【作者】 张雅珩；

【导师】 陈兴国；

【作者基本信息】 兰州大学 ， 分析化学， 2009， 博士

【摘要】 小分子与生物大分子相互作用的研究是化学生物学的重要研究内容。血清白蛋白是血浆中含量最丰富的重要载体蛋白,它能广泛地与许多内源性和外源性物质结合。IgG (γ-球蛋白)是生物体内最主要的免疫球蛋白分子之一,它在人类正常血清中含量最丰富。IgG具有超常的可逆结合药物、有机小分子和相关抗原的能力。研究小分子与血清白蛋白及免疫球蛋白的结合在药代动力学、毒理学上具有重要意义,已成为从事生命科学、化学和临床医学科研工作者共同关注的课题之一。本论文基于开展小分子与蛋白质相互作用的重要意义及国内外研究趋势,在前人工作的基础上,从以下几方面进行了创新性研究:(1)通过计算机分子模拟技术研究了染料小分子、中药活性组分与人γ-球蛋白(HGG)、人血清白蛋白(HSA)的作用模式,提出了小分子与蛋白质的相互作用的分子模型,为通过实验进一步研究二者相互作用提供了理论参考和重要信息;(2)综合利用光谱集成分析技术(荧光光谱、紫外-可见吸收光谱、傅里叶变换红外光谱(FT-IR )、圆二色谱(CD))研究了染料小分子、中药活性组分与HGG及HSA的相互作用,获得了准确一致的信息并验证了分子对接结果;(3)根据Scatchard方程、Sips方程和Van’t Hoff方程详细研究计算了中药活性组分、染料小分子与蛋白质的结合机理包括结合常数、结合位点数,推测了主要作用力类型;(4)利用数学方法(二阶导数,去卷积以及曲线拟合)对蛋白质红外光谱图进行解析,定量分析了不同小分子与HSA作用前后蛋白质二级结构的变化;(5)通过竞争实验,确定了小分子在HSA的结合位点,取得与分子对接基本一致的结果;(6)利用同步荧光光谱提供的信息,探讨了不同小分子-蛋白质体系中的蛋白质发色团微环境的改变;(7)研究了HSA在AOT/异辛烷/水的微乳介质中与中药活性组分的相互作用,为蛋白质与小分子的相互作用开拓了新的研究领域。论文共分为四章。第一章:简要介绍了蛋白质的结构功能,综述了研究小分子与蛋白质相互作用的各种方法的原理、应用情况及该领域的研究进展。第二章:应用计算机模拟技术和光谱集成分析技术对HGG与染料小分子中性红的相互作用进行了详细的研究。通过分子对接考察了中性红与HGG的作用模式,提出了二者相互作用的分子模型。利用Sips方法计算了中性红与HGG反应的平均亲和力常数和结合位点数,根据Van’t Hoff方程计算了反应的热力学参数,讨论了二者相互作用的主要作用力类型。利用FT-IR和CD考察了中性红对HGG二级结构的影响。第三章:首次利用分子模拟技术和光谱法详细研究了丹皮酚、柚皮苷分别与HSA和HGG的相互作用。通过分子对接确定这两种药物分别与HSA、HGG的结合区域和结合模式。光谱法研究结果表明,这两种药物与蛋白质之间可以发生结合作用,并猝灭蛋白质的荧光;利用荧光光谱法提供的信息计算了相互作用的结合常数、结合位点数、热力学参数;FT-IR及CD数据揭示了不同药物对两种蛋白质二级结构含量的影响程度。第四章:利用荧光光谱法、紫外-可见吸收光谱法、圆二色性光谱法、傅里叶变换红外光谱法和动态激光散射技术首次系统研究了在AOT/异辛烷/水构成的反相微乳介质中岩白菜素、秦皮甲素、没食子酸和咖啡酸与HSA之间的相互作用。分子对接从理论上分别研究了这四种药物与HSA的结合区域和结合模式。光谱数据表明,微乳液为HSA的氨基酸残基提供了非极性更强的微环境,发色团在微乳液中的活动性比起在水溶液中受到更大的限制;在微乳液中这些中药活性组分能够猝灭HSA的内源荧光,其结合常数随温度升高而降低。由热力学数据推测了在微乳液中药物分子与HSA之间的主要作用力类型。FT-IR和CD数据表明,药物与HSA的结合使其二级结构发生了变化。动态激光散射技术揭示了HSA在微乳液中的可能位置,并证明药物与HSA在微乳液中的相互作用。更多还原

【Abstract】 The interactions between small molecules and biological molecules are importantfor chemistry biology investigation.Serum albumin,the most abundant carrier proteinin blood plasma,can bind many exogenous and endogenous compounds extensively.IgG (gammaglobulin) is one of the most impartment immunoglobulin in organism.Itis most abundant in normal human serum.IgG is capable of binding with drugs,smallorganic molecules and related antigen reversibly.Investigation on the bindingmechanism of small molecules with serum albumin and immunoglobulin is muchimportant in pharmacokinetics and toxicology.Thus,it became an interesting researchfield of life sciences,chemistry and clinical medicine.In this dissertation,on the basisof the previous research,the following major innovative works were carried out:(1) The molecular modeling method was used to study the binding mode of dyemolecule,active components of Chinese medicines with human gammaglobulin(HGG) and human serum albumin (HSA),obtain the molecule model of smallmolecules with proteins,giving the referenced information for the followingexperiment.(2) Integrated spectroscopy analytical technique including fluorescence spectrum,uv absorption spectrum,fourier transform infrared (FT-IR) spectrum and circulardichroism (CD) spectrum were used to study the interactions of dye molecule,activecomponents of Chinese medicines with HGG and HSA,and the results obtained fromevery method were in good agreement.This also verified the results of molecularmodeling.(3) The binding constants,the numbers of binding site and the interaction forceinvolving in the interaction of small molecules and proteins were confirmed byScatchard equation,Sips equation and Van’t Hoff equation.(4) The secondary structure compositions of HSA and their small moleculescomplexes were estimated by quantitative analysis using IR self deconvolution withsecond-derivative resolution enhancement and curve-fitting procedure.(5) The binding locations of small molecules on HSA were confirmed by competitive binding experiments,the results verified the results of molecularmodeling technique.(6) The information obtained from the synchronous fluorescence spectra wereused to determine the microenvironment changes of chromophore in different smallmolecule-protein systems.(7) The interactions between active components of Chinese medicines and HSAwere studied in AOT/isooctane/water microemulsions,which open up the new studyfield for the interaction between proteins and small molecules.This dissertation consists of four chapters.Chapter 1:The structures,functions of proteins were briefly introduced firstly.The developments of interaction of small molecules with proteins were reviewed,andthe methods used to study the interaction of small molecules with proteins weresummarized.Chapter 2:The interaction of HGG with small dye molecule neutral red wasstudied by integrated spectroscopy analytical technique combined with molecularmodeling study.The binding mode between neutral red and HGG were studied bymolecular docking technique,and the molecular model between them was established.The binding parameters including the average affinity constant,the number of bindingsites and the thermodynamic parameters of this dye bound to HGG were calculatedaccording to Sips method and Van’t Hoff equation,respectively.And the main actingforces between neutral red and HGG were discussed.The effects of this molecule onthe secondary structure of HGG were investigated by FT-IR and CD techniques.Chapter 3:The interactions between paeonol,naringin and HSA,HGG wereinvestigated by spectroscopy methods and the molecular modeling technique,respectively.The binding regions and binding modes of the two drugs on proteinswere obtained from the molecular modeling results.To compare the results,it showedthat the two drugs could bind with proteins and quench the fluorescence of proteins.The fluorescence methods were used to calculate the binding constants,the number ofbinding sites and thermodynamic parameters of the reactions.The results from FT-IRand CD spectra indicated the different degree on the changes of the secondary structure compositions of proteins and their drugs complexes.Chapter 4:The interactions between bergenin,esculin,gallic acid and caffeic acidwith HSA in AOT/isooctane/water microemulsions were characterized for the firsttime using fluorescence spectroscopy in combination with UV absorptionspectroscopy,FT-IR spectroscopy,CD spectroscopy and dynamic light scattering(DLS) technique.The molecular modeling method was applied to study theoreticallythe binding regions and binding modes for four drugs with HSA.The spectroscopydata suggested that a less polar environment of amino acid residues was provided bymicroemulsion and the mobility of the chromophores of HSA in microemulsion wasmore confined than in aqueous solution.The binding of HSA to drugs inmicroemulsion quenched the intrinsic fluorescence of HSA and the binding constantsdecreased with the increasing temperature.And the main acting forces between drugsand HSA were discussed through thermodynamic parameters of the reactions.FT-IRand CD data suggested that the protein conformations were altered after binding withdrugs.The DLS data suggested the possible location of HSA in microemulsion andproved the interaction between drugs and HSA.更多还原