| 1. |
- Böddi, Béla, et al.
(författare)
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Tissue specific protochlorophyll(ide) forms in dark-forced shoots of grapevine (Vitis vinifera L.)
- 2004
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Ingår i: Photosynthesis Research. - : Springer Science and Business Media LLC. - 0166-8595 .- 1573-5079. ; 82:2, s. 141-150
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Tidskriftsartikel (refereegranskat)abstract
- Cuttings of grapevine (Vitis vinifera L. cv. Chardonnay) were dark-forced at least three weeks. Pigment contents, 77 K fluorescence emission and excitation spectra of the leaves, petioles and stems and transmission electron micrographs of the etioplasts from leaves and the chlorenchyma tissues of the stems were analysed. The dark-grown leaves and stems contained 8 to 10 and 3 to 5 mug/g fresh weight protochlorophyllide and its esters, respectively. HPLC analysis showed that the molar ratio of the unesterified and esterified pigments was 7:3 in the shoot developed in darkness. The dark-forced leaves contained carotenoids identified as: neoxanthin, violaxanthin, antheraxanthin, lutein and beta-carotene. Detailed analyses of the fluorescence spectra proved that all tissues of the dark-forced shoots had protochlorophyllide or protochlorophyll forms with emission maxima at 628, 636, 644, 655 and 669 nm. The 628 and 636 nm emitting forms were present in all parts of the dark-forced shoot, but dominated in the stems, which may indicate an organ specificity of the etioplast development. Variations in the distribution of the pigment forms were even found in the different tissues of the stem. The subepidermal layers were more abundant in the 655 nm form than the parenchyma cells of the inner part of the cortex and the pith. In the latter cells, the plastid differentiation stopped in intermediary stages between proplastids and etioplasts. The plastids in the subepidermal layers had developed prolamellar body structures, which were similar to those of etiolated leaves. The results highlight the importance of organ- and tissue specificity of plastid differentiation for chlorophyll biosynthesis and greening of different plant organs.
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| 2. |
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| 3. |
- Igamberdiev, A U, et al.
(författare)
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Decarboxylation of glycine contributes to carbon isotope fractionation in photosynthetic organisms
- 2001
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Ingår i: Photosynthesis Research. - 0166-8595 .- 1573-5079. ; 67:3, s. 177-184
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Tidskriftsartikel (refereegranskat)abstract
- Carbon isotope effects were investigated for the reaction catalyzed by the glycine decarboxylase complex (GDC; EC 2.1.2.10). Mitochondria isolated from leaves of pea (Pisum sativum L.) and spinach (Spinacia oleracea L.) were incubated with glycine, and the CO2 evolved was analyzed for the carbon isotope ratio (delta C-13). Within the range of parameters tested (temperature, pH, combination of cofactors NAD(+), ADP, pyridoxal 5-phosphate), carbon isotope shifts of CO2 relative to the C-1-carboxyl carbon of glycine varied from +14 parts per thousand to -7 parts per thousand. The maximum effect of cofactors was observed for NAD(+), the removal of which resulted in a strong C-12 enrichment of the CO2 evolved. This indicates the possibility of isotope effects with both positive and negative signs in the GDC reaction. The measurement of delta C-13 in the leaves of the GDC-deficient barley ( Hordeum vulgare L.) mutant (LaPr 87/30) plants indicated that photorespiratory carbon isotope fractionation, opposite in sign when compared to the carbon isotope effect during CO2 photoassimilation, takes place in vivo. Thus the key reaction of photorespiration catalyzed by GDC, together with the key reaction of CO2 fixation catalyzed by ribulose-1,5-bisphosphate carboxylase, both contribute to carbon isotope fractionation in photosynthesis.
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| 4. |
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| 5. |
- Mamedov, Fikret, et al.
(författare)
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Influence of protein phosphorylation on the electron-transport properties of Photosystem II
- 2002
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Ingår i: Photosynthesis Research. - 0166-8595 .- 1573-5079. ; 74:1, s. 61-72
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Tidskriftsartikel (refereegranskat)abstract
- Many of the core proteins in Photosystem II (PS II) undergo reversible phosphorylation. It is known that protein phosphorylation controls the repair cycle of Photosystem II. However, it is not known how protein phosphorylation affects the partial electron transport reactions in PS II. Here we have applied variable fluorescence measurements and EPR spectroscopy to probe the status of the quinone acceptors, the Mn cluster and other electron transfer components in PS II with controlled levels of protein phosphorylation. Protein phosphorylation was induced in vivo by varying illumination regimes. The phosphorylation level of the D1 protein varied from 10 to 58% in PS II membranes isolated from pre-illuminated spinach leaves. The oxygen evolution and Q A- to Q B(Q B-) electron transfer measured by flash-induced fluorescence decay remained similar in all samples studied. Similar measurements in the presence of DCMU, which reports on the status of the donor side in PS II, also indicated that the integrity of the oxygen-evolving complex was preserved in PS II with different levels of D1 protein phosphorylation. With EPR spectroscopy we examined individual redox cofactors in PS II. Both the maximal amplitude of the charge separation reaction (measured as photo-accumulated pheophytin-) and the EPR signal from the Q A- Fe2+ complex were unaffected by the phosphorylation of the D1 protein, indicating that the acceptor side of PS II was not modified. Also the shape of the S2 state multiline signal was similar, suggesting that the structure of the Mn-cluster in Photosystem II did not change. However, the amplitude of the S2 multiline signal was reduced by 35% in PS II, where 58% of the D1 protein was phosphorylated, as compared to the S2 multiline in PS II, where only 10% of the D1 protein was phosphorylated. In addition, the fraction of low potential Cyt b559 was twice as high in phosphorylated PS II. Implications from these findings, were precise quantification of D1 protein phosphorylation is, for the first time, combined with high-resolution biophysical measurements, are discussed.
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| 6. |
- Schröder, Wolfgang, et al.
(författare)
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Update on chloroplast proteomics
- 2003
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Ingår i: Photosynthesis Research. - 0166-8595 .- 1573-5079. ; 78:3, s. 181-93
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Tidskriftsartikel (refereegranskat)abstract
- Currently, relatively few proteomics studies of chloroplast have been published, but the field has just started emerging and is likely to develop more rapidly in the future. While the complex membrane structure of the chloroplast makes it difficult to study its entire proteome by global approaches, proteomics has considerably increased our knowledge of the proteins of single compartments such as, for instance, the envelope and the thylakoid lumen. Proteomics has also succeeded in the subunit characterisation of select protein complexes such as the ribosomes and the cytochrome b 6f complex. In addition, proteomics was successfully applied to find new potential target pathways for thioredoxin-mediated signal transduction. In this review, we present an overview of the latest developments in the field of chloroplast proteomics and discuss their impact on photosynthesis research. In addition, we summarise the current state of research in proteomics of the photosynthetic cyanobactrium Synechocystis sp. PCC 6803.
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| 7. |
- Vink, M, et al.
(författare)
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Regulation of Photosystem II core protein phosphorylation at the substrate level : Light induces exposure of the CP43 chlorophyll a protein complex to thylakoid protein kinase(s)
- 2000
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Ingår i: Photosynthesis Research. - 0166-8595 .- 1573-5079. ; 64:2-3, s. 209-219
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Tidskriftsartikel (refereegranskat)abstract
- Light induces conformational changes in the CP43 chl-a-protein antenna complex in isolated PS II core-complexes exposing phosphorylation site(s) to PS II core-associated protein kinase(s), to added solubilized thylakoid protein kinase(s), as well as to tryptic cleavage. The substrate-activation effect is demonstrated by exposure of the PS II cores to light during the kinase assay as well as by preillumination of the PS II cores in which the endogenous kinase(s) has been inactivated by treatment with N-ethylmaleimid. In the latter case, phosphorylation was performed in darkness following addition of the solubilized protein kinase(s). The solubilized protein kinase(s) does not require light activation. The apparent molecular masses of the main protein kinase(s) associated with the PS II cores (about 31-35 kDa and 45 kDa) differ from that of the major protein kinase present in solubilized preparations obtained from spinach thylakoids (64 kDa). The light-induced exposure of CP43 increases with the light intensity in the range of 20-100 mu mol photons m(-2) s(-1) as demonstrated by preillumination of N-ethylmaleimid treated cores followed by addition of the solubilized protein kinase(s) and performing the phosphorylation assay in darkness.
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| 8. |
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| 9. |
- Yang, DH, et al.
(författare)
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The redox state of the plastoquinone pool controls the level of the light-harvesting chlorophyll a/b binding protein complex II (LHC II) during photoacclimation - Cytochrome b(6)f deficient Lemna perpusilla plants are locked in a state of high-light acclimation
- 2001
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Ingår i: Photosynthesis Research. - 0166-8595 .- 1573-5079. ; 68:2, s. 163-174
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Tidskriftsartikel (refereegranskat)abstract
- A cytochrome bf deficient mutant of Lemna perpusilla maintains a constant and lower level of the light-harvesting chl a/b-binding protein complex II (LHC II) as compared to the wild type plants at low-light intensities. Inhibition of the plastoquinone pool reduction increases the LHC II content of the mutant at both low- and high-light intensities but only at high-light intensity in the wild type plants Proteolytic activity against LHC II appears during high-light photoacclimation of wild type plants. However, the acclimative protease is present in the mutant at both light intensities. These and additional results suggest that the plastoquinone redox state serves as the major signal-transducing component in the photoacclimation process affecting both, synthesis and degradation of LHC II and appearance of acclimative LHC II proteolysis. The plastoquinol pool cannot be oxidized by linear electron flow in the mutant plants which are locked in a `high light acclimation state. The cytochrome bf complex may be involved indirectly in the regulation of photoacclimation via 1) regulation of the plastoquinone redox state; 2) regulation of the redox-controlled thylakoid protein kinase allowing exposure of the dephosphorylated LHC II to acclimative proteolysis
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| 10. |
- Albertsson, Per-Åke
(författare)
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The contribution of photosynthetic pigments to the development of biochemical separation methods: 1900-1980
- 2003
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Ingår i: Photosynthesis Research. - 0166-8595. ; 76:1-3, s. 217-225
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Forskningsöversikt (refereegranskat)abstract
- The role of photosynthetic pigments in the development of separation methods in biochemistry during the period 1900-1980 is described beginning with M. Tswett who introduced separation of chlorophylls and carotenoids on columns and coined the term chromatography in 1906. In Uppsala, T. Svedberg developed the ultracentrifuge in the 1920s. A. Tiselius improved electrophoresis in the 1930s and developed chromatography of proteins in the 1940s and 1950s. Others of `The Uppsala school in separation science' include J. Porath, P. Flodin and S. Hjertén who further developed various gel chromatographic methods. Hjertén introduced free zone electrophoresis in narrow tubes, a forerunner of capillary electrophoresis. Two proteins, phycoerythrin and phycocyanin, were used as test substances in all these methodological studies. Aqueous two-phase partitioning as a separation method was introduced in 1956 by the author. In this work, chloroplast particles were used, and the method was applied for the separation and purification of intact chloroplasts, inside-out thylakoid vesicles and plasma membranes. My research was carried out in cooperation with G. Blomquist, G. Johansson, C. Larsson, B. Andersson and H.-E. Akerlund during a 20-year period, 1960-1980.
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