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1.
In this communication, a novel, green, efficient and economically viable light mediated protocol for generation of Au-nanoparticles using most vital organelle, chloroplasts, of the plant system is portrayed. Thylakoids/chloroplasts isolated from Potamogeton nodosus (an aquatic plant) and Spinacia oleracea (a terrestrial plant) turned Au3+ solutions purple in presence of light of 600 µmol m−2 s−1 photon flux density (PFD) and the purple coloration intensified with time. UV-Vis spectra of these purple colored solutions showed absorption peak at ∼545 nm which is known to arise due to surface plasmon oscillations specific to Au-nanoparticles. However, thylakoids/chloroplasts did not alter color of Au3+ solutions in dark. These results clearly demonstrated that photosynthetic electron transport can reduce Au3+ to Au0 which nucleate to form Au-nanoparticles in presence of light. Transmission electron microscopic studies revealed that Au-nanoparticles generated by light driven photosynthetic electron transport system of thylakoids/chloroplasts were in range of 5–20 nm. Selected area electron diffraction and powder X-ray diffraction indicated crystalline nature of these nanoparticles. Energy dispersive X-ray confirmed that these nanoparticles were composed of Au. To confirm the potential of light driven photosynthetic electron transport in generation of Au-nanoparticles, thylakoids/chloroplasts were tested for their efficacy to generate Au-nanoparticles in presence of light of PFD ranging from 60 to 600 µmol m−2 s−1. The capacity of thylakoids/chloroplasts to generate Au-nanoparticles increased remarkably with increase in PFD, which further clearly demonstrated potential of light driven photosynthetic electron transport in reduction of Au3+ to Au0 to form nanoparticles. The light driven donation of electrons to metal ions by thylakoids/chloroplasts can be exploited for large scale production of nanoparticles. 相似文献
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Addition of nitrate to a suspension of NO3 --depleted Chlorella vulgaris cells raised the O2-evolving capacity of the organism by 60%. The rate of O2-evolution under flash irradiation of the depleted cells was drastically reduced, which could be restored by addition of NO3 -. The 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB)-insensitive O2-evolution, i.e., photosystem (PS) 2 activity of NO3--depleted cells, showed a 75% stimulation by addition of NO3 -. PS1-mediated electron transport was also stimulated (50%) by addition of NO3 -. Fluorescence yields of the NO3 --depleted cells were significantly reduced. A normal fluorescence response was restored by the addition of NO3 -. The fluorescence yield of the NO3 --depleted and DCMU-treated-cells increased significantly after addition of NO3 - ions, indicating a further reduction of the primary acceptor of PS2 (Q). In addition, the low temperature fluorescence emission spectra showed that energy transfer to PS2 and PS1 was much higher when nitrate was present. Hence nitrate accelerates the light-induced charge transfer from the intact O2-evolving system to the primary electron acceptor of PS2 and stimulates the PS1-mediated electron transport. This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
4.
V. D. Samuilov D. B. Bezryadnov M. V. Gusev A. V. Kitashov T. A. Fedorenko 《Biochemistry. Biokhimii?a》2001,66(6):640-645
The effect of H2O2 on photosynthetic O2 evolution and photosynthetic electron transfer in cells of cyanobacteria Anabaena variabilis and Anacystis nidulans was studied. The following experiments were performed: 1) directly testing the effect of exogenous H2O2; 2) testing the effect of intracellular H2O2 generated with the use of methyl viologen (MV); 3) testing the effect of inhibiting intracellular H2O2 decomposition by salicylic acid (SA) and 3-amino-1,2,4-triazole (AT). H2O2 inhibited photosynthetic O2 evolution and light-induced reduction of p-benzoquinone (BQ) + ferricyanide (FeCy) in the Hill reaction. The I50 value for H2O2 was 0.75 mM. Photosynthetic electron transfer in the cells treated with H2O2 was not maintained by H2O2, NH2OH, 1,5-diphenylcarbazide, tetraphenylboron, or butylated hydroxytoluene added as artificial electron donors for Photosystem (PS) II. The H2O CO2, H2O MV (involving PSII and PSI) and H2O BQ + FeCy (chiefly dependent on PSII) electron transfer reactions were inhibited upon incubation of the cells with MV, SA, or AT. The N,N,N",N"-tetramethyl-p-phenylenediamine MV (chiefly dependent on PSI) electron transfer was inhibited by SA and AT but was resistant to MV. The results show that H2O2 inhibits photosynthetic electron transfer. It is unlikely that H2O2 could be a physiological electron donor in oxygenic photosynthesis. 相似文献
5.
Riznichenko Galina Yu. Belyaeva Natalya E. Kovalenko Ilya B. Antal Taras K. Goryachev Sergei N. Maslakov Aleksei S. Plyusnina Tatiana Yu. Fedorov Vladimir A. Khruschev Sergei S. Yakovleva Olga V. Rubin Andrew B. 《Biochemistry. Biokhimii?a》2022,87(10):1065-1083
Biochemistry (Moscow) - Summarized results of investigation of regulation of electron transport and associated processes in the photosynthetic membrane using methods of mathematical and computer... 相似文献
6.
Koichi Yoneyama Makoto Konnai Tetsuo Takematsu Hajime Iwamura Tadao Asami Nobutaka Takahashi 《Bioscience, biotechnology, and biochemistry》2013,77(7):1953-1959
A series of 3-acyl-2,4,6-trihydroxybenzamides was synthesized, and the compounds’ PET inhibitory activities were examined in isolated chloroplasts. In general, the PET inhibitory activity was found to depend on the overall lipophilicity of the molecule. Low activities of the mono and dihydroxy derivatives indicated that the three hydroxyl groups on the nucleus were essential for high activity. The PET inhibition study, on chloroplasts isolated from an atrazine resistant biotype of Brassica napus and using thermoluminescence analysis, suggested that the trihydroxybenzamide derivatives would be classified as a urea type rather than a phenol type of PET inhibitor. However the trihydroxybenzamide derivatives, like the phenol type of PET inhibitor, showed a lag time before inhibition started, which was followed by constant activity. These results indicate that the binding domain for the trihy-droxybenzamide derivatives overlapped with those of both the urea type and phenol type of PET inhibitors. 相似文献
7.
Photosynthetic Electron Transport Chain of Chlamydomonas reinhardi VI. Electron Transport in Mutant Strains Lacking Either Cytochrome 553 or Plastocyanin 总被引:6,自引:10,他引:6
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A mutant strain of Chlamydomonas reinhardi, ac-206, lacks cytochrome 553, at least in an active and detectable form. Chloroplast fragments of this mutant strain are inactive in the photoreduction of NADP when the source of electrons is water, but they are active when the electron source is 2,6-dichlorophenolindophenol and ascorbate. The addition of either cytochrome 553 or plastocyanin, obtained from the wild-type strain, has no effect upon the photosynthetic activities of the mutant strain. Cells of the mutant strain lack both the soluble and insoluble forms of cytochrome 553, but they possess the mitochondrial type cytochrome c. Thus, the loss of cytochrome 553 appears to be specific. 相似文献
8.
Rates of thermoinduced conformational transitions of reaction center (RC) complexes providing effective electron transport were studied in chromatophores and isolated RC preparations of various photosynthesizing purple bacteria using methods of fast freezing and laser-induced temperature jump. Reactions of electron transfer from the primary to secondary quinone acceptors and from the multiheme cytochrome c subunit to photoactive bacteriochlorophyll dimer were used as probes of electron transport efficiency. The thermoinduced transition of the acceptor complex to the conformational state facilitating electron transfer to the secondary quinone acceptor was studied. It was shown that neither the characteristic time of the thermoinduced transition within the temperature range 233-253 K nor the characteristic time of spontaneous decay of this state at 253 K exceeded several tens of milliseconds. In contrast to the quinone complex, the thermoinduced transition of the macromolecular RC complex to the state providing effective electron transport from the multiheme cytochrome c to the photoactive bacteriochlorophyll dimer within the temperature range 220-280 K accounts for tens of seconds. This transition is thought to be mediated by large-scale conformational dynamics of the macromolecular RC complex. 相似文献
9.
Liu J. Li H. J. Guo Y. Y. Wang G. X. Zhang H. J. Zhang R. H. Xu W. H. 《Russian Journal of Plant Physiology》2020,67(5):912-922
Russian Journal of Plant Physiology - Effects of drought stress on photosynthesis have been well-documented. However, photosynthetic electron transport process in response to combined drought... 相似文献
10.
Pogoryelov D Sudhir PR Kovács L Gombos Z Brown I Garab G 《Journal of bioenergetics and biomembranes》2003,35(5):427-437
Arthrospira (Spirulina) platensis (A. platensis) is a model organism for investigation of adaptation of photosynthetic organisms to extreme environmental conditions: the cell functions in this cyanobacterium are optimized to high pH and high concentration (150–250 mM) of Na+. However, the mechanism of the possible fine-tuning of the photosynthetic functions to these extreme conditions and/or the regulation of the cellular environment to optimize the photosynthetic functions is poorly understood. In this work we investigated the effect of Na-ions on different photosynthetic activities: linear electron transport reactions (measured by means of polarography and spectrophotometry), the activity of photosystem II (PS II) (thermoluminescence and chlorophyll a fluorescence induction), and redox turnover of the cytochrome b
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f complex (flash photolysis); and measured the changes of the intracellular pH (9-aminoacridine fluorescence). It was found that sodium deprivation of cells in the dark at pH 10 inhibited, within 40 min, all measured photosynthetic reactions, and led to an alkalinization of the intracellular pH, which rose from the physiological value of about 8.3–9.6. These were partially and totally restored by readdition of Na-ions at 2.5–25 mM and about 200 mM, respectively. The intracellular pH and the photosynthetic functions were also sensitive to monensin, an exogenous Na+/H+ exchanger, which collapses both proton and sodium gradients across the cytoplasmic membrane. These observations explain the strict Na+-dependency of the photosynthetic electron transport at high extracellular pH, provide experimental evidence on the alkalization of the intracellular environment, and support the hypothesized role of an Na+/H+ antiport through the plasma membrane in pH homeostasis (Schlesinger et al. (1996). J. Phycol.
32, 608–613). Further, we show that (i) the specific site of inactivation of the photosynthetic electron transport at alkaline pH is to be found at the water splitting enzyme; (ii) in contrast to earlier reports, the inactivation occurs in the dark and, for short periods, without detectable damage in the photosynthetic apparatus; and (iii) in contrast to high pH, Na+ dependency in the neutral pH range is shown not to originate from PSII, but from the acceptor side of PSI. These data permit us to conclude that the intracellular environment rather than the machinery of the photosynthetic electron transport is adjusted to the extreme conditions of high pH and high Na+ concentration. 相似文献
11.
Quantum Requirements of Photosynthetic Electron Transport In Sitka Spruce from Different Light Environments 总被引:1,自引:0,他引:1
Quantum requirements of photosynthetic electron transport have been measured in shoots of Picea sitchensis (Bong.) Carr. (Sitka spruce) from different levels in a forest canopy and in shoots from plants grown in contrasting light environments in controlled environment chambers. Neutral density filters were used to obtain very low photon flux densities. The light absorbed by the chloroplast suspensions was calculated from measurements of the transmittance of the suspensions. The shoots from the top of the forest canopy (“sun” shoots) had lower quantum requirements for photosystems I and II than the shoots from the bottom of the forest canopy (“shade” shoots). High light grown plants and “sun” shoots had higher rates of electron transport at light saturation than low light grown plants and “shade” shoots. Thus a higher potential for electron transport was found to exist in “sun” shoots than in “shade” shoots at both high and low photon flux densities. 相似文献
12.
Photosynthetic Electron Transport in Single Guard Cells as Measured by Scanning Electrochemical Microscopy 总被引:4,自引:0,他引:4
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Scanning electrochemical microscopy (SECM) is a powerful new tool for studying chemical and biological processes. It records changes in faradaic current as a microelectrode ([less than equal]7 [mu]m in diameter) is moved across the surface of a sample. The current varies as a function of both distance from the surface and the surface's chemical and electrical properties. We used SECM to examine in vivo topography and photosynthetic electron transport of individual guard cells in Tradescantia fluminensis, to our knowledge the first such analysis for an intact plant. We measured surface topography at the micrometer level and concentration profiles of O2 evolved in photosynthetic electron transport. Comparison of topography and oxygen profiles above single stomatal complexes clearly showed photosynthetic electron transport in guard cells, as indicated by induction of O2 evolution by photosynthetically active radiation. SECM is unique in its ability to measure topography and chemical fluxes, combining some of the attributes of patch clamping with scanning tunneling microscopy. In this paper we suggest several questions in plant physiology that it might address. 相似文献
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The activities of photosystem 2 (PS2) and whole chain electron transport declined in high temperature treated cells at the room temperature beyond 35 °C, while photosystem 1 (PS1) showed increased activity. Thylakoid membrane studies did not exhibit increase in PS1 activity indicating that the enhancement of PS1 activity is due to permeability change of cell membranes. However, the electron transport activity measured from reduced duroquinone to methylviologen which involves intersystem electron transport was extremely sensitive to high temperature. The activity of PS2 at different irradiance, which was accompanied by alterations in absorption and fluorescence emission properties, indicated changes in the energy transfer processes within phycobilisomes. Thus high temperature has multiple target sites in photosynthetic electron transport system of Spirulina platensis. 相似文献
14.
Osman, M. E-A. H. and El-Shentenawy, F. 1988. Photosyntheticelectron transport under phosphorylating conditions as influencedby different concentrations of various salts.J. exp.Bot. 39: 859863. The rate of light-induced electron transport by isolated spinachthylakoids under phosphorylating conditions, as affected bydifferent concentrations of Br, Cl, NO3,HCO3, SO42 and CO32 has been investigated.The results show that both low and high concentrations of HCO32stimulated the oxygen evolution capacity under phosphorylatingconditions, whereas only low concentrations of CO32,SO42 and Cl stimulated the oxygen evolution capacity.However, irrespective of concentration, both Br and NO3reduced this capacity. The rate of photosynthetic electron transportwas generally stimulated by addition of ADP, even in cases whereelectron transport was inhibited by addition of bromide andnitrate. The different concentrations of these anions also causedreduction of the power generated by proton pumping and usedfor phosphorylation. The greatest level of reduction was observedin the presence of high concentrations of Cl and HCO3. Key words: Spinach thylakoids, photosynthetic electron transport, phosphorylation 相似文献
15.
W. Wiessner G. Dubertret Y. Henry-Hiss D. Mende M. Lefort-Tran 《Plant biology (Stuttgart, Germany)》1981,94(1):503-515
In green algae several characteristic differences in the slope of the fast 685 nm fluorescence transient indicate the existence of different mechanisms for the regulation of the photosynthetic electron transport in vivo with respect to the requirements for ATP and NADPH. Autotrophically cultivated Chlamydobotrys stellata exhibits a normal time curve of the fluorescence yield. Anaerobiosis and C02-deficiency raise the O-, I- and S-level, whereas the P- level is lowered and the I-D-decay disappears. The readdition of oxygen increases the fluorescence significantly. Supplementation of aerobic cells with CO2 restores the normal fluorescence transients. The replacement of carbon dioxide by acetate as a carbon source in the light lowers the overall fluorescence emission and abolishes the D-P-increase and the P-S-decline. The presence of DCMU increases fluorescence only at high intensities of incedent light. Anaerobiosis in these photoheterotrophic algae lowers the fluorescence emission. In this case DCMU increases fluorescence even at low light intensities. In Gonium multicoccum, which shows a normal fluorescence transient when cultivated autotrophically, CO2-deficiency abolishes the O-level and increases the I- and S-niveau. Additional anaerobiosis in CO2-deficient cells raises the steady state emission. Readdition of oxygen to these cells raises the I- and S-level even more and prevents the build up of the P-level. In Gonium 相似文献
16.
Photosynthetic Electron Transport Chain of Chlamydomonas reinhardi. IV. Purification and Properties of Plastocyanin 总被引:6,自引:5,他引:6
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The copper protein plastocyanin has been found to be an essential component of the photosynthetic electron transport chain of Chlamydomonas reinhardi, and in this paper we describe a method for its isolation and purification from the wild-type strain. In addition, we describe some of its properties and compare them with those reported for spinach plastocyanin. 相似文献
17.
Photosynthetic Electron Transport in Plants of Sitka Spruce Subjected to Differing Light Environments during Growth 总被引:4,自引:0,他引:4
Seedlings of Picea sitchensis (Bong.) Carr. (Sitka spruce) have been grown in four different light regimes in growth chambers. Chloroplast fragments have been isolated from the needles and Photosystem I and Photosystem II activities measured. Measurements were made at eight photon flux densities giving light response curves for photosystem activity in needles grown in the four different light regimes. Chlorophyll concentration was higher in needles from the low cultivation light environments than in those from the high light environments. Photosystem activity was higher in needles from the high cultivation light environments. Evidence that Photosystem I was limiting photosynthesis in needles grown in the high light environments was obtained. 相似文献
18.
Formation of the Photosynthetic Electron Transport System during the Early Phase of Greening in Barley Leaves 总被引:1,自引:2,他引:1
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The development of photochemical activity in isolated plastids during the early phase of greening of 5-day-old etiolated barley seedlings was studied and related to the appearance of chlorophyll-protein complexes. Photochemical activities of PSI (DCIPH2 → MV) and PSII (H2O → DCIP, DPC → DCIP) appeared at 1 and 1.5 hours after the onset of illumination, respectively. However, PSI + PSII activity (H2O → MV, H2O → NADP) appeared at 4 hours. The functional plastoquinone pool was noticed, at the latest, from 4 hours. Chloroplast preparations from seedlings of 1 h of greening showed O2 uptake upon illumination in the absence of MV (−MV activity). This activity peaked at 2 hours of greening, then fell to zero by 6 hours. In contrast to the −MV activity, MV-Hill activity began to increase at 2 hours. Although PSI activity appeared at 1 hour, it failed to reduce ferredoxin until 2 hours. NADP began to be photoreduced at 4 hours in accordance with the appearance of the ferredoxin:NADP reductase activity. After formation of PSI and PSII, electron transport systems between them and between PSI and NADP developed in coordination with each other. Thus, the whole electron transport from water to NADP began to operate at 4 hours. 相似文献
19.
Size of the Plastoquinone Pool Functioning in Photosynthetic and Respiratory Electron Transport of Synechococcus sp. 总被引:1,自引:0,他引:1
The size of the plastoquinone pool on the reducing side of photosystem2 in the cyanobacterium Synechococcus sp. was estimated by measuringthe area over the fluorescence induction curve in the presenceof 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone relativeto the area in the presence of 3-(3,4-dichlorophenyl)-l,l-dimethylurea.Plastoquinone was found mostly in the reduced state in freshlyharvested cells but was oxidized by aeration of the cells inthe dark. The pool in the starved cells usually consisted offive or six plastoquinone molecules with a maximum of eightper photosystem 2 reaction center. Addition of glucose or fructoseto the starved cells completely reduced the plastoquinone poolunder anaerobic conditions or in the presence of KCN. The quinonereduced by brief illumination was rapidly and completely oxidizedin the dark. The dark oxidation proceeded at a rate comparableto that of respiratory O2 uptake in the cyanobacterium and wasstrongly inhibited by KCN. It is concluded that a major populationof the plastoquinone molecules present in the cells functionsas the acceptor pool of photosystem 2 and that the pool is entirelyshared by respiratory electron transport in the cyanobacterium. (Received June 22, 1983; Accepted August 20, 1983) 相似文献
20.
Relationship between Photosynthetic Electron Transport and Stromal Enzyme Activity in Pea Leaves : Toward an Understanding of the Nature of Photosynthetic Control 总被引:4,自引:7,他引:4
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The responses of the quantum efficiencies of photosystem (PS) II and PSI measured in vivo simultaneously with estimations of the activities and activation states of NADP-malate dehydrogenase, chloroplast fructose-1,6-bisphosphatase, and ribulose-1,5-bisphosphate carboxylase were used to study the relationship between electron transport and carbon metabolism. The effects of varying irradiance and CO2 partial pressure on the relationship between the quantum efficiencies of PSI and II, and the activity of these enzymes shows that the interrelationships vary according to the limitations placed on the system. The relationship between the quantum efficiencies of PSII and PSI was linear in most situations. In response to increasing irradiance, the activity of all three enzymes increased. In the case of NADP-malate dehydrogenase this increase was well correlated with the estimated flux of electrons through PSI and PSII. The other two enzymes showed a more complex relationship with the estimated flux of electrons through both photosystems. These relationships are consistent with the known interactions between these stromal enzymes and the thylakoids. The response to varying CO2 partial pressure is more complex. The efficiencies of PSI and II declined with decreasing CO2 partial pressure and the activity of each enzyme varied uniquely. However, there are clear correlations between the activities of the enzymes and the flux of electrons through the photosystems. In contrast to the data obtained under conditions of varying irradiance, there is clear evidence of photosynthetic control of electron transport when the CO2 concentration is varied. 相似文献