High-light induced superoxide radical formation in cytochrome b₆f complex from Bryopsis corticulans as detected by EPR spectroscopy.

The generation of superoxide radical (O₂·⁻) in Cyt b₆f of Bryopsis corticulans under high light illumination was studied using electron paramagnetic resonance (EPR) spectroscopy. This could be evidenced by the addition of SOD which specifically reacted with O₂·⁻. The generation of O₂·⁻ was lost in the absence of oxygen and was found to be suppressed in the presence of NaN₃ and be scavenged by extraneous antioxidants such as ascorbate, β-carotene and glutathione which could also scavenged ¹O₂*.

Proteomic analysis of hydrogen photoproduction in sulfur-deprived Chlamydomonas cells.

The green alga Chlamydomonas reinhardtii is a model organism to study H(2) metabolism in photosynthetic eukaryotes. To understand the molecular mechanism of H(2) metabolism, we used 2-DE coupled with MALDI-TOF and MALDI-TOF/TOF-MS to investigate proteomic changes of Chlamydomonas cells that undergo sulfur-depleted H(2) photoproduction process. In this report, we obtained 2-D PAGE soluble protein profiles of Chlamydomonas at three time points representing different phases leading to H(2) production.

High-light induced singlet oxygen formation in cytochrome b(6)f complex from Bryopsis corticulans as detected by EPR spectroscopy.

Electron paramagnetic resonance (EPR) spectroscopy was used to detect the light-induced formation of singlet oxygen ((1)O(2)*) in the intact and the Rieske-depleted cytochrome b(6)f complexes (Cyt b(6)f) from Bryopsis corticulans, as well as in the isolated Rieske Fe-S protein. It is shown that, under white-light illumination and aerobic conditions, chlorophyll a (Chl a) bound in the intact Cyt b(6)f can be bleached by light-induced (1)O(2)*, and that the (1)O(2)* production can be promoted by D(2)O or scavenged by extraneous antioxidants such as l-histidine, ascorbate, beta-carotene and glutathione. Under similar experimental conditions, (1)O(2)* was also detected in the Rieske-depleted Cyt b(6)f complex, but not in the isolated Rieske Fe-S protein.

Proteomic analysis of plasma membranes of cyanobacterium Synechocystis sp. Strain PCC 6803 in response to high pH stress.

Cyanobacteria are unique prokaryotes possessing plasma-, outer- and thylakoid membranes. The plasma membrane of a cyanobacterial cell serves as a crucial barrier against its environment and is essential for biogenesis of cyanobacterial photosystems. Previously, we have identified 79 different proteins in the plasma membrane of Synechocystis sp.

Singlet oxygen formation and chlorophyll a triplet excited state deactivation in the cytochrome b6f complex from Bryopsis corticulans.

We have attempted to investigate the correlation between the detergent-perturbed structural integrity of the Cyt b (6) f complex from the marine green alga Bryopsis corticulans and its photo-protective properties, for which the nonionic detergents n-octyl-beta-D-glucopyranoside (beta-OG) and n-dodecyl-beta-D-maltoside (beta-DM), respectively, were used for the preparation of Cyt b (6) f, and the singlet oxygen ((1)O(2)*) production as well as the triplet excited-state chlorophyll a ((3)Chl a*) formation and deactivation were examined by spectroscopic means. Near-infrared luminescence of (1)O(2)* (approximately 1,270 nm) on photo-irradiation was detected for the beta-OG preparation where the complex is mainly in oligomeric state, but not for the beta-DM one in which the complex exists in dimeric form. Under anaerobic condition, photo-excitation of Chl a in the beta-DM preparation generated (3)Chl a* with a lower quantum yield of Phi(T) approximately 0.

Exploring the mechanism of Physcomitrella patens desiccation tolerance through a proteomic strategy.

The moss Physcomitrella patens has been shown to tolerate abiotic stresses, including salinity, cold, and desiccation. To better understand this plant's mechanism of desiccation tolerance, we have applied cellular and proteomic analyses. Gametophores were desiccated over 1 month to 10% of their original fresh weight.

The effects of detergents DDM and beta-OG on the singlet excited state lifetime of the chlorophyll a in cytochrome b6f complex from spinach chloroplasts.

The singlet excited state lifetime of the chlorophyll a (Chl a) in cytochrome b(6)f (Cyt b(6)f) complex was reported to be shorter than that of free Chl a in methanol, but the value was different for Cyt b(6)f complexes from different sources ( approximately 200 and approximately 600 ps are the two measured results). The present study demonstrated that the singlet excited state lifetime is associated with the detergents n-dodecyl-beta-D-maltoside (DDM) and n-octyl-beta-D-glucopyranoside (beta-OG), but has nothing to do with the different sources of Cyt b(6)f complexes. Compared with the Cyt b(6)f dissolved in beta-OG, the Cyt b(6)f in DDM had a lower fluorescence yield, a lower photodegradation rate of Chl a, and a shorter lifetime of Chl a excited state.

The guanidine hydrochloride-induced denaturation of CP43 and CP47 studied by terahertz time-domain spectroscopy.

Terahertz time-domain spectroscopy (THz-TDS) is a new technique in studying the conformational state of a molecule in recent years. In this work, we reported the first use of THz-TDS to examine the denaturation of two photosynthesis membrane proteins: CP43 and CP47. THz-TDS was proven to be useful in discriminating the different conformational states of given proteins with similar structure and in monitoring the denaturation process of proteins.

WITHDRAWN: Effect of monogalactosyldiacylglycerol on the interactions between light-harvesting complexes II and photosystem II core complexes reconstituted into liposomes constituted of thylakoid lipids.

This article has been withdrawn consistent with Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy).

Hydrogen peroxide-induced chlorophyll a bleaching in the cytochrome b6f complex: a simple and effective assay for stability of the complex in detergent solutions.

The instability of cytochrome b ( 6 ) f complex in detergent solutions is a well-known problem that has been studied extensively, but without finding a satisfactory solution. One of the important reasons can be short of the useful method to verify whether the complex suspended in different detergent is in an intact state or not. In this article, a simple and effective assay for stability of the complex was proposed based on the investigation on the different effects of the two detergents, n-octyl-beta-D: -glucopyranoside (OG) and dodecyl-beta-D: -maltoside (DDM), on the properties of the complex.

Study on energy transfer between carotenoid and chlorophyll a in cytochrome b6f complex from Bryopsis corticulans.

The excitation energy transfer between carotenoid and chlorophyll (Chl) in the cytochrome b ( 6 ) f complex from Bryopsis corticulans (B. corticulans), in which the carotenoid is 9-cis-alpha-carotene, was investigated by means of fluorescence excitation and sub-microsecond time-resolved absorption spectroscopies. The presence of efficient singlet excitation transfer from alpha-carotene to Chl a was found with an overall efficiency as high as approximately approximately 24%, meanwhile the Chl a-to-alpha-carotene triplet excitation transfer was also evidenced.

Steady state fluorescence spectroscopy of the photosystem II core complex.

Spectroscopic properties within the core complex of photosystem II were investigated by studying the influence of the wavelength of excitation on the fluorescence emission spectrum. At two temperatures, when the core complex of PSII isolated from spinach was excited at six different excitation wavelengths ranging from 436 nm to 520 nm, there is no difference in the maxima of the emission spectra of the core complex, and when the core complex was excited at 480, 489, 495 and 507 nm respectively, fluorescence intensities of maxima decrease with increasing of the absorbance of the beta-carotene molecules at the four excitation wavelengths. The extent of change of the shoulder of the spectra beyond 700 nm depends on the kind of pigment molecule excited.

Ultrafast carotenoid-to-chlorophyll singlet energy transfer in the cytochrome b6f complex from Bryopsis corticulans.

Ultrafast carotenoid-to-chlorophyll (Car-to-Chl) singlet excitation energy transfer in the cytochrome b(6)f (Cyt b(6)f) complex from Bryopsis corticulans is investigated by the use of femtosecond time-resolved absorption spectroscopy. For all-trans-alpha-carotene free in n-hexane, the lifetimes of the two low-lying singlet excited states, S(1)(2A(g)(-)) and S(2)(1B(u)(+)), are determined to be 14.3 +/- 0.

Photosynthesis research in the People's Republic of China.

The first research paper on photosynthesis in China was published by T.T. Li(2) in 1929.

[Effects of Triton X-100 on the oxygen uptake rate of photosystem I particles treated at 70 degrees C].

The characteristics including oxygen uptake rates, fluorescence spectra and absorption spectra of photosystem I particles with or without Triton-X 100 treatment before or after the incubation at 70 degrees C for 10 min were compared. The oxygen uptake rates of photosystem I particles decreased after being incubated at 70 degrees C for 10 min, which could be recovered by the addition of Triton-X 100. Singlet oxygen was formed when the light-harvesting complex I was separated from the core complex of photosystem I, which resulted in high oxygen uptake rate.

Three-dimensional architecture of phycobilisomes from Nostoc flagelliforme revealed by single particle electron microscopy.

Phycobilisomes are protein complexes that harvest light and transfer energy to the photo system. Here, the three dimensional structure of intact phycobilisomes from Nostoc flagelliforme is studied by a combination of negative stain electron microscopy and cryo-electron microscopy. Results show that the intact phycobilisomes are composed of a tricylindrical core and six rods.

Effect of various temperatures on phosphatidylglycerol biosynthesis in thylakoid membranes.

Lipid unsaturation, the major factor to maintain thylakoid membrane fluidity, is affected by temperature. In this work, we analysed the molecular species composition of phosphatidylglycerol (PG) in thylakoid membranes during spinach (Spinacia oleracea) and squash (Cucurbita pepo) cotyledon growth to investigate how the growth temperature affects the PG biosynthesis. Of the 10 molecular species detected, temperature affected mainly the relative content of molecular species containing linolenic acid (18:3) and those containing palmitic acid (16:0) at the sn-1 position of glycerol backbone.