INTERCONVERSION OF BACTERIOCHLOROPHYLL c AGGREGATES IN SOLID FILMS UPON ORGANIC VAPOR TREATMENT

Bacteriochlorophyll c (BChl c) solid films were prepared from a carbon tetrachloride solution on CaF₂ plates as artificial aggregates. Effects of organic vapor such as acetone and tetrahydrofuran (THF) on the BChl c films were studied by absorption and Fourier-transform infrared spectroscopy. Two major homologs (R[E,E]BChl c_F and R[P,E]BChl c_F) and one minor homolog (S[I,E]BChl c) isolated from the green photosynthetic bacterium Chlorobium limicola strain 6230 were examined for the experiments. The BChl c polymeric aggregates absorbing at739–753 nm similar to those in the chlorosome were induced for all homologs upon the treatment of BChl c solid film with acetone vapor. The 13¹-keto C=O stretching band in the R[E,E]BChl c_F solid film showed a downward shift from 1651 cm^?1to 1643 cm^?1 with a concomitant shift of the 3¹-OH stretching bands from 3337 and 3238 cm^?1 to 3163 cm^?1. It was suggested that the lower aggregates brought about by Mg…O=C(13¹) and (3¹)O…O=C(13¹) bonds were transformed into the higher aggregates strongly hydrogen-bonded in a Mg…(3¹)O-H…O=C(13^l) interaction. They were transformed to a monomer-like form absorbing at 667 nm upon exposure to THF vapor and were reversibly converted to the higher aggregates upon removal of THF molecules in vacuo.     

AQUEOUS AGGREGATES OF BACTERIOCHLOROPHYLL c AS A MODEL FOR PIGMENT ORGANIZATION IN CHLOROSOMES

Chlorosomes isolated from Chloroflexus aurantiacus were extracted with chloroform/methanol. The extract contained bacteriochlorophylls c and a and lipids, but was devoid of proteins. This crude extract spontaneously formed aggregates when a methanol solution was dispersed in aqueous buffer. The aggregates could be sedimented by ultracentrifugation and appeared in electron micrographs as stain-excluding bodies with diameters between 70 and 170 nm. The absorption spectrum is remarkably similar to that of intact chlorosomes with an absorption maximum of bacteriochlorophyll c at around 740 nm. The circular dichroism spectrum of the aggregate is also very similar to that of intact chlorosomes. A conservative (±) band centered at 740 nm confirms the highly aggregated state of bacteriochlorophyll c in both systems. Steady-state fluorescence studies showed that in the aggregate energy-transfer from bacteriochlorophyll c to a component emitting at 830 nm took place. When the aggregate was suspended in buffer saturated with 1-hexanol the 740 nm form of bacteriochlorophyll c was reversibly converted to a form with spectral properties resembling the monomer absorbing at 670 nm but still in an aggregated state. This form of bacteriochlorophyll c showed no circular dichroism signal.     

CONTROL OF SYNTHESIS OF REACTION CENTER BACTERIOCHLOROPHYLL IN PHOTOSYNTHETIC BACTERIA

Abstract— The ratio of total bacteriochlorophyll (BChl) to reaction center BChl has been determined in the wild-type and carotenoid-less mutants of Rhodopseudomonas spheroides and Rhodospirillum rubrum with various specific BChl contents. In wild-type R. spheroides the ratio increases as the specific BChl content increases; in the other strains the ratio is almost invariant.
The ability of the wild-type of R. spheroides to alter the size of the photosynthetic unit is apparently correlated with its multi-component BChl spectrum. The amount of reaction center BChl relative to the amount of the longest wavelength component of the spectrum is constant. The variation in the size of the photosynthetic unit is due to variation in the amount of this component relative to total BChl.
The size of the photosynthetic unit does not change as the specific BChl content decreases during growth under aerobic conditions of a culture grown previously under photosynthetic conditions.     

单磺化酞菁镓在水、微乳液中的解聚反应动力学研究

本文研究了单磺化酞菁镓（ＳＰｃＧａ）在水、微乳液（ＴｒｉｔｏｎＸ－１００－壬烷－正戊醇－水）中的二聚现象和解聚反应动力学，测定了二聚平衡常数ＫＤ和解聚速率常数ｋ。结果表明：ＳＰｃＧａ的解聚反应速率与ＳＰｃＧａ的单体浓度ＣＭ和双体浓度ＣＤ的关系为：Ｖ＝ｋ１ＣＤ－ｋ２ＣＭ２     

胶束中的磺化酞菁镓、磺化酞菁的二聚行为研究

本文研究了二磺化酞菁镓(S₂PcGa)、三磺化酞菁(S₃Pc)在胶束(TritonX-100)中的二聚行为。计算了S₃Pc、S₂PcGa在胶束中的二聚常数K_D及分配系数K。并对磺化酞菁在胶束中的增敏,解聚机理进行了探讨。     

MAGNETIC CIRCULAR DICHROISM OF BACTERIOCHLOROPHYLL a IN SOLUTION AND IN A PROTEIN

Abstract— The magnetic circular dichroism (MCD) (300–850nm) of the bacteriochlorophyll (Bchl) a -protein from the green photosynthetic bacterium Prosthecochloris aestuarii 2 K is qualitatively similar to the MCD of Bchl a in methanol and ether solution. This result implies that the transition dipole of the lowest energy electronic transition (near 800 nm) is roughly perpendicular to the transition dipole of the next higher electronic band (near 600nm) for Bchl a molecules in the protein just as it is for molecules in solution. This result provides no support for the recent proposal that interactions with the protein rotates the direction of the transition dipoles of the 800nm band of all the Bchl a molecules in the protein by 90°. While a rotation of the 800nm transition dipoles cannot be rigorously excluded, it would be necessary for the postulated perturbation to rotate the transition dipoles of both the 800 and 600nm bands by 90°. In a broader sense, any postulated perturbation would have to be shown to leave both the absorption spectrum and the MCD largely unaffected. MCD is a more sensitive test than absorption spectroscopy for perturbations of electronic states and changes in the relative orientation of transitions, because it depends on both the magnitudes and directions of at least two electric and one magnetic transition dipole.     

CAROTENOID PIGMENTS AND THE IN VIVO SPECTRUM OF BACTERIOCHLOROPHYLL

Abstract— The isolation of a mutant, strain PM-9, of Rhodopseudonionus spheroides with an abnormal complement of carotenoid pigments is described.
PM-9 accumulates phytoene, phytofluene, ζ-carotene and neurosporene. Semi-aerobic cultures form more ζ-carotene and neurosporene relative to total carotenoids than do photo-synthetic cultures.
PM-9 is killed on exposure to light and oxygen.
By making use of the effect of oxygen on the nature of the carotenoids in PM-9, we have shown that these pigments do not directly influence the in vivo spectrum of bacteriochlorophyll.
Diphenylamine inhibits the synthesis of coloured carotenoids in Rhodopseudonionos gelatinosa but does not change the bacteriochlorophyll spectrum.     

REVERSIBLE OXIDATION OF ANTENNA BACTERIOCHLOROPHYLL IN TWO PHOTOREACTION CENTERLESS MUTANTS OF RHODOSPIRILLVM RUBRUM

Abstract— Reversible oxidation of bacteriochlorophyll in two independent mutants of Rhodospirillum rubrum lacking photoreaction center has been studied to obtain further information about the antenna system of that bacterium. Oxidation of antenna bacteriochlorophyll with ferricyanide is accompanied by three distinct absorbance changes in the near infrared: the appearance of a new band at 1230 nm (B1230) and the bleaching of two bands, a major one at 882 nm (B882) and a minor one at 888 nm (B888). The three absorbance changes take place at potentials higher than those required for complete oxidation of photoreaction-center bacteriochlorophyll in wild-type strains. On the other hand, the B882 bleaching and the B1230 appearance occur under similar redox conditions. The above data suggest, first, that in Rds. rubrum , contrary to the current generalized idea, antenna bacteriochlorophyll exhibits at least two absorption bands, B888 and B882; second, that B882 and B1230 correspond to the same bacteriochlorophyll component. In addition, the appearance of B1230 may indicate that antenna bacteriochlorophyll can be partially arranged in an oligomeric fashion, for bands in that spectral region are not exhibited by oxidized monomeric bacteriochlorophyll.     

SPONTANEOUS AGGREGATION OF BACTERIORHODOPSIN IN BROWN MEMBRANE

Abstract— Halobacterium halobium cells grown in nicotine-containing medium synthesize bacterio-opsin (bO) but little bacteriorhod-opsin (bR) because nicotine inhibits retinal synthesis. In nicotine-grown cells, bacterio-opsin is found in a specific cell membrane fraction, the brown membrane (b.m.), which consists mainly of small round sheets. Freeze-fracture of isolated brown membrane reveals a dense particle population on its cytoplasmic fracture face, with few particles on the external face. There is no apparent order in the particle distribution and the fracture faces are practically indistinguishable from those of red membrane (r.m.). The absorbance spectrum of b.m. shows peaks at 550 and 410nm, the circular dichroism (CD) spectrum a positive band around 540nm and positive and negative bands around 410nm with a cross-over at 412nm. The photoreaction cycle of bR in b.m. has the same intermediates found in purple membrane (p.m.), but the apparent kinetics resemble those of bR monomers. Addition of 13-cis-, or all-trans-retinal to b.m. induces a rapid 5- to 10-fold increase in the visible absorbance band, and the absorbance maximum shifts to 560nm in the dark. Kinetic analysis of the absorbance increase shows three first order kinetic constants with t_½= 0.5 min, 6 min and 100 min, with most of the increase contributed by the fastest component. The CD bilobal pattern typical for purple membrane appears together with the strong negative band at 320nm. Ellipticity change at 590nm is nearly as rapid as the absorbance increase; within 5 min, 85% of the negative band is formed. Electron microscopy after addition of retinal reveals structurally distinct domains in the b.m. sheets which have the characteristic appearance of p.m. However, X-ray reflections are more diffuse compared to p.m. Flash spectroscopy of reconstituted b.m. detects the same photocycle intermediates as in b.m. or p.m., but with apparent kinetics closer to those of purple membrane than before reconstitution. These results show that bO in the b.m. binds retinal to form bR which spontaneously aggregates into a lattice. However, the reconstituted bR lattice is not as well-ordered as in p.m. and some bR is still present in the form of monomers and/or small aggregates.     

双金属引发体系苯乙烯活性聚合活性种的交互缔合动力学

自从发现烷氧基钾(ＲＯＫ)/烷基锂(ＲＬｉ)双金属引发体系对丁二烯苯乙烯阴离子共聚具有高效竟聚率调节作用以来[1],相关的机理研究一直十分活跃[2～6].在这类双金属引发体系中,由于含有Ｋ、Ｌｉ两种反离子,因此可能存在钾活性种(ＰＫ)和锂活性种(ＰＬｉ)的交互缔合体.但迄今有关不同反离子活性种形成交互缔合体的研究报道较少.本工作利用2甲基2己醇钾对苯乙烯均聚反应速度具有较大影响这一特性,对低Ｋ/Ｌｉ情况下可溶性醇钾/ｎＢｕＬｉ双金属引发体系苯乙烯均聚动力学进行了研究.建立了以交互缔合体为基础的反应动力学模型.求得了ＰＫ的增…     

稳态荧光探针研究支链烷基苯磺酸钠的聚集行为

以芘为荧光探针、二苯酮为猝灭剂,用稳态荧光探针法测定了合成的4种带干扰基(磺酸基邻位的短链烷基)的支链烷基苯磺酸钠的临界胶团浓度、合适猝灭剂浓度下的胶团聚集数以及在不同浓度氯化钠水溶液中的胶团聚集数.结果表明,支链烷基苯磺酸钠分子中长链烷基碳数增加,临界胶团浓度大幅度降低,胶团聚集数减小;分子中短链烷基碳数增加,临界胶团浓度降低幅度小,胶团聚集数增大;胶团聚集数随氯化钠浓度增大而增大.     

石墨炉原子吸收光谱法直接测定全血中砷

研究了石墨炉原子吸收光谱法测定全血中砷的方法。用硝酸镍—重铬酸钾为基体改进剂，1：10稀释，建立了基体匹配校准加入法，方法检出限低，灵敏度高，测定结果满意。     

THE ASSOCIATION OF LIVING POLYSTYRYLLITHIUM IN BENZENE

The effects of the chain length,active end group and concentration on the association of living polystyryllithium (PS~-Li~+)chains in benzene were examined by a combination of static and dynamic laser light scattering in a cuvette equipped with a high-vacuum stopcock.The results show that long PS~-Li~+ chains(M_w>1×10~4)usually form dimers in the solution. In contrast,shorter PS~-Li~+ chains exhibit two relaxation modes,where the fast mode is related to the translational diffusion of the living chain dim...     

AGGREGATION OF MONOVINYL- and DIVINYL-PROTOCHLOROPHYLLIDE IN ORGANICSOLVENTS*

Abstract— Two different protochlorophyllides (PChlide), PChlide 629/433 (absorption data in methanol) and PChlide 630/441 (the monovinyl (MV) and divinyl (DV) forms) were isolated from the pigment mutant C-2A'of Scenedesmus obliquus. Their spectroscopic behaviour in several organic solvents and their aggregation in toluene was investigated. In polar solvents such as ether, acetonitril or acetone, absorption maxima similar to those in methanol were observed, while in solvents such as tetrahydrofuran and pyridine a bathochromic shift of the blue absorption band compared to the spectra in methanol occurred. The absorption maxima of MV-PChlide shifted from 629 nm and 433 nm in methanol (monomeric form), to 631 nm and 443 nm in toluene (aggregated form). The absorption maxima of DV-PChlide shifted from 630 nm and 441 nm in methanol to 655 nm and 483 nm in toluene (aggregated form). The fluorescence excitation and emission spectra of the two protochlorophyllides yielded the according results. The aggregation process was faster for DV-PChlide than for MV-PChlide and was reversible upon addition of small amounts of polar solvents. The similarity of the spectral characteristics of the aggregated forms of the different protochlorophyllides after toluene treatment with those reported for “active”-PChlide in vivo are discussed.     

THE ORIENTATION OF CHLOROPHYLL AND BACTERIOCHLOROPHYLL MOLECULES IN AN ORIENTED LECITHIN MULTILAYER

Abstract— Chlorophyll a and b and bacteriochlorophyll a have been incorporated in an oriented phospholipid multilayer. The orientation of the chlorophyll molecules in this layer has been measured by polarization spectroscopy. Formulas are given expressing the dichroic ratio R as a function of the angle of tilt θ between the molecule and the plane of the multilayer and the angle μ between this plane and the transition dipole moment measured in the plane of the molecule. The possibility of overlapping bands of mutually perpendicular polarization has been taken into account. Analysis of the experimental results gives the angles θ and μ as well as an estimate for the fraction of polarization of some bands along the dihydro axis in the plane of the chlorophyll molecule.     

全谱段H点标准加入法研究

改进了Ｈ点标准加入法。这种方法称为“全谱段Ｈ点标准加入法”，当分析物质和干扰物质同时存在于样品中时，这种方法可获得分析物质的无偏差分析浓度，全谱段Ｈ点标准加入法，采用干扰物质吸收光谱图上多个成直线的波长点，以Ｈ点标准加入法和Ｋ比例Ｈ点标准加入法为判据，测定多组分体系，并以水杨酸－对硝基苯甲酸－对氨基苯甲酸的不同混合物为例，对方法进行验证，结果满意，并采用先进的Ｗｉｎｄｏｗｓ应用程序设计语言Ｖｉｓｕａｌ Ｂａｓｉｃ４．０设计出具有Ｗｉｎｄｏｗｓ“图形用户界面”特点的应用程度，这使得原本枯燥杂乱的多数据计算，分析工作变得简洁有序并饶有趣味。     

DISTRIBUTION OF DI-SULFONATED ALUMINUM PHTHALOCYANINE AND PHOTOFRIN II IN LIVING CELLS: A COMPARATIVE FLUOROMETRIC STUDY

Microspectrofluorometric and fluorescence imaging techniques have been employed to study the internalization and intracellular distribution of both Photofrin II, an experimental drug used in photodynamic therapy, and di-sulfonated aluminum phthalocyanine, a very promising photosensitizer. The results obtained by microscopic techniques in living cells have been compared with those obtained in solution on cell extracts. Experimental results indicated that the complexity of the drug-cell interaction can be explained according to the chemico-physical nature of the drugs. In particular, the presence of both monomeric and aggregated fractions, which are supposed to be internalized through different mechanisms, accounts for the intracellular distributions observed for both drugs, depending on the treatment conditions. Equilibria among the drug fractions take place within the cells, resulting in the persistence of the intracellular fluorescence. On the whole, the behavior of the two drugs appears very similar, except for some aspects related to the intracellular distribution, which can be explained in terms of different degree of lipophilicity of the drugs.     

以双硫酯为链转移剂的活性自由基聚合

合成并研究了两种双硫酯链转移剂的纯化方法 ,进行了多种单体以双硫酯为链转移剂的活性自由基聚合及嵌段共聚 .发现以PhC(S)SC(CH3) 2 Ph为链转移剂的效果比PhC(S)SCH(CH3)Ph好 ,聚合产物的多分散性系数较小 .引发剂与链转移剂的摩尔数比为 1∶3 5～ 1∶4 2时 ,得到多分散性系数小 ,实测分子量与理论分子量相近的聚合产物 .聚合物的分子量随时间和转化率的增加而增加 ,加入第二单体形成嵌段共聚物 ,具有活性聚合特征 .聚甲基丙烯酸酯大分子引发剂引发丙烯酸酯单体聚合时 ,聚合速度最快 .     

阴离子碳菁染料的合成与聚集动力学研究

自从1938年,Scheibe^[1]发现了菁染料聚集体中的能量传递现象,人们对菁染料的聚集行为展开了大量的研究^[2,3].由于菁染料聚集体对乳剂具有特殊的增感作用,人们主要研究聚集体在乳剂中的增感机理^[4,5]以及菁染料聚集的溶剂效应与浓度效应^[6]等,而对于菁染料聚集的动力学行为研究较少.