锌离子对缓冲液中槲皮素和牛血清白蛋白相互作用的影响

采用荧光光谱法和紫外光谱法研究了Zn2+离子对槲皮素(Qct)和牛血清白蛋白(BSA)在pH=7.4的Tris-HCl缓冲溶液中相互作用的影响;根据荧光猝灭双倒数图计算了Qct和BSA之间的结合常数和结合位点数.结果表明,Qct和Zn2+离子都可以使BSA的荧光强度发生猝灭;Qct和BSA之间的结合常数为3.17×107L.mol-1.s-1,结合位点数为1.32.定量计算表明,加入Zn2+离子后,Qct与BSA间的结合常数显著降低、结合位点数减小,表明Zn2+离子参与了Qct与BSA的结合过程.     

荧光光谱法研究共存物对白杨素与BSA相互作用的影响

运用荧光光谱法研究了共存物亚硝酸钠、葡萄糖或维生素C对白杨素(CHR)与牛血清白蛋白(BSA)相互作用的影响.结果表明:无共存物时,白杨素对BSA的荧光猝灭过程为静态猝灭,结合常数K值为10~3～10~4数量级,结合位点数n近似等于1,分子间相互作用力以疏水作用力为主;亚硝酸钠、葡萄糖、维生素C分别参与下,白杨素对BSA的荧光猝灭类型由静态猝灭转变为动态猝灭,葡萄糖的参与使白杨素与BSA之间作用力类型由疏水作用力转为氢键与范德华力,亚硝酸钠或维生素C的分别存在不影响白杨素与BSA的作用力类型;三种外加试剂的单独参与均使得白杨素与BSA的结合常数明显增大,结合位点数略有增加,但仍维持在1左右.初步探讨了共存物影响白杨素与BSA结合的可能方式.     

盐酸异丙肾上腺素与牛血清白蛋白相互作用

采用荧光猝灭法和毛细管区带电泳法研究了盐酸异丙肾上腺素（IH）与牛血清白蛋白（BSA）的相互作用。荧光猝灭法研究表明:IH对BSA有较强的荧光猝灭作用,根据Stern-Volmer方程得到猝灭速率常数（K_q）为2.53×10¹³ L·mol^-1·s^-1,该荧光猝灭属于静态猝灭。采用位点结合模型公式计算得结合常数为1.72×10⁴ L·mol^-1,结合位点数n为1;毛细管区带电泳法研究表明:IH与BSA的结合常数为4.07×10⁴ L·mol^-1,结合位点数n为1。     

金属离子对齐多夫定与牛血清白蛋白结合作用的影响

用荧光光谱法和紫外分光光度法研究了水溶液(Tris-HCl缓冲溶液, pH 7.1)中齐多夫定(ZDV)与牛血清白蛋白(BSA)的结合作用及三种金属离子(Cu2+, Mg2+, Zn2+)对其的影响. 结果表明: 齐多夫定及金属离子均导致BSA的内源荧光猝灭, 猝灭机制均为静态猝灭; 齐多夫定与BSA间存在较强结合作用, 热力学参数△H和△S分别为-10.2 kJ·mol-1和77.5 J·mol-1·K-1 (298 K), 表明其结合力以静电作用力为主; 298 K下结合常数、结合位点数和结合距离分别为6.92×105 L·mol-1、1.18和2.28 nm; 温度升高结合常数和结合位点数减小. 三种金属离子均导致ZDV与BSA的结合常数减小, 结合距离增大.     

荧光光谱法研究注射用头孢美唑钠与牛血清白蛋白的相互作用

运用荧光光谱法研究了注射用头孢美唑钠(Cefmetazole Sodium,CS)与牛血清白蛋白(BSA)的相互作用.CS对BSA具有荧光猝灭作用,其猝灭方式为静态猝灭,求出了猝灭常数,结合常数及结合位点数.在297 K和311 K时用Stern-Volmer方程和热力学方程处理实验数据,得到了结合常数KA、热力学参数...     

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

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.     

荧光光谱法研究辛硫磷与牛血清白蛋白的相互作用

用荧光光谱法研究了在生理pH条件下杀虫剂辛硫磷与牛血清白蛋白(BSA)的相互作用. 结果表明: 辛硫磷对BSA的荧光有较强的猝灭作用, 该猝灭属于静态猝灭. 根据猝灭结果求得了不同温度下辛硫磷与牛血清白蛋白结合作用的结合位点数、结合常数及反应热力学参数, 并据此确定它们之间主要的相互作用力为疏水作用力. 用同步荧光光谱法探讨了辛硫磷对BSA构象的影响.     

几种金属离子对胭脂红与牛血清白蛋白相互作用的影响——荧光光谱研究

利用荧光光谱法研究了不同温度(15、27、39℃)下食用合成色素胭脂红对牛血清白蛋白(BSA)的内源荧光猝灭特性,考察了Cu2+、Ni 2+、Pb2+等金属离子对二者相互作用的影响,并测定了不同温度下的猝灭常数KSV、结合常数KA和结合位点数n.结果表明,3种金属离子基本不影响胭脂红对BSA荧光猝灭机理,但Cu2+、Ni 2+、Pb2+离子都与BSA有一定的结合能力,可在不同程度上增强胭脂红与BSA的结合作用及其对BSA内源荧光的猝灭.     

荧光法研究金属离子对橙皮素与牛血清白蛋白相互作用的影响

采用荧光光谱和三维荧光光谱法研究了橙皮素(HSP)与牛血清白蛋白(BSA)之间的相互作用,并考察了共存金属离子Cu2+,Zn2+对二者相互作用的影响。实验结果表明,HSP对BSA的内源性荧光具有猝灭作用,猝灭类型为静态猝灭,作用力类型是氢键和范德华力,Cu2+,Zn2+的加入未改变HSP对BSA的猝灭类型和作用力类型。通过比较猝灭常数、结合常数、结合位点数、猝灭效率和三维荧光光谱图变化,推知Cu2+,Zn2+能与BSA产生结合作用,使其成为受制状态下的刚性肽链,从而影响HSP进入BSA疏水腔,减弱了HSP与BSA的结合能力,表现为与HSP存在竞争作用。     

吡蚜酮与牛血清白蛋白的相互作用

利用紫外吸收、荧光、同步荧光光谱及圆二色谱研究了吡蚜酮与牛血清白蛋白(BSA)的相互作用. 结果发现, 吡蚜酮使BSA的紫外吸收峰强度降低, 峰位红移; BSA的特征荧光峰猝灭, 荧光猝灭常数KSV随着温度的升高而降低, 表明吡蚜酮与BSA发生了较强的相互作用, 且吡蚜酮对BSA的荧光猝灭机制属于静态猝灭. 计算了不同温度下的结合常数和结合位点数; 由van′t Hoff方程计算出体系的ΔH和ΔS值, 得出二者之间的作用力主要为氢键和范德华力; 根据非辐射能量转移理论确定了给体-受体间的结合距离r=2.4 nm. 采用同步荧光光谱和圆二色谱考察了吡蚜酮对牛血清白蛋白构象的影响.     

Studies on the interaction of cinnamic acid with bovine serum albumin

The interaction between cinnamic acid and bovine serum albumin (BSA) have been studied at three temperatures, 296, 303 and 310 K. Fluorescence quenching spectra in combination with Fourier transform infrared (FT-IR) spectroscopy and circular dichroism (CD) spectroscopy was used to investigate the drug-binding mode, the binding constant and the protein structure changes in the presence of cinnamic acid in aqueous solution at pH 7.40. The fluorescence quenching constant K(q), K(sv) and the binding constant K were calculated according to Stern-Volmer equation based on the quenching of the fluorescence of BSA in the presence of cinnamic acid. The thermodynamic parameters, the enthalpy (DeltaH) and the entropy change (DeltaS) were estimated to be -16.457 kJ mol(-1) and 38.028 J mol(-1) K(-1) according to the van't Hoff equation. The displacement experiment shows that cinnamic acid can bind to the subdomain IIA (corresponding to Sudlow's drug binding site I). The distance between the tryptophan residues in BSA and cinnamic acid bound to site I was estimated to be 1.63 nm using F?ster's equation on the basis of fluorescence energy transfer. The decreased binding constant in the presence of common ions indicates that common ions have effect on drug-BSA system.     

桂皮酸-1,10-二氮杂菲镧配合物的合成及与牛血清白蛋白的相互作用

合成并表征了桂皮酸-1,10-二氮杂菲-镧三元配合物,运用紫外和荧光光谱研究了三元配合物与牛血清白蛋白（BSA）的相互作用.结果表明：随三元配合物浓度的增加,BSA的紫外光谱表现增色效应和较小的蓝移;三元配合物可有规律地猝灭BSA的内源荧光,使BSA发生较强的静态荧光猝灭.在室温下,三元配合物与BSA的结合常数KA和结...     

激光光散射与荧光光谱法研究大豆苷与牛血清白蛋白作用及聚集态

荧光光谱法和动态光散射法研究大豆苷与牛血清白蛋白在生理条件下的相互作用. 研究表明, 大豆苷与牛血清白蛋白能形成2∶l复合物, 荧光猝灭属于静态猝灭过程; 大豆苷与牛血清白蛋白分子间主要的结合作用力为疏水作用; 310 K下, 两者结合常数和结合位点数分别为7.4×l04 L•mol―1和1.75; 大豆苷使牛血清白蛋白的构象发生了变化; 动态光散射数据探讨了牛血清白蛋白与大豆苷分子产生聚集与之相互作用, 进一步证实了牛血清白蛋白在大豆苷水溶液中的构象变化. 实验结果为进一步研究大豆苷对心血管疾病的药理作用, 特别是对血浆蛋白构象的影响提供了重要依据.     

Binding of naproxen to bovine serum albumin and tryptophan-modified bovine serum albumin

Two classes of binding sites, a single high-affinity site with an association constant of 4·8×10⁶ M⁻¹ and two low-affinity sites with association constant of about 0·05×10⁶ M⁻¹ have been observed in the interaction of Naproxen with bovine serum albumin (BSA). Chemical modification of two tryptophan residues in BSA with 2-hydroxy-5-nitrobenzyl bromide has led to a reduction in the association constant of the high-affinity site by 89% and its number of binding sites by 66% suggesting the involvement of tryptophan residues in the high-affinity site. In contrast, the two low-affinity sites were not affected by the modification. Binding of Naproxen to the low-affinity sites of BSA induces microdisorganisation of the albumin structure leading to conformational changes as evident from fluorescence measurements with 1-anilino-8-naphthalenesulphonic acid as the probe.     

Mechanism of interaction of vincristine sulphate and rifampicin with bovine serum albumin: A spectroscopic study

The mechanism of interaction of vincristine sulphate (VS) and rifampicin (RF) with bovine serum albumin (BSA) has been studied by quenching of BSA fluorescence by RF/VS. The Stern-Volmer plot indicates the presence of a static component in the quenching mechanism. Results also show that both the tryptophan residues of BSA are accessible to VS and RF. The high magnitude of rate constant of quenching indicates that the process of energy transfer occurs by intermolecular interaction and VS/RF-binding site is in close proximity to the tryptophan residues of BSA. Binding studies in the presence of a hydrophobic probe, 8-anilino-1-naphthalene-sulphonic acid sodium salt (ANS) indicate that the VS and RF compete with ANS for hydrophobic sites on the surface of BSA. Small decreases in critical micellar concentrations (CMC) of anionic surfactants in presence of VS/ RF show that the ionic character of VS/RF also contributes to binding. The temperature dependence of the association constant is used to estimate the values of the thermodynamic parameters involved in the interaction of VS/RF with BSA and the results indicate that hydrophobic forces play a significant role in the binding. Circular dichroism studies reveal that the change in helicity of BSA are due to binding of VS/RF to BSA.     

Analysis of binding interaction between pegylated puerarin and bovine serum albumin by spectroscopic methods and dynamic light scattering

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.     

谷胱甘肽-二茂铁的合成及其与牛血清白蛋白的相互作用

采用液相合成法, 以O-苯并三唑-N,N,N',N'-四甲基脲六氟磷酸酯(HBTU)和1-羟基苯并三氮唑(HOBT)为缩合剂, 将二茂铁胺和还原型谷胱甘肽(GSH)反应, 合成了具有电化学活性的谷胱甘肽-二茂铁(GSH-Fc), 其收率为23.2%, 并对目标产物进行了红外、核磁、质谱表征. 通过电化学方法研究了GSH-Fc与牛血清白蛋白(BSA)之间的相互作用特性. 电化学实验结果表明, BSA和GSH-Fc结合位点位于BSA的亚结构域IIA, 结合常数为1.71×106 L·mol-1, 结合位点数为1.30. 同时通过荧光光谱法研究了GSH-Fc与BSA相互作用是一种静态猝灭的过程, 结合常数和结合位点数分别为2.74×106 L·mol-1和1.57, 与电化学方法得到的结果相吻合.