螺旋藻细胞脱水与再吸纳引起的谱学变化

极大螺旋藻活细胞经过冻干脱水处理，得到脱水的干细胞，在避光条件下，使干细胞再吸纳水，测定处理前后螺旋藻细胞的谱学性质．结果表明：鲜活细胞经脱水处理其光谱发生了明显变化，再吸水后从吸收光谱可以观察到一个恢复的过程．荧光发射光谱则发现，再吸水14h后，藻细胞的光合系数(PSI)逐渐闭合，使传递到PSI的能量发生转移，最终以捕光色素藻蓝蛋白的发射释放出来．     

Crystal structure of plant photosystem I

Oxygenic photosynthesis is the principal producer of both oxygen and organic matter on Earth. The conversion of sunlight into chemical energy is driven by two multisubunit membrane protein complexes named photosystem I and II. We determined the crystal structure of the complete photosystem I (PSI) from a higher plant (Pisum sativum var. alaska) to 4.4 A resolution. Its intricate structure shows 12 core subunits, 4 different light-harvesting membrane proteins (LHCI) assembled in a half-moon shape on one side of the core, 45 transmembrane helices, 167 chlorophylls, 3 Fe-S clusters and 2 phylloquinones. About 20 chlorophylls are positioned in strategic locations in the cleft between LHCI and the core. This structure provides a framework for exploration not only of energy and electron transfer but also of the evolutionary forces that shaped the photosynthetic apparatus of terrestrial plants after the divergence of chloroplasts from marine cyanobacteria one billion years ago.     

Expression, purification and characterization of the soluble CuA domain of cytochrome c oxidase ofParacoccus versutus

The key subunit Ⅱ of cytochrome c oxidase (CcO) contains a soluble binuclear copper center (Cu_A) domain. The Cu_A domain of Paracoccus versutus was cloned, expressed, purified and characterized. The gene encoding the Cu_A domain in pET11d vector was expressed in E. coli BL21 (DE3). The results showed that the Cu_A domain was expressed mostly in inclusion bodies and the Cu_A domain protein synthesized in E. coli cells represents approximately 10 percent of the total cellular proteins. Dissolved in urea, dialyzed and recombined with Cu⁺/Cu²⁺ and purified by the Q-sepharose fast flow anion-exchange column and Sephadex G-75 gel filtration column, the soluble purple-colored protein, which shows a single band in electrophoresis, was obtained. The UV-visible absorption spectrum of Cu_A domain showed that there are intense band at 478 nm and a shoulder peak at 530 nm, and two weak bands at 360 and 806 nm respectively, which can be assigned to the charge transfer and the interactions of obitals of Cu—S and Cu——Cu in the mixed-valence binuclear metal center (Cu₂S₂R₂). The far-UV CD spectrum indicated that this domain is predominantly in β-sheet structure. The fluorescence spectra showed that its maximal excitation wavelength and maximal emission wavelength are at 280 and 345 nm, respectively.     

吴茱萸次碱结构和振动光谱的密度泛函理论研究

采用密度泛函理论B3LYP和B3PW91方法对吴茱萸次碱的几何结构进行了全优化,得到吴茱萸次碱的平衡几何结构参数,结果表明,吴茱萸次碱是一个平面结构的分子.在相同水平上计算了吴茱萸次碱的红外和拉曼振动光谱,依据计算结果,对吴茱萸次碱分子的振动基频进行了理论指认和归属.在红外光谱中,所有振动模式均具有红外活性,最强的振动频率为1 729 cm-1,摩尔吸光系数为1 461 L/(mol·cm),归属于C21O22的伸缩振动.在拉曼光谱中,吴茱萸次碱的所有振动模式也表现出了拉曼活性,最强的吸收峰频率为1 630 cm-1,吸收强度为170.8km/mol,由C21O22键的伸缩振动吸收所贡献.该研究结果可为进一步探讨吴茱萸次碱的结构和生物活性关系提供理论参考.     

Expression,purification and spectra characterization of neuroglobin

The expression, purification and spectra characterization of recombinant human neuroglobin （NGB） are reported. The pET3a plasmid with the gene of NGB was transformed to E. coli BL21 （DE3） plys cells and expressed in TB culture medium. The results indicated that the expression amount of NGB is about 10 percent of the total protein in cells. The NGB protein was purified by ammonium sulfate precipitation, DEAE-Sepharose anion exchange column, Hiload 16/60 superdex 75 size exclusion chromatography and a Hiprep 16/10 Q FF anion exchange column, and a red soluble protein was obtained which showed a single band in electrophoresis. Electrospray ionization mass spectrometry （ESI-MS） showed that its molecular weight is 16930.0 Da. UV-spectra indicated that the reduced NGB has a strong absorption peak at 425 nm, and two weak peaks at 531 and 559 nm, which can be assigned to γ, β and α bands of porphyrin, respectively, and the oxidized NGB has a strong absorption peak at 413 nm which corresponds to the transition of π electrons in the porphyrin ring. The fluorescence maximal excitation wavelength is at 281 nm and its maximal emission wavelength is at 338 nm. CD spectra indicated that its secondary structure is a typical α helix, and has a positive peak at 410 nm induced by heme, The NGB protein is stable when the pH is higher than 4.     

N-甲基甲酰胺在水溶液中的氢键动力学行为

在B3LYP/6-31++G水平下,利用密度泛函理论方法优化了N-甲基甲酰胺单体和氢键体系NMF-nH2O(n=1,2,3)的基态几何构型;用含时密度泛函理论方法计算了N-甲基甲酰胺单体和氢键体系NMF-nH2O(n=1,2,3)在不同电子激发态的跃迁能、振子强度和电子吸收光谱.结果表明,随着结合水分子个数的增加,氢键强度是加强的.分子间氢键引起电子吸收光谱发生红移,光谱红移程度与氢键加强的程度一致.     

[M(S-S)(N-N)]配合物分子内荷移跃迁性能及其影响因素研究

测量了新近合成的配合物[M(S-S)(N-N)]在溶剂吡啶、乙醇和氯仿中的电子吸收光谱,比较了二亚胺上不同取代基形成的镍配合物在DMSO和DMF中的电子吸收光谱.并从分子轨道理论角度探讨了这类配合物电子吸收光谱中主要谱带的电子跃迁特性.着重研究了标题配合物分子内配体间荷移跃迁吸收带(LL'CT)与配合物构型、中心离子、配体取代基电子效应和溶剂极性之间的内在本质关系.     

Regional patterns of particulate spectral absorption in the Pearl River estuary

Knowledge about the spectral absorption properties of marine particulate matters is of important signification for various goals of optical oceanography, among them the most concerns are the bio-optical algorithms for ocean color remote sensing[1], basic theory of light radiative transfer in water column[2], bio-optical models for estima-tion of primary productivity and simulation of the upper ocean ecological process[3,4]. The spectral absorption by marine particulate matter is combined influe…     

光照对盾叶薯蓣荧光光谱和叶绿体结构的影响

对生长在10,55,100,270 μmol·m^-2·s^-1光强下弱光生态型盾叶薯蓣的长期适应性进行了测定.结果表明,生长光条件不同其77 K荧光峰也出现明显的变化.弱光条件(10,55 μmol·m^-2·s^-1)下无F595和F740荧光峰(55 μmol·m^-2·s^-1下有F740肩峰),但有F720主峰;能量主要分配到光系统II;暗适应后引起了LHCII和CP43组成的功能发生改变;红光诱导分配到光系统II的能量比例下降;类囊体膜折叠指数较大,淀粉粒较小.较强光条件(100,270 μmol·m^-2·s^-1)下77 K荧光光谱无F720,但有F740峰较强;光系统II的激发能量较强;暗适应后增加了LHCI到PSI-RC的传递效率;红光诱导分配到光系统II的能量比例下降;类囊体膜折叠指数较小,淀粉粒较大.     

Laser cooling using anti-stokes fluorescence in Yb3+-doped fluorozirconate glasses

The fluorozirconate glasses ZBLANP (ZrF₄−BaF₂−LaF₃−NaF−PbF₂) doped with different Yb³⁺ concentration were prepared. The Raman spectra and absorption spectra are measured to substantiate the existence of phonon-assisted emission. After analyzing the normalized absorption spectra of samples with different Yb³⁺-doped concentration, we calculated the maximum cooling effect in the 3 wt% Yb³⁺-doped sample pumped at 1 012.5 nm. The corresponding cooling capability is about −4.09 °C/W and the cooling efficiency reaches 1.76%. Foundation item: Supported by the Key Science Foundation of Wuhan (9601P0223) Biography: Xu Tian-ming (1978-), female, Master candidate, research direction: information optics and nonlinear optics.     

Effects of Cholate on the Stability of Bacteriorhodopsin in Alkaline Solution

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Flexible dye-sensitized solar cell based on PCBM/P3HT heterojunction

Using blend heterojunction consisting of C60 derivatives [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and poly(3-hexylthiophene) (P3HT) as charge carrier transferring medium to replace I3–/I– redox electrolyte,a novel flexible dye-sensitized solar cell (DSSC) is fabricated.The characterization of infrared spectra and ultraviolet-visible spectra shows that the PCBM/P3HT heterojunction has not only the absorption in ultraviolet light for PCBM,but also the absorption in visible and near infrared light for P3HT,which widens the photoelectric response range for DSSC.The influence of PCBM/P3HT mass ratio on the performance of the solar cell is discussed.Under 100 mW cm–2 (AM 1.5) simulated solar irradiation,the flexible solar cell achieves a lightto-electric energy conversion efficiency of 1.43%,open circuit voltage of 0.87 V,short circuit current density of 3.0 mA cm–2 and fill factor of 0.54.     

Interaction of aloe-emodin with human serum albumin

The presence of several high affinity binding sites on human serum albumin (HSA) makes it a possible target for many drugs. This study is designed to examine the effect of aloe-emodin on HSA by fluo-rescence, CD spectroscopy and molecular modeling. The results of fluorescence measurements sug-gested that the hydrophobic interaction was the predominant intermolecular force stabilizing the AE-HSA complex, which was in good agreement with the result of molecular modeling study. And the enthalpy change ΔH0 and the entropy change ΔS0 were calculated to be -7.041 kJ·mol-1 and 76.619 J·mol-1·K-1 according to the Van't Hoff equation. The alterations of protein secondary structure in the presence of AE in aqueous solution were quantitatively calculated from CD spectra, and the content of α-helices obviously increased.     

含蒎烯基联吡啶的新型手性Mo(0)络合物的合成和表征

为了探讨含手性蒎烯基联吡啶的手性钼(0)络合物的结构对光谱(特别是CD光谱)性质的影响,合成了两个新型手性钼络合物( )CD452[Mo(CO)4(LRR)]和[Mo(CO)4(LSS)].用元素分析、IR、UV vis、CD、1HNMR和13CNMR等对其进行了充分表征.研究结果表明:两种络合物为一对具有几乎完全相同物理化学性质、配体互为对映体的光学异构体;两者在可见区的CD曲线呈现弱Cotton效应,且大致为镜象对称,说明在相应的手性络合物中,由于联吡啶上相反手性的蒎烯基通过中心金属钼对MLCT发色团产生了手性微扰作用,从而产生诱导CD效应.     

4-氨基安替比林电子光谱及溶剂效应理论研究

采用含时密度泛函理论方法(TD-PBE0)研究了4-氨基安替比林(4-AAP)在水和乙醇溶液环境中的电子光谱特性,通过电子跃迁轨道分析归属了4-AAP电子光谱谱带的跃迁轨道贡献并探究了其电子跃迁特征。研究结果表明,4-AAP在乙醇溶液中理论吸收谱带与实验谱带吻合较好,但其在水溶液中计算所得吸收谱带波长与实验所得相应值相差较大,溶剂水分子可与4-AAP通过氢键强烈相互作用形成复合物,诱导电子跃迁吸收谱带发生明显移动,氢键结合位点对其电子光谱中的最强吸收峰位置亦有影响,呈现显著的溶剂化效应。分子动力学模拟获得了水溶液中4-AAP溶剂团簇模型4-AAP-(H_2O)_3,基于此模型所得的理论电子光谱吸收谱带与实验光谱特征谱带波长相吻合,并从分子水平上对团簇结构吸收谱带的电子跃迁贡献进行了分析和归属。     

尼泊金丙酯与β-环糊精包结物溶液的光谱研究

采用紫外吸收光谱、荧光光谱研究β-CD、尼泊金丙酯及其包结物在水溶液中的性能.结果表明:室温下加入β-CD,可使尼泊金丙酯在水中的溶解度由0.38 g.L-1增至0.81 g.L-1;稀溶液中,随着β-CD浓度的增大,尼泊金丙酯的紫外吸收性能没有明显规律性的变化,但其荧光强度却显著增强;稀溶液中,β-CD与尼泊金丙酯主要生成摩尔比为1∶1的包结物,包结常数Ka为7.7×102L.mol-1;而饱和溶液法制备的包结物,其摩尔包结比为2∶1,在水中的溶解度约为0.43 g.L-1,略大于尼泊金丙酯在水中的溶解度.     

Sensitive Determination of DNA by RLS Enhancement of Metal Ions

0　IntroductionThequantitativeanalysisofnucleicacids,especiallythemi cro determinationofnucleicacids,isbecomingmoreandmoreimportantinmanybiologicalstudies.Recently ,apromisingspectraltechnique ,whichwasbasedonthemeasurementofen hancedresonancelightscattering (RLS) [1 ,2 ] ,hasgivenrisetostronginterestbyanalystsandbiochemistsfornucleicacidsandproteinassay[3 9] .Uptonow ,manykindscompoundshavebeenfoundRLSenhancementwhilebindingtoDNA ,andallthesecompoundsarecharacterizedofpositivechargewhicha…     

FTIR-ATR chamber for observation of efflorescence and deliquescence processes of NaClO4 aerosol particles on ZnSe substrate

NaClO4 aerosol particles with diameter of 5-20 microns are deposited on the ZnSe substrate. An FTIR-ATR chamber on the ZnSe substrate is set up to observe the structural changes of NaClO4 aerosol particles at crystallization relative humidity （CRH） and deliquescence relative humidity （DRH）. With the decrease of RH （relative humidity） from 96% to 24% in the efflorescence process, the absorbance of O-H stretching band of the aerosol solutions continuously decreases. A sudden decrease of the water peak is observed at RH20%, where solid particles form. Very small amount of residual interfacial water, with two weak peaks at 3602 and 3533 cm^-1, can still be resolved in the FTIR-ATR spectra of the solid particles. In the deliquescence process of the same sample, little spectral changes are observed when the value of RH varies from 5% to 29%. Before the abrupt increase of the O-H stretching band at the DRH of about RH46%, a pre-deliquescence process is observed, i.e. in the RH range between 33% and 46%, there is really a slow absorbance increase for the peak area of O-H stretching band. The O-H stretching band shows an arciform O-H en- velope, totally different from not only the FTIR-ATR spectra of ClO4^- solutions either under supersaturated state or in diluted state, but also the characteristic of the residually interfacial water discussed in the efflorescence process. Such kind of water is considered as pure water, indicating that small amount of water aggregates in the microspaces of solid aerosol particles due to the capillary cohesion effect. When the RH arrives at RH44%, two weak shoulders at 3384 and 3260 cm^-1 can be resolved, and the solid NaClO4 particles begin to be dissolved by increasing capillary cohesion water. The spectral characteristic of the v3-ClO4^- band also shows the transition from solid particles to mainly solvated ClO4^- ions.     

Hydrogen ions directly regulating the oligomerization state of Photosystem I in intact <Emphasis Type="Italic">Spirulina platensis</Emphasis> cells

H^＋ concentration induced-monomerization or trimerization of photosystem Ⅰ （PSI） in cyanobacteria has never been directly observed. In this work, taking characteristic spectra for the trimers and monomers as the indicators, it was experimentally demonstrated that H^＋ could induce the oligomeric changes of PSI reaction centers in the intact Spirulina platensis cells and also in the isolated thylakoid membrane complexes. Especially, the higher concentration of H^＋ would induce the monomerization while the lower the trimerization, suggesting the electrostatic interaction should be mainly responsible for changes in the oligomeric state of PSI in Spirulina platensis.     

铝-铬天青S-Triton X-100光度法测定蛋白质

在pH 3 0～ 4 3的酸性介质中 ,铝 铬天青S TritonX 10 0配合物与蛋白质迅速反应生成多元配合物 ,从而引起吸收光谱的改变 ,在 2 2 0nm和 6 36nm附近吸光度增大 ,且吸光度差ΔA(=A0 -A)值与蛋白质的浓度成正比 .不同蛋白质在 0～ 5 0mg/L和 10～ 80mg/L范围内遵循比尔定律 ,各反应的摩尔吸光系数分别在 4 2 3× 10 5～ 2 0 1× 10 6(2 2 0nm附近 )和 2 6 4× 10 5～ 1 6 4× 10 6(6 36nm附近 )之间 .基于此 ,建立了一种测定蛋白质的新光度法 .该法简便、快速、选择性好 ,用于人血清和尿液样品中蛋白质总量的测定 ,结果满意