scholarly journals β-Carotene as a factor in the reconstitution of cyclic phospho rylation in damaged chloroplast membranes

2014 ◽  
Vol 49 (4) ◽  
pp. 435-443 ◽  
Author(s):  
Anna Tukendorf ◽  
Zbigniew Krupa ◽  
Tadeusz Baszyński
Keyword(s):  
Photosystem I ◽  
Chloroplast Membranes ◽  
Nonspecific Effect ◽  
Spinach Chloroplasts ◽  
Phenazine Methosulphate ◽  
Β Carotene

Phenazine methosulphate mediated cyclic phosphorylation suppressed by heptane extraction or galactolipase treatment of spinach chloroplasts is restored by β -carotene, in 100% and 50%, respectively. Xanthophylls are not able to reconstitute this reaction. β-Carotene replaces galactolipids in reactivation of galactolipase treated chloroplasts, indicating a nonspecific effect of lipids in photosystem I dependent reactions.

Structure of the plant photosystem I

2018 ◽  
Vol 46 (2) ◽  
pp. 285-294 ◽  
Author(s):  
Ido Caspy ◽  
Nathan Nelson
Keyword(s):  
Crystal Structure ◽  
Photosystem I ◽  
Excitation Energy Transfer ◽  
Transmembrane Helices ◽  
Iron Sulfur Clusters ◽  
Crystal Forms ◽  
Light Harvesting Complex ◽  
Monogalactosyl Diglyceride ◽  
Prosthetic Groups ◽  
Β Carotene

Plant photosystem I (PSI) is one of the most intricate membrane complexes in nature. It comprises two complexes, a reaction center and light-harvesting complex (LHC), which together form the PSI–LHC supercomplex. The crystal structure of plant PSI was solved with two distinct crystal forms. The first, crystallized at pH 6.5, exhibited P21 symmetry; the second, crystallized at pH 8.5, exhibited P212121 symmetry. The surfaces involved in binding plastocyanin and ferredoxin are identical in both forms. The crystal structure at 2.6 Å resolution revealed 16 subunits, 45 transmembrane helices, and 232 prosthetic groups, including 143 chlorophyll a, 13 chlorophyll b, 27 β-carotene, 7 lutein, 2 xanthophyll, 1 zeaxanthin, 20 monogalactosyl diglyceride, 7 phosphatidyl diglyceride, 5 digalactosyl diglyceride, 2 calcium ions, 2 phylloquinone, and 3 iron sulfur clusters. The model reveals detailed interactions, providing mechanisms for excitation energy transfer and its modulation in one of nature's most efficient photochemical machine.

On the question of the light-harvesting role of β-carotene in photosystem II and photosystem I core complexes

2014 ◽  
Vol 81 ◽  
pp. 121-127 ◽  
Author(s):  
Kostas Stamatakis ◽  
Merope Tsimilli-Michael ◽  
George C. Papageorgiou
Keyword(s):  
Photosystem Ii ◽  
Photosystem I ◽  
Light Harvesting ◽  
Β Carotene

Evidence for the Existence of Two β-Carotene Pools and Two Biosynthetic β-Carotene Pathways in the Chloroplast

1979 ◽  
Vol 34 (12) ◽  
pp. 1205-1208 ◽  
Author(s):  
K. H. Grumbach
Keyword(s):  
Photosystem I ◽  
The Other ◽  
Photo Oxidation ◽  
The One ◽  
Β Carotene

Abstract Two β-Carotene pools were obtained in the chloroplast. It is concluded that one pool is very small like α-carotene and responsible exclusively for the biosynthesis of β-ionone-xanthophylls. The other β-carotene pool is proposed to be the one, that is located close to photosystem I and is involved in photosynthesis as a light protecting agent for chlorophylls against photo-oxidation. Furthermore evidence is given that both β-carotene pools are synthesized by independent biosyn thetic pathways.

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