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1.
在pH 7.40的Tris-HC1缓冲溶液体系中,采用荧光光谱法和同步荧光光谱法研究了甲基紫(MV)与牛血清白蛋白(BSA)相互作用.结果表明MV与BSA相互作用两者存在一个结合位点,结合常数(KA)为7.628×103 L/mol,MV与BSA主要发生疏水作用,反应是一个吸热、熵增的自发过程.  相似文献   

2.
在模拟生理条件下,通过荧光光谱法研究染料木素(Ge)与牛血清蛋白(BSA)间相互作用,在水溶液中Ge能够有效地猝灭BSA的荧光发射。考查了溶液p H、水浴温度、水浴时间等参数对于Ge猝灭BSA的影响,并且通过StemVolmer方程计算了Ge与BSA之间的结合类型、结合位点数和结合常数等参数。结果表明,Ge猝灭BSA的类型为静态猝灭,Ge与BSA可形成1∶1型非共价复合物。通过同步荧光光谱法结合分子对接研究了Ge与BSA间的作用情况,结果表明,氢键作用与疏水作用是Ge与BSA形成复合物的主要驱动力,Ge通过改变BSA中Trp134残基微环境的疏水情况猝灭BSA的荧光发射。  相似文献   

3.
蛋白质与刚果红结合反应的研究   总被引:1,自引:0,他引:1  
研究了酸性溶液中蛋白质(BSA)与刚果红(CGR)的结合反应。BSA与CGR相互作用形成复合物,溶液颜色由蓝色变为红色,最大吸收波长紫移,表明在蛋白质正电荷作用下,CGR由游离态酸色型变为结合态碱色型。测得CGR与BSA的结合最大结合数约为43,符合Scatchard模型。荧光光谱表明,CGR与BSA作用导致BSA荧光猝灭,结合位点为BSA第212位色氨酸残基,相互作用为非辐射能量转移。  相似文献   

4.
采用荧光光谱、同步荧光光谱、三维光谱和循环伏安曲线法研究了溴化阻燃剂四溴双酚-A(TBBPA)与牛血清白蛋白(BSA)的相互作用。研究表明,TBBPA对BSA的内源荧光有显著的猝灭作用,根据不同温度下TBBPA对BSA的荧光猝灭作用及室温的循环伏安曲线,证实猝灭机理为静态猝灭。运用位点模型计算出结合常数KA和结合位点数n,说明TBBPA与BSA仅有1个结合位点。由ΔH0和ΔS0分别为-33.06 kJ/mol和-64.73 J/(mol.K),推断范德华力或氢键在二者结合过程中起主要作用。并通过同步荧光光谱和三维光谱研究了TBBPA对BSA构象的影响,结果表明,TBBPA分子的引入改变了BSA疏水腔内疏水微环境,从而导致BSA的构象发生变化。  相似文献   

5.
用荧光法研究了二价铅离子与牛血清白蛋白的相互作用,测定了不同条件下pb2+与BSA作用的荧光光谱,并通过热力学计算探讨了二者的作用方式、BSA荧光的猝灭机理、Pb2+与BSA之间的结合常数及结合位点.结果表明,Pb2+对BSA的荧光猝灭属于静态猝灭,pb2+通过疏水作用力进入BSA的疏水腔与之发生相互作用,反应的△G=...  相似文献   

6.
用荧光光谱法研究了肉桂酸与牛血清白蛋白(BSA)在生理条件下的相互作用. 实验结果表明, 肉桂酸与BSA能形成1:1复合物, 荧光猝灭属于静态猝灭过程; 与BSA分子间主要的结合作用力为疏水作用; 310 K 下结合常数和结合位点数分别为3.07×104 L·mol-1和1.10; 肉桂酸使BSA的构象发生了变化; 另外, 酒精的加入使其结合常数和结合位点数减小.  相似文献   

7.
金属离子对次野鸢尾黄素与牛血清白蛋白相互作用的影响   总被引:2,自引:1,他引:1  
应用荧光光度法研究了金属离子Fe3 、Ca2 、Cu2 或Mn2 对次野鸢尾黄素(IFR)与牛血清白蛋白(BSA)相互作用的影响.实验结果表明,不存在金属离子时,IFR对BSA的荧光猝灭过程为动态猝灭,其结合过程的表观结合常数KA值为104~105数量级,结合位点数n约等于1.由热力学参数得出IFR与BSA结合过程是一个熵增加、Gibbs自由能降低的自发过程,分子间相互作用力以疏水作用力为主.在Fe3 或Ca2 抖的存在下,IFR对BSA的荧光猝灭类型由动态猝灭转变为静态猝灭,作用力类型也由以疏水作用力为主转变为以氢键与范德华力为主或以静电引力为主.Cu2 或Mn3 存在下,IFR对BSA的荧光猝灭类型及分子间作用力类型均没有发生改变.四种金属离子的参与都使得IFR与BSA结合作用的袁观结合常数发生了明显的变化,但结合位点数仍维持在1左右.  相似文献   

8.
采用分子对接技术和同步荧光光谱法、红边激发荧光位移法(REES法)及圆二色谱法(CD)共同研究了山柰酚与牛血清白蛋白(BSA)在pH7.40的缓冲溶液中的相互作用。分子对接的结果表明,山柰酚的B环插入到BSA的ⅡA结构域中的疏水腔内,与色氨酸残基(Trp212)的距离为12.96,维系药物与蛋白质的主要作用力为疏水作用。通过荧光光谱法测得二者之间相互作用力主要为疏水性相互作用,结合位点为1,与分子模拟结果一致。同步荧光光谱及REES法的研究表明,发生相互作用的过程中BSA的色氨酸残基处于运动受限的微环境中,而适当增加山柰酚的浓度能够改变色氨酸微环境的流动性,进而对BSA的构象产生一定影响;同时,圆二色谱的定量计算结果也表明,一定浓度的山柰酚与BSA的相互作用引起了α-螺旋含量的显著降低,从11.91%降低到1.67%,对BSA的二级结构产生一定影响。  相似文献   

9.
十溴联苯醚与牛血清白蛋白相互作用的荧光光谱研究   总被引:1,自引:0,他引:1  
在模拟生理条件下,采用荧光光谱法研究十溴联苯醚(Deca-BDE)与牛血清白蛋白(BSA)的相互作用.结果表明: Deca-BDE对BSA的内源荧光有静态猝灭作用.Deca-BDE与BSA在277, 298和310 K的结合常数分别为1.92×105, 1.97×105和2.16×105 L/mol.Deca-BDE在BSA接近于色氨酸残基附近有2个结合位点.热力学参数表明, Deca-BDE与BSA相结合的主要驱动力是疏水作用力. 与Deca-BDE结合后,BSA色氨酸残基附近肽键伸展程度增加,蛋白分子结构疏松.  相似文献   

10.
采用荧光光谱法研究了水溶液中四溴荧光素、四氯四溴荧光素、二碘荧光素、乙基罗丹明B、健那绿B等5种荧光染料探针与牛血清白蛋白(BSA)的相互作用.实验表明,这5种染料探针同牛血清白蛋白结合时,疏水作用力起决定性作用,静电力起次要作用,相比之下牛血清白蛋白(BSA)结合阴离子的能力最强,其次为中性分子,最后为阳离子.通过疏水作用力,5种染料均是以非极性苯基进入BSA疏水性腔体中同色氨酸残基发生作用,弱氢键的形成加强了这种作用力,且使得光谱间能量转移效率明显提高.5种染料探针的极性部位由于极性和空间效应的原因难以进入腔体内部,致使反应均按接近1∶1的方式进行.  相似文献   

11.
This work attempts to calculate the binding-site number using fluorescence spectroscopic method with bovine serum albumin (BSA) and Indo-1 as protein and ligand models, respectively. The method for calculating the binding-site number in BSA for Indo-1 was developed based on the relationships between changes in Indo-1 fluorescence intensity and the analytical concentration of BSA. The interaction between BSA with Indo-1 was investigated comprehensively using fluorescence techniques as well as fluorescence resonance energy transfer, and the thermodynamic parameters were calculated according to the effect of enthalpy on temperature. Three binding sites in BSA for Indo-1 were revealed, and the distances from Trp212 in BSA to the three binding sites were 2.93, 2.57 and 2.40 nm, respectively. It was also proven that Indo-1 embedded into the three hydrophobic cavities of BSA by hydrophobic association. This paper provides a reference on calculating the binding-site number in proteins for ligands and studying their interactions by fluorescence spectroscopic methods. In fluorescent quenching experiments, fluorescence changes were automatically recorded in real time by combining the Microlab 500 Series Dispenser and PTI fluorescence apparatus. __________ Translated from Chemical Journal of Chinese Universities, 2007, 28(2): 227–233 [译自: 高等学校化学学报]  相似文献   

12.
在人体生理pH条件下,利用紫外吸收光谱和荧光光谱研究了槲皮素(QUE)、大豆甙元(DAI)、4′,7-二甲氧基-3′-异黄酮磺酸钠(DISS)和3′-大豆甙元磺酸钠(DSS)四种黄酮类化合物与牛血清白蛋白(BSA)的相互作用,结合反应机理对其进行了初步探讨;并计算了结合位点数和结合常数.紫外吸收光谱分析结果表明,在pH=7.4条件下,黄酮类化合物中疏水性的苯环与BSA疏水腔中的氨基酸残基发生作用,从而导致药物分子的吸收峰红移,用Scatchard拟合法可求得DAI及DSS与BSA的结合常数.荧光光谱分析结果表明,BSA对DAI、DISS和DSS均有明显的敏化增强效应,计算得到的增强速率常数分别为1.39×1011,7.72×1011和1.93×1012L·s-1·mol-1,并可求得结合位点数和结合常数.  相似文献   

13.
The interaction between cefixime (antibacterial) and tolcapone (Parkinson’s disease) drugs with bovine serum albumin (BSA) was investigated using several spectroscopic techniques viz. UV–Vis, fluorescence and circular dichroism. The thermodynamic parameters of the interactions were calculated, which indicated that the binding processes are spontaneous and H-bonding and van der Waals forces play a major role in BSA–cefixime interaction and hydrophobic interactions dominate BSA–tolcapone complexation. Cefixime quenches the intrinsic fluorescence of BSA by dynamic process while tolcapone through static process. The binding constant of the BSA–tolcapone complex (107 L mol?1) is found to be relatively higher than that of BSA–cefixime complex (104 L mol?1). The binding distance between BSA and cefixime and tolcapone is calculated to be 3.3 and 4.2 nm, respectively. Both fluorescence and circular dichrosim spectral studies confirmed conformational changes in BSA upon binding with these drugs. Molecular docking studies suggest the possible binding sites in the protein molecule.'  相似文献   

14.
Binding of the drugs naproxen (which is an anti-inflammatory) and amitriptyline (which is an anti-depressant) to bovine serum albumin (BSA) has been studied using isothermal titration calorimetry (ITC), in combination with fluorescence and circular dichroism spectroscopies. Naproxen is observed to bind more strongly to BSA than amitriptyline. The temperature-dependent ITC results indicate the interaction of one molecule of naproxen with more than one protein molecule. On the other hand, amitriptyline binds to BSA with a reaction stoichiometry that varies from 1:1.2 to 1:2.9. The van't Hoff enthalpy, which is calculated from the temperature dependence of the binding constant, agrees well with the calorimetric enthalpy in the case of naproxen binding to BSA, indicating adherence to a two-state binding process. However, their disagreement in the case of amitriptyline indicates conformational changes in the protein upon ligand binding, as well as with the rise in temperature. The spectroscopic results did not suggest appreciable conformational changes as a result of binding; hence, the discrepancy could be attributed to the temperature-induced conformational changes. With increases in the ionic strength, a reduction in the binding affinity of naproxen to BSA is observed. This suggests the prevailing electrostatic interactions in the complexation process. The preponderance of the hydrophobic interactions in the binding of amitriptyline to BSA is indicated by the absence of any dependence of the ionic strength. A predominance of electrostatic interactions in the case of naproxen binding to BSA and that of hydrophobic interactions in the case of amitriptyline binding to BSA is further strengthened by the results of the binding experiments performed in the presence of ionic and nonionic surfactants. The binding parameters indicate that Triton X-100 blocks the hydrophobic binding sites on BSA, thereby altering the binding affinity of amitriptyline toward BSA. A partial overlap of the binding sites for these drugs is indicated by the binding parameters obtained in the titration of naproxen to the amitriptyline-BSA complex and vice versa. Thus, the results provide a quantitative understanding of the binding of naproxen and amitriptyline to BSA, which is important in understanding their effect as therapeutic agents individually and in combination therapy.  相似文献   

15.
The interaction between bovine serum albumin (BSA) and pegylated puerarin (Pur) in aqueous solution was investigated by UV-Vis spectroscopy, fluorescence spectroscopy and circular dichroism spectra (CD), as well as dynamic light scattering (DLS). The fluorescence of BSA was strongly quenched by the binding of pegylated Pur to BSA. The binding constants and the number of binding sites of mPEG(5000)-Pur with BSA were 2.67±0.12 and 1.37±0.05 folds larger after pegylating, which were calculated from the data obtained from fluorescence quenching experiments. The enthalpy change (ΔH) and entropy change (ΔS) were calculated to be 4.09 kJ mol(-1) and 20.01 J mol(-1) K(-1), respectively, according to Van't Hoff equation, indicating that the hydrophobic force plays a main role in the binding interaction between pegylated Pur and BSA. In addition, the negative sign for Gibbs free energy change (ΔG) implies that the interaction process is spontaneous. Moreover, the results of synchronous fluorescence and CD spectra demonstrated that the microenvironment and the secondary conformation of BSA were changed. Comparing with Pur, all our data collected indicated that pegylated Pur interacted with BSA in the same way as that of Pur, but docked into the hydrophobic pocket of BSA with more accessibility and stronger binding force. DLS measurements showed monomethoxy polyethylene glycol (mPEG) have an effect on BSA conformation, and revealed that changes in BSA size might be due to increases in binding constant and the absolute values of ΔG after Pur pegylation.  相似文献   

16.
光谱法与分子模拟研究胡椒碱对牛血清白蛋白的键和作用   总被引:5,自引:1,他引:4  
何文英  陈光英  杜娟  姚晓军 《化学学报》2008,66(21):2365-2370
利用荧光光谱法及紫外吸收光谱法结合计算机模拟技术研究了在模拟生理条件下胡椒碱(piperine)与牛血清白蛋白(Bovine Serum Albumin, BSA)的相互作用. 根据荧光猝灭的有关方程分别求得不同温度下(298, 308和318 K)药物与蛋白相互作用的结合常数、结合位点数及键合距离. 实验所得到的热力学参数(ΔHӨ=-9.55 kJ/mol, ΔSӨ=46.75 J•mol-1•K-1)表明维持药物与蛋白质的相互作用力主要是疏水作用和静电作用. 分子模拟的结果显示了胡椒碱与BSA的键合机理和键合模式, 表明维持药物与蛋白质的相互作用力主要是疏水作用和氢键(位于氨基酸残基His 242, Arg 222和Arg 218位). 此外, 基于胡椒碱的荧光猝灭效应, 首次探讨了药物-蛋白质体系的几种物理化学参数, 包括电荷密度(δ)、离解常数(Kd)及量子产率(F)的变化效应.  相似文献   

17.
The interaction between hyperoside and bovine serum albumin (BSA) was examined by fluorescence spectroscopy at 298, 304, and 310 K. The spectroscopic data were analyzed using Tachiya model and Stern–Volmer equation to determine the binding sites and apparent binding constant between hyperoside and BSA. For Tachiya model, both binding sites and apparent binding constants increased with the increasing of temperature, whereas for Stern–Volmer equation, the corresponding binding constants decreased as temperature increasing and the binding sites were independent of temperature. The positive sign of enthalpy change (ΔH) and entropy change (ΔS) suggested that hydrophobic forces played a major role in the interaction. Synchronous fluorescence spectra indicated that the conformation of protein was perturbed by the interaction of hyperoside with BSA. Moreover, the presence of metal ion affected the hyperoside-BSA binding.  相似文献   

18.
This study examined the interaction of indirubin with bovine serum albumin (BSA) at three temperatures (286, 297, 308 K) at pH 7.40. In the presence of indirubin, the drug-BSA binding mode, binding constant and the protein structure changes in aqueous solution were determined by fluorescence quenching methods including Fourier transform infrared (FT-IR) spectroscopy and UV-Vis spectroscopy. The FT-IR change indicates that indirubin binds to BSA. The change in protein secondary structure accompanying ligand binding has been proved by fluorescence spectra data. The thermodynamic parameters, the enthalpy change (DeltaH), and the entropy change (DeltaS) calculated by the van't Hoff equation possess small negative (-2.744 kJ.mol(-1)) and positive values (112.756 J.mol(-1).K(-1)), respectively, which indicated that hydrophobic interactions play the main role in the binding of indirubin to BSA. Furthermore, the displacement experiment shows that indirubin can bind to the subdomain IIA and the distance between the tryptophan residues in BSA and indirubin bound to site I was estimated to be 2.24 nm according to F?ster's equation on the basis of fluorescence energy transfer.  相似文献   

19.
The mechanism and conformational changes of farrerol binding to bovine serum albumin (BSA) were studied by spectroscopic methods including fluorescence quenching technique, UV–vis absorption, circular dichroism (CD) spectroscopy and Fourier transform infrared (FT-IR) spectroscopy under simulative physiological conditions. The results of fluorescence titration revealed that farrerol could strongly quench the intrinsic fluorescence of BSA through a static quenching procedure. The thermodynamic parameters enthalpy change and entropy change for the binding were calculated to be −29.92 kJ mol−1 and 5.06 J mol−1 K−1 according to the van’t Hoff equation, which suggested that the both hydrophobic interactions and hydrogen bonds play major role in the binding of farrerol to BSA. The binding distance r deduced from the efficiency of energy transfer was 3.11 nm for farrerol–BSA system. The displacement experiments of site markers and the results of fluorescence anisotropy showed that warfarin and farrerol shared a common binding site I corresponding to the subdomain IIA of BSA. Furthermore, the studies of synchronous fluorescence, CD and FT-IR spectroscopy showed that the binding of farrerol to BSA induced conformational changes in BSA.  相似文献   

20.
The interactions between riboflavin (RF) and human and bovine serum albumin (HSA and BSA) were studied by using absorption and fluorescence spectroscopic methods. Intrinsic fluorescence emission spectra of serum albumin in the presence of RF show that the endogenous photosensitizer acts as a quencher. The decrease of fluorescence intensity at about 350 nm is attributed to changes in the environment of the protein fluorophores caused by the ligand. The quenching mechanisms of albumins by RF were discussed. The binding constants and binding site number were obtained at various temperatures. The distance between albumins and RF in the complexes suggests that the primary binding site for RF is close to tryptophan residue (Trp214) of HSA and Trp212 of BSA. The hydration process of albumins has also been discussed.  相似文献   

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