螺旋藻中藻蓝素的提取研究

从螺旋藻中提取藻胆蛋白,用甲醇解离其硫醚键得藻蓝素。其最佳解离条件是：温度为４０℃,解离时间为２４ｈ,Ｖ（甲醇）∶ｍ （藻胆蛋白） ＝２００∶１ 。提取率可达１－５％ ,产物的ＵＶ,ＩＲ和文献相符。藻蓝素发色团在酸性溶液中呈比较扩展型,而在中性溶液中呈比较闭合的结构。     

藻蓝素的提取及其光学性质研究

以螺旋藻粉为原料,采用反复冻融法将细胞破碎,然后分别用25%和50%饱和度的硫酸铵溶液盐析等方法制得藻蓝蛋白;用10 mol/L浓盐酸在80℃下处理30 min,破坏了蛋白质与发色团之间的硫醚键,得到游离的发色团-藻蓝素。通过分析产物的紫外可见吸收光谱和荧光光谱了解产物的光学性质,测得所制的产物在660 nm处有荧光;藻蓝素可以溶解在有机溶剂中,在改善有机高分子材料的光学性质方面具有应用价值。     

多变鱼腥藻藻胆蛋白共价复合物的合成及其分子内能量传递

利用双功能基偶联剂３－（２－吡啶联巯基）丙酸Ｎ－羟基琥珀酰亚胺酯（ＳＰＤＰ）合成了两个藻胆蛋白复合物,藻红蓝蛋白－变藻蓝蛋白复合物ＰＥＣ－ＡＰＣ和藻红蓝蛋白－藻蓝蛋白复合物ＰＥＣ－ＰＣ．利用吸收光谱和荧光光谱证明了藻胆蛋白构型与构象在反应后得到保持．通过荧光光谱观察到能量传递现象．计算出复合物ＰＥＣ－ＡＰＣ的分子内能量传递效率约为９０％．复合物ＰＥＣ－ＰＣ中藻红蓝蛋白ＰＥＣ的荧光寿命比ＰＥＣ本身的寿命大大缩短,证明存在分子内能量传递．二硫苏糖醇（ＤＴＴ）还原二硫桥键后能量传递被阻断．这进一步证明复合物合成成功及分子内能量传递．     

红藻条斑紫菜R—藻红蛋白中的能量传递过程

本文通过对条斑紫菜Ｒ－ＰＥ（藻红蛋白）及其α、β、２亚基的吸收光谱和荧光光谱进行计算机解叠，研究了Ｒ－ＰＥ内发色团之间的能量传递过程，并对Ｒ－ＰＥ及亚基门的各发色团进行了“Ｓ”和“ｆ”型的指认。发现在亚基中为“ｆ”型的发色团在Ｒ－ＰＥ中起着“ｓ”型发色团的作用，且将能量传递给量最后的“ｆ”型发色团。荣光激发偏振光谱进一步证明了Ｒ－ＰＥ内的能量转移过程与计算机解叠的结果一致。     

红藻条斑紫菜R－藻红蛋白中的能量传递过程

本文通过对条斑紫菜Ｒ－ＰＥ（藻红蛋白）及其α－β－γ亚基的吸收光谱和荧光光谱进行计算机解叠，研究了Ｒ－ＰＥ内发色团之间的能量传递过程，并对Ｒ－ＰＥ及亚基内的各发色团进行了“ｓ”和“ｆ”型的指认。发现在亚基中为“ｆ”型的发色团在Ｒ－ｐＥ（αβ）＿６γ中起着“ｓ”型发色团的作用，且将能量传递给最后的“ｆ”型发色团。荧光激发偏振光谱进一步证明了Ｒ－ＰＥ内的能量转移过程与计算机解叠的结果一致。     

过渡金属离子（Cu^2＋,Cd^2＋）对藻红蛋白单体的漂白机制

过渡金属离子（Ｃｕ２＋、Ｃｄ２＋）对藻红蛋白单体的漂白机制＊赵继全赵井泉张建平杨紫萱蒋丽金＊＊（中国科学院感光化学研究所，北京１００１０１）关键词漂白，藻红蛋白单体，藻红蛋白亚基，多肽链残基，色团络合物藻胆蛋白是一组同源捕光色素蛋白，由多肽链及相连的...     

苯基生色团修饰壳聚糖甲酸溶液中手性研究

在甲基磺酸体系中,分别将苯甲酰氯、对氯苯甲酰氯与壳聚糖反应,制备了具有发色团的苯甲酰化壳聚糖和对氯苯甲酰化壳聚糖。紫外光谱表征表明产物具有目标产物的结构特征。苯甲酰化壳聚糖、对氯苯甲酰化壳聚糖分别在254 nm和258 nm处具有苯基特征吸收峰。温度25℃,在质量浓度为250 mg/L时,苯甲酰化壳聚糖和对氯苯甲酰化壳聚糖甲酸溶液的圆二色谱信号均出现以苯基相应紫外吸收最大波长为中心的耦合裂峰（一个正峰和一个负峰）,表明发色团在壳聚糖螺旋链有序规则排列,壳聚糖分子链为左旋构象。对氯苯甲酰基发色团更适合测量甲酸溶液中壳聚糖构象特性。苯甲酰化壳聚糖和对氯苯甲酰化壳聚糖分子链构象受温度影响。     

1，3－二β－萘甲酰基杯［4］芳烃的荧光光谱与光二聚反应

本文合成了含荧光发色团的杯芳烃衍生物１，３－二β－萘甲基杯［４］芳烃１，研究了它在极性溶剂及非极性溶剂中的光物理与光化学行为，并通过萘发色团荧光及光二聚反应研究了杯［４］芳烃衍生物的构象。     

反胶团萃取分离地木耳中藻蓝蛋白

采用阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)反胶团萃取分离地木耳中藻蓝蛋白。分别考察水相pH值、离子强度和种类、有机相中有机溶剂配比、表面活性剂浓度和助溶剂浓度对萃取行为的影响;同时采用正交试验法,考察反萃取过程中反萃液种类、浓度和pH值对萃取液中藻蓝蛋白反萃取行为的影响,最终得到适宜的萃取分离工艺条件。结果表明:0.05mol/LCTAB/正己醇-正辛烷(体积比1∶4)的反胶团体系用于萃取pH=7的地木耳细胞破碎液,藻蓝蛋白萃取率可达98.1%,分配系数达到50.7;溶液中不同离子种类和强度对萃取率影响不同,萃取率随着离子强度增大而降低;采用pH=4.0、3mol/LKBr反萃液反萃藻蓝蛋白,反萃率可达98.5%,其纯度可达16.8。     

1,3—二β—萘甲酰基杯[4]芳烃的荧光光谱与光二聚反应

本文合成了含荧光光发色团的杯芳烃衍生物１，３－二β－萘甲基杯「４」芳烃１，研究了它在极性溶剂及非极性溶剂中的光物理与光化学行为，并通过萘发色团荧光及光二聚反应研究了杯「４」芳烃衍生物的构象。     

Biliproteins: Some Relationships Among Aggregation States,Spectra, and Excitation-Energy Transfer

The key aggregation steps for C-phycocyanin consist of denatured subunits (α and β polypeptide chains), monomers, trimers, hexamers and stacks. For allophycocyanin the steps are denatured subunits, monomers and trimers. Ultimately these assembly states lead to the formation of phycobilisomes in blue-green and red algae. The spectroscopic changes that accompany each stage in the assembly can be monitored as a function of the ratio of visible to near-UV absorption. For C-phycocyanin, monomers and hexamers are the important levels in the modulation of tetrapyrrole conformation by protein-chromophore interaction. The effect of protein aggregation on the protein-chromophore interactions is the key to solar-energy harvesting and excitation-energy migration in photosynthesis.     

A pre-modification-direct synthesis route for the covalent incorporation and monomeric dispersion of hydrophobic organic chromophores in mesoporous silica films

Mesoporous silica films covalently doped with hydrophobic disperse red chromophores have been prepared with a new pre-modification-direct synthesis route via a dip-coating technique using P123 surfactant as the structure-directing agent under acidic conditions. The disperse red chromophores were pre-modified with hydrophilic alkoxylsilanes and then hydrolyzed and co-condensed with tetraethylorthosilicate to form mesostructured hybrid films. The effect of aging time of starting sols and chromophore concentrations on the mesostructures and dye aggregations were investigated. Non-mesostructured films were also prepared as a reference. In the mesostructured hybrid films, the hydrophilic silane groups of the modified disperse red were covalently linked onto the pore surface while the hydrophobic disperse red chromophores monomerically dispersed in the pore spaces of the films rather than restricted within the silica walls due to its hydrophobic nature.     

Chain organization and photophysics of conjugated polymer in poor solvents: Aggregates, agglomerates and collapsed coils

UV/vis absorption, excitation, and emission spectroscopies are utilized to explore the association behavior of conjugated polymer, poly[2-methoxy, 5-(2′-ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV), in a homologous series of linear alcohols and solvent-nonsolvent systems. We demonstrate that the aggregation, agglomeration, and collapse of isolated chains, which all take place in the poor solvents, exhibit different optical signatures. The aggregate, in which chromophores interact electronically, causes a red shift of absorption and emission spectra while the weak interaction of chromophores in the agglomerates leaves electronic properties unaltered. The collapse of isolated chain is accompanied by a blue shift of the spectra. Energy transfer from excited chromophores of non-aggregated chains to the lower energy aggregates is significantly diminished in the system of alcohol solvents, allowing separate emissions from various chromophores to occur. The optical signatures and extent of energy transfer are used as tools to elucidate the association mechanism and chain organization of isolated chains into large particles upon decreasing solvent quality. The extreme collapse of isolated chains in the very poor solvents is found to inhibit the chain organization into aggregates.     

Polymer-bound pyrrole compounds. V. On the optical properties of an insoluble polystyrene matrix bearing di- and tetrapyrroles covalently anchored

The absorption and fluorescence spectra of samples of variable particle size, consisting of an insoluble polystyrene matrix bearing different covalently attached di- and tetrapyrroles, are studied and compared with solutions of the same chromophores present as their methyl ester derivatives. The specific chromophores consist of xanthobilirubinic acid, N′-methyl xanthobilirubinic acid, bilirubin IX-α, biliverdin IX-α, mesoporphyrin IX and Zn(II) mesoporphyrin IX, anchored as esters to α-4-[(ylmethyl-3-nitrobenzamido)benzyl]-poly(styrene-co-1%-divinylbenzene). The spectral differences observed are: (1) an apparent decrease in the extinction coefficient of the high energy band relative to the low energy band of the verdin and porphyrin chromophores; and (2) variable shifts of the absorption wavelength maxima depending on the specific system. Scattering by the polymer is mainly responsible for the first, but chromophore aggregation also contributes to band shifts. Both phenomena are more important in particles of comparatively larger size, as has been confirmed by comparing spectroscopic properties of micellar and vesicular systems containing the same chromophores. The present systems are interesting because: (1) one can derive qualitative information on several aspects of the polymer matrix itself, such as the interactions of a given site with its immediate surroundings; and (2) they serve as models for investigations of chromophore-imbedded tissue optics, and in general, of energy absorption by dyes in a light-scattering medium.     

Relevant chiroptical and thermal properties in optically active methacrylic copolymers containing carbazole and azoaromatic chromophores in the side-chain

Novel optically active methacrylic copolymers, bearing carbazole and azoaromatic moieties linked to the main chain with a rigid (S)-hydroxysuccinimide residue of one prevailing absolute configuration, have been prepared and characterized with the aim to establish the effects of the chiral group and of the dipolar interactions between the two side-chain chromophores on their properties.In particular, the observed chiroptical properties suggest the presence of ordered chiral conformations at least for chain segments of the macromolecules. Spectroscopic, thermal and chiroptical characterizations of these copolymers demonstrate the occurrence of significant electronic interactions between carbazole chromophores and azobenzene moieties. These interactions are related to the unusual partially alternating structure of the investigated copolymers and the relevant chiroptical and thermal properties. In fact, the polymeric derivates show high glass transition temperatures and good thermal stability, thus opening the way to a variety of potential applications based on photoconductive and optoelectronic properties.     

Aqueous two-phase countercurrent distribution for the separation of c-phycocyanin and allophycocyanin from Spirulina platensis

C-phycocyanin (C-PC) and allophycocyanin (APC) with similar molecular structures were separated, respectively from Spirulina platensis cell homogenate by single extraction and multi-stage countercurrent distribution (CCD) using an aqueous two-phase system (ATPS) composed of polyethylene glycol (PEG) and potassium phosphate (KPi). The partition coefficients of C-PC and APC were 10.64 and 0.57, respectively, and the extraction selectivity of C-PC was 18.67 from 0.5% (w/w) S. platensis crude extract by single extraction using PEG6000/KPi ATPS (pH 7.0) with 34% (w/w) tie line length (TLL). In ten-stage CCD under the same ATPS extraction condition with 2% (w/w) S. platensis crude extract, the purity of C-PC increased nearly twice and the recovery of APC increased more than nine-fold compared with single extraction. The results displayed that most C-PC (82.1%) followed the mobile phase was enriched in the top phases of the last three tubes, while more APC (41%) remained in the stationary phase was enriched in the bottom phases of the first three tubes in the ten-stage CCD. Hence, aqueous two-phase CCD technology provided an effective and low cost method for C-PC and APC separation from S. platensis cell homogenate directly.     

Conformational Analysis of Nitroglycerin

The conformation of the energetic plasticizer, nitroglycerin, has been studied by classical potential energy calculations. The calculations reveal three low energy conformations, each of which has a different dipole moment. The three conformations found are consistent with the published NMR data if an equilibrium between the three conformers is assumed. The results have implications for the interaction of nitroglycerin with solvents and propellant bases.     

Athabasca油砂沥青中重组分的分子模拟

利用分子模拟技术对加拿大Athabasca油砂沥青超临界萃取分馏残渣组分的化学分子结构进行了研究，首先选用长度不同的桥链构建了其三维平均结构，然后采用分子力学(MM)和分子动力学(MD)方法得到能量最低也即最稳定的构象.研究发现，即使分子的二维结构相同，其三维结构差别也很大，由此可见仅用二维模型来表征重质油大分子的结构和物理化学性质远远不够.另外，分子模拟还可以预测沥青质残渣中最有可能存在的桥链长度.Athabasca沥青残渣组分中长度为C5到C7的桥链存在的可能性最大，而C1和C2桥链则由于其总能量相对较高，存在的可能性较小.     

Shear thickening behavior of dilute poly(diallyl dimethyl ammonium chloride) aqueous solutions

Using dynamic light scattering (DLS) and capillary dynamic viscoelasticity (DVE) analyzer, we investigated dilute (0.5 mg/ml) poly(diallyl dimethyl ammonium chloride) (PDADMAC) aqueous solution properties for three different molecular weights of PDADMACs mixed with various concentrations of NaCl. The dependence of PDADMAC molecular chain conformations in aqueous solutions on polymer molecular weight and NaCl concentration were studied. By analyzing dynamic shear viscosity η′(ω), viscoelastic relaxation times t_r, and shear rate at tube wall ?_a(ω) of PDADMAC aqueous solutions in oscillatory flows, we proposed that polymer chain conformations varied with increasing shear frequency ω via the following steps: intra-polymer associations, dissociation of intra-polymer associations, stretching of polymer chains, inter-polymer aggregations, and dissociations of inter-polymer aggregations. The intra-polymer associations lowered the n′ exponent of storage modulus G′(ω) (G′(ω) ∼ ω^n′) with n′ < 2, and the polymer chain stretching and inter-polymer aggregations caused shear thickening (i.e. upturn of η′(ω)) of PDADMAC aqueous solutions. The behaviors of the lowering of n′ exponent with n′ < 2 and the shear thickening were favored by increasing ionic strength of solutions. By comparing η′(ω) data with DLS hydrodynamic radii (R_h) data, we also confirmed the possibility of inter-polymer aggregations in dilute solutions when polymer chains were stretched in oscillatory flows.     

ESR and ENDOR Probes of Skeletal Conformations Implications for Conformations and Orientations of Chlorophylls In Vivo

ESR and ENDOR studies of sterically hindered porphyrins and chlorins provide clear evidence of the flexibility of the porphyrin skeleton, in agreement with crystallographic results. Examples considered are the cation radicals of zinc tetraphenyl-octaethylporphyrin and of the zinc and cobaltous nitrosyl complexes of octaethyl- and methyl octaethyl-chlorins. Extrapolation of the above results suggests that, in vivo, the protein pocket into which the chromophores fit and neighboring residues provide ready means of altering the conformations and properties of the pigments. These considerations can be applied to the primary acceptors of photosystems I and II: a combination of theoretical calculations, model studies and ENDOR results for the chlorophyll and pheophytin acceptors of photosystems I and II, respectively, suggests specific orientation of the 2-vinyl substituents of the chromophores and, in addition, supports the existence of hydrogen bonding at the 9-keto group. The implications of these results are that the protein environment helps control the orientations of the macrocycles and substituents, and thereby optimizes the relative orientations of donors and acceptors to facilitate electron transfer.