes place at 100% transfer efficiency. (3) LHC exhibits an unusual acid stability: in contrast to complexes of photosystem I or II, LHC-bound chlorophylls are not converted to phaeophytin and LHC apoprotein is not denatured at pH 1.5; also, energy transfer is maintained. (4) Pronase or trypsin treatment do not affect acid stability and energy transfer. (5) Treatments that break down acid stability (heat, urea or TritonX–100) also inhibit energy transfer. The coincidental breakdown of energy transfer and acid stability points at one underlying process, namely, the breakdown of a structure that enables protection of chlorophylls from proton attack and close contiguity of xanthophylls and chlorophylls as required for energy transfer. Dense packing of xanthophylls and chlorophylls within lipophilic crevices of the LHC is suggested.

The keto-carotenoids of two marine coccoid members of the Eustigmatophyceae

Abstract: In addition to previously reported major xanthophylls, Nannochloropsis (Nannochloris) oculata (Droop) Hibberd and Nannochloropsis (Monallantus) salina (Bourrelly) Hibberd were found to produce minor amounts of cryptoxanthin epoxides, zeaxanthin, antheraxanthin, neoxanthin, and eight to ten keto-carotenoids during photoautotrophic growth in culture. Five of the keto-carotenoids were identified as echinenone, canthaxanthin, astaxanthin and its monoester, and astacene. Culture ageing of both algal species from about 2 to 14 weeks caused a three- to fivefold increase in the proportions of both canthaxanthin and the astaxanthin family, and this increase was accompanied by a corresponding decrease in the combined zeaxanthin-antheraxanthin-violaxanthin group. However, the keto-carotenoids never achieved ageing-associated predominance in the total carotenoid mixture, where violaxanthin and vaucheriaxanthin ester persisted as the major xanthophylls. Astaxanthin and astacene have not been previously recorded from a...

Stereochemical aspects of carotenoid biosynthesis

Abstract: The stereochemistry of cyclisation or quasi-cyclisation in the C 50 -carotenoids is compared with that in the C 40 -carotenoids: the chiral and prochiral sites involved show mirror-image symmetry in the two series. The absolute configuration at C-2, in the cyclic and acyclic C 50 compounds, the inhibition of the enzymes by diphenylamine, and its antagonism by thiamin, suggest that the enzyme that forms the acyclic carotenoids may represent an ancestral form of the cyclase. The 4- pro - R hydrogen atom of mevalonate is retained in lycopene and at C-2, and C-6 of e and γ C 50 -carotenoids and at C-2 of β C 50 -carotenoids; both C-2 hydrogen atoms of mevalonate are retained at C-4 of the β and γ isomers. This excludes the possibility that β, γ and e-rings are inter-converted. The elaboration of C 40 -carotenoids by the marine dinoflagellate Amphidinium carterae has been followed by feeding [ 14 C]lycopene, [ 14 C] zeaxanthin and 14 C and 3 H labelled mevalonates. Zeaxanthin is converted into neoxanthin and then into diadinoxanthin or peridinin. The allene group retains a hydrogen atom at C-8 derived from C-2 of mevalonate. This shows that the allene is converted into an acetylene, rather than the reverse. The labelling pattern of peridinin shows that it is formed by the deletion of C-13, C-14 and C-20 (C-13Me) from neoxanthin. The absolute configuration at C-3′ of the e-ring of lutein was originally deduced to be the same as that at C-3 of the β-ring from the apparent retention of the 5- pro - S hydrogen atom of mevalonate. The 14 C: 3 H ratios of lutein formed from [2- 14 C,5 R -5- 3 H 1 ] and [2- 14 C,5 S -5– 3 H 1 ]mevalonate, and those of 3′-monooxolutein formed by oxidation, show that the 5- pro - R hydrogen atom is retained at C-3′. Other recent advances in carotenoid biosynthesis will be reviewed.

Carotenoids in ripe green and in autumn senescing leaves of apple tree: I - Qualitative composition of free carotenoids, xanthophyll esters and fatty acids of esters

Abstract: By different chemical, spectral and chromatographic procedures seven carotenoids, two carotenes (α- and β-carotene) and five free xanthophylls (violaxanthin, lutein, antheraxanthin, zeaxanthin and neoxanthin) have been isolated and identified in green apple leaves. In autumn senescing leaves, besides the above seven carotenoids, the occurrence of at least seven xanthophyll esters has also been proved. Four esters, violaxanthin mono- and diester and lutein mono- and diester, (≥90% of total esters) and a minor component, neoxanthin triester, have been identified. Another minor component is most probably a monoester of antheraxanthin; the seventh, present in traces, has not been identified. The fatty acids combined with the above xanthophyll esters have been analysed by gas-chromatography. The unusual presence of low molecular weight fatty acids, C7-C11, has been registered (1,5-8% of the total); caprilic and capric acids have been identified. Lauric acid with three minor homologous (2-7% and myrist...