DNA分子结构的多态性研究：（Ⅱ）吖啶橙凝聚体变化诱导的质粒DNA？…

利用吸收光谱和荧光光谱方法，研究了吖啶橙（ＡＯ）与质粒ＤＮＡ水溶液，以及含胶束介抽的吖啶橙与质粒ＤＮＡ溶液体系的相互结合作用及减色效应。结果表明：吖啶橙时质粒ＤＮＡ的吸收光谱有减色效应；含十二烷基硫酸钠（ＳＤＳ）的ＡＯ水溶液体中，随着ＳＤＳ浓度的增加，其光谱结果表明由凝聚态向单体的转化。而在含十二烷基硫酸钠（ＤＳ）的ＡＯ与质粒ＤＮＡ溶液体系中，吖啶橙凝聚态随ＳＤＳ浓度的增加，对ＡＯ与质粒ＤＮＡ相互     

二氯二乙基锡与DNA作用的研究

利用循环伏安、紫外光谱和粘度测定等手段,对二氯二乙基锡［Ｅｔ２ＳｎＣｌ２］与ＤＮＡ的作用机制进行了研究。结果表明,Ｅｔ２ＳｎＣｌ２主要作用于ＤＮＡ的骨架磷酸基团,使ＤＮＡ构象收缩,相对粘度增加,产生减色效应,始终未观察到增色效应,提出了Ｅｔ２ＳｎＣｌ２对ＤＮＡ可能的作用机制模型。     

吖啶橙染料在表面活性剂存在时溶液状态的光谱研究

应用紫外－可见吸收光谱和荧光光谱，研究了激光染料吖淀橙（ＡＯ）的溶液状态以及添加表面活性剂时吖啶橙染料的溶液状态变化，并应用Ｋａｓｈａ理论推算出二聚体时的状态，结果表明：在吖啶橙溶液中，ＡＯ二聚体的α＝４９°，ｒ＝１．３９ｎｍ。     

淋巴细胞核DNA—吖啶橙体系荧光抑制法筛选抗癌药物的研究

以人外周血淋巴细胞为标准细胞，用荧光探针吖啶橙（ＡＯ）示踪药物和细胞ＤＮＡ的作用，提出一种用Ｈａｄａｍａｒｄ变换显微荧光图象分析法初步筛选抗癌药物的新方法，对五晨特异性抗癌药物（ＣＣＮＳＡ）的实验结果和药物细胞ＤＮＡ作用的原理相符，表明此方法地筛选此类抗癌芗，对四种氯代苯甲醛丙氨酸Ｓｃｈｉｆｆ碱（ＣＡ）金属配合物一淋巴细胞ＤＮＡ作用，研究结果表明：３－ＣＡＣｏ、３－ＣＡＺｎ、２－ＣＡＫ和４－ＣＡＤ     

血管紧张素Ⅱ(AngⅡ)的溶液构象研究

用固相多肽合成方法合成了ＡｎｇⅡ，并用２Ｄ ＮＭＲ技术测定其在Ｄ２Ｏ与ＤＭＳＯ－ｄ５中的构象。通过偶合常数，ＲＯＥ效应，化学位移温度系数，确定其二面角约束，距离约束及氢键约束结果表明，ＡｎｇⅡ在Ｄ２Ｏ与ＤＭＳＯ－ｄ６中构象极为相近，呈无规卷曲状态，排除了其构象为α螺旋３，１０螺旋，β转有，γ转角，平行与反平行β折叠的可能性，且其在水中的构象对温度不敏感。     

分子模拟及光谱法研究2-乙基-3-(3-硝基苯基)喹唑啉-4-酮与小牛胸腺DNA的相互作用

合成了2-乙基-3-(3-硝基苯基)喹唑啉-4-酮(ENPQO),用紫外光谱法、荧光光谱法、荧光偏振法、离子强度法及分子模拟法研究了ENPQO与小牛胸腺DNA(ct DNA)的相互作用。紫外光谱法显示ct DNA与ENPQO作用后,引起ENPQO紫外吸收光谱的增色效应;在以吖啶橙(AO)为荧光探针的实验中,随着ENPQO浓度的增加,ct DNA-AO体系的荧光被猝灭,其猝灭过程主要是静态猝灭,ENPQO对ct DNA-AO体系的荧光偏振基本无影响;不同浓度的Na Cl溶液未削弱ENPQO对ct DNA-AO的猝灭程度。以上结果均表明ENPQO与ct DNA之间的作用方式主要为沟槽结合。利用分子模拟对接技术预测了ENPQO与ct DNA的结合最优构象,与光谱实验结果一致。     

不同价态金属离子对DNA构象的影响

用紫外分光光度法研究了不同价态金属离子对DNA大分子溶液构象的影响。研究结果显示: 金属离子与DNA的作用使DNA溶液的紫外吸收值下降, 即呈现减色效应, 同时减色效应的强弱与金属离子的价态有关。随着价态升高, 减色效应增强。由此说明, 金属离子与DNA的作用使DNA的构象趋于缩拢; 且随着金属离子价态升高, 缩拢程度增强, 甚至产生缩合。还用现代多聚电解质理论对以上现象进行了讨论, 结果是令人满意的。     

光谱法研究Ge-132与DNA的作用机理

利用吸收光谱、DNA碱变性曲线、荧光光谱研究了Ge-132与DNA的相互作用。在Ge-132存在下，DNA的紫外吸收光谱产生明显的减色效应。同时，Ge-132的存在使DNA碱变性的pH值增大，变性后增色效应减小，实验结果表明，Ge-132主要是以嵌入方式与DNA结合的。     

O，O′－2，2′－联苯基，S－苄基二硫代磷酸酯分子的构象研究

本文用ＡＳＥＤ－ＭＯ法研究了Ｏ，Ｏ′－２，２′－联苯基，Ｓ－苄基二硫代磷酸酯单个分子的构象，得到４种低能构象。分析了常温下４种构象的分布，稳定构象之间的转化以及与晶态分子构象之间的关系．     

稀土离子对DNA作用的循环伏安法和光谱法研究

运用循环伏安法，紫外光谱和拉曼光谱等方法研究了Ｅｕ＾３＋，Ｃｅ＾３＋，Ｅｒ＾３＋，Ｓｍ＾３＋，Ｔｂ＾３＋，Ｌａ＾３＋，Ｎｄ＾３＋等稀土金属离子与ＤＮＡ（小牛胸腺）的相互作用，Ｃｅ＾３＋与ＤＮＡ作用后，Ｃｅ＾３＋的ＣＶ曲线的峰电流密度明显降低，且氧化峰降低的程度大于还原峰，Ｃｅ＾３＋的差示ＵＶ曲线呈减色效应，且在２７２ｎｍ处出现新峰，ＤＮＡ的差示ＵＶ曲线呈增色效应；ＤＮＡ的拉曼谱线中８１４ｃｍ＾－１     

用紫外光谱和荧光光谱研究三丁基锡化合物与脱氧核糖核酸的相互作用

用紫外光谱和荧光光谱研究了三丁基锡(TBT)化合物与脱氧核糖核酸(DNA)的相互作用。结果表明,在不同条件下,TBT既作用于DNA的磷酸基团,使DNA构象发生变化;又作用于DNA的碱基基团,对DNA双螺旋结构有一定影响。而且,TBT与DNA作用时间越长,则减色越明显。还考察了TBT和磷酸根浓度,以及溶液pH值对TBT与DNA作用的影响。     

光谱法研究R-(+)-萘普生与DNA的相互作用

采用荧光光谱及紫外光谱法研究了R-(+)-萘普生与DNA相互作用的光谱特性.结果表明:DNA的加入使R-(+)-萘普生的紫外光谱产生减色、红移效应;荧光光谱发生了一定程度的猝灭.R-(+)-萘普生与DNA之间的作用主要是嵌插作用,它们之间的结合常数KA=1.236×104L·mol-1,结合位点数n=0.98.     

十二烷基磺酸钠对大豆过氧化物酶活性和构象的影响

在不同的pH值体系中, 利用酶活测量、圆二色谱、荧光谱和电子吸收谱研究了十二烷基磺酸钠(SDS)对大豆过氧化物酶(SBP)活性与构象的影响情况. 在pH 2.6和4.2 的体系中, 少量的SDS分子可通过静电作用与SBP结合, 进而与SBP分子中的His169残基结合, 降低其与铁卟啉的配位能力, 使其Soret吸收带蓝移, 二级结构发生轻微的变动, 活性永久丧失. 在pH 5.2体系中, SDS和SBP分子都带负电, 由于静电排斥作用, SDS无法进入SBP的分子内部, 失去与SBP分子中His169残基结合的能力, 对SBP分子的二级结构没有影响, 仅对SBP分子的三级结构有所影响. 当SDS的浓度大于临界胶束浓度时, 由于胶束与SBP的静电排斥作用增强, 限制了铁卟啉中乙烯基的运动, 乙烯基与卟啉环的共轭程度增大, Soret 吸收带红移. 由于SBP活性可完全恢复, 此变化是可逆的.     

苏木素与DNA相互作用的光谱研究

以吖啶橙(AO)作探针研究了苏木素(HE)与DNA的相互作用. 吸收光谱和荧光光谱研究表明, 苏木素与DNA发生作用生成了复合物. 其结合比n_HE∶n_DNA＝3∶1, 22 ℃时苏木素与DNA的结合常数K＝5.96×10⁴ L/mol. 同时研究了酸度、盐效应和温度等对苏木素与DNA相互作用的影响以及它们之间的作用方式, 确定了苏木素与鲱鱼精DNA之间为混合作用方式.     

S-异丙甲草胺与小牛胸腺DNA的相互作用

应用紫外光谱、荧光光谱、DNA热变性法以及黏度法研究了S-异丙甲草胺与小牛胸腺DNA(ctDNA)的相互作用.结果表明,S-异丙甲草胺使ctDNA在200 nm处的吸收峰发生明显改变,表现出红移和减色效应,而对260 nm处的吸收峰产生影响较小,排除了嵌插作用的可能;ctDNA对S-异丙甲草胺内源性荧光表现出很强的猝灭作用,且随温度的升高,其猝灭程度有所下降,表明S-异丙甲草胺是以形成加合物的方式与ctDNA结合的,并求得了它们在不同温度下的结合常数;将不同离子强度条件下S-异丙甲草胺与ctDNA作用以及不同S-异丙甲草胺浓度下ctDNA的热变性温度和黏度变化的研究结果与紫外光谱和荧光光谱相结合,可以判断S-异丙甲草胺是以沟槽作用的方式与ctDNA结合的.     

曙红B及变色酸与核酸作用的光谱学性质研究

利用荧光光谱法、紫外-可见吸收光谱法、圆二色谱法、凝胶电泳法对曙红B及变色酸与核酸的作用机理进行了探讨. 当ct-DNA浓度增加时,曙红B和变色酸的荧光光谱呈荧光增强趋势;紫外-可见光谱呈下降趋势;并使ct-DNA圆二色谱正负峰吸收强度呈现一定的降低;琼脂糖凝胶电泳实验中,二者在泳道中与DNA作用发出的荧光在紫外灯下皆清晰可见. 并将所得结果与溴化乙锭-DNA体系性质进行对比,为寻找高效低毒的DNA分子荧光探针提供了实验基础.     

Celestine blue as a new indicator in electrochemical DNA biosensors

Celestine blue(CB)was introduced as a new electroactive indicator in DNA biosensors.The interaction of CB with DNA was investigated by electrochemical and spectroscopic methods.The effect of buffer kind and p H on the electrochemical behavior of CB was studied.The peak currents of CB were linearly related to DNA concentration in the range of 5.0×10~(-9) to 1.0×10~(-7)mol/L.The detection limit of this approach was 4.76×10~(-10) mol/L.Based on spectrometry data a hypochromic effect was observed in UV-Vis spectra of CB with increasing DNA concentration.The results illustrate the possible interaction mode between CB and DNA is electrostatic binding.     

Terahertz absorption of DNA decamer duplex

This work combines experimental and theoretical approaches to investigate terahertz absorption spectra of the DNA formed by the sequence oligomer 5'-CCGGCGCCGG-3'. The three-dimensional structure of this self-complimentary DNA decamer has been well-studied, permitting us to perform direct identification of the low-frequency phonon modes associated with specific conformation and to conduct comprehensive computer simulations. Two modeling techniques, normal-mode analysis and nanosecond molecular dynamics with explicit solvent molecules, were employed to extract the low-frequency vibrational modes based on which the absorption spectra were calculated. The absorption spectra of the DNA decamer in aqueous solution were measured in the frequency range 10-25 cm(-1) using the terahertz Fourier transform infrared spectroscopy. Multiple well-resolved and reproducible resonance modes were observed. When calculated and experimental spectra were compared, the spectrum based on molecular dynamics simulations showed a better correlation with the experimental spectra than the one based on normal-mode analysis. These results demonstrate that there exist a considerable number of active low-frequency phonon modes in this short DNA duplex.     

Ru(TAP)3]2+-photosensitized DNA cleavage studied by atomic force microscopy and gel electrophoresis: a comparative study

Topological modifications of plasmid DNA adsorbed on a variety of surfaces were investigated by using atomic force microscopy (AFM). On mica modified with 3-aminopropyltriethoxysilane (APS) or poly-L-lysine, the interaction between the plasmid DNA and the surface "freezes" the plasmid DNA conformation deposited from solution, and the AFM images resemble the projection of the three-dimensional conformation of the plasmid DNA in solution. Modified mica with low concentrations of Mg(2+) leads to a decrease in the interaction strength between plasmid DNA and the substrate, and the AFM images reflect the relaxed or equilibrium conformation of the adsorbed plasmid DNA. Under these optimized deposition conditions, topological modifications of plasmid DNA were produced under irradiation in the presence of [Ru(TAP)(3)](2+) (TAP = 1,4,5,8-tetraazaphenanthrene), which is a non-intercalating complex, and were followed as a function of illumination time. The observed structural changes correlate well with the conversion of the supercoiled covalently closed circular form (ccc form) into the open circular form (oc form), induced by a single-strand photocleavage. The AFM results obtained after fine-tuning of the plasmid DNA-substrate interaction compare well with those observed from gel electrophoresis, indicating that under the appropriate deposition conditions, AFM is a reliable technique to investigate irradiation-induced topological changes in plasmid DNA.     

Crystal structure and DNA binding studies of a cobalt(Ⅱ) complex containing mixed-ligands of 1,10-phenathroline and glycollic acid

A cobalt（11） complex containing mixed-ligands of 1,10-phenathroline（phen） and glycollic acid（GA）.|Co（GA）₂（phen）| was synthesized and its structure was characterized by X-ray diffraction.The interaction of the complex with DNA was investigated by electronic absorption spectra and electrochemical methods.Electronic absorption spectrum experiments showed that after interaction with DNA.the characteristic absorption peaks of |Co（GA）₂（phen）| underwent hypochromic effect as well as redshift. Also,the binding strength of 3.8×10⁴L/mol was estimated by titration method.Electrochemical assays revealed that the redox peak currents of the complex decreased obviously accompanied by a positive shift of the formal potential after association with DNA.All these results revealed that the synthesized cobalt complex bound with DNA via an intercalation mode.