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2. Excitation energy transfer in cyanobacteria Synechocystis embedded in polymer film and partially bleached by polarized irradiation
- Creator:
- Goc, J., Klecha, K., Waszkowiak, A., Miyake, J., and Frąckowiak, D.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- absorption spectra, fluorescence spectra, photoacoustic spectra, phycobilisomes, and polarized radiation spectroscopy
- Language:
- Multiple languages
- Description:
- The polarized absorption, photoacoustic, fluorescence emission, and fluorescence excitation spectra of whole cells of cyanobacteria Synechocystis sp. embedded in a polymer film were measured. The bacteria cells, as it follows from anisotropy of absorption and fluorescence spectra, were even in a non-stretched polyvinyl alcohol film oriented to a certain extent. The measurements were done for such film in order to avoid the deformation of cyanobacteria shapes. Part of the samples was bleached by irradiation with strong polarized radiation with electric vector parallel to the orientation axis of cells. The anisotropy of photoacoustic spectra was higher than that of absorption spectra and it was stronger changed by the irradiation. Polarized fluorescence was excited in four wavelength regions characterised by different contribution to absorption from various bacteria pigments. The shapes of emission spectra were different depending on wavelength of excitation, polarization of radiation, and previous irradiation of the sample. The fluorescence spectra were analysed on Gaussian components belonging to various forms of pigments from photosystems (PS) 1 and 2. The results inform about excitation energy transfer between pools of pigments, differently oriented in the cells. Energy of photons absorbed by phycobilisomes was transferred predominantly to the chlorophyll of PS2, whereas photons absorbed by carotenoids to chlorophylls of PS1. and J. Goc ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3. Interactions of chlorophyll and polypeptide mixture with bacterial reaction centres
- Creator:
- Enomoto, H., Takeda, S., Nakamura, C., Miyake , J., Ptak, A., Dudkowiak, A., and Frąckowiak, D.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- absorption spectra, fluorescence spectra, photoacoustic spectra, Rhodobacter sphaeroides, and thermal deactivation
- Language:
- Multiple languages
- Description:
- In aqueous solutions of chlorophyll (Chl) a with synthesized polypeptides, at high ratios of Chl to polypeptides (about 75-150 µM to 500 µM) clusters of polypeptides and pigment molecules were formed. The main absorption maxima of more than one formed cluster were located at about 500 nm (Soret band) and in the region of 720-806 nm (red band). The formation of these clusters was fairly slow (some hours) at room temperature and even slower at 4 °C. The rate of cluster formation increased with the increase in Chl concentration. The addition of the even low amount of reaction centres (RCs), separated from the purple bacteria Rhodobacter sphaeroides, to the sample of Chl with polypeptides caused a very strong decrease in the efficiency of cluster formation, and a change in concentration ratios of various pigment-polypeptide aggregates. It was probably a competition between the interaction of Chl with polypeptides and with the RCs. The yield of thermal deactivation of the clusters was high, much higher than that for the RCs alone and it was different for various types of cluster. The clusters absorbing at 725-750 nm were fluorescent with maximum of emission at about 770 nm, whereas clusters absorbing at about 800 nm were nonfluorescent. and H. Enomoto ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4. Irradiation-induced in vivo re-localization of NADPH-protochlorophyllide oxidoreductase from prolamellar body to stroma of barley etioplast
- Creator:
- Kovacevic, D., Dewez, D., and Popovic, D.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chlorophyll(ide), chloroplast development, envelope, fluorescence spectra, Hordeum vulgare, and prothylakoid
- Language:
- Multiple languages
- Description:
- Distribution of NADPH-protochlorophyllide oxidoreductase (POR) in etioplast of etiolated barley leaf was studied by using Western blot analyses of etioplast fractions isolated on a sucrose gradient. When the leaf was exposed to light, POR content decreased in the etioplast inner membrane and prolamellar body sub-membrane fraction while it was simultaneously increased in the stroma. By using 77 K fluorescence spectroscopy analyzes, we found for irradiated etiolated leaf that the POR protein in the stroma was co-localized with chlorophyllide (Chlide) emitting at 678 nm. Relocalization of the POR-Chlide complex induced by irradiation suggests that POR participates in the pigment transport processes during early stages of the thylakoid membrane development. and D. Kovacevic, D. Dewez, R. Popovic.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
5. Isolation and characterization of oxygen-evolving photosystem II particles and photosystem II core complex from the filamentous cyanobacterium Spirulina platensis
- Creator:
- Šetlíková, E., Sofrová, Danuše, Kovář, V., and Budáč, P.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- fotosyntéza, photosynthesis, antibodies, fluorescence spectra, IMAC chromatography, selectivity of detergents, 2, and 581
- Language:
- Multiple languages
- Description:
- a1_Photosystem (PS) II particles retaining a high rate of O2 evolution were isolated from the mesophilic filamentous cyanobacterium, Spirulina platensis. To achieve high production of PSII complexes in the cells, irradiance from halogen incandescent lamps was used. Disruption of cells by vibration of glass beads proved to be the most suitable procedure for isolation of thylakoid membranes. The selectivity of detergents for PSII particle preparation rose in the order of Triton X-100 < decyl-β-D-glucopyranoside < dodecyldimethyl-aminooxide < n-heptyl-β-D-thioglucoside < N-dodecyl-N,N-dimethylammonio-3-propane sulphonate < n-octyl-β-thioglycoside < octylglucoside < n-dodecyl-β-D-maltoside. The last four detergents yielded extracts, from which pure PSII particles not contaminated by PSI complexes could be obtained by sucrose-gradient centrifugation (20-45%) at the 43% sucrose level. We assumed both the acceptor and donor sides of the isolated n-dodecyl-β-D-maltoside (DM) particles to be intact due to high oxygen production by DM particles [1,500 meq(e-) mol-1 (Chl) s-1] achieved in the presence of all artificial acceptors tested. The PSII particle fraction from the sucrose gradient was used with immobilized metal (Cu2+) affinity chromatography (IMAC) for the preparation of the PSII core complex. By washing the column with a MES buffer containing MgCl2 and CaCl2, the phycobiliproteins were stripped off. The PSII core complex was eluted in a buffer containing 1% DM, mannitol, MgCl2, NaCl, CaCl2, and ɛ-aminocaproic acid. SDS-PAGE of the core complex provided pure bands of D1 and D2 proteins and PsbO protein from thylakoid membrane, which were used to raise polyclonal antibodies in rabbits. These antibodies recognized D1 and D2 not only as monomers of 31 and 32 kDa proteins, but also as heterodimers of D1, D2 corresponding to the band of 66 kDa on SDS-PAGE. This was in contrast to antibodies of, a2_synthetic determinants, which reacted only with the monomers of D1 and D2 proteins. These negative reactions against heterodimers of D1, D2 supported the hypothesis that dimeric forms of PSII reaction centre proteins have a C-terminal sequence sterically protected against a reaction with specific antibodies., and E. Šetlíková ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
6. Photosynthetic and growth responses of two mustard cultivars differing in phytocystatin activity under cadmium stress
- Creator:
- Per, T. S., Khan, S., Asgher, M., Bano, B., and Khan, N. A.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- kadmium, bavlna, chlorofyl, cadmium, cotton, chlorophyll, fluorescence chlorofylu, fluorescenční spektra, oblast listu, phytocystatin, suchá rostlinná hmota, kultivary, rychlost přenosu elektronů, kaštan, chlorophyll fluorescence, fluorescence spectra, leaf area, plant dry mass, ascorbate peroxidase, ATP-sulphurylase, cultivars, effective quantum yield of PSII photochemistry, electron transport rate, chestnut, maximal quantum yield of PSII photochemistry, 2, and 581
- Language:
- Multiple languages
- Description:
- Cadmium inhibits photosynthetic capacity of plants by disturbing protein conformations, whereas phytocystatins prevent degradation of target proteins and are involved in abiotic stress tolerance. Two mustard (Brassica juncea L.) cultivars, Ro Agro 4001 and Amruta, were grown with Cd (50 µM) in order to study physiological and biochemical basis of differences in Cd tolerance. Amruta accumulated higher Cd and H2O2 concentrations in leaves than that of Ro Agro 4001. Cd significantly decreased photosynthesis and growth of plants in both cultivars by reducing a chlorophyll content, gas exchange parameters, and activity of Rubisco; the effects were more prominent in Amruta than those in Ro Agro 4001. The greater photosynthesis and growth of Ro Agro 4001 under Cd stress might be attributed to its higher phytocystatin activity together with greater ascorbate peroxidase activity, photosynthetic nitrogen-use efficiency, sulphur assimilation (ATP-sulphurylase activity and S content), and contents of cysteine and reduced glutathione compared to Amruta. In contrast, the activity of superoxide dismutase (SOD) was higher in Amruta than that of Ro Agro 4001 under control conditions, whereas the Cd treatment increased significantly the SOD activity in both cultivars with the greater increase in Ro Agro 4001. The fluorescence spectra of phytocystatin showed a lesser change in Ro Agro 4001 under Cd stress than that in Amruta suggesting higher resistance of Ro Agro 4001 to Cd. The higher phytocystatin activity under Cd stress in Ro Agro 4001 compared to Amruta enabled the plants to protect their proteins more efficiently. This resulted in a greater increase of photosynthetic capacity in Ro Agro 4001 than that of Amruta. Thus, the phytocystatin activity may be considered as a physiological parameter for augmenting photosynthesis and growth of mustard under Cd stress., T. S. Per, S. Khan, M. Asgher, B. Bano, N. A. Khan., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
7. Regulation mechanism of excitation energy transfer in phycobilisome-thylakoid membrane complexes
- Creator:
- Li, Ye, Zhang, Jianping, Zhao, Jingquan, and Jiang, Lijing
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- absorption spectra, allophycocyanin, betaine, DCMU, fluorescence spectra, models of energy transfer, N-ethylmaleimide, photosystems 1 and 2, and state transition
- Language:
- Multiple languages
- Description:
- Regulation mechanism of excitation energy transfer between phycobilisomes (PBS) and the photosynthetic reaction centres was studied by the state transition techniques in PBS-thylakoid membrane complexes. DCMU, betaine, and N-ethylmaleimide were applied to search for the details of energy transfer properties based on the steady fluorescence measurement and individual deconvolution spectra at state 2 or state 1. The closure of photosystem (PS) 2 did not influence on fluorescence yields of PS1, i.e., energy could not spill to PS1 from PS2. When the energy transfer pathway from PBS to PS1 was disturbed, the relative fluorescence yield of PS2 was almost the same as that of PS2 in complexes without treatment. If PBSs were fixed by betaine, the state transition process was restrained. Hence PBS may detach from PS2 and become associated to PS1 at state 2. Our results contradict the proposed "spill-over" or "PBS detachment" models and support the mobile "PBS model". and Ye Li ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
8. Spectra and exciton dynamics in circular aggregates of the photosynthetic apparatus
- Creator:
- Novoderezhkin, V.I. and Razjivin, A.P.
- Format:
- Type:
- model:internalpart and TEXT
- Subject:
- absorbance spectra, light-harvesting pigments, fluorescence spectra, fluorescence kinetics, depolarization, bleaching, and absorption anisotropy
- Language:
- Multiple languages
- Description:
- A theory of spectra and excitation dynamics in antenna based on the notion of exciton interactions in the cyclic structures of light-harvesting pigments is reported. The theory provides an explanation for the picosecond absorbance difference spectra, the induced absorption anisotropy decay, the anomalously high bleaching valné, as well as for the fluorescence spectra, kinetics and depolarizatio
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public