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101.
A locus for binding a mobile water molecule was searched for in the immediate vicinity of the special pair in the reaction center. Using the PROTEUS PC-program (a part of the GRASP package) atomic structures of the reaction centers were analyzed in purple bacteria Rhodopseudomonas viridis and Rhodobacter sphaeroides. In both structures the loci for binding mobile water molecules were found at the distance of about 4.5 Å from the middle of the special pair in the reaction center. The reorientation of a hydrogen atom of this water molecule in the electric field of the excited special pair required energy of no less than 40 MeV that corresponded to predictions of the water-polarization model of trapping of electron excitation which was developed by M. V. Fok and one of the authors of this article. 相似文献
102.
103.
Jacqueline L. Padilla-Gami?o Morgan W. Kelly Tyler G. Evans Gretchen E. Hofmann 《Proceedings. Biological sciences / The Royal Society》2013,280(1759)
Ocean warming and ocean acidification, both consequences of anthropogenic production of CO2, will combine to influence the physiological performance of many species in the marine environment. In this study, we used an integrative approach to forecast the impact of future ocean conditions on larval purple sea urchins (Strongylocentrotus purpuratus) from the northeast Pacific Ocean. In laboratory experiments that simulated ocean warming and ocean acidification, we examined larval development, skeletal growth, metabolism and patterns of gene expression using an orthogonal comparison of two temperature (13°C and 18°C) and pCO2 (400 and 1100 μatm) conditions. Simultaneous exposure to increased temperature and pCO2 significantly reduced larval metabolism and triggered a widespread downregulation of histone encoding genes. pCO2 but not temperature impaired skeletal growth and reduced the expression of a major spicule matrix protein, suggesting that skeletal growth will not be further inhibited by ocean warming. Importantly, shifts in skeletal growth were not associated with developmental delay. Collectively, our results indicate that global change variables will have additive effects that exceed thresholds for optimized physiological performance in this keystone marine species. 相似文献
104.
C Cooksey 《Biotechnic & histochemistry》2013,88(4):123-134
The origin, production, and means of confirming the authenticity of some historic dyes are described. The underlying chemistry is revealed. The evolution of analytical techniques from early times, when the main criterion for a good textile dye was fitness for use, to more modern chromatographic techniques, where the emphasis is on chemical identity, is illustrated. Recent developments have led to smaller sample size requirements, greater speed of analysis and have led to a more detailed knowledge of the chemical components of historic dyes. 相似文献
105.
Weissgerber T Zigann R Bruce D Chang YJ Detter JC Han C Hauser L Jeffries CD Land M Munk AC Tapia R Dahl C 《Standards in genomic sciences》2011,5(3):311-330
Allochromatium vinosum formerly Chromatium vinosum is a mesophilic purple sulfur bacterium belonging to the family Chromatiaceae in the bacterial class Gammaproteobacteria. The genus Allochromatium contains currently five species. All members were isolated from freshwater, brackish water or marine habitats and are predominately obligate phototrophs. Here we describe the features of the organism, together with the complete genome sequence and annotation. This is the first completed genome sequence of a member of the Chromatiaceae within the purple sulfur bacteria thriving in globally occurring habitats. The 3,669,074 bp genome with its 3,302 protein-coding and 64 RNA genes was sequenced within the Joint Genome Institute Community Sequencing Program. 相似文献
106.
使用响应面法优化了紫甘薯花色苷的水解条件.使用高效液相色谱-多波长检测器测定花青素含量.采用3因素3水平Box-Behnken中心组合设计,优化了水解时间、盐酸浓度和水解温度对矢车菊素和芍药素峰面积之和的综合影响.结果显示,紫甘薯花色苷的最佳水浴水解条件为:盐酸浓度4.54 mol/L,水浴温度100℃,水解时间45.8 min.在最优条件下进行验证试验,响应值为理论值的96.5%,说明该响应面法优化方法可行. 相似文献
107.
为研究NaHCO3胁迫对紫根水葫芦的形态学指标及光合参数的影响,该文以紫根水葫芦为材料,采用不同浓度碱性盐NaHCO3溶液处理成株紫根水葫芦,测定在NaHCO3胁迫下紫根水葫芦的植株株高、根长、根冠比、生物量、含水量和光合参数[净光合速率(Pn)、胞间CO2浓度(Ci)、蒸腾速率(Tr)、气孔导度(Gs)]。结果表明:紫根水葫芦在20 mmol·L-1 NaHCO3浓度下的水溶液pH值最为平缓; 在低浓度NaHCO3溶液中(≤40 mmol·L-1),相比CK,紫根水葫芦的形态学指标呈现增长或无显著影响情况,而在高浓度NaHCO3溶液中(≥60 mmol·L-1),随着NaHCO3浓度的升高,紫根水葫芦形态学指标显著降低,且与NaHCO3浓度呈负相关; NaHCO3胁迫对紫根水葫芦的光合参数影响显著,随着NaHCO3浓度的增加及试验处理时间的延长,紫根水葫芦的Pn呈持续下降的趋势,Ci、Tr和Gs整体呈上升趋势,其光合作用受到的主要是非气孔限制。综合分析显示,紫根水葫芦具有一定的耐NaHCO3能力,能正常生存在不超过40 mmol·L-1 NaHCO3浓度的水体中,且能改善低NaHCO3浓度下的水体pH值。 相似文献
108.
Photobiological hydrogen production has advanced significantly in recent years, and on the way to becoming a mature technology. A variety of photosynthetic and non-photosynthetic microorganisms, including unicellular green algae, cyanobacteria, anoxygenic photosynthetic bacteria, obligate anaerobic, and nitrogen-fixing bacteria are endowed with genes and proteins for H2-production. Enzymes, mechanisms, and the underlying biochemistry may vary among these systems; however, they are all promising catalysts in hydrogen production. Integration of hydrogen production among these organisms and enzymatic systems is a recent concept and a rather interesting development in the field, as it may minimize feedstock utilization and lower the associated costs, while improving yields of hydrogen production. Photobioreactor development and genetic manipulation of the hydrogen-producing microorganisms is also outlined in this review, as these contribute to improvement in the yield of the respective processes. 相似文献
109.
Relationship between structure, dynamics and function of hydrated purple membrane investigated by neutron scattering and dielectric spectroscopy 总被引:1,自引:0,他引:1
We investigated the influence of hydration water on the relationship between structure, dynamics and function in a biological membrane system. For the example of the purple membrane (PM) with its protein bacteriorhodopsin (BR), a light-driven proton pump, complementary information from neutron diffraction, quasi-elastic neutron scattering (QENS) and dielectric spectroscopy will form a comprehensive picture of the structural and dynamic behavior of the PM in the temperature range between 150 and 290 K. Temperature- and humidity-dependent changes in the membrane system influence the accessibility of the different photocycle intermediates of BR. The melting of the 'freezing bound water' between 220 and 250 K could be related to the transition from the M1 to the M2 intermediate, which represents the key step in the photocycle. The dynamic transition in the vicinity of 180 K was shown to be necessary to ensure that the M1 intermediate can be populated and that the melting of crystallized bulk water above 255 K enables the completion of the photocycle. 相似文献
110.
Cooperative interaction of the high-potential hemes (Ch) in the cytochrome subunit of the photosynthesizing bacterium Ectothiorhodospira shaposhnikovii was studied by comparing redox titration curves of the hemes under the conditions of pulse photoactivation inducing single
turnover of electron-transport chain and steady-state photoactivation, as well as by analysis of the kinetics of laser-induced
oxidation of cytochromes by reaction center (RC). A mathematical model of the processes of electron transfer in cytochrome-containing
RC was considered. Theoretical analysis revealed that the reduction of one heme Ch facilitated the reduction of the other heme, which was equivalent to a 60 mV positive shift of the midpoint potential. In
addition, reduction of the second heme Ch caused a three-to four-fold acceleration of the electron transfer from the cytochrome subunit to RC.
Published in Russian in Biokhimiya, 2007, Vol. 72, No. 11, pp. 1540–1547. 相似文献