Characterization of a dissolved oxygen sensor made of plastic optical fiber coated with ruthenium-incorporated solgel

A dissolved oxygen sensor made of plastic optical fiber as the substrate and dichlorotris (1, 10-phenanthroline) ruthenium as a fluorescence indicator is studied. Oxygen quenching characteristics of both intensity and phase were measured; the obtained characteristics showed deviation from the linear relation described by the Stern-Volmer equation. A two-layer model is proposed to explain the deviation, and main parameters can be deduced with the model. (C) 2009 Optical Society of America

Proton magnetic resonance studies of ribonucleic acid complexes. I. Complexes of biological bases and oligonucleotides with RNA. II. Template recognition and the degeneracy of the genetic code

Part I. Complexes of Biological Bases and Oligonucleotides with RNA

The physical nature of complexes of several biological bases and oligonucleotides with single-stranded ribonucleic acids have been studied by high resolution proton magnetic resonance spectroscopy. The importance of various forces in the stabilization of these complexes is also discussed.

Previous work has shown that purine forms an intercalated complex with single-stranded nucleic acids. This complex formation led to severe and stereospecific broadening of the purine resonances. From the field dependence of the linewidths, T₁ measurements of the purine protons and nuclear Overhauser enhancement experiments, the mechanism for the line broadening was ascertained to be dipole-dipole interactions between the purine protons and the ribose protons of the nucleic acid.

The interactions of ethidium bromide (EB) with several RNA residues have been studied. EB forms vertically stacked aggregates with itself as well as with uridine, 3'-uridine monophosphate and 5'-uridine monophosphate and forms an intercalated complex with uridylyl (3' → 5') uridine and polyuridylic acid (poly U). The geometry of EB in the intercalated complex has also been determined.

The effect of chain length of oligo-A-nucleotides on their mode of interaction with poly U in D₂0 at neutral pD have also been studied. Below room temperatures, ApA and ApApA form a rigid triple-stranded complex involving a stoichiometry of one adenine to two uracil bases, presumably via specific adenine-uracil base pairing and cooperative base stacking of the adenine bases. While no evidence was obtained for the interaction of ApA with poly U above room temperature, ApApA exhibited complex formation of a 1:1 nature with poly U by forming Watson-Crick base pairs. The thermodynamics of these systems are discussed.

Part II. Template Recognition and the Degeneracy of the Genetic Code

The interaction of ApApG and poly U was studied as a model system for the codon-anticodon interaction of tRNA and mRNA in vivo. ApApG was shown to interact with poly U below ~20°C. The interaction was of a 1:1 nature which exhibited the Hoogsteen bonding scheme. The three bases of ApApG are in an anti conformation and the guanosine base appears to be in the lactim tautomeric form in the complex.

Due to the inadequacies of previous models for the degeneracy of the genetic code in explaining the observed interactions of ApApG with poly U, the "tautomeric doublet" model is proposed as a possible explanation of the degenerate interactions of tRNA with mRNA during protein synthesis in vivo.

Optical parameters and absorption of copper (II)-azo complexes thin films as optical recording media

Smooth thin films of three kinds of azo dyes of 2-(5'-tert-butyl-3'-azoxylisoxazole)-1, 3-diketones and their copper (II)-azo complexes were prepared by the spin-coating method. Absorption spectra of the thin films on a glass substrate in the 300-600 nm wavelength region were measured. Optical constants (complex refractive index N=n+ik) and thickness of the thin films prepared on single-crystal silicon substrate in the 300-600 nm wavelength region were investigated on rotating analyzer-polarizer type of scanning ellipsometer, and dielectric constants epsilon(epsilon=epsilon(1)+i epsilon(2)), absorption coefficients alpha as well as reflectance R of thin films were then calculated. In addition, one of the copper (II)-azo complex thin film prepared on glass substrate with an Ag reflective layer was also studied by atomic force microscopy (AFM) and static optical recording. AFM study shows that the copper (II)-azo complex thin film is very smooth and has a root mean square surface roughness of 1.89 nm. Static optical recording shows that the recording marks on the copper (II)-azo complex thin film are very clear and circular, and the size of the minimal recording marks can reach 200 nm. (c) 2004 Elsevier B.V. All rights reserved.

Synthesis, spectroscopic and thermal properties of nickel (II)-azo complexes with blue-violet light wavelength

A novel azo dye containing isoxazole ring and beta-diketone derivative (TIAD) and its two nickel (II) complexes (Ni (II)-ETIAD and Ni (II)-HTIAD) were synthesized in order to obtain a blue-violet light absorption and better thermal stability as a promising organic storage material for next generation of high density digital versatile disc-recordable (HD-DVD-R) systems that uses a high numerical aperture of 0.85 at 405 nm wavelength. Their structures were confirmed on the basis of elemental analysis, MS, FT-IR, UV-Vis and magnetic data. Their solubility in 2,2,3,3-tetrafluoro-1-propanol (TFP) and absorption properties of thin film were measured. The difference of absorption maximum from the complexes to their ligands was discussed. In addition, the TG analysis of the complexes was also determined, and their thermal stability was evaluated. (C) 2004 Elsevier Ltd. All rights reserved.

Preparation, characterization and gas sensing properties of high soluble metal (II) phthalocyanine thin films by spin-coating method

Three novel metal (II) phthalocyanine complexes were synthesized by cyclic tetramerisation reaction of a dicyano benzene component and different metal ions (Pd2+, Co2+, Zn2+). The structure of complexes was confirmed by elemental analysis, mass and IR spectrum. The excellent solubility of the complexes in benzene enabled us to obtain films by a spin-coating method. The films were characterized by IR, electronic spectral and AFM. The gas sensing properties to NO2 of the metal (II) phthalocyanine complex films were studied. In addition, the effects of different metal ions and the gas sensing temperature on the sensing properties were studied. (C) 2005 Elsevier B.V. All rights reserved.

Determination and analysis of the optical constants of thin films of nickel(II) and copper(II) hydrazone complexes by spectroscopic ellipsometry

Thin films of four nickel(II) and copper(II) hydrazone complexes, which will hopefully be used as recording layers for the next-generation of high-density recordable disks, were prepared by using the spin-coating method. Absorption spectra of the thin films on K9 optical glass substrates in the 300-700 nm wavelength region were measured. Optical constants (complex refractive indices N) and thickness d of the thin films prepared on single-crystal silicon substrates in the 275-675 nm wavelength region were investigated on a rotating analyzer-polarizer scanning ellipsometer by fitting the measured ellipsometric angles (Psi(lambda) and Delta(lambda)) with a 3-layer model (Si/dye film/air). The dielectric functions epsilon and absorption coefficients alpha as a function of the wavelength were then calculated. Additionally, a design to achieve high reflectivity and optimum dye film thickness with an appropriate reflective layer was performed with the Film Wizard software using a multilayered model (PC substrate/reflective layer/dye film/air) at 405 nm wavelength.

Optical properties of nickel(II)-azo complexes thin films for potential application as high-density recordable optical recording media

Smooth thin films of three kinds of nickel(II)-azo complexes were prepared by the spin-coating method. Absorption spectra of the thin films on K9 glass substrate in the 300-600 nn wavelength region were measured. Optical constants (complex refractive index N = n + ik) and thickness of the thin films prepared on single-crystal silicon substrate in the 300-600 nm wavelength region were investigated on rotating analyzer-polarizer type of scanning ellipsometer, and dielectric constants epsilon (epsilon = epsilon(1) + i epsilon(2)), absorption coefficients a as well as reflectance R of thin films were then calculated at 405 nm. In addition, in order to examine the possible use of nickel(II)-azo complex thin film as an optical recording medium, one of the nickel(II)-azo complex thin film prepared on K9 glass substrate with an Ag reflective layer was also studied by atomic force microscopy and static optical recording. The results show that the nickel(II)-azo complex thin film is smooth and has a root mean square surface roughness of 2.25 nm, and the recording marks on the nickel(II)-azo complex thin film are very clear and circular, and their size can reach 200 nn or less. (c) 2006 Elsevier Ltd. All rights reserved.

M(C6H16N3)2(VO3)4 as heterogeneous catalysts. Study of three new hybrid vanadates of cobalt(II), nickel(II) and copper(II) with 1-(2-aminoethyl)piperazonium.

postprint

Deep coral and associated species taxonomy and ecology: (DeepCAST) II Expedition Report, Roatan, Honduras, May 21-28, 2011

NOAA has a mandate to explore and understand deep-sea coral ecology under Magnuson-Stevens Sustainable Fisheries Conservation Act Reauthorization of 2009. Deep-sea corals are increasingly considered a proxy for marine biodiversity in the deep-sea because corals create complex structure, and this structure forms important habitat for associated species of shrimp, crabs, sea stars, brittle stars, and fishes. Yet, our understanding of the nature of the relationships between deep-corals and their associated species is incomplete. One of the primary challenges of conducting any type of deep-sea coral (DSC) research is access to the deep-sea. The deep-sea is a remote environment that often requires long surface transits and sophisticated research vehicles like submersibles and remotely operated vehicles (ROVs). The research vehicles often require substantial crew, and the vehicles are typically launched from large research vessels costing many thousands of dollars a day. To overcome the problem of access to the deep-sea, the Deep Coral and Associated Species Taxonomy and Ecology (DeepCAST) Expeditions are pioneering the use of shore-based submersibles equipped to do scientific research. Shore-based subs alleviate the need for expensive ships because they launch and return under their own power. One disadvantage to the approach is that shore-based subs are restricted to nearby sites. The disadvantage is outweighed, however, by the benefit of repeated observations, and the opportunity to reduce the costs of exploration while expanding knowledge of deep-sea coral ecology.

Ca 2+对叶绿体膜流动性及光系统II叶绿素蛋白质复合物的影响

通过实验我们证明Ca2+对叶绿体膜的流动性，对PS I和PS II叶绿素蛋白质复合物的相对含量，以及PS I和PS II的多肽均有影响。 Ca2+对叶绿体膜表层的流动性影响不大，但降低了叶绿体膜深层脂质分子的流动性。从另一个角度阐明了Ca2+抑制光能从PS II向PS I传递的机制。 Ca2+可使PS I的21，23，110KD的多肽转移至PS II，LHCP1和LHCP2中的CF1的两个亚基（55，60KD）转至CPa和LHCP3，从而增加了PS II的捕光截面，引起激发能在两个系统之间的分配的改变。 用免疫学方法可以证明CPIa2和LHCP2的Ab为复合抗体，CPIa1的Ab为单抗，我们可以推测向日葵的不同叶绿素蛋白质复合物具有同源性。

光系统II反应中心D1/D2/Cyt b559复合物的光谱特性及其光破坏作用的研究

采用柱层析法从菠菜叶绿体中分离纯化得到高等植物光系统Ⅱ(PSⅡ)反应中心色素蛋白复合体Dl/D2/Cyt b559，并对其性质，特别是光破坏作用的分子机理进行了研究。主要结果如下： 1、PSⅡ反应中心复合物所含的色素比大约为Chla／2 Pheo a=6.0。其四阶导数光谱在红区有两个峰，表明该反应中心至少存在两种结合状态的Chla。 2、Dl/D2/Cyt b559复合物的荧光相对产率及发射光谱的谱带位置与样品的浓度直接相关。只有当样品的浓度达到足够稀的程度(Chla和Pheo a总浓度小于1μg／ml)，才能得到较真实的荧光光谱，其峰位在681nm处。 3、Dl/D2/Cyt b559复合物的CD光谱在红区（Qy带）有一对反向谱带，正蜂为680nm,负峰为660nm，而在β-胡萝卜素的吸收区没有明显的CD信号。当该反应中心复合物受光破坏后，CD信号明显下降，而且当正峰完全消失后，负峰仍然存在，说明负峰不仅包含P680 的信号，也包含其它色素分子的信号，很可能有部分来源于Pheo a。 4、Dl/D2/Cyt b559复合物在488nm处激发的共振拉曼光谱显示四个主要谱带，其峰位分别在1532(ν1)、1165(ν2)、1010(ν3)和970cm-1（ν4）处，表明PSⅡ反应中心结合的B-胡萝卜素分子是全反式构型。Dl/D2/Cyt b559复合物的色素抽提液的拉曼光谱也显示四个主要的拉曼峰，其中ν4谱带的强度急剧下降，说明PSⅡ反应中心内部结合的β-胡萝卜素分子与抽提液中自由的β-胡萝卜素分子的构象不同，而与光合细菌反应中心内部的类胡萝卜素分子的构象相似，其共轭多烯链的平面也处于扭曲状态。 5、光照使PSⅡ反应中心的原初电子供体P680受到破坏，在光照后的暗放置过程中P680分子继续受到破坏，表明在光照过程中很可能有一个相对稳定的反应中间体产生，以至于光照后暗放置过程中Dl/D2/Cyt b559复合物的光谱特性继续发生变化。也就是说，PSⅡ反应中心Dl/D2/Cyt b559复合物的光破坏不是一步反应，而是一个多步反应或多条途径。 6、光照使Dl/D2/Cyt b559复合物中的组氨酸(His)残基受到很大程度的破坏，甲硫氨酸(Met）残基的含量也略有下降，而其它氨基酸的含量基本保持不变。His残基的破坏很可能与光照后暗放置过程中Dl/D2/Cyt b559复合物的光谱特性变化相关。我们认为His残基的光照破坏很可能是Dl/D2/Cyt b559复合物受光照破坏的另一分子机理。 7、人工电子受体癸基质体醌(DPQ)可以与Dl/D2/Cyt b559复合物进行重组。Dl/D2/Cyt b559复合物的荧光衰减分析表明，在DPQ重组之后，两个长寿命荧光组分（24ns和73ns）的寿命减小，而且占整个荧光的分数也下降，表明这两个长寿命荧光衰减组分均来源于电荷重组过程。同时，β-胡萝卜素分子在DPQ重组之后更易于被光照破坏，这个过程可能与β-胡萝卜素分子的生理功能相关。 8、在没有外加人工电子受体的情况下，光照使DDl/D2/Cyt b559 复合物的多肽组成发生一定变化。SDS-PAGE图谱中出现一个约40KDa的新谱带，同时Dl与D2多肽的表观分子量增加，谱带染色强度下降。 9、本文根据以上实验结果，着重对Dl/D2/Cyt b559复合物光破坏的分子机理进行了分析和讨论，并在D1蛋白裂解的两种可能途经中又增加了一个新的可能导致Dl蛋白裂解的途径，即：His残基的光照破坏可以作为Dl/D2/Cyt b559复合物光破坏及Dl蛋白裂解的又一分子机理，这为深入研究PSⅡ反应中心的光破坏提供了新的线索，也为今后研究活体内光抑制现象的分子机制打下了良好的基础

光系统II反应中心吸能和转能的分子机理研究

全文分两部分，(1)．PsⅡ反应中心色素分子光破坏的分子机理研究;(2)．PSⅡ反应中心原初反应的动力学机理研究。 在第一部分中，在分离纯化的光系统Ⅱ反应中心Dl/D2/Cyt b559复合物中，采用高效液相色谱技术，首次发现PSⅡ反应中心去镁叶绿素分子的光照破坏，研究了去镁叶绿素的光破坏机理，观察到PsⅡ反应中心内部存在一个与光化学活性无关的去镁叶绿素分子，从而提供了PSⅡ反应中心存在两条电子传递链的第一个实验证据，提出了去镁叶绿素对PsⅡ反应中心的光保护假说和光合作用反应中心第二条电子传递支路的光保护假说。用高效液相色谱技术还观察到PSⅡ反应中心的6个叶绿素a分子，有三种不同的存在状态，认为PSl反应中心的最小色素组成为每个反应中心含有4个叶绿素a和2个去镁叶绿素。用光破坏的方法证明PsⅡ原初电子供体P680是由两个叶绿素n分子组成，认为P680是以一个二聚体形式存在，首次发现P680的光破坏过程包含失去中心镁原子的反应。 在第二部分中，用皮秒和飞秒时间分辨光谱技术，在PsⅡ颗粒、PsⅡ核心复合物和PSⅡ反应中心三个层次上，研究了PsⅡ原初反应的动力学性质，着重研究电荷分离和PsⅡ反应中心内部的能量传递过程。结果表明，B-胡萝卜素和P680之间的能量传递时间常数为350p8左右，去镁叶绿素a与P680之间的能量传递时间为lOOp8左右，提出了可能的动力学模型。 在目前分歧最大的原初电荷分离时间常数测定这一焦点问题上，得到的初步结果表明PsⅡ反应中心电荷分离时间为3-3.5pa左右，这一结论与文献上报道的21pa不同，丽倾向于支持国际上3p8的观点。

光系统II反应中心复合物组成性质与光仰制分子机理研究

由于光系统Ⅱ反应中心Dl/D2/Cyt b559色素蛋白复合物(PSII-RC)的红 区吸收光谱严重重叠，给其组成特性研究及光抑制分子机理研究造成 了困难，因此我们运用多种光谱分析技术配合计算机数据处理技术对 PSII-RC复合物的组成特性进行了研究，并用自己建立的方法对PSII-RC 的色素和多肽的化学计量进行了进一步确定，另外还重点研究了单线 态氧在PSII-RC光破坏中的作用，据此提出新的PSD[-RC光抑制分子机 理。主要结果如下： 1．用反相HPLC外标法测定我们制备的色谱纯PSR-RC样品的色素化 学计量结果为Chl:Pheo:Car= 6:2:2。我们发现，当PSII-RC中存在微量CP47 时，Chl: Pheo的比例与CP47的含量呈正相关关系，说明较高的Chl比例 可能表示样品中有CP47污染。结果还表明PSII-RC中Car: Pheo的比例也与 CP47含量有关，说明CP47可影响Car在PSII-RC上的结合，这暗示CP47可 能结合Car，或者CP47对PSII-RC上Car的结合位点有影响，这一推测对阐 明CP47的功能有一定启发作用。 2．建立了一种估算PSII-RC多肽化学计量的理论计算方法，即利用计 算机统计PSII-RC中各多肽组分的不同氨基酸残基数量，以确定不同多 肽化学计量时的理论氨基酸残基组成，并与PSlI-RC的实测氨基酸残基 组成进行比较，得到所用PSII-RC样品的多肽化学计量值为D1+D2:Cyt b559-o+邮：I=2:1:1. 3．对PSII-RC的红区吸收光谱进行了高斯解析，发现680 nm附近含有 峰高和半高宽明显不同的两个高斯组分，它们对光抑制处理的响应具 有明显差别，分别表现了P680和Pheo的特征。由此可知，在680nm处除了 有P680的信号外，PSII-RC中的Pheo在这个区域也有跃迁组分。这个结果 表明光抑制进程中PSII-RC红区吸收光谱信号的下降除了P680的破坏 外，还与Pheo的破坏有关。 4．用Ste)anov关系式分析了PSII-RC色素激发态分布的平衡状态，发现 经过暗适应的PSII-RC的激发态可达到充分的平衡，光抑制处理可导致 PSIL-RC激发态平衡受到破坏。 5．用荧光发射光谱观察到PSII-RC在光抑制进程中有弱光破坏和强光 破坏两个破坏过程，前者是与色素间能量传递的色素结合状态与 取向的破坏，后者与色素本身化学结构的破坏有关。通过研究不同激发波长下的发射光谱发现Car的弱光破坏过程比Chl快，暗示Car可能的保护作用，而Pheo的破坏程度比Chl小。从发射光谱组分的光破坏时间 进程推断强光破坏过程导致的色素破坏是多步反应，验证我们小组原 先报导的PSII-RC的多步反应特性。 6．首次将磁圆二色光谱( MCD)技术应用于PSII-RC研究，发现MCD明显表现出比吸收光谱要丰富得多的光谱精细结构，同时还具有较高的灵敏度和分辨率，不经过任何解析就可直接观察到680 nm组分及其它色素组分的变化，而且PSⅡ-RC中的Car没有明显MCD信号，使PSII-RC谱 图简化，便于进一步分析。用MCD技术还观察到光抑制初期Chl从PSII- RC复合物上脱离及Pheo的光破坏现象。 7．分别用HPLC法、吸收光谱高斯解析法、荧光发射光谱分析法和MCD法共四种方法证明了PSII-RC中Pheo的光破坏，充分证实我们小组关于Pheo光破坏的报导，同时还证明Pheo的光破坏是单线态氧作用的结果。 8．给出了单线态氧参与PSII-RC色素和蛋白光破坏的直接实验证 据，即发现光抑制过程中色素和蛋白的破坏受到单线态氧的特异性清除剂的保护，用化学方法在暗中产生的单线态氧同样造成与光抑制相 似的PSII-RC各组分的损伤，由此说明单线态氧是PSII-RC光抑制过程中 的直接破坏因子。 9．提出了PSII-RC中Hiis残基光破坏的一种新的分子机理。用组氨酸残基的特异性化学修饰剂证实以前我们实验室发现的PSI[-RC组氨酸残基的光破坏，根据比较蛋白变性前后的测定结果，初步证明PSIl-RC中 受光破坏的His残基位于P680附近。我们还观察到光抑制处理后，PSII- RC表现与组氨酸残基被修饰后的样品相似的紫外吸收特征，由此提出 PSII-RC中His残基光破坏的一种分子机理，即His残基的眯唑环上的两个氮原子与其它多肽上的游离氨基在单线态氧的作用下发生反应形成酰 胺键而导致PsII-RC多肽间的共价交联，推测PSII-RC中His残基的光破坏与其蛋白的光致交联和降解有直接的因果联系。

高等植物光系统II捕光天线结构与功能的研究

高等植物光系统II的捕光天线蛋白（LHC II）在光能的吸收、传递和调节激发能在两个光系统之间的分配以及维持类囊体膜的垛叠等方面都起着重要的作用，因而得到了广泛的研究。目前普遍认为LHC II在植物体内是以三聚体的形式存在并行使功能的，但也有研究者发现了单体和寡聚体等多种形式的LHC II。本论文以菠菜为研究对象，采用改进的方法从类囊体膜中提取纯化了LHC II三聚体，对膜脂和色素在三聚体形成和蛋白空间结构中的影响，以及不同聚集态LHC II组成、结构和功能的差异进行了较系统的研究。此外，还将Lhcb2基因反向插入到烟草中，利用转基因植物来研究其生理功能。获得了如下结果： 1，采用改进的方法从菠菜类囊体膜中分离纯化了LHC II。与改进前比，其流程可以缩短2小时且产率也有明显的提高。SDS变性电泳和Triton X-100非变性电泳的检测结果表明，此样品纯度较高，是由三条分子量分别为29KD、28KD和26KD的多肽组成的异质三聚体。同时样品的吸收光谱和荧光光谱分析结果也与前人的报道一致。 2，分析了LHC II三聚体中的膜脂和脂肪酸组成及含量。与PSII相比，LHC II含有相同的四种膜脂：MGDG、DGDG、PG和SQDG。但LHC II中PG的含量是PSII的两倍，说明PSII中的PG主要富集在外周天线区域。同时PG中含有特异的反式十六碳一烯酸，且含量很高。用专一消化PG上Sn-2位脂肪酸链的磷脂酶A2（PLA2）处理LHC II三聚体，然后再加入PG重组的方法证明了含十六碳一烯酸的PG在三聚体结构的维持中起着至关重要的作用。去掉PG后， LHC II三聚体的结构受到了影响，部分解聚成了单体，同时其光谱特性也发生了变化，表现为叶绿素b分子的吸收峰及其激发的荧光发射峰都明显下降。回加PG则可使解聚的单体又重新聚集成三聚体。 3，分别用电洗脱和蔗糖密度梯度离心两种方法分离了LHC II三聚体、二聚体和单体。两者比较，电洗脱对样品的破坏较大，而蔗糖密度梯度离心更加温和，对蛋白上结合的色素影响不大。系统研究了不同聚集态LHC II的组成和光谱特性后发现，三种聚集态的LHC II有相同的多肽组成，并且都结合着5种色素，但是色素的含量差异较大。二聚体和单体中，叶绿素b和类胡萝卜素分子的含量比三聚体的低很多，此外，单体叶绿素a分子的含量也明显减少。对三种聚集态LHC II的各种光谱特性进行分析的结果表明，由于叶绿素b和类胡萝卜素分子含量较少，二聚体和单体中叶绿素b和类胡萝卜素的吸收均有所下降，而且从类胡萝卜素到叶绿素b以及从叶绿素b到叶绿素a的能量传递效率都低于LHC II三聚体，总体表现为三聚体 > 二聚体 > 单体。此外，不同单体之间叶绿素a到叶绿素a的能量传递也被破坏。推测三种聚集态LHC II在吸能、传能和结构上的差异，可能是植物适应不同外界环境的一种调控机制。 4，模拟体内过程，在体外将大肠杆菌中表达的Lhcb2蛋白和色素进行重组，以此来研究色素与蛋白组装过程中蛋白二级结构和色素结合状态的变化。结果表明色素在脱辅基蛋白的体外重折叠中至关重要。在与色素重组的过程中，蛋白二级结构中-螺旋含量逐渐上升并最终接近天然水平，而无规卷曲逐渐减少。从光谱的变化可以看出，色素分子与蛋白的结合经历了一个由无序到有序的过程，色素蛋白复合物的光谱信号由弱变强，重组得到的样品与天然LHC II十分相似。 5，为了更好地研究LHC II异质三聚体中单体可能具有的独特生理功能，建立了Lhcb2基因的反义抑制植物表达载体pBI-antiLhcb2，用根癌农杆菌介导法转化烟草，获得了转基因植株。酶切和PCR鉴定证明，Lhcb2基因已经成功地插入到烟草里。进一步的分子鉴定和生理生化功能分析还在进行中。

假根羽藻不同聚集态捕光色素蛋白复合物（LHC II）的纯化与功能分析

应用温和、非变性的液相色谱层析技术以及蔗糖密度梯度分级分离技术，从假根羽藻类囊体膜直接分离、纯化出5种不同聚集态的光系统II捕光色素蛋白复合物(LHC II)，即LHC II单体、同质三聚体、异质三聚体、寡聚体l和寡聚体2。这种分离、纯化LHC II的方法与传统的等电聚焦(IEF)电泳分离方法相比，具有蛋白质提取条件温和，纯化的蛋白质样品纯度高且数量大等优点，为进一步研究LHC II分子的晶体结构和功能创造了有利的条件。 SDS-PAGE电泳分析和MALDI-TOF质谱分析结果表明，纯化得到的LHC II单体和同质三聚体都具有一种分子量为24.3 kDa的脱辅基蛋白质，而异质三聚体和两种寡聚体除含有这个脱辅基蛋白外，还含有另一种分子量为23 kDa的脱辅基蛋白。 采用室温吸收光谱、低温荧光光谱及园二色(CD)光谱技术对LHC II单体、同质三聚体、异质三聚体、寡聚体l和寡聚体2内的叶绿素组成以及叶绿索之间的能量传递特性进行分析研究表明，在同一条组成LHC II的脱辅基蛋白多肽链上结合着Chl a二聚体，二聚体内的两个Chl a分子之间存在偶极子相互作用。在这5种LHC II亚复合物中均具有Chl a-Chl a相Chl biChl a→ Chl a能量传递途径，其中同质三聚体表现出最高的能量传递效率，而寡聚体的传能效率大大低于单体和三聚体，同时出现Chl a的淬灭现象。当LHC II脱辅基蛋白质高度聚集形成寡聚体时，其蛋白质上结合的Chlb大量减少，引起这两种寡聚体吸能和传能能力的急剧下降。 LHC II单体、同质三聚体、异质三聚体、寡聚体1和寡聚体2的二级结构数据表明，自由堆积的脱辅基蛋白的二级结构以8．折叠构象为主，当LHC II蛋白质有序聚集形成三聚体时，可能每条蛋白质多肽链上的叶绿素结合区域形成两个跨膜a-螺旋，对称排列在脂双层膜内，而非叶绿素结合区则形成一条跨膜a-螺旋。当LHC II蛋白质高度聚集形成寡聚体 时，LHC II蛋白质的二级结构似乎对其上结合着的叶绿素的影响不大，而LHC II寡聚体内蛋白质的高密度聚集引起的更高级的蛋白质相互之间的空间结构可能对叶绿素的影响起主要作用，特别是破坏Chlb结合位点。 依据上述的实验结果推测在类囊体膜内，LHC II可能通过其脱辅基蛋白聚集形式的转换，调控其光能吸收和激发能传递的过程和效率。