环丙氟沙星荧光探针对小牛胸腺DNA相互作用的研究

使用紫外和荧光光谱法研究了环丙氟沙星(CIF)和小牛胸腺DNA(ctDNA)之间的相互作用。在pH 7.0磷酸盐缓冲液中,CIF在270 nm激发和在420 nm处有很强的荧光发射。它们间的沟槽作用导致小牛胸腺ctDNA对CIF的荧光存在着很强的猝灭作用,猝灭常数为2.64×104 mol-1L(25 ℃)。利用ctDNA对CIF的荧光猝灭作用建立了核酸测定的新方法,线性范围为80 nmol·L-1～45 μmol·L-1,对25 μmol·L-1ctDNA的相对标准偏差为4.2％。     

Interaction Mechanism of Trp-Arg Dipeptide with Calf Thymus DNA

The interaction between Trp-Arg dipetide (WR) and calf thymus DNA (ctDNA) in pH 7.4 Tris-HCl buffer was investigated by multi-spectroscopic techniques and molecular modeling. The fluorescence spectroscopy and UV absorption spectroscopy indicated that WR interacted with ctDNA in a minor groove binding mode and the binding constant was 4.1?×?10³. The ionic strength effect and single-stranded DNA (ssDNA) quenching effect further verified the minor groove binding mode. Circular dichroism spectroscopy (CD) was employed to measure the conformation change of ctDNA in the presence of WR. The molecular modeling results illustrated that electrostatic interaction and groove binding coexisted between them and the hydrogen bond and Van der Waals were main acting forces. All the above methods can be widely used to investigate the interaction of peptide with nucleic acids, which contributes to design the structure of new and efficient drugs.

5-N-甲基化苯并呋喃[3,2-b]喹啉衍生物的合成及其与小牛胸腺DNA相互作用

设计并合成了天然产物喹叨啉(Quindoline)的两个衍生物:苯并呋喃[3,2-b]喹啉和5-N-甲基苯并呋喃[3,2-b]喹啉,通过MS、1H NMR等手段确认其结构.运用紫外(可见光谱、荧光光谱和圆二色光谱研究了合成的衍生物与小牛胸腺DNA结合能力的强弱和结合方式.实验结果表明,5-N季铵化引入的正电荷能提高苯并...     

以吖啶橙为荧光探针研究士的宁和布鲁辛与小牛胸腺DNA的相互作用

以吖啶橙(AO)为荧光探针,应用各种光谱法和热力学方法研究士的宁和布鲁辛与小牛胸腺DNA(ct-DNA)的相互作用情况。实验结果表明,在模拟人体生理环境下,把士的宁和布鲁辛这两种药物加入到DNA-AO体系中时,DNA-AO的光谱特征发生了明显的变化:在200nm和260nm处的紫外光谱吸收峰均有明显的减色效应,但没有红移和蓝移现象,表明药物与DNA不是典型的嵌插作用结合;DNA-AO的荧光光谱被药物显著的猝灭,根据Stern-Volmer方程可计算出士的宁和布鲁辛与DNA的成键常数分别是9.85×103L.mol-1和4.76×103L.mol-1。热变性温度,离子强度法和黏度法进一步证明药物与DNA不是嵌插结合,而是以沟槽作用的方式结合。     

重金属Cu2+增强农药甲萘威对ctDNA作用的光谱法研究

运用荧光光谱和紫外吸收光谱研究了在Cu2 的参与下农药甲萘威与小牛胸腺DNA(ctDNA)的相互作用.实验结果表明,甲萘威可以嵌入小牛胸腺DNA的双链中形成DNA加合物,从而使甲萘威的荧光光谱发生猝灭.通过计算这种猝灭为静态猝灭.当有Cu2 的参与下,甲萘威的猝灭常数增大,结合位点数n也有很大的增加.通过对热力学函数的计算和分析,在有Cu2 参与时,金属离子可能在甲萘威分子与ctD-NA分子间起"离子架桥作用",使甲萘威分子与ctDNA分子间静电相互作用增强,故△H对△G的贡献增大.     

硫堇与DNA分子作用机理的光谱研究

用紫外-可见吸收光谱、荧光光谱、圆二色谱和光电子能谱等光谱方法研究了硫堇(TH)与小牛胸腺DNA(CT-DNA)的作用机理。实验结果表明,在pH 7.2的磷酸盐缓冲溶液中, TH与CT-DNA之间的作用方式以嵌入作用为主,嵌入作用使TH的紫外最大吸收峰强度减小,且峰位发生红移。由紫外光谱实验结果线性拟合求得TH与CT-DNA的表观结合常数K＝1.45×104 L·mol-1。荧光光谱实验结果表明：TH与CT-DNA的嵌入作用使TH的荧光发生强烈猝灭,猝灭常数K_SV为1.01×104 L·mol-1。嵌入作用位点主要发生在CT-DNA的鸟嘌呤(G)-胞嘧啶(C)碱基序列富集区。通过对TH的光电子能谱中N,S原子的结合能变化分析,TH分子以杂环上S原子端与CT-DNA的G-C碱基对结合,两者的相互作用对CT-DNA的二级结构构象产生影响。     

克百威与DNA之间作用的光谱学研究

利用吸收光谱法和荧光光谱法研究了克百威与ct DNA之间的相互作用。结果表明,ct DNA可使克百威的吸收光谱发生减色以及红移现象;ct DNA对克百威的荧光存在静态的荧光猝灭。两种光谱都支持克百威是以嵌插方式与ct DNA形成两者的加合物。溶剂以及离子强度对于两者加合作用存在不同的影响。     

Spectroscopic and Electrochemical Studies on the Interaction of Carmoisine Food Additive with Native Calf Thymus DNA

ABSTRACT

In this work, for the first time interaction between a carmoisine food additive and native calf thymus DNA was monitored using UV-Vis absorption, fluorescence, and circular dichroism (CD) spectroscopy, as well as cyclic voltammetry and viscosity measurements. It can be concluded that carmoisine could interact with DNA via a groove-binding mode as evidenced by a hyperchromic effect of absorption spectra, increases in the fluorescence quenching effect of DNA, certain induced CD spectral changes, and relatively small changes in the viscosity of DNA. The binding constants (K_b) for the carmoisine with DNA was estimated to be 6.2 × 10⁴ M^?1 through spectroscopic titrations. The cyclic voltammetry method showed that both anodic and cathodic peak currents of carmoisine decreased upon addition of the DNA. Circular dichroism spectra indicated that there are certain detectable conformational changes such as conversion from B-like to A-like in the DNA double helix when carmoisine was added.     

山姜素与脱氧核糖核酸的相互识别研究

应用荧光光谱法及紫外-可见光谱法研究了生理条件下(pH 7.4)山姜素(ALP)与DNA分子之间的相互识别。考察了不同温度下(25,32和39 ℃),DNA对山姜素荧光猝灭情况。实验发现, DNA能猝灭山姜素的内源性荧光,随着温度的升高,荧光猝灭常数K_SV逐渐减小(K_SV分别为3.288×103, 2.923×103和2.467×103 L·mol-1),并且DNA对山姜素的猝灭速率常数K_q要大于药物小分子与生物大分子之间的最大扩散所控制的碰撞猝灭常数,得出DNA对山姜素的荧光猝灭是单一的静态猝灭过程。DNA与山姜素相互作用紫外-可见光谱显示,DNA不能使得山姜素的吸收峰发生减色效应和红移现象,而山姜素也不能使溴化乙锭-DNA体系的荧光强度及最大荧光峰位置发生变化,即山姜素不和溴化乙锭竞争与DNA的结合位点。DNA热变性实验发现,解链DNA对山姜素的荧光猝灭程度要大于正常DNA的猝灭程度,由此推断山姜素与DNA不存在嵌插作用。同时,I-离子效应和盐效应表明,山姜素与DNA之间主要以沟槽模式相结合。     

Influence of Mg+2 and Cu+2 on the Interaction Between Quinolone and Calf Thymus DNA

Mg⁺² and Cu⁺² have different binding capacities to quinolone drugs and have different binding modes with calf thymus DNA. Using the method of absorption and fluorescence spectroscopy, the influence of Mg⁺² and Cu⁺² on the binding between calf thymus DNA and each of four quinolone drugs has been studied. The results show that both Mg⁺² and Cu⁺² can bind with the four drugs. In the absence of divalent metal ions, quinolone drugs interact with DNA double helix by forming hydrogen bonds between the carboxyl and carbonyl groups of the drugs and the phosphate groups of the DNA bases, and the binding capacity shows a close relationship with the drug structures. The two metal ions show different influences on the binding between the drug and DNA, which depends on the type of ion, concentration of the metal ions and the structure of drugs. Mg⁺² in lower concentrations (0.01 mM to 3.0 mM) can act as a bridge between the carboxyl group/carbonyl group of the drug and the phosphate group of the DNA by electrostatic interaction, while Cu⁺² can act as an intermediary ion between carboxyl group/carbonyl group of the drug and the DNA bases by a co-ordinate bond. Both actions can increase the interaction of the ?? electron between the condensed rings of the drugs and the DNA bases. In some conditions, Cu⁺² can weaken the binding between the drug and the DNA by competitive inhibition if there is a site on the drug that can directly bind both DNA bases and Cu⁺².     

DNA温度效应的Raman光谱研究

测定了不同温度下DNA纤维和溶液的拉曼光谱。结果表明: 当温度变化时, 碱基、磷酸根等特征振动都不同程度的受到影响, 谱线强度、频率随温度呈非线性变化。在所有的振动模式中, 腺嘌呤A的特征振动受到温度的影响最大。除了磷酸根的谱线1 101 cm-1以外, 其余谱线的波数变化均随温度的升高向低波数移动, 而且波数的移动主要集中在变性峰的起始点70 ℃左右。另外还讨论了拉曼谱线强度随温度的变化关系, 得到了38,82 ℃(纤维为85 ℃)2个峰, 其中38 ℃与DNA的功能活跃区有关, 82 ℃(和85 ℃)为DNA的变性点, 与DSC(差示扫描量热法)的测量结果一致。     

Spectroscopic Characterization of the Interaction of Phenosafranin and Safranin O with Double Stranded, Heat Denatured and Single Stranded Calf Thymus DNA

Interaction of phenosafranin and safranin O with double stranded, heat denatured and single stranded calf thymus DNA has been studied by fluorescence, absorbance and circular dichroic techniques. Binding to the double stranded and heat denatured DNA conformations induced strong quenching in the fluorescence spectra of both dyes. Linear Scatchard plots indicated the binding to be of one type and the affinity evaluated to be of the order of 10(5) M(-1) with double stranded and heat denatured DNAs. Fluorescence quenching was much weaker with the single stranded DNA and the binding affinity was one order lower. Ferrocyanide quenching studies revealed that the fluorescence emission of the dye molecules bound to the double stranded and heat denatured DNAs was quenched much less compared to that bound to the single stranded DNA. Further, there was significant emission polarization for the bound dyes and strong energy transfer from the DNA base pairs to the dye molecules indicating intercalative binding. Salt dependence of the binding phenomenon revealed that electrostatic forces have significant role in the binding process. The intercalation of these molecules to double stranded and heat denatured DNA and simple stacking to single strands was proved by these fluorescence techniques. Support to the fluorescence results have been derived from absorption and circular dichroic results. Phenosafranin was revealed to be a stronger binding species compared to safranin O.     

氢氯噻嗪与DNA相互作用的光谱研究

用紫外光谱法和荧光光谱法研究了氢氯噻嗪(HCT)和小牛胸腺DNA(ctDNA)之间的相互作用.在pH 7.0的磷酸盐缓冲溶液中,HCT的荧光激发峰和发射峰分别位于278nm和360nm处.ctDNA的加入对HCT的荧光存在着很强的荧光猝灭作用,这种荧光静态猝灭作用是由ctDNA和HCT键合引起,键合常数为1.12×10-4L/mol(25℃).采用紫外光谱,离子强度的影响和Ⅰ-猝灭等条件实验研究了HCT与DNA间的相互作用.DNA浓度的变化不改变它们的作用,属于沟槽作用模式.     

Fluorescence Interaction and Determination of Sulfathiazole with Trypsin

The mechanism of interaction of trypsin with the sulfathiazole was studied through using fluorescence quenching and UV-visible absorption spectra at pH 7.4. The Stern-Volmer quenching constants, binding constants, number of binding sites and the corresponding thermodynamic parameters ΔH^o, ΔS^o and ΔG^o were calculated at different temperatures. The effect of common metal ions on the constants was also discussed. The results suggest that sulfathiazole can interact strongly trypsin and that there is the formation of trypsin-sulfathiazole complex and the interaction can be explained on the basis of hydrogen bonds and van der Waals forces. The binding distance (r) between the donor (trypsin) and acceptor (sulfathiazole) was 3.52 nm based on the Förster’s non-radiative energy transfer theory. The detection and quantification limits of sulfathiazole were calculated as 2.52 and 8.40 μM in the presence of trypsin, respectively. The relative standard deviation (RSD) was 4.086 % for determinations (n?=?7) of a sulfathiazole solution with the concentration of 7.54 μM.     

共振光散射法研究维多利亚蓝B与DNA的作用和分析应用

利用共振光散射光谱法研究了维多利亚蓝B与小牛胸腺DNA作用的影响因素和最佳条件,在室温,pH为5.2—6.2的(CH2)6N4-HCl的缓冲溶液和表面活性剂OP的条件下,维多利亚蓝B与小牛胸腺DNA作用对应有两个最大的共振光散射峰,相应的波长在410nm和572nm附近,当DNA的浓度在0.05—0.8mg·L-1范围内,共振光散射峰的增强与DNA的浓度成正比,检出限(3σ/k)为20μg·L-1,该方法用于合成样品中DNA的测定,相对标准偏差为1.4%—2.9%(n=10),加标回收率为97%—103%。     

氯唑西林钠与镧离子、DNA之间的作用研究

共沉淀法制得氯唑西林钠与镧离子的固体配合物,并对其进行了红外,荧光,核磁共振等研究,确定了该配合物的配位点并探讨了配位机理.同时进一步研究了该配合物与DNA形成三元配合物的荧光特性.研究结果发现:配合物的荧光发射峰强度随着DNA的加入而逐渐减小,而后随着DNA浓度的继续增大,发射峰又增高,说明此配合物与DNA可能是先嵌入结合,而后伴随有静电结合,配合物在DNA分子表面进行长距离自组装.研究证明所合成的配合物能够与DNA作用,可作为DNA的荧光探针.     

两种卤代荧光素与DNA作用荧光特性的研究

对四溴荧光素(TBF)、四氯四溴荧光素(TTF)两种卤代荧光素与DNA作用的荧光特性进行了研究,结果表明：TBF和TTF的最大λ_ex/λ_em为518/540 nm和540/560 nm,DNA的存在会使TBF和TTF的荧光强度发生变化;荧光猝灭实验和偏振实验表明：TBF与DNA的作用方式可能是沟槽键合和嵌插作用,而TTF 嵌插在了DNA碱基对之间;盐效应实验表明：溶液离子强度的大小会影响TBF和TTF与DNA的作用;荧光法测得TBF和TTF与DNA的结合常数为1×106和2×106 L·mol-1,结合位点数为0.62和0.16。     

Binding Studies of Isoxsuprine Hydrochloride to Calf Thymus DNA Using Multispectroscopic and Molecular Docking Techniques

In the present work, the interaction of Isoxsuprine (ISX) with Calf thymus DNA (ct-DNA) under physiological conditions (Tris–HCl buffer of pH 7.4) was investigated by using electronic absorption, circular dichroism, viscosity, electrochemical studies, fluorescence techniques, salt effect studies and computational studies. Competitive fluorimetric studies with Hoechst 33258 have shown that ISX exhibit the ability to displace the DNA-bound Hoechst 33258, indicating that it binds to ct-DNA in strong competition with Hoechst 33258 for the minor groove binding. Furthermore, the resulting data showed that ISX cannot displace methylene blue or acridine orange, which are the common intercalator molecules. The viscosity of ct-DNA solution was almost unchanged on addition of ISX and circular dichroism (CD) spectra of ct-DNA showed small changes in the presence of ISX which is in agreement with groove binding mode of interaction. Thus all above studies showed that the ISX drug binds to ct-DNA in a groove binding mode.The salt-effect studies showed the non-electrostatic nature of binding of ISX to ct-DNA. Moreover, molecular docking results support the above experimental data and suggest that ISX prefers to bind on the minor groove of ct-DNA.     

二溴羟基卟啉与核酸相互作用的光谱行为研究

研究了meso-4(3,5-二溴-4-羟基苯基)卟啉(T(DBHP)P)与小牛胸腺DNA (ct DNA)相互作用的光谱行为,探讨了以T(DBHP)P作为光谱探针测定核酸的最佳条件及作用机理。在 pH 4.92 HAc-NaAc缓冲液中,T(DBHP)P在最大吸收波长425 nm处的吸收峰强度显著下降,且下降程度与ct DNA含量呈线性关系,ct DNA含量在0.20～1.80 μg·mL-1范围内符合比尔定律,检出限为0.024 μg·mL-1。实验中发现Tween-80微乳液的加入能显著增加体系的灵敏度。同时,用摩尔比法测定了DNA与卟啉的结合数为21,并初步探讨了反应机理。     

SYBR Green I: Fluorescence Properties and Interaction with DNA

In this study, we have investigated the fluorescence properties of SYBR Green I (SG) dye and its interaction with double-stranded DNA (dsDNA). SG/dsDNA complexes were studied using various spectroscopic techniques, including fluorescence resonance energy transfer and time-resolved fluorescence techniques. It is shown that SG quenching in the free state has an intrinsic intramolecular origin; thus, the observed >1,000-fold SG fluorescence enhancement in complex with DNA can be explained by a dampening of its intra-molecular motions. Analysis of the obtained SG/DNA binding isotherms in solutions of different ionic strength and of SG/DNA association in the presence of a DNA minor groove binder, Hoechst 33258, revealed multiple modes of interaction of SG inner groups with DNA. In addition to interaction within the DNA minor groove, both intercalation between base pairs and stabilization of the electrostatic SG/DNA complex contributed to increased SG affinity to double-stranded DNA. We show that both fluorescence and the excited state lifetime of SG dramatically increase in viscous solvents, demonstrating an approximate 200-fold enhancement in 100?% glycerol, compared to water, which also makes SG a prospective fluorescent viscosity probe. A proposed structural model of the SG/DNA complex is compared and discussed with results recently reported for the closely related PicoGreen chromophore.