THE MECHANISM OF INTERACTION OF SULPHUR AND p-PHENYLENEDIAMINE

Abstract

Several studies which have been undertaken on reaction of sulphur and p-pheaylenediamine give controversial proposals of mechanisms. Many authors postulate an attack of sulphur diradicals directed onto amino group.     

蛋氨酸与化学增感剂的相互作用机理

运用X射线光电子能谱 (XPS)的ESCA扫描技术研究了蛋氨酸与不同化学增感剂相互作用及其中的硫、金、碳和氧等元素的化学形态和相对含量的变化规律 .发现蛋氨酸与不同的化学增感剂的反应机理是不尽相同的 .蛋氨酸与S增感剂不会发生任何化学反应 ,它们可以稳定地共存于同一体系之中 ;蛋氨酸可以将全部Au3+ 增感剂还原为Au ,其自身部分被氧化为蛋氨酸亚砜 ,并且在其脱质子的羟基部位与Au形成Au -O -C结构的金属配合物 .向蛋氨酸体系中加入S +Au增感剂后 ,体系中的氧化还原反应发生在外加的Au3+ 和S2 O32 - 之间 ,此时蛋氨酸的作用是将被S增感剂还原的Au络合 ,亦形成Au -O -C结构的配合物 .     

重氮树脂与十二烷基硫酸钠相互作用研究

重氮树脂与十二烷基硫酸钠相互作用研究罗杨磊曹维孝（北京大学化学与分子工程学院北京１００８７１）关键词重氮树脂，十二烷基硫酸钠，负性ＰＳ版随着化学与生命科学领域的发展，大分子与小分子在溶液的相互作用越来越受到关注．表面活性剂因其具有自组装能力，...     

THE PHOTOCHEMICAL INTERACTION BETWEEN THE TRIPLET STATE OF 8-METHOXYPSORALEN AND THE MELANIN PRECURSORL–3, 4 DIHYDROXYPHENYLALANINE

Abstract— The photochemical interaction between 8-methoxypsoralen (8-MOP) and the melanin precursorL–3,4-dihydroxyphenylalanine(dopaH₂) has been studied using laser flash photolysis. Triplet excited 8-MOP was thus found to abstract electrons from dopaH₂ ( k ∼ 2 × 10⁹ dm³ mol^-1 s^-1) to form semireduced 8-MOP and semioxidised dopaH₂.The technique of pulse radiolysis was used to establish separately the spectra of (a) the semi-reduced form of 8-MOP at pH 6.5 and (b) the semioxidised forms of dopaH₂ at pH 6.5, 5.8, 4.6 and 3.3. The corresponding λ_max and extinction coefficients found were: for 8-MOP at pH 6.5, λ_max= 350 nm (= 9050 dm³ mol^-1 cm^-1); for dopa at pH 6.5, λ_max= 305 nm (ε= 12000 dm³ mol^-1 cm^-1) and for dopaH at pH 3.3, λ= 305 nm (ε= 5900 dm³ mol^-1 cm^-1).     

INTERACTION OF 8-METHOXYPSORALEN AND NEAR-UV LIGHT CAUSES MUTATION AND CYTOTOXICITY IN MAMMALIAN CELLS

Abstract The interaction of near-UV light and a photosensitizer, 8-methoxypsoralen (8-MOP), was studied in the Chinese hamster ovary cell/hypoxanthine-guanine phosphoribosyl transferase system; cell survival (cloning efficiency) and mutation induction (resistance to 6-thioguanine) were quantified. Exposure of cells to either 8-MOP up to 20 μg/m l (93 μ M ) or near–UV light up to 40000 J/m² had no effect on either survival or mutation frequency. Preincubation of cells with 8–MOP from 5 to 120 min prior to irradiation with various fluences did not affect cell survival or mutation frequency. Survival decreased and mutation frequency increased linearly when either the 8-MOP concentration or fluence was increased while the other factor was held as a constant. Mutation frequency appears to show reciprocity relative to the product of 8-MOP concentration times fluence of near–UV light [(μg/m l )·(J/m²)] throughout a range apparently limited by high cell lethality. The observed pooled data on mutation, f (x), as a function of (μg/m l )·(J/m²), x , fit a linear dose–response line, f (x) = (34.2 + 0.05 x ) × 10^-6. Cell survival, however, does not appear to exhibit such reciprocity.     

壳聚糖与尿素的相互作用及其应用研究进展

尿素能够显著破坏甲壳素/壳聚糖分子氢键结构和疏水相互作用,增加其临界胶束浓度,促进多糖大分子的溶解,并能减少其在溶液中的自聚集现象.碱-尿素水溶液可以作为一种新型的甲壳素/壳聚糖绿色溶剂,有望用于对刺激性要求较为苛刻的食品、生物医学等领域.壳聚糖衍生物特别是其与过渡金属离子的配合物具有良好的尿素吸附功能,可用于尿毒症患者血液中小分子毒物的吸附,对机体刺激性小且不吸附血清蛋白等生物大分子.有望成为血液灌流治疗法中清除尿素等小分子毒性物质的良好吸附剂.壳聚糖还可以作为包膜材料,制备壳聚糖包膜尿素,与普通的包膜尿素相比性能更为优越.     

NATURE OF THE INTERACTION BETWEEN THE PHOTOACTIVE COMPOUND PHENYLHEPTATRIYNE AND ANIMAL VIRUSES

Abstract— The levels of DNA excision repair, as measured by unscheduled DNA synthesis (UDS) and the UV-endonuclease sensitive site assay, were compared in cells derived from human fetal brain and dermal tissues. The level of UDS induced following ultraviolet (UV) irradiation was found to be lower (approx. 60%) in the fetal brain cells than in fetal dermal cells. It was determined, using the UV-endonuclease sensitive site assay to confirm the UDS observation, that 50% of the dimers induced by UV in fetal dermal cells were repaired in 8h, while only 15% were removed in the fetal brain cells during the same period of time. Even after 24 h, only 44% of the dimers induced by UV in the fetal brain cells were repaired, while 65% were removed in the dermal cells. These data suggest that cultured human fetal brain cells exhibit lower levels of excision repair compared to cultured human fetal dermal cells.     

INTERACTION BETWEEN UPOSOMES AND MONOLAYERS IN THE PRESENCE OF CALCIUM

Abstract

The interaction between phospholipid vesicles (phosphatidylcholine : phosphatide acid, 90:10 w/w) and phosphatidylcholine : cholesterol (70:30, molar ratio) monolayers at air/water interfscks has been studied at. several concentrations of calcium cation ( Ca²⁺). The liposome vesicles were SUVs and MLVS.

The vesicles interact with the monolayers, rapidly causing a large increase in surface pressure. Limiting values of surface pressure, 2.07-6.99 mN.m-1 for SUVs, and 7.01-11.11 mN.m^?1 for MLVs, were reached in less than 40?min.

Calcium ion concentration affects the liposome size in MLVs, producing an increase of gyration radius. The SUVs are little influenced. The change in size can be due to a variation of liposome composition induced by calcium: cholesterol molecules can migrate from monolayer to liposomes and the redistribution of exchanged lipids in the outer bilayer can also explain the size variation.     

不对称卟啉化合物的合成及其与氨基酸甲酯的作用

本文合成了含有单取代酰胺基的不对称卟啉及其锌(Ⅱ)络合物Zn(m,2-CNTPP)及Zn(m,3-CNTPP).对三氯甲烷溶液中它们与谷氨酸二甲酯、亮氨酸甲酯以及苯丙氨酸甲酯的作用进行了系统的研究,讨论了卟啉化合物对氨基酸甲酯分子的结合能力、结合方式,以及二者之间的多种存在形式。结果表明,锌卟啉与氨基酸甲酯以1:1的化学计量结合,中心金属锌(Ⅱ)离子和氨基酸甲酯中的氨基配位,卟啉环上的取代基与氨基酸甲酯中的残基可形成氢键、范德华力等弱相互作用。在卟啉和氨基酸甲酯的作用中,氨基与金属离子直接配位,α-碳上的质子靠近卟啉环平面,而酯基中的甲氧基处于远离卟啉环平面的位置。     

菁染料与溴化银相互作用性质的研究

本文用计时电位法及电位滴定研究了十六种不同染料与溴化银之间的相互作用,进一步证明了具有离域π-电子的菁染料才能与卤化银形成络合物的论点。从得到的平衡常数K表明,固体表面上的卤化银-染料与溶液中银离子-染料具有相同键性质,都是银离子与染料离域π-电子作用的结果。     

THE INTERACTION OF MELANIN WITH 8-METHOXYPSORALEN: EFFECT ON RADIATIVE AND NONRADIATTVE TRANSITIONS. A FLUORESCENCE AND PULSED PHOTOACOUSTIC STUDY

Abstract: The interaction of 8-methoxypsoralen (8-MOP) with synthetic eumelanin was investigated using static and time-resolved fluorescence and pulsed photoacoustic calorimetry. Due to the strong overlap of the absorption bands of melanin and 8-MOP, a method is presented to account for the systematic errors introduced by the optical filter effect exerted by each absorbing species in the fluorescence and the photoacoustic measurements. As a preliminary step to the understanding of the nonradiative behavior of the psoralen-melanin complexes, the photoacoustic parameters of 8-MOP in various solvents were determined. Spectroscopic data indicate the absence of interaction at the ground-state level, whereas the singlet excited state of 8-MOP is quenched by the pigment; the average fluorescence lifetimes are independent of the melanin concentration, thus indicating a static quenching mechanism. The photoacoustic data show that the quenching process involves an increased intersystem crossing probability, which is almost unaffected by the presence of oxygen, as expected for a molecule essentially acting as a type I photosensitizing agent.     

SYNTHESIS AND DETERMINATION OF THE BIOLOGICAL ACTIVITIES OF YEAST ALANINE tRNA ANALOGUES

The role of base modification in yeast tRNAAl(?) function in protein synthesis was examined by the use of unmodified tRNA analogues. Unmodified full length tRNAs, 5'-half tRNAs (nucleotides 1-35) and 3'-half tRNAs (nucleotides 37-75) were transcribed in vitro using T7-RNA polymerase. Unmodified tRNA half molecules were joined to normally modified half molecules (5'-half, nucleotides 1-36; 3'-half, nucleotides 36-75) by T4-RNA ligase. Using this method, we synthesized three analogues of yeast tRNAAl(?): (i) tRNAAl(?) which lacks base modifications in the 5'-half of the molecule; (ii) tRNAAl(?) which lacks base modifications in the 3'-half of the molecule; and (iii) tRNAAla completely lacking base modifications. We determined the biological activities of these analogues. In rat aminoacyl-tRNA synthetase reactions, the alanine acceptance activity decreased by 52%, 79% and 85% when modified bases were absent from the 5'-half molecule, the 3'-half molecule or the total molecule, respectively. In rabbit retic     

光度法研究染料与非离子表面活性剂的相互作用

染料与表面活性剂的相互作用对纺织品的染色有重要影叫,一直是广泛研究的课题.近年来由于胶束增溶光度法的发展,它又引起了分析化学家的注意.但是现有的研究多集中于染料与电性相反的离子型表面活性剂的相互作用,且缺乏深入的定量研究.本文研究一种阴离子染料——漂蓝6B与非离子表面活性剂Triton X-100间的相互作用,用光度法定量地确定了二者的结合比,并进而研究了阴离子表面活性剂SDS对此种相互作用的影响.     

THE INTERACTION OF ETHYL BENZOATE AND TRIFLUOROACETIC ACID IN EXCITED STATE

This paper is concerned with the interaction of ethyl benzoate (EBA) and trifluoroaceticacid (TFA) molecules in the excited state by measurements of steady--state and transient fluo-rescence spectra at room and low temperatures. The results show that not only the 1:1 exci-plex but also the 2:1 triplex between EBA and TFA was formed. The formation pathway ofthe triplex is that the exciplex formed at first, then by the interaction with the EBA mole-cule it transformed into triplex. But it could not be formed by the dimer of EBA by interac-tion with TFA. The dimer of EBA is confirmed in the concentrated solution. So there arefour components in EBA/TFA--concentrated solution and their fluorescence lifetimes aremeasured respectively.     

增感染料与卤化银微晶之间的作用及其聚集态的研究

本文研究了光谱增感染料的结构对立方体卤化银乳剂的感光性能的影响,并利用反射光谱和彩色分析荧光电镜研究了染料在卤化银微晶上的聚集态和Ｊ 聚集体的相对尺寸,通过测定乳剂离子电导率研究了染料的结构对乳剂离子电导率的影响．实验结果表明：本文中所用的九个染料不管是增感还是减感染料都能在立方体卤化银乳剂上形成Ｊ 聚集态;对噻碳菁染料而言,其５位上无论是吸电子基团还是推电子基团的染料形成的Ｊ 聚集体的平均尺寸皆较未取代染料的大,其增感效果也较好;苯环５位上吸电子基取代或平面性好的噻碳菁染料可提高立方体ＡｇＢｒＩ乳剂的离子电导率,证明它们的增感效果也好;６位硝基取代的吲哚碳菁染料是典型的减感染料,其在立方体乳剂上所形成的Ｊ 聚集体较小,但是对乳剂的离子电导无影响．此外,本文还试图对不对称插烯菁染料Ｄｙｅ９使立方体ＡｇＢｒＩ乳剂减感的作用进行了解释     

THE DEPENDENCE OF PHOTOSENSITIZING EFFICACY OF ACRIDINE ORANGE AND TOLUIDINE BLUE ON THE DEGREE OF SENSITIZER-CELL INTERACTION

Abstract— Previous work of photosensitizing action in vivo has commonly been performed under the 'steady' conditions where the sensitizing dye is equilibrated with the cells by allowing ample time for the sensitizer-cell interaction prior to light illumination. The present experiments, by combining a fast mixing technique (20 ms) with short illumination (mostly & < 10 s), intended to measure the change in the efficacy of the sensitizing action on yeast cells during a short period of time starting from the mixing of the two components, sensitizers and cells. We found that the efficacy of the sensitizing action of acridine orange (AO) began to increase within 20 s and continued to do so until at least 10 min. This was true both for the inactivation and the induction of genetic changes. Similar experiments with toluidine blue (TB), which is believed to be normally unpenetrable into the cell, showed no such fast change characterized by a time of less than 60 s, but unexpectedly revealed a small but significant increase in the efficacy after 20–30 min of mixing. This slow change may indicate that TB can penetrate slowly into the hydrophobic region in the membrane, and as a result, it exerts action with a higher efficiency than it remains in the outside medium. The increased induction of genetic changes beyond control level with the fast (& < 60s)TB sensitization in H₂O and D₂O medium is discussed in terms of the diffusiveness of ¹O₂ into the cell interior.     

染料和聚电解质间的相互作用——在染料-磺化聚苯乙烯络合物中的能量转移和染料荧光强度的增强

本工作对磺化聚苯乙烯-吖啶橙体系的光物理行为进行了研究。发现吖啶橙的荧光强度强烈地依赖于所用染料和聚电解质的当量比(P/D)。在P/D=100时观察到有最大的荧光强度。经过校正,此值和Fox等研究苯乙烯和乙烯基共聚物的能量转移中所得结果基本一致。这表明在高分子电解质-染料络合物中能发生有效的能量转移。 本工作还研究了亚甲蓝对吖啶橙荧光的猝灭效应。观察到当体系中加入聚电解质时猝灭效应得以增强。     

SOLUTE-SOLVENT INTERACTION AND ITS EFFECT ON THE VIBRONIC AND VIBRATIONAL STRUCTURE OF PYRENE SPECTRA

Abstract— The enhancement of weakly allowed electronic and vibrational transitions of pyrene in polar solvents at room temperature has been studied by optical and infrared techniques. We previously reported the formation of molecular complexes between pyrene and alcohols by monitoring the changes in the fundamental stretching vibrational band of the —OH group of alcohols in the presence of pyrene. The infrared spectrum of pyrene in the region 1575–1700cm^-1 has been found in the present work to undergo changes in polar solvents, consistent with complex formation, with the appearance of new bands at wavenumbers where symmetry-forbidden transitions exist. The enhancement of weak bands in the electronic spectra is attributed to the reduction in the symmetry of the pyrene molecule brought about by complex formation. Further support for this interpretation is provided by the finding that I-methylpyrene, which has reduced symmetry, shows the enhancement in the electronic spectra and the appearance of new bands in the infrared spectra even in inert solvents. The anomalous behavior of aromatic solvents is discussed.     

刚果红与蛋白质相互作用的分光光度研究及其分析应用

在pH4.1的Britton-Robinson缓冲介质中,刚果红与蛋白质在室温下能迅速结合生成红色复合物,其最大吸收波长为488nm,比刚果红本身紫移了32nm。用光度法研究了该结合反应的最佳条件,并在此基础上建立了测定蛋白质的方法。测定蛋白质(BSA)的表观摩尔吸光系数4ε88为2.876×105L.mol-1.cm-1,该法简便、快速、选择性好、灵敏度高,用于人血清样品和含乳饮料中蛋白质的测定,结果与考马斯亮蓝法一致。