DNA与5-Br-PAN-S分子间结合反应

利用光谱修正技术研究脱氧核糖核酸(DNA)与5-Br-PAN-S(L)分子间的相互作用,通过pH 8.04的介质中DNA与5-Br-PAN-S反应的光谱研究,测定了结合产物的物理化学参数10 ℃时探针L与DNA的结合比为4.3,结合常数K=0.6118×106;30 ℃时探针L与DNA的结合比为3.7,结合常数K=0.676 9×106.此结合反应符合Langmuir吸附方程,该方法可应用于痕量DNA的测定.     

一个新型钌(Ⅱ)配合物的合成、表征与DNA的键合及溶剂变色性质

合成和表征了1个新的钌(Ⅱ)配合物[Ru(bpy)₂(dpapz)](ClO₄)₂,其中bpy=2,2'-联吡啶,dpapz=联吡啶并[3,2-a:2,'3-'c]-6-氮杂-吩嗪.通过紫外可见光谱、荧光光谱、与溴化乙锭的竞争键合实验和粘度测量研究了该配合物与小牛胸腺DNA的键合性质,并研究了该配合物的紫外可见光谱和荧光光谱的溶剂变色性质.结果表明,该配合物是具有键合常数Kb=6.9×10⁵L/mol(50mmol/LNaCl)的DNA嵌入键合试剂和优良的荧光溶剂传感分子.     

一种苊并杂环有机小分子嵌入DNA的几何学模式研究

利用圆二色谱(CD)、紫外-可见吸收光谱以及荧光光谱等方法对苊并杂环化合物8-氧-8H-苊并[1,2-b]吡咯-9-腈(A1) 与小牛胸腺DNA(CT DNA) 的相互作用进行了研究. 结果表明, 随着n(A1)/n(CT DNA)的变化存在两种不同的几何学结合构型. 当n(A1)/n(CT DNA)值低于0.20时, A1分子与DNA的结合方式是不均一的, 化合物分子以多种角度嵌入到DNA碱基对之间. 表现为A1-DNA复合物的诱导圆二色光谱图上较小的正峰和紫外吸收光谱图缺省等吸收点. DNA的特征圆二色谱图表明, 在n(A1)/n(CT DNA)≤0.20范围内, CT DNA的构象从标准的B型转化为A-like型; 当n(A1)/n(CT DNA)>0.20时, 诱导圆二色光谱由正峰转变为强度大、波形复杂的负峰, 表明A1分子开始堆积到DNA螺旋的表面, 同时DNA的二级结构发生了进一步变化.     

Meso-四-（4-磺基苯基）卟啉钴/过硫酸钠-过氧化氢催化氧化降解农药敌敌畏

研究了CoTPPS4/Na2S2O8-H2O2体系(CoTPPS4:meso-四-（4-磺基苯基）卟啉钴)对农药敌敌畏(DDVP)催化氧化降解效果,探讨了氧化剂种类及比例、催化剂用量、农药初始浓度、pH值及反应温度等因素对催化降解速度的影响,并在优化条件下对降解反应的动力学进行了考察。结果表明,随着催化剂用量增加、初始农药浓度的降低、pH值升高(pH值为5～9)和温度的上升,DDVP降解速率增加。室温时,在pH=9缓冲溶液中,农药初始浓度为1.015×10-4 mol/L、CoTPPS4加入量为2.4×10-3 g时,5 mL 0.050 mol/L Na2S2O8-H2O2（体积比4∶1）混合氧化剂存在条件下,7 h后DDVP农药降解率可达72.8%,反应速率常数为0.190 h-1。降解反应动力学研究表明,CoTPPS4催化混合氧化剂降解DDVP农药为表观一级反应,反应表观活化能Ea为5.052 kJ/mol。     

β-环糊精衍生物与吡罗昔康的包合特性

采用荧光光谱、差热扫描和核磁共振法,研究了不同酸度下吡罗昔康（PX）与β-环糊精（β-CD）、羟丙基-β-环糊精（HP-β-CD）和磺丁醚-β-环糊精（SBE-β-CD）的包合特性。 结果表明,吡罗昔康与3种环糊精均形成了1∶2.5的包合物。 以包合常数为包合能力的量度,中性条件下,包合平衡常数分别为1.2×106、1.8×106、2.0×106,3种环糊精的包合能力为SBE-β-CD＞HP-β-CD＞β-CD。     

光谱法和电化学法研究中性红与小牛胸腺DNA的相互作用

利用紫外 可见和圆二色光谱(CD)法和伏安方法,研究了小分子染料中性红(NR)与小牛胸腺DNA(CTDNA)的相互作用。实验表明在NR低浓度下,NR能嵌入至核酸双螺旋的碱基内部在G C处与核酸结合,而在较高浓度情况下,嵌入的NR分子与后来的在核酸双螺旋外部的NR分子相互作用发生聚集,从而堆积在DNA双螺旋的表面,同时使核酸的构象由B型转变为Z型。用光谱滴定的方法获得NR与CTDNA作用内部结合常数,分别为:Ka1=2 4×104mol·L-1·cm-1和Ka2=2 1×10-2mol·L-1·cm-1。     

基于Hg2+诱导DNA双链形成的荧光增强法检测Hg2+

基于Hg2+与胸腺嘧啶(T)形成“T-Hg2+-T”结构的原理建立了一种简单、灵敏的荧光增强法检测H92+的方法.两条部分互补的富含T碱基的ssDNA在常温下分别以单链状态存在.当加入Hg2+,由于T-Hg2+-T键的形成,两条ssDNA形成DNA双螺旋结构,溶液中荧光分子溴化乙锭(EB)嵌入DNA双螺旋结构,EB荧光...     

有机氯农药与肿瘤相关基因DNA间的作用机制研究

利用紫外可见(UV-vis)吸收光谱、荧光(FL)光谱和圆二色谱(CD)研究了3种有机氯农药[DDT,DDE和DDD]与人类肿瘤相关基因(p53 DNA和C-myc DNA)的相互作用,阐明有机氯农药的基因毒性。UV-vis和FL光谱实验表明,有机氯农药主要通过嵌插方式与DNA碱基作用,形成非共价复合物。通过FL实验得到的农药分子与p53 DNA的结合能力顺序为:DDE>DDT>DDD,对C-myc DNA为:DDD>DDE>DDT;并通过计算结合过程的热力学常数证实以疏水作用为主要的作用力。CD实验表明,部分有机氯农药能够影响DNA的碱基对堆积和二级结构,很可能进一步造成DNA损伤,并最终导致基因突变。     

儿茶酚胺衍生物与DNA之间相互作用的光谱和电化学法研究

用光谱和电化学方法研究了儿茶酚胺衍生物与小牛胸腺DNA之间的作用机制.结果表明,低浓度的多巴酚丁胺和肾上腺素与DNA之间主要为静电作用;而在高浓度时,则主要为插入作用.对于多巴胺,在5.00×10^-5～9.00×10^-4mol/L范围内,它与DNA之间主要为插入作用.同时,采用电化学方法测得多巴胺、肾上腺素和多巴酚丁胺与DNA之间的表观结合常数分别为1.55×10³,9.77×10³和1.74×10⁴L/mol.     

一种可视化液体传感阵列农药检测新方法

以筛选出的7种染料与合成的纳米金共同构建了液体传感器阵列,每个敏感点对不同农药样品产生不同的响应光谱,通过酶标仪采集光谱数据,结合主成分分析(PCA)、分层聚类分析(HCA)、判别分析(LDA)等模式识别方法建立了一种快速检测有机磷、氨基甲酸酯、有机氯、拟除虫菊酯类农药残留的新方法。PCA结果表明,前三个主成分反映了总信息量的92.69%,且能够对5种农药进行区分;HCA结果表明,对25个样品能够正确的归类;LDA结果表明,对5种农药识别的准确率达100%。表明这种可视化的液体阵列可为农药残留检测提供一个可靠平台,在农药残留检测中具有潜在的应用价值。     

Affinity capillary electrophoresis and fluorescence spectroscopy for studying enantioselective interactions between omeprazole enantiomer and human serum albumin

Baseline separation of omeprazole (OME) enantiomers was achieved by affinity capillary electrophoresis (ACE), using human serum albumin (HSA) as the chiral selector. The influence of several experimental variables such as HSA concentration, the type and content of organic modifiers, applied voltage and running buffer concentration on the separation was evaluated. The binding of esomeprazole (S‐omeprazole, S‐OME) and its R‐enantiomer (R‐omeprazole, R‐OME) to HSA under simulated physiological conditions was studied by ACE and fluorescence spectroscopy which was considered as a reference method. ACE studies demonstrated that the binding constants of the two enantiomers and HSA were 3.18 × 10³ M⁻¹ and 5.36 × 10³ M⁻¹, respectively. The binding properties including the fluorescence quenching mechanisms, binding constants, binding sites and the number of binding sites were obtained by fluorescence spectroscopy. Though the ACE method could not get enough data when compared with the fluorescence spectrum method, the separation and binding studies of chiral drugs could be achieved simultaneously via this method. This study is of great significance for the investigation and clinical application of chiral drugs.     

补骨脂素和异补骨脂素与人免疫球蛋白的相互作用

将互为同分异构体的两种植物药活性组分补骨脂素和异补骨脂素作为研究对象, 应用荧光光谱法、紫外光谱法以及红外光谱法并结合分子对接技术对这两种香豆素类化合物与人-γ球蛋白(Human gammago-bulin, HG)的相互作用进行了比较研究. 荧光光谱法研究结果表明, 补骨脂素和异补骨脂素与蛋白之间均有较强的结合(结合常数位于0.251×10⁴～3.503×10⁴之间), 且对HG都表现为静态猝灭. 不同温度(298, 308和318 K)下两种药物与HG相互作用的结合参数均有所差别, 维持药物-蛋白质体系的作用力也不相同. 依据Förster能量转移理论, 得到补骨脂素和异补骨脂素分子与蛋白质色氨酸残基间的结合距离r值(分别为3.65和4.21 nm)都小于7 nm, 说明发生了能量转移. 利用同步荧光与红外光谱法研究了药物对蛋白质二级结构的影响. 分子对接研究结果表明, 这两种药物与蛋白有相似的结合区域和相同的结合模式.     

Interactions of Phenanthroline Compounds with i-Motif DNA

The interactions of each of three phenanthroline derivatives 1, 2 and 3 with the human telomeric/-motif DNA were investigated. The results suggest these compounds are potent binders. The compounds could stabilize the structure of i-motif DNA by π-π stacking. Moreover, the binding constants of the compounds with/-motif DNA were （2.71-8.12）×10^4 L·mol^-1, and the binding stoichiometry ratio was 1：1. CD studies reveal that the binding by phenanthroline comoounds perturbs the conformation of i-motif DNA.     

Mechanistic study of opposite migration order of dimethindene enantiomers in capillary electrophoresis in the presence of native beta-cyclodextrin and heptakis(2,3,6-tri-O-methyl)-beta-cyclodextrin

The possible mechanisms of the opposite affinity pattern of the enantiomers of dimethindene [(R,S)-N,N-dimethyl-3[1(2-pyridyl)ethyl]indene-2-ethylamine] (DIM) towards native beta-cyclodextrin (beta-CD) and heptakis(2,3,6-tri-O-methyl-)-beta-CD (TM-beta-CD) were studied using capillary electrophoresis (CE), NMR spectrometry, electrospray ionization mass spectrometry (ESI-MS) and X-ray crystallography. NMR spectrometry allowed to estimate the stoichiometry of the complex and to determine the binding constants. As found using ESI-MS, together with more abundant 1:1 complex, a complex with 1:2 stoichiometry may also be present in a rather small amount in a solution of DIM and beta-CD. One-dimensional ROESY experiments indicated that the geometry of the complexes of DIM with native beta-CD depends on the ratio of the components in the solution. In the 1:1 solution of DIM and beta-CD the complex may be formed by inclusion of the indene moiety of DIM into the cavity of beta-CD on the primary side and into the cavity of TM-beta-CD into the secondary side. The most likely structural reason for lower affinity of the enantiomers of DIM towards the cavity of TM-beta-CD compared to native beta-CD could be elucidated. The indene moiety does not enter the cavity of TM-beta-CD as deeply as the cavity of beta-CD. This may be the most likely explanation of significantly higher affinity constants of DIM enantiomers towards the latter CD compared to the former one. The marked difference between the structure of the complexes may also be responsible for the opposite affinity pattern of the DIM enantiomers towards beta-CD and TM-beta-CD.     

小檗碱与人免疫球蛋白在仿生膜中的相互作用

利用荧光光谱、圆二色谱(CD)和动态激光散射技术研究了小檗碱与人免疫球蛋白(HGG)在以双(2-乙基己酯)-磺酸基琥珀酸钠(AOT)/异辛烷/水微乳液为膜的模拟环境下的结合反应. 通过Scatchard方程分别计算了不同温度下的反应结合常数. CD光谱结果表明: 小檗碱与HGG键合改变了蛋白原有的构象. 同时由热力学结果可知, 小檗碱与HGG之间的相互作用主要以疏水作用为主, 同时存在静电作用力和氢键作用力. 动态激光散射结果进一步证明了药物与HGG在微乳液中的相互作用. 通过计算机模拟技术, 在不考虑环境影响的条件下从理论上探讨了HGG与小檗碱的结合区域和结合模式.     

氮杂大环铈(Ⅲ)配合物与pUC19 DNA的相互作用

以一种1,4,7,10,13,16,19,22,25,28,31-十一氮杂2,5,8,11,14,17,20,23,26,29,32-十一酰基-环三十三烷的衍生物（CYC）为配体,在溶液中和Ce（Ⅲ,M）离子形成氮杂大环铈配合物（M-CYC）作为仿生催化剂,通过紫外光谱法、荧光光谱法和凝胶电泳法研究了M-CYC配合物与DNA的相互作用. 结果表明,M-CYC与小牛胸腺DNA（CT DNA）以嵌插方式相互作用,在pH = 8.16的缓冲体系中,其结合常数K_b = 2.0×10⁴ L/mol. 凝胶电泳结果表明,当自由基捕捉剂存在时,M-CYC可将超螺旋pUC19 DNA切割为缺刻型DNA,其切割方式为水解切割.     

DNA Binding Properties and Cytotoxic Activities of Two Trinuclear Ruthenium（Ⅱ） Polypyridyl Complexes

The interactions between two trinuclear Ru（II） complexes and calf thymus DNA（CT DNA） were studied via absorption spectroscopy, reverse salt titrations, binding stoichiometry, DNA melting experiments, as well as viscosity measurement. The results indicate that complexes 1 and 2 bind to DNA via the interaction of the planar π-delocalized system of the complexes with intrinsic binding constants of 4.18 × 10^5 and 3.85 × 10^6 L/tool, respectively, and non-electrostatic binding free energy makes a predominant contribution to the binding free energy. The in vitro cytotoxic activity of complexes 1 and 2 was evaluated by the MTT[3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyl- 2H-tetrazolium bromide] method. Complex I shows higher anticancer potency than complex 2 against four tumor cell lines. Further mechanism study indicates that complexes 1 and 2 can cause cell cycle arrest in the G2/M phase.     

配合物[Co2(EGTB)Cl2]•(BF4)2•5H2O与DNA相互作用的研究

用紫外光谱法、荧光光谱法、黏度法、凝胶电泳法研究了双核钴(II)配合物[Co2(EGTB)Cl2]•(BF4)2•5H2O和DNA的相互作用, 在pH＝7.2的缓冲体系中, 求得配合物与DNA的结合常数. 结果表明, 配合物在接近生理条件下能有效地断裂pBR322DNA, 同时可使DNA的粘度增加, 使EB-DNA体系的荧光强度降低. 配合物与DNA的荧光光谱和紫外光谱表明, 配合物与DNA的作用既存在部分插入结合又存在静电结合模式.     

花旗松素与牛血清白蛋白相互作用的光谱和电化学

采用紫外光谱法、荧光光谱法和循环伏安法,研究了牛血清白蛋白(BSA)与花旗松素（taxifolin）的相互作用。 用荧光法和循环伏安法测得花旗松素与BSA的结合常数K分别为1.3×106和1.6×106 L/mol,结合位点数均接近1.3。花旗松素对牛血清白蛋白是静态猝灭。BSA荧光强度的降低与花旗松素浓度在一定范围内呈线性关系,其线性范围为6.00×10-7~2.00×10-5 mol/L,检出限为2.00×10-7 mol/L。花旗松素氧化峰电流的下降与BSA浓度在一定范围内呈线性关系,其线性范围为7.00×10-7~1.00×10-4 mol/L,检出限为3.00×10-7 mol/L。用于合成样品中花旗松素和BSA的测定,结果满意。     

Preparation and physicochemical characterization of omeprazole:methyl-beta-cyclodextrin inclusion complex in solid state

In this work, we illustrate the usefulness of cyclodextrins, namely, methyl-β-cyclodextrin (MβCD), an amorphous, methylated derivative of the natural β-cyclodextrin (βCD), as a tool to form an inclusion complex with omeprazole (OME), a poorly water soluble drug. Solid binary systems between OME and MβCD were prepared experimentally in a stoichiometry 1:1 by different techniques (physical mixing, kneading, spray-drying and freeze-drying). Afterward these products were characterized by Fourier transformation-infrared spectroscopy (FTIR); X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The results obtained suggest that spray-drying and freeze-drying methods yield a higher degree of amorphous entities suggesting the formation of inclusion complexes between OME and MβCD.