【作者】 苏布道；

【导师】 龚国权；

【作者基本信息】 兰州大学 ， 分析化学， 2006， 硕士

【摘要】 小分子化合物与生物大分子相互作用的研究已经成为了化学生物学中重要的研究课题。DNA是生物体中重要的一类生物大分子,对生命密码的翻译、转录、复制起着非常重要的作用,一方面,DNA靶向化合物成为很重要的核酸探针选择对象;另一方面,临床上使用的许多抗癌药物都以DNA为作用靶点。为了进一步探索和认识DNA的性质、结构、行为、形态,揭开生命的奥秘,人们研究了大量小分子与DNA之间的相互作用,并且许多小分子现己成功地用作DNA足迹试剂,定位碱基错配试剂,以及结构探针,而且有助于从分子水平上了解抗癌药物的作用机理,为设计临床上更为有效的抗癌药物提供理论指导。本文在此基础上主要采用荧光光谱、紫外可见吸收光谱以及粘度等方法研究了抗病毒药物冰片、丁香酚及大黄素与DNA的相互作用。 本论文主要由以下三部分组成: 1 冰片与DNA的相互作用研究 利用共振光散射、紫外可见吸收光谱以及粘度法研究了冰片与DNA的相互作用。发现在接近人体生理的条件(pH7.40,温度37℃)下,冰片与DNA反应较迅速,并且反应体系至少于12小时内稳定。这可能是多种抗菌及抗炎中药的配方中均含有冰片的原因之一。通过改变反应体系的离子强度、pH值及试剂加入的顺序,发现反应体系对离子强度及溶液的pH值具有较强的敏感性,而试剂加入的顺序对反应影响不明显。共振光散射光谱显示:冰片的加入使缓冲溶液--DNA体系在410、470nm处的共振光散射信号增强,说明冰片与DNA发生了相互作用。紫外可见吸收光谱的研究表明,冰片导致缓冲溶液--DNA体系在260nm处发生增色效应,并产生4.0nm的红移,证明了冰片是以嵌入方式与DNA发生作用的。同时通过EB(溴化乙锭)荧光探针竞争实验和粘度实验发现:冰片使EB-DNA体系的荧光强度降低,DNA的粘度减小,证明冰片与DNA的作用为嵌插模式,但不能完全嵌入,属于部分嵌插模式。更多还原

【Abstract】 The nature and dynamics of binding small molecules to biopolymers represents an area of active investigation. Studies directed toward the design of site- and conformation-specific reagents provided routes toward rational drug design as well as a means to develop sensitive chemical probes of polymer structure. Deoxyribonucleic acid (DNA) is a kind of key biologic large molecule, it plays very important role in life genetic code’ interpretation, transcription and copy, it is the primary target molecule for most of anticancer and antiviral therapies according to the cell biology. The investigation of interaction of DNA with other molecules is of great importance in elucidating the structure of DNA and their functions. It is also helpful to understand some diseases and the mechanism by which some medicines (especially antitumor drugs) act. In this thesis the results of interaction of some antitumor compounds with DNA were reported.This thesis consists of three sections as follows:First, resonance light scattering spectra and UV-VIS spectra were used to study the interaction of borneol with DNA. The results indicate that the addition of DNA can increase RLS intensity of borneol at 410 and 470 nm under a physiological condition (pH=7. 40 and t=37°C), which may be one of the reasons why borneol can be one of antibacterial Chinese medicines. UV-VIS spectra showed that there appear two iso-absorptive points and a red shift of 4.0 nm, which means that borneol intercalates into the double helix of DNA. Ionic strength and pH of reaction system were changed to investigate the influencing factors. It is showed that reaction system of borneol-DNA is sensitive to increasing ionic strength and changing pH. The above results suggested that borneol binds to DNA via a weak partial intercalation, revealed by competitive and viscosity experiments. The additional sequence of reagents has little effect on RLS and Absorption intensity, and calibration graphs and linear rangewere determined under the optimal conditions.Second, the interaction of eugenol and DNA in Tris-HCl buffer solution (pH7. 40) and under low ionic strength (less than 0. 0035mol/L) was investigated by scattering spectrum. Results showed that long range assembly of three enhanced resonance light-scattering (RLS) peaks appear at 420 > 455> 470 nm. The RLS intensity can be increased in linear relationship with the increasing of DNA concentration. UV-VIS spectra were surveyed to gain more information of the mode of eugenol with DNA. Two iso-absorptive points were observed at 255 and 317 nm. Results showed that a new complex is produced and eugenol can interfere with the replication of DNA. The influencing factors and the optimum reaction conditions have been determined. The additional sequence of reagents has little effect on reaction system. As an effective ingredient of high antibacterial coefficient, eugenol can react on DNA easier and more efficient, and reaction system was steadier than borneol.Third, emission spectra, absorption spectra and viscosimetric studies have been carried out on the interaction of emodin with calf thymus DNA. Results showed that, under pH7. 40, in the presence of DNA the system of emodin-DNA exhibited a large decrease in emission spectra. A hypochromic effect at 424 nm, a red shift of 5. 0 nm and two iso-absorptive points were observed in the UV-VIS spectra, which suggested that emodin binds to DNA via an intercalation mode. Competitive experiments and viscosity studies were carried out for the further research. The fluorescence quenching data were plotted according to the Stern-Volmer equation. Ksv and Ksv were quenching constants in the absence and in the presence of DNA, respectively. Results showed that Ksv / Ksv =0. 73. In the presence of DNA, the effect of I on fluorescence intensity becomes smaller than that of emodin in the absence of DNA, which also proved that emodin react on DNA by an intercalation mode.更多还原