塑化剂邻苯二甲酸二丁酯与小牛胸腺DNA的沟槽结合

运用多种光谱学方法,结合化学计量学多元曲线分辨-交替最小二乘法(MCRALS),以及分子模拟技术,在人体生理酸度(pH=7.4)条件下研究了邻苯二甲酸二丁酯(DBP)与小牛胸腺DNA(ctDNA)的相互作用。采用MCR-ALS法分析了DBP与ctDNA作用的紫外光谱数据矩阵,结果表明DBP与ctDNA作用形成了DBP-ctDNA复合物。荧光猝灭实验显示,ctDNA对DBP的荧光猝灭属于形成复合物的单一静态猝灭,其主要驱动力为疏水作用和氢键。通过单双链、熔点和粘度等实验证明DBP与ctDNA发生了沟槽结合,结合区域为A、T碱基富集区。圆二色谱和琼脂糖凝胶电泳分析表明,DBP与ctDNA结合导致ctDNA结构变得更为松散,但未造成质粒DNA损伤。分子模拟形象直观地展现了两者的结合姿态,预测结果与实验结果吻合。     

乙酰阿魏酰酪氨酰酪氨酸的合成及其与DNA相互作用初探

用固相法合成了乙酰阿魏酰酪氨酰酪氨酸(F-Tyr-Tyr),并用ESI-MS、IR、NMR对其结构进行表征。应用紫外光谱法、荧光光谱法研究了F-Tyr-Tyr与小牛胸腺DNA(ctDNA)的相互作用。结果表明,F-Tyr-Tyr与ctDNA相互作用后体系的紫外吸收呈减色效应,且F-Tyr-Tyr加入后,DNA-EB体系的荧光强度减弱。根据Stern-Volmer方程求出F-Tyr-Tyr-DNA-EB体系的猝灭常数为K SV=6.28×103L·mol-1,猝灭方式为静态猝灭,推测F-Tyr-Tyr与ctDNA的相互作用模式主要是静电结合。     

沙丁胺醇与小牛胸腺DNA相互作用研究

在生理酸度条件下(pH7.4),运用紫外–可见吸收光谱、荧光光谱、圆二色谱(CD)和傅立叶红外光谱(FT–IR)并结合分子模拟、DNA熔点及粘度测定,研究了沙丁胺醇(Sal)与小牛胸腺DNA(ctDNA)的相互作用。结果表明,ctDNA以静态方法猝灭Sal的内源荧光,25℃时ctDNA与Sal的结合常数为1.26×104L·mol,氢键和范德华力是两者结合的主要驱动力。Sal存在下,ctDNA的熔点无明显变化,KI荧光猝灭效应和盐效应不明显,证实Sal与ctDNA主要通过沟槽模式结合。FT-IR与分子模拟结果显示,Sal倾向于与ctDNA的胸腺嘧啶(T碱基)结合。CD和凝胶电泳分析表明,Sal与ctDNA结合没有对DNA产生明显损伤,DNA仍维持B型构象。     

抗癌药物4'-O-(α-L-夹竹桃糖基)柔红霉素与小牛胸腺DNA相互作用的荧光光谱法

在pH=7.4的Tris-HCl介质中,利用荧光光谱和紫外吸收光谱法,研究了一种新型蒽环类抗癌药物柔红霉素衍生物(4′-O-(α-L-夹竹桃糖基)柔红霉素,ODNR)与小牛胸腺DNA(ctDNA)的相互作用。 通过离子强度的影响、KI荧光猝灭实验和单双链ctDNA作用的比较实验,分析了ODNR与ctDNA的相互作用模式。 结果表明,ODNR通过嵌插方式与ctDNA发生作用。 ctDNA对ODNR的荧光有明显的猝灭作用,其机理属于静态猝灭。 通过Scatchard方程求得不同温度下的结合常数和结合位点数,由热力学参数确定分子间作用力为疏水作用,也可能存在静电作用。     

烷基酚与DNA相互作用的荧光光谱法研究

用荧光光谱法研究了环境激素辛基酚(OP)、壬基酚(NP)与小牛胸腺DNA(ctDNA)的相互作用.实验发现,随着ctDNA的加入,辛基酚、壬基酚的荧光光谱产生了有规律地猝灭,且最大发射峰红移.其中荧光猝灭是由于形成了烷基酚-DNA加合物而引起的静态猝灭.辛基酚、壬基酚与ctDNA均以插嵌模式相互作用,其结合常数分别为5.1×105 L·mol-1 和1.4×106 L·mol-1 ,结合位点分别为1.31和1.45.热力学参数确定了辛基酚及壬基酚与ctDNA的作用力类型主要是疏水作用力.     

荧光光谱法研究磷酰化5,7-二羟基黄酮与ctDNA的相互作用

以溴化乙锭(EB)为荧光探针,研究了磷酰化5,7-二羟基黄酮与ctDNA的相互作用。实验结果表明,磷酰化5,7-二羟基黄酮与ctDNA间存在相互作用。随着温度的升高,磷酰化5,7-二羟基黄酮对ctDNA-EB体系的荧光猝灭常数降低,磷酰化5,7-二羟基黄酮可与ctDNA形成复合物,此猝灭过程为静态猝灭。根据Stern-Volmer方程,算出25℃及37℃下磷酰化5,7-二羟基黄酮对ctDNA-EB体系的荧光猝灭常数分别为Kq1=30 860 L/mol及Kq2=27 760 L/mol,并且算出它与ctDNA结合的平衡常数为KM=2.39×107L/mol。     

三聚氰胺对DNA潜在损伤作用的研究

在生理酸度条件下(pH 7.4),采用溴化乙锭(EB)为荧光探针的荧光光谱法、I-离子荧光猝灭效应、DNA熔点和粘度效应等手段,研究了三聚氰胺与DNA的相互作用。随着DNA的加入,三聚氰胺的荧光强度明显减小而且三聚氰胺能够猝灭DNA-EB复合物的荧光,说明三聚氰胺能够竞争置换EB而与DNA作用;三聚氰胺的加入使得DNA的粘度增大,DNA-EB的熔点降低;DNA的加入减小了I-对三聚氰胺荧光的猝灭程度。三聚氰胺以嵌插方式作用于DNA的亲核位点,意味着三聚氰胺进入生物体后有可能通过形成DNA加合物的形式造成DNA损伤,从而最终导致基因突变。     

光谱法研究硫酸奎宁与小牛胸腺DNA的相互作用

本文采用紫外吸收光谱、荧光光谱、荧光偏振等方法研究了硫酸奎宁(QN)与小牛胸腺DNA(ctDNA)的相互作用,考察了影响其相互作用的各种因素,探讨了作用机理和作用方式。DNA存在时,QN的荧光被显著猝灭,吸收光谱出现减色现象。荧光偏振和阴离子猝灭等实验证实QN通过嵌插方式与ctDNA作用。测得QN与DNA的本征键合常数为1.51(±0.13)×104 L/mol,结合位点数为0.997,一分子的QN可以和大约1个碱基对作用。     

荧光可逆调控研究CdTe量子点-吖啶橙-小牛胸腺DNA的相互作用及分析应用

水相合成了谷胱甘肽(GSH)修饰的CdTe 量子点(QDs). 在PH＝7.4的Tris-HCl缓冲溶液中, 吖啶橙(AO)通过静电引力吸附到GSH-CdTe QDs 的表面, 与GSH-CdTe QDs形成了基态复合物, 导致GSH-CdTe QDs的荧光猝灭. 在GSH-CdTe QDs-AO体系中加入小牛胸腺DNA (ctDNA), ctDNA诱导AO从GSH-CdTe QDs表面脱落嵌入其双螺旋结构中, 导致GSH-CdTe QDs的荧光恢复. 根据GSH-CdTe QDs荧光的猝灭和恢复, 实现了量子点荧光的可逆调控. ctDNA引起GSH-CdTe QDs-AO体系荧光恢复强度与ctDNA浓度成良好的线性关系, 检出限为0.13 ng•mL^－1, 据此提出了简便快捷、准确、高灵敏测定ctDNA的新方法. 还结合共振瑞利散射(RRS)光谱、吸收光谱和原子力显微镜照片研究了GSH-CdTe QDs-AO-ctDNA三者之间的相互作用, 对相互作用机理进行了讨论并提出了相应的作用模型.     

含芘荧光化学敏感器化合物同小牛胸腺DNA分子间的相互作用

研究了含芘荧光化学敏感器分子被ctDNA猝灭的荧光光谱.ctDNA分子对该化学敏感器中芘的激发单体,激基缔合物都有猝灭作用.对激发单体的猝灭速度顺序为;化合物(2)>化合物(1)>芘丁酸>化合物(3);对激基缔合物的猝灭速度顺序为;化合物(2)化合物(3).由得到的荧光猝灭数据,可按公式(2)求得荧光化学敏感器分子与ctDNA分子相互作用的稳定常数.发现化合物(2)与ctDNA分子间有着最强的相互作用能力.按ctDNA和含芘荧光化学敏感器的分子结构、构型以及分子内原子-原子的间距等提出了ctDNA分子与该荧光化学敏感器的作用模型,并对上述结果进行了初步解释.     

Spectroscopic analysis on the resveratrol-DNA binding interactions at physiological pH

The interaction of resveratrol with calf thymus deoxyribonucleic acid (ctDNA) under physiological conditions (Tris–HCl buffer solutions, pH 7.4) was studied by spectroscopy, fluorescence spectroscopy and viscosity measurement method, respectively. Results indicated that a complex of resveratrol with ctDNA was formed with a binding constant of K_{17 °C} = 5.49 × 10³ L mol⁻¹ and K_{37 °C} = 1.90 × 10⁴ L mol⁻¹. The fluorescence quenching mechanism of acridine orange (AO)-ctDNA by resveratrol was shown to be a static quenching type. The thermodynamic parameters of the complex were calculated by a double reciprocal method: , and (37 °C). Spectroscopic techniques together with viscosity determination provided evidences of intercalation mode of binding for the interaction between resveratrol and ctDNA.     

Determination of acetamiprid partial-intercalative binding to DNA by use of spectroscopic, chemometrics, and molecular docking techniques

Acetamiprid (ACT) is an insecticide widely used for controlling a variety of insect pests. The binding mode associated with calf thymus DNA (ctDNA) upon interaction with ACT was determined using spectroscopic, chemometrics, and molecular docking techniques to clarify the interaction mechanism at the molecular level. Fluorescence titration suggested that the fluorescence quenching of ACT by ctDNA is a static procedure. The binding constants between ACT and ctDNA at different temperatures were calculated to be of the order 10³?10⁴ L mol^?1. The positive values of enthalpy and entropy change suggested that the binding process is primarily driven by hydrophobic interactions. Multivariate curve resolution?alternating least squares (MCR?ALS), a chemometrics approach, was used to resolve the expanded UV–visible spectral data matrix. The concentration profiles and the spectra for the three reaction components (ACT, ctDNA, and ACT?ctDNA complex) of the system, which formed a highly overlapping composite response, were then successfully obtained and used to evaluate the progress of ACT interacting with ctDNA. The results of the single-stranded ctDNA and iodide quenching experiments, ctDNA-melting investigations, and viscosity measurements indicated that ACT binds to ctDNA by means of a partial intercalation. Molecular docking studies showed that the specific binding site is mainly located between the ACT and G–C base pairs of ctDNA. This docking prediction was confirmed by use of Fourier-transform infrared (FT-IR) spectral analysis. Results from circular dichroism (CD) spectroscopy revealed that ACT induced a conformational change from the B–ctDNA form to the A–ctDNA form.

Interaction of an anthracycline disaccharide with ctDNA: Investigation by spectroscopic technique and modeling studies

This study was designed to examine the interaction of an anthracycline disaccharide, 4′-O-(β-L-oleandrosyl) daunorubicin (DNR–D2), with calf thymus deoxyribonucleic acid (ctDNA) by UV–vis in combination with fluorescence spectroscopy and molecular modeling techniques under physiological conditions (Britton–Robinson buffer solutions, pH 7.4). By the analysis of UV–vis and fluorescence spectrum, it was observed that the binding mode between DNR–D2 and ctDNA might be intercalation, and fluorescence quenching mechanism of DNR–D2 by ctDNA was a static quenching type. Upon binding to ctDNA, the anthraquinone chromophore of DNR–D2 could slide into the C–G rich region of ctDNA. Hydrogen bonding forces may play an essential role in the binding of DNR–D2 to ctDNA. Furthermore, the results obtained from computational modeling corroborated the experimental results obtained from spectroscopic investigations. These studies are valuable for a better understanding the datailed mode of DNR–D2–DNA interaction, which should be important in deeper insight into the therapeutic efficiency of DNR–D2.     

Spectroscopic investigation of interaction of 6-methoxyflavanone and its β-cyclodextrin inclusion complex with calf thymus DNA

The interaction of 6-methoxyflavanone (6MF, 6-methoxy-2-phenyl-4H-1-benzopyran-4-one) with calf thymus DNA (ctDNA) was investigated by absorption spectroscopy, fluorescence spectroscopy, and cyclic voltammetry in the presence and absence of ??-cyclodextrin (??-CD) acting as capping agent. Molecular modelling was used to optimise the study of 6MF-??-CD and 6MF-DNA interactions. Enhancement in the fluorescence intensity of 6MF was observed due to the formation of 1 : 1 complex with ??-CD. In the presence and absence of DNA, 6MF showed different characteristics such as hyperchromic effect, red shift of absorption spectra and fluorescence quenching of 6MF due to binding between 6MF and ctDNA. The nature of the binding group was found to be different for the 6MF-ctDNA and 6MF-ctDNA-??-CD systems. An increase in fluorescence intensity was observed for the 6MF-ctDNA system while varying the concentration of ??-CD due to encapsulation of a part of 6MF in cyclodextrin. The results are compatible with the possibility of the interaction of dihydrobenzopyran-4-one moiety of 6MF with ctDNA as well as with ??-CD. Cyclic voltammetric studies confirmed the binding interaction between 6MF and ctDNA in the absence and presence of ??-CD and molecular modelling explains the site of the interaction of 6MF with cyclodextrin and ctDNA.     

Study on the phosphorescence characterizations of palmatine chloride on the solid substrate and its interaction with ctDNA

The spectroscopic characterizations of solid substrate room temperature phosphorescence (SS-RTP) of palmatine (Pal) have been studied. Strong RTP signal at 615 nm can be induced on filter paper in the presence of TIAc. The interaction between calf thymus DNA (ctDNA) and Pal has been investigated at pH 6.90 using fluorescence, UV-vis, SS-RTP and cyclic voltammogram spectroscopy. Strong binding affinity of Pal with DNA is revealed from the absorption and fluorescence studies in the liquid state. With the addition of ctDNA, the fluorescence intensity of Pal is enhanced greatly and UV-vis spectra show no apparent hypochromicity and red shift, which indicates that Pal intercalates into ctDNA bases. However, this conclusion could not explain the phenomena from fluorescence polarization and denatured DNA measurements, which indicate that groove binding is at least the main binding mode. Binding constant and binding site size have been calculated to be 2.57 × 10⁴ L/mol and 0.16 based on Scatchard plot from fluorescence titration data. Groove binding has also been supported by phosphorescence lifetime and anion quenching experiments. Above studies demonstrate that there should exist intercalative binding and groove binding in the interaction of Pal and DNA. Furthermore, cyclic voltammogram study suggests that electrostatic binding exists at the same time exactly. Taken together, the binding model obtained in this study is mixed-mode.     

Multiplex binding modes of toluidine blue with calf thymus DNA and conformational transition of DNA revealed by spectroscopic studies

It is noteworthy to understand the details of interactions between antitumor drugs and DNA because the binding modes and affinities affect their antitumor activities. Here, The interaction of toluidine blue (TB), a potential antitumor drug for photodynamic therapy of tumor, with calf thymus DNA (ctDNA) was explored by UV–vis, fluorescence, circular dichroism (CD) spectroscopy, UV-melting method and surface-enhance Raman spectroscopy (SERS). The experimental results suggest that TB could bind to ctDNA via both electrostatic interaction and partial intercalation. The fluorescence quenching of TB by ctDNA was static and due to electron transfer from bases to the excited singlet state of TB. At low [TB]/[DNA] ratio, TB mainly partially intercalated into ctDNA resulting in the slight increase of base stacking degree; at high [TB]/[DNA] ratio, excessive TB externally stacked along the helix surface via coupling with partially intercalated ones, thereby inducing B-A transition of ctDNA. The conformational transition of DNA was confirmed by the obvious improvement of the thermal stability of ctDNA. The SERS spectra suggest that TB could partially intercalate into DNA basepairs with its ring C₁NC_1′ side buried.     

Study on spectroscopic characterization of Pd porphyrin and its interaction with ctDNA

The fluorescence and solid substrate room temperature phosphorescence (SS-RTP) properties of Pd(II) meso-tetrakis (4-N-methyl-pyridiniumyl) porphyrin (Pd(II)TMPyP) were studied. The factors influencing the SS-RTP emission, such as filter type, inorganic salt sort, drying temperature, pre-drying time and drying time were investigated in detail. Strong SS-RTP signal can be induced on the slow speed filter paper in the presence of the external inorganic salt, Ca(NO₃)₂, with the maximum excitation and emission wavelengths at 421 nm and 675 nm, respectively. The interaction between calf thymus DNA (ctDNA) and Pd(II)TMPyP was investigated at pH 7.2 using SS-RTP, fluorescence and UV-vis spectroscopy. The SS-RTP intensity of Pd(II)TMPyP was enhanced efficiently with the increasing amount of ctDNA. This phenomenon demonstrates that the intercalated porphyrin is shielded by ctDNA to avoid collision quenching. This result was supported by SS-RTP lifetime measurement, SS-RTP anion quenching experiment and fluorescence polarization measurement. Furthermore, with the addition of ctDNA, the UV-vis spectra of Pd(II)TMPyP shows apparent hypochromicity (40%) at the Soret maximum of 417 nm and a red shift of Δλ = 15 nm, also indicating that Pd(II)TMPyP intercalates into ctDNA bases. The binding constant of Pd(II)TMPyP to ctDNA was calculated to be 4.41 × 10⁵ L/mol based on the derivative McGhee-von Hippel plots.     

大黄素与DNA相互作用方式的研究

通过分子荧光分析、紫外可见吸收光谱及粘度分析以及与溴化乙锭的竞争性实验对大黄素与DNA之问的作用模式进行了考察.在pH 7.4,低离子强度(30 mmol/L NaCl)及恒温37℃条件下反应35 min,大黄素的荧光强度随DNA加入浓度的增加而递减,紫外可见吸收光谱在380、475 nm处出现等吸收点并红移5nm,表...     

白藜芦醇探针同步荧光法测定蛋白质含量

在Tris-HCl缓冲溶液体系中(pH=7.4),白藜芦醇与人血清白蛋白相互作用,对蛋白的内源性荧光产生猝灭作用,而且,同步荧光的强度与人血清白蛋白的浓度成正比。 基于此,建立了以白藜芦醇为荧光探针,运用固定波长同步荧光光谱法测定生物样品中蛋白质含量的新方法。 体系同步荧光光谱特征及强度受Δλ、反应介质和离子强度等因素的影响。 在最佳实验条件下,体系的同步荧光强度(I)与人血清白蛋白在1.380~276.0 mg/L的浓度范围内呈良好的线性关系,检测限为1.037 mg/L(n=11)。 对血清、尿样和唾液等生物样品进行测定,回收率在93.5%~105.8%之间,与传统的考马斯亮蓝(G-250)法作对照,结果一致。