Physicochemical and Cytochemical Investigations on the Binding of Ethidium and Acridine Dyes to DNA and to Organelles in Living Cells

Ethidium and acridine dyes are classical model substances for studying the binding of small, pharmacologically active molecules to DNA. Intercalation between the DNA base pairs is nearly always proposed as the most important type of binding. According to our investigations, however, there is a second type of binding, which also occurs when the concentration of the bound molecules is low and will be referred to here as external or preintercalative binding. The experimental binding isotherms show that the binding constant for intercalation K_S1 is considerably smaller than that for external binding K_S2 (K_S1 > K_S2). This surprising result is not due to the binding enthalpy (ΔH ≈ ΔH) but to the binding entropy (ΔS > ΔS). Electrostatic interactions between the dye and the DNA represent the most important contribution to both types of binding; they are supplemented by hydrogen bonds and hydrophobic interactions. The behavior of a substance in living cells, however, cannot be reliably predicted from its in vitro binding to DNA. Very few substances are bound to the DNA of the nuclear chromatin in cell culture; for example, dyes often accumulate instead in the lysosomes. In some cases the dye binds specifically and very efficiently to the mitochondria of the living cell, especially to the mitochondrial membranes, the sites of oxidative phosphorylation.     

氢化物发生—分光光度法测定染发剂中的微量铅

本文提出了用铁氰化钾将铅氧化至高价,再用氢化物发生-分光光度法测定铅的一种新方法。该法灵敏度高,简便快速,用于分析染发剂中的铅,取得了较好的效果。     

The effects of solvation in the theoretical spectra of cationic dyes

We present a quantum-mechanical study on the solvent effects in the structure and electronic spectra of some cationic dyes: acridine orange, proflavine, safranine, neutral red, thionine and methylene blue. The geometry optimizations were carried out with the AM1 and DFT (with B3LYP functional) methods and the theoretical spectra of the dyes under study were obtained with Zindo time-dependent methods (TD–DFT and TD–HF). The solvation methodology adopted was the integral equation formulation (IEF) version of the polarizable continuum model (PCM).     

Structures of terminal heterocyclic groups and fluorescence-spectral properties of polymethine dyes

The fluorescence and absorption bands of carbocyanines containing pyrylium or benzoxazolium groups, their nitrogen-, sulfur-, and selenium-containing analogs, their benzohomologs, or isomeric analogs of pyrylium as terminal groups were mathematically processed using the method of moments. The regularities in the displacement of the absorption and fluorescence bands following the replacement of the heteroatom and variations of the positions of substituents in the terminal groups were explained using perturbation theory. Based on quantum-chemical calculations, the changes in the bond orders in the ground and excited states of the dyes were studied. The correlations between the moments of the experimental absorption and fluorescence bands and the frequency and the form of the chromophore vibrations were analyzed. The transition from pyrylo-4-cyanines to isomeric pyrylo-2-cyanines leads to substantial broadening of the bands, an increase in the Stokes shifts, decreases in the coefficients of asymmetry, kurtosis, and fine structure of the bands, as well as a decrease in the quantum yield of fluorescence.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2194–2203, September, 1996.     

Analyses of carcinogenic aromatic amines released from harmful azo colorants by Streptomyces SP. SS07

Extracellular fluid protein (ECFP) of Streptomyces species SS07 has been used to reduce water soluble azo dyes and the carcinogenic amines released have been compared with that from chemical reduction. The effect of temperature, pH and contact time on the recovery of amines using ECFP was studied. The ECFP releases carcinogenic amines at a pH of 9.2 and a temperature of 37 degrees C for a contact period of 24 h. The reduction products were analyzed with HPLC and their structures confirmed by LC-MS and GC-MS. It was observed that both the ECFP and chemical reduction methods released similar type of amine products. In the case of dye samples, compared to chemical reduction, 5-20% increase in the release of carcinogenic amines by ECFP was observed. The percentage of amine products released by chemical reduction was higher for leather garment samples compared to ECFP treatment.     

Cis-trans-isomerization of cationic-anionic polymethine dyes

The effect of solvent polarity and ion pair formation oncis-trans-isomerization of cationic-anionic polymethine dyes and of related simple cationic and anionic dyes is studied by flash photolysis. The change in the rate constant for reversecis-trans- isomerization of photoisomers due to the interaction of a cation with an anion in an ion pair is observed in nonpolar solvents. A drop in the yield of the photoisomers to zero is observed for a number of cationic-anionic dyes in weakly polar and nonpolar solvents which is possibly due to steric hindrances in the photoisomerization process in ion pairs.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 719–724, April, 1993.     

Singlet oxygen generation ability of squarylium cyanine dyes

The quantum yields for singlet oxygen generation of several squarylium cyanine dyes derived from benzothiazole, benzoselenazole and quinoline, displaying absorption within the so-called “phototherapeutic window” (600–1000 nm), were determined, envisioning their potential usefulness for photodynamic therapy (PDT). The determination was performed by a direct method measuring the luminescence decay of the dyes in the near infrared. Considering the absorption and the quantum yields displayed by some of the dyes, these seemed to be potential candidates as sensitizers for PDT.     

超高效液相色谱-四极杆/静电场轨道阱高分辨质谱快速筛查染发剂中32种染料成分

建立了超高效液相色谱-四极杆/静电场轨道阱高分辨质谱快速筛查和分析染发剂中32种禁限用染料的分析方法。样品经甲醇-2 g/L抗坏血酸水溶液溶解提取,正己烷净化,用ZORBAX Eclipse Plus C_(18)(3.0 mm×100 mm,1.8μm)色谱柱分离,以甲醇-5 mmol/L乙酸铵水溶液为流动相进行梯度洗脱,采用正、负离子切换同时测定了32种染料成分,显著提高了检测通量。以全扫描模式下提取的保留时间和一级母离子精确质量数以及同位素丰度比,实现对染发剂中多种染料成分的快速筛查;以自动触发采集的二级碎片离子精确质量数进行确证。32种染料在相应的质量浓度范围内线性关系良好,相关系数(r~2)均大于0.99;定量下限(LOQ)为0.2～40μg/g,回收率为81.0%～110%,相对标准偏差(RSD)为3.3%～9.9%。该方法简单、准确、快速,适用于染发剂中多种禁限用染料成分的高通量快速定性筛查和定量分析。     

SNAP-tag蛋白标签技术与荧光分析法在蛋白原位分析中的联合应用

为将生物体内微观的蛋白行为可视化并以宏观信号呈现出来对蛋白进行实时、动态分析，借助SNAP-tag蛋白标签技术与有机小分子荧光染料，构建了一系列用于活细胞内实时监测目标蛋白的免洗荧光探针。标签蛋白SNAP-tag能够特异性识别探针中的苄基鸟嘌呤，从而使目标蛋白共价连接上荧光团（萘酰亚胺），携带上荧光信使。此外，由于萘酰亚胺从水环境中被牵引至SNAP-tag蛋白的疏水空腔，其荧光信号呈现出2~13倍的增强。通过SNAP-tag标签蛋白与目标蛋白的融合，该荧光探针实现了对活细胞内线粒体蛋白CoX8A及核内蛋白H2B特异性识别，在免洗条件下完成了对目标蛋白的实时追踪及原位分析。     

Fluorescence derivatisation of amino acids in short and long-wavelengths

3-(Naphthalen-1-ylamino)propanoic acid was coupled to the amino group of the main and lateral chains of various amino acids in order to evaluate its applicability as a fluorescent derivatising reagent. The resulting amino acid derivatives are strongly fluorescent with a maximum emission of about 415 nm. Condensation of these derivatives with 5-ethylamino-4-methyl-2-nitrosophenol hydrochloride resulted in the corresponding blue benzo[a]phenoxazinium conjugates, also revealing strong fluorescence in ethanol and water at physiological pH and good quantum yields, but with emission wavelengths between 644 and 657 nm, which was preferable in biological assays.