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2. Analysis of the disk-to-disk energy transfer processes in C-phycocyanin complexes by computer simulation technique
- Creator:
- Xie, Jie, Zhao, Jing-quan, and Peng, Chenghang
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- allophycocyanin, dynamics, kinetics, model, and phycobilisome
- Language:
- Multiple languages
- Description:
- Based on the crystal structure and spectral properties of C-phycocyanin (C-PC) from cyanobacteria, models for complexes with 2 and 3 C-PC hexamer disks were built and the energy transfer dynamic properties were studied by the use of stochastic computer simulation approach. In addition, an experimental parameter of 0.056 ps-1, corresponding to a time constant of 18 ps, derived from the previous time-resolved measurement, was used for simulation of the energy transfer process from the three terminal symmetrically equivalent β84 chromophores of the core-linked disk to an α84 chromophore of the allophycocyanin (APC) core. The simulation showed: (1) The disk-to-disk energy transfer can be as fast as several picoseconds. (2) The energy transfer efficiencies from the first disk to the core would depend on the length of the rod (i.e. the number of disks). Efficiencies of 0.95, 0.87, and 0.75 were found for the rods with 1, 2 and 3 hexamer disks, respectively. (3) The energy transfer along a rod in a native phycobilisome (PBS) is probably very close to the one-way manner. It is the core of PBS that makes the excitation energy be transferred fast in a nearly one-way manner. and Jie Xie, Jing-quan Zhao, Chenghang Peng.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3. Effect of sodium thiosulfate on the depletion of photosynthetic apparatus in cyanobacterium Synechocystis sp. PCC 6803 cells grown in the presence of glucose
- Creator:
- Wang, Zeneng, Xu, Yinong, Yang, Zhenle, Hou, Haitong, Jiang, Guizhen, and Kuang, Tingyun
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- allophycocyanin, chlorophyll, fluorescence, oxygen evolution, photosystems 1 and 2, phycobilisome, and phycocyanin
- Language:
- Multiple languages
- Description:
- Fluorescence spectroscopy at 77 K showed that the application of glucose lead to the depletion of phycobilisomes (PBS) and photosystems (PS) 2 and 1, and that PS2 was more sensitive to glucose than PS1. The application of sodium thiosulfate, an effective scavenger of reactive oxygen intermediates, counteracted the effects of glucose. Sodium thiosulfate effectively protected photosynthetic apparatus, PS2, PS1, and PBS against glucose-induced depletion. Sodium thiosulfate showed strong capability to inhibit the disappearance of chlorophyll induced by glucose. At a relatively low concentration of glucose, the application of sodium thiosulfate can even be helpful for the assembly of photosynthetic apparatus. Hence the reactive oxygen species might be involved in the depletion of the photosynthetic apparatus in the cyanobacterium Synechocystis sp. PCC 6803 cells grown in the presence of glucose. and Zeneng Wang ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4. Phycobilisome from Anabaena variabilis Kütz. and its model conjugates
- Creator:
- Zhao, Jiquan, Zhao, Jingquan, Zhang, Jingmin, and Jiang, Lijin
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- allophycocyanin, dithiothreitol, energy transfer, N-succinimidyl-3-(2-pyridyldithio)propionate, phycocyanin, phycoerythrocyanin, and rod-core complex (αβ)6PCLRC27 (αβ)3APCLC8.9
- Language:
- Multiple languages
- Description:
- The model conjugates phycocyanin-allophycocyanin (C-PC-APC) and phycoerythrocyanin-phycocyanin-allophycocyanin (PEC-C-PC-APC) were synthesized by using a heterobifunctional coupling reagent N-succinimidyl-3-(2-pyridyldithio)propionate. The rod-core complex (αβ)6 PCLRC 27(αβ)3 APCLC 8.9 and phycobilisomes were separated from Anabaena variabilis. Energy transfer features for the conjugates and the complexes were compared. The absorption and fluorescence emission spectra indicated that the linker-peptides mediate interaction of phycobiliproteins and prompt energy transfer. The energy transfer in the conjugates was detected by fluorescence emission spectra and confirmed by the addition of dithiothreitol. The conjugates may be used as models for studying the energy transfer mechanism in phycobilisomes. and Jiquan Zhao ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
5. Protection of energy transfer process in isolated phycobilisome by "white light" from ultraviolet-B induced damage in the cyanobacterium Spirulina platensis
- Creator:
- Rajagopal, S., Mohanty, Prasanna, and Murthy, S. D. S.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- allophycocyanin, chlorophyll fluorescence, and phycocyanin
- Language:
- Multiple languages
- Description:
- Effect of UV-B (1.9 W m-2) alone or in combination with supplemental "white light". WL (20 W m-2) exposure was studied on the energy transfer process of intact phycobilisomes isolated from Spirulina platensis. Exposure of UV-B or supplemental irradiation induced a decrease in room temperature fluorescence intensity and caused a shift towards shorter wavelengths. The low temperature fluorescence measurements showed that UV-B impairs energy transfer from phycocyanin to allophycocyanin B and the extent of damage may be reduced by the exposure to supplemental WL. and S. Rajagopal, Prasanna Mohanty, S. D. S. Murthy.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
6. 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