【作者】 刘晓慧；

【导师】 曾正志；

【作者基本信息】 兰州大学 ， 无机化学， 2008， 硕士

【摘要】 血清白蛋白是血浆中含量最丰富的蛋白质,有许多生理学功能,它可以同许多内源性、外源性物质结合,在体内起着存储和转运作用。研究药物或小分子与血清白蛋白的相互作用机理和作用过程,在药物代谢动力学上具有重要意义,已经成为生命科学、化学和临床医学科研领域的重要课题之一。本论文基于开展小分子与蛋白质相互作用的意义及国内外研究趋势,综合利用多种光谱技术,分别研究了模拟生理条件下1-苯基-3-（6-香豆素基）磺酰脲（SU22）、3-L酰乙酰基-4-羟基香豆素（H₂aac）及其La（Ⅲ）配合物La（Haac）₃、N²-（2″-羟基苯甲酰基）-N-（4′-甲苯磺酰胺基）甲酰肼（M）及其Sm（Ⅲ）配合物（SmM₃（NO₃）₃,以SmL₃表示）、N-邻羟基苯甲烯基-3-氨基香豆素（SAC）与牛血清白蛋白（BSA）的相互作用。研究内容共分为四个部分:1.研究了SU22与BSA的相互作用,证明SU22对BSA的荧光淬灭机理属于形成了复合物的静态淬灭,结合位点数约等于1,复合物的形成常数达到1.569×10⁵L·mol^-1,说明二者具有较强的结合,SU22能够被BSA所储存和转运。热力学参数显示二者之间主要以氢键和范德华力结合,利用Forster理论计算出SU22与BSA色氨酸残基的距离为3.20nm,通过CD和FTIR光谱发现SU22使BSA的构象发生了变化。2.用相似的方法证明H₂aac或La（Haac）₃对BSA的荧光淬灭属于静态淬灭,结合位点数都约等于1,形成常数分别为2.236×10⁵L·mol^-1和4.085×10⁵L·mol^-1,说明二者与BSA具有较强的结合,都能够被BSA所储存和转运,而配合物的结合力更强。H₂aac与BSA主要以疏水作用结合,La（Haac）₃与BSA主要以疏水和静电作用结合。利用Forster理论计算出二者与色氨酸残基的距离分别为3.48nm和3.35nm。标记物竞争实验表明H₂aac在BSA的SiteⅡ结合,La（Haac）₃在SiteⅠ结合。通过CD和FTIR光谱发现二者使BSA的构象发生了变化。3.研究了模拟生理条件下M或SmL₃与BSA的相互作用,证明它们与BSA形成了复合物,结合位点数都约等于1,形成常数分别为1.294×10⁵L·mol^-1和1.465×10⁵L·mol^-1,说明二者与BSA具有较强的结合,M形成配合物SmL₃后与BSA的结合力变强但程度不大。M与BSA主要以氢键和范德华力结合,而SmL₃主要以疏水和静电作用结合。利用Forster理论计算出M或SmL₃与BSA色氨酸残基的距离分别为3.83nm和3.71nm。标记物竞争实验表明M在BSA的SiteⅠ结合,SmL₃在SiteⅡ结合。同步荧光表明它们使BSA色氨酸残基附近的微环境极性增加。通过CD光谱发现二者使BSA的构象发生了变化,均使BSA的α-螺旋结构含量减少。4.荧光和紫外光谱证明SAC对BSA的荧光淬灭机理属于静态淬灭,结合位点数约为1,SAC-BSA复合物的形成常数K_A达到1.632×10⁵L·mol^-1,说明二者具有较强的结合,SAC能够被BSA所储存和转运。热力学参数显示它们主要以氢键和范德华力结合。计算出SAC距离色氨酸残基3.61nm,SAC在BSA的SiteⅠ位结合。同步荧光表明SAC使BSA的构象发生了变化,酪氨酸残基附近的微环境极性减小,CD光谱研究发现SAC与BSA结合使BSA的α-螺旋结构含量减少。通过这些研究发现:不同的化合物由于结构差异,与BSA在结合力类型、结合力强度、结合位置上都产生了明显的差异,使BSA的构象产生不同程度的扰动;配体在形成金属配合物后与BSA的结合力变强,结合力类型变得更为多样,结合位置也存在差别。本论文从分子水平的角度探讨了小分子与血清白蛋白分子之间相互作用的机理,对于认识它们之间相互作用的一般规律具有重要意义,对新型药物的设计具有参考和借鉴价值。更多还原

【Abstract】 Serum albumin,the most abundant protein in blood plasma,has many important physiological functions.The most remarkable property of albumin is that it serves as a depot and transport protein for numerous endogenous and exogenous compounds. Investigating the binding mechanism of drugs with serum albumin has importance in pharmacokinetics.It has been an interesting research field of life science,chemistry and clinical medicine.In this dissertation,on the basis of previous research,the interactions of bovine serum albumin（BSA）with 1-phenyl-3-（coumarin-6-yl）sulfonyl -urea（SU22）,3-acetylacetyl-4-hydroxycoumarin（H₂aac）and its La（Ⅲ） complex（La（Haac）₃）,N²-（2"-hydroxybenzoyl）-N-（4’-tolylsulfonamido）carboxhydrazine （M）and its Sm（Ⅲ）complex（SmL₃）,and N-salicylidene-3-aminocoumarin（SAC）, respectively,have been studied by using spectroscopy under simulative physiological conditions.The thesis contains four parts:1.Through studying the interaction of SU22 with BSA,the quenching mechanism of BSA fluorescence by SU22 was proved to be a static quenching and the number of binding sites was about 1;the association constant at 298K was 1.569×10⁵L·mol^-1, which,indicated it can be deposited and transported by albumin;the thermodynamic parameters explained that hydrogen bond and Van der Waals interaction were the main binding force stabilizing the complex.The binding average distance between SU22 and tryptophan（Trp）of BSA was 3.20 nm on the basis of the Forster’s theory. In addition,The CD spectra and FTIR spectra have proved that BSA has some conformational changes in the presence of SU22 in aqueous solution.2.Using similar methods,the quenching mechanism of BSA fluorescence by H₂aac or La（Haac）₃ was a static quenching process and both of the number of binding sites were about 1;the association constants at 298K were 2.236×10⁵L·mol^-1and 4.085×10⁵L·mol^-1,respectively,which indicated they can be deposited and transported by albumin and La（Haac）₃ had higher affinity;hydrophobic interaction was the main binding force stabilizing H₂aac-BSA complex,and electrostatic and hydrophobic force for La（Haac）₃-BSA complex.The binding average distance between them and Trp was 3.48nm and 3.35nm,respectively;the binding location of H₂aac in BSA was in siteⅡ,and La（Haac）₃ in siteⅠ;In addition,The CD and FTIR spectra have proved that BSA conformation changed in the presence of them. 3.The binding of M or SmL₃ to BSA was studied under simulative physiological conditions.The quenching mechanism of BSA fluorescence by M or SmL₃ was a static quenching process and both of the number of binding sites were about 1;the association constants at 298K were 1.294×10⁵L·mol^-1and 1.465×10⁵L·mol^-1, respectively,Which indicated they can be deposited and transported by albumin; hydrogen bond and Van der Waals force was the main affinity for M-BSA system,but electrostatic and hydrophobic interaction for SmL₃-BSA system.The binding average distance between them and Trp was 3.83nm and 3.71nm,respectively;the binding average location of M in BSA was in siteⅠ;and SmL₃ in siteⅡ;In addition,the Synchronous fluorescence spectra of BSA indicated that the tryptophan residues were place in a less hydrophobic microenvironment after binding to them;The CD spectra proved that BSA conformation changed in the presence of them.4.Fluorescence and UV-absorption spectra suggested that the quenching mechanism of BSA fluorescence by SAC was a static quenching and the number of binding sites was about 1;the association constant at 298K was 1.632×10⁵L·mol^-1, which indicated SAC can be deposited and transported by albumin;hydrogen bond and Van der Waals force was the main affinity for SAC-BSA complex.The binding average distance between SAC and Trp was 3.61 nm,and the binding location of SAC in BSA was in site I.In addition,the synchronous fluorescence spectra of BSA indicated that the tyrosine residues were place in a more hydrophobic microenvironment after binding to SAC;The CD spectra proved that BSA secondary structure changed in the presence of it.Based on above results,various compounds had different affinities,strength and binding location to BSA.To various degrees,they also changed BSA conformation. Binding to BSA,the complex had stronger binding force,more various affinities than the ligand,and had different binding location to it.These results are important to understand the role of these molecules in biological process,and the knowledge of the binding capacity of the compounds and BSA may prompt us to design the most suitable derivatives existed in thenew therapeutic drugs,which will be important in modern medical research.更多还原