Multiple spectroscopic studies on the interaction between olaquindox,a feed additive,and bovine serum albumin

The interaction between olaquindox (OLA) and bovine serum albumin (BSA) was investigated using fluorescence, UV–vis absorption and circular dichroism (CD) spectroscopy. The results showed that the fluorescence quenching of BSA by OLA was a static quenching process induced by the formation of OLA–BSA complex. The binding constant of OLA–BSA complex was calculated to be 1.299 × 10⁴ L mol⁻¹ (293 K). The negative values of ΔH⁰ and ΔS⁰ indicated that hydrogen bond and van der Waals interactions played major roles in stabilizing the complex. Site probe competition experiments and number of binding sites (n) revealed that OLA could bind to site I in subdomain IIA of BSA, and the binding distance (r) was evaluated to be 3.643 nm according to Förster’s non-radiative energy transfer theory. The results of CD and three-dimensional fluorescence spectra suggested some conformational changes of BSA after OLA binding.     

Analysis of binding interaction between puerarin and bovine serum albumin by multi-spectroscopic method

The interaction of puerarin and bovine serum albumin (BSA) was investigated by means of fluorescence spectroscopy, resonance light-scattering spectroscopy, infrared spectroscopy, and synchronous fluorescence spectra. The apparent binding constants (K(a)) between puerarin and BSA were 1.13 x 10(4) (20 degrees C), and 1.54 x 10(4) lmol(-1) (30 degrees C), and the binding sites values (n) were 0.95+/-0.02. The experimental results showed that the puerarin could be inserted into the BSA, quenching the inner fluorescence by forming the puerarin-BSA complex. The addition of increasing puerarin to BSA solution leads to the gradual decrease in RLS intensity, exhibiting the formation of the aggregate in solution. It was found that both static quenching and non-radiation energy transfer were the main reasons for the fluorescence quenching. The positive entropy change and enthalpy change indicated that the interaction of puerarin and BSA was driven mainly by hydrophobic forces. The process of binding was a spontaneous process in which Gibbs free energy change was negative. The competing binding reaction with BSA between Fe(3+), Cu(2+) and puerarin was investigated. The effect of Fe(3+) and Cu(2+) on the binding of puerarin with BSA is discussed.     

Spectroscopic studies on the interaction between silicotungstic acid and bovine serum albumin

The interaction between silicotungstic acid and bovine serum albumin (BSA) was investigated using fluorescence and UV/vis. The experimental results showed that the fluorescence quenching of BSA by silicotungstic acid is a result of the formation of SiW–BSA complex; static quenching and non-radiative energy transferring were confirmed to result in the fluorescence quenching. The binding site number n, apparent binding constant K_A and corresponding thermodynamic parameters were measured at different temperatures. The process of binding SiW molecule on BSA was a spontaneous molecular interaction procedure in which entropy increased and Gibbs free energy decreased. Hydrophobic interaction force plays a major role in stabilizing the complex. The effect of silicotungstic acid on the conformation of BSA was analyzed using synchronous fluorescence spectroscopy.     

荧光光谱法研究忍冬苷与牛血清白蛋白的相互作用

本文首次采用荧光光谱法研究了忍冬瞢与牛血清白费白（BSA）在模拟人体生理条件下的相互作用。结果表明忍冬苷对BSA的荧光猝灭作用属于静态猝灭．且296K下结合常数Ka为3．82×10^-5L·mol^-1,结合位点数n为1．16;热力学分析表明二者主要靠氢键和范德华力结合;位点竞争实验则显示忍冬苷主要通过Site I与BSA相结合;最后还考察了几种常见的共存离子对相互作用的影响。     

金合欢素-7-O-葡萄糖苷与BSA相互作用的荧光光谱法研究

应用荧光光谱法研究了生理条件下金合欢素-7-O-葡萄糖苷与牛血清白蛋白（BSA）的相互作用。结果表明,其对BSA荧光的猝灭机制属于形成复合物的静态猝灭过程,并求得结合常数Ka为8.57×104L.mol-1,结合位点数n为1。根据热力学参数确定了其与BSA之间的主要作用力类型为静电作用力。采用同步荧光考察了药物对BSA构象的影响。此外,讨论了共存离子Cu2＋,Al3＋,Zn2＋,Mg2＋对药物与BSA结合作用的影响。     

荧光光谱法研究塞曲司特与牛血清白蛋白的相互作用

目的:研究不同pH条件下塞曲司特与牛血清白蛋白的相互作用机制.方法:利用荧光光谱法,并以Stern-Volmer方程确定药物与蛋白的作用类型.结果:根据Stern-Volmer方程求出了不同二者pH条件下塞曲司特与牛血清白蛋白之间的猝灭常数,并依据 Foster能量转移理论确定了生理条件下药物与蛋白的结合距离为 2.53 nm.结论:在pH 5.0和人体生理pH条件下塞曲司特对牛血清白蛋白具有荧光猝灭作用且为动态猝灭过程,在pH 8.4时塞曲司特与牛血清白蛋白之间的猝灭为静态猝灭;人体生理pH条件下塞曲司特与牛血清白蛋白之间相互作用力主要为范德华力.     

灯盏乙素与牛血清白蛋白相互作用的研究

目的采用荧光、紫外光谱法研究在模拟人体生理条件下灯盏乙素与牛血清白蛋白(BSA)之间的相互作用。方法将灯盏乙素对牛血清白蛋白进行荧光淬灭滴定,利用Scatchard模型和F"rster非辐射能量转移理论得出灯盏乙素和牛血清白蛋白的结合参数。结果灯盏乙素与BSA的结合常数K=1.240×106,结合距离r=2.94nm,相互作用力主要为疏水作用力。结论阐明了灯盏乙素和牛血清白蛋白相互作用的机制,建立了灯盏乙素和牛血清白蛋白的结合模型。     

Study of the interaction between fluoroquinolones and bovine serum albumin

The mechanism of interaction between norfloxacin (NRF) and ciprofloxacin (CPF) with bovine serum albumin has been investigated using circular dichroism, fluorescence and absorption spectroscopy. The quenching mechanism of fluorescence of bovine serum albumin by fluoroquinolones was discussed. The binding sites number n and apparent binding constant K were measured by fluorescence quenching method. The thermodynamic parameters obtained from data at different temperatures were calculated. The distance r between donor (bovine serum albumin) and acceptor (fluoroquinolones) was obtained according to Forster theory of non-radiation energy transfer. The effect of common ions on binding constant was also investigated. The results of synchronous fluorescence spectra, UV–vis absorption spectra and circular dichroism of BSA in presence of fluoroquinolones show that the conformation of bovine serum albumin changed.     

Study of the interaction between mercury (II) and bovine serum albumin by spectroscopic methods

Mercury is a significant environmental pollutant that originates from industry. Mercury will bind with albumin and destroy biological functions in humans if it enters the blood. In this paper, the interaction between mercury (II) and bovine serum albumin (BSA) was investigated in vitro by fluorescence, UV–Vis absorption and circular dichroism (CD) under simulated physiological conditions. This study proves that the probable quenching mechanism of BSA by mercury (II) was mainly static quenching due to the formation of a mercury (II)–BSA complex. The quenching constant K_a and the corresponding thermodynamic parameters (ΔH, ΔS and ΔG) at four different temperatures were calculated by a modified Stern–Volmer equation and the van’t Hoff equation, respectively. The results revealed that the interaction between mercury (II) and BSA was mainly enthalpy-driven and that hydrogen bonding and van der Waals forces played a major role in the reaction. The obtained data for binding sites of n approximately equal to 1 indicated that there was a single class of binding site for the BSA with mercury (II). The value of the distance r (3.55 nm), determined by Föster's non-radioactive energy transfer theory, suggested that the energy transfer from BSA to mercury (II) occurred with a high probability. The conformational investigation from synchronous fluorescence, CD spectroscopy and three-dimensional fluorescence showed that the presence of mercury (II) resulted in micro-environmental and conformational changes of the BSA molecules, which may be responsible for the toxicity of mercury (II) in vivo.     

木犀草素与牛血清白蛋白相互作用的荧光光谱法研究

本文首次采用荧光光谱法研究传统中药白毛夏枯草中活性成分木犀草素与牛血清白蛋白（BSA）的猝灭机制。实验研究了木犀草素在291 k和310 k条件下与BSA的猝灭情况,通过计算求得不同温度下的热力学参数。结果表明木犀草素对牛血清白蛋白荧光的猝灭机制属于静态猝灭过程,二者之间的作用力主要为范德华力和氢键。此外,实验还考察了木犀草素对BSA构象的影响。     

大黄素甲醚和牛血清蛋白相互作用的电化学性质研究

在pH4.0的Britton-Robinson(B-R)缓冲体系中,应用循环伏安法和示差脉冲伏安法对大黄素甲醚与牛血清白蛋白(BSA)相互作用的电化学性质进行研究。结果表明,二者结合生成了一种非电活性的超分子化合物,同时对结合反应的机理进行了探讨。BSA的存在导致大黄素甲醚氧化还原峰电流降低,峰电位基本不变,峰电流的下降值同所加入的BSA浓度在一定范围内呈线性关系。线性范围5.0×10-6~1.0×10-7mol/L,检出限3×10-7mol/L。     

应用荧光光谱法和紫外光谱法研究士的宁与牛血清白蛋白的相互作用

目的研究士的宁与牛血清白蛋白(BSA)的相互作用。方法采用荧光光谱法(FS)和紫外光谱法(UV)。结果确定了静态猝灭和非辐射能量转移是士的宁导致BSA荧光猝灭的主要原因；求得了士的宁与BSA之间的表观结合常数k_a分别为3.72×10³(27 ℃)，4.27×10³(37 ℃)，4.47×10³(47 ℃)；以及它们之间的结合位点数n为1.01±0.03；根据Frster非辐射能量转移机制求得给体与受体间的结合距离r为3.795 nm和能量转移效率E为0.033 8。结论牛血清白蛋白与士的宁分子间有结合作用，且结合力以疏水作用为主。     

曲克芦丁与牛血清白蛋白的相互作用研究

目的采用荧光光谱法和紫外吸收光谱法研究曲克芦丁与牛血清白蛋白(BSA)结合反应的特征。方法将曲克芦丁对BSA内源性荧光的猝灭数据分别应用Stern-Volmer方程和Lineweaver-Burk双倒数方程计算反应的荧光猝灭常数和结合常数,应用双对数方程计算结合位点数,热力学公式计算二者结合主要作用力类型,在此基础上应用Frster非辐射能量转移理论,计算曲克芦丁与BSA相互结合时给体-受体间的距离和能量转移效率。结果结果表明曲克芦丁能够有效降低BSA的内源性荧光,其猝灭机制属于静态猝灭,二者之间的结合力为疏水作用力,二者的结合常数为106数量级,结合位点数为1,作用距离为1.97nm,能量转移效率为0.529。结论曲克芦丁可与BSA通过疏水作用结合为复合物,经静态猝灭机制引起BSA内源性荧光的猝灭。     

阿柔比星与人血白蛋白相互作用的特点

目的研究阿柔比星与人血清白蛋白的相互作用特点。方法用荧光猝灭光谱及同步荧光光谱技术测定在不同温度下阿柔比星对人血清白蛋白荧光的猝灭规律。结果阿柔比星对人血清白蛋白荧光呈规律性猝灭,17℃时的n为1.11,K为6.21×104,37℃时的n为1.12,K为6.41×104。阿柔比星使白蛋白的同步光谱中最大发射峰红移。结论阿柔比星与人血清白蛋白只有一个结合位点,表现为疏水作用,两者结合使白蛋白的极性略有增加。     

卡马西平与牛血清白蛋白的相互作用

目的研究卡马西平(CBZ)与牛血清白蛋白(BSA)在缓冲溶液中、不同温度下的相互作用。方法采用荧光光谱法和紫外光谱法。结果运用荧光猝灭双倒数图计算在不同条件下二者的结合常数KA;根据F rster非辐射能量转移理论,求出37℃时给体(BSA)和受体(CBZ)之间能量转移的效率和结合距离;并根据热力学参数确定了CBZ和BSA之间的作用力类型。结论CBZ和BSA之间有较强的相互作用,以疏水作用力为主。同步荧光技术表明,CBZ对BSA的构象有影响。     

荧光猝灭法研究二氢槲皮素和二氢杨梅素与牛血清白蛋白的相互作用

目的 研究二氢槲皮素和二氢杨梅素与牛血清白蛋白(BSA)的相互作用。方法 运用荧光光谱法结合Stern-Volmer方程和Line Weaver-Burk双倒数函数计算出BSA与二氢槲皮素和二氢杨梅素相互作用的猝灭常数和结合常数,通过反应前后热力学参数如焓变ΔH和熵变ΔS的大小对作用力类别进行判断。结果 测得二氢槲皮素与BSA在不同温度下的结合常数293 K为2.27×10⁴ L·mol-1,298 K为2.06×10⁴ L·mol-1,303 K为1.89×10⁴ L·mol-1,二氢杨梅素与BSA在不同温度下的结合常数293 K为2.43×10⁴ L·mol-1,298 K为2.39×10⁴ L·mol-1,303 K为2.13×10⁴ L·mol-1。确定其使牛血清白蛋白荧光猝灭的过程为静态猝灭过程,通过热力学参数确定其结合力主要为疏水作用。结论 应用荧光猝灭法了解二氢槲皮素和二氢杨梅素与牛血清白蛋白之间有较强的结合反应,结合力以疏水作用力为主。     

亚甲蓝类似物的合成及其与牛血清白蛋白相互作用的研究

目的 合成3种亚甲蓝类似物3,7-二(二正丙胺基)-吩噻嗪-5-鎓碘化物、3,7-二(二正丁胺基)-吩噻嗪-5-鎓碘化物和3,7-二(二正戊胺基)-吩噻嗪-5-鎓碘化物,并研究模拟生理条件下这3种亚甲蓝类似物与牛血清白蛋白的相互作用.方法 通过1H-NMR及MS对这3种亚甲蓝类似物进行结构表征,应用荧光光谱法研究了模拟生理条件下这3种亚甲蓝类似物与牛血清白蛋白的相互作用.结果 3种亚甲蓝类似物和BSA相互作用形成了蛋白质-药物复合物并猝灭其固有荧光,亚甲蓝类似物与BSA相互作用过程的ΔG0<0,亚甲蓝类似物与BSA荧光残基间的距离r均小于7 nm.结论 亚甲蓝类似物和BSA相互作用的猝灭机制为静态猝灭,二者之间的反应是自发进行的.非辐射能量转移理论表明BSA与亚甲蓝类似物之间存在非辐射能量转移.同步荧光光谱和三维荧光光谱的研究结果表明,亚甲蓝类似物与BSA的相互作用导致BSA构象发生变化.     

The interaction of plant-growth regulators with serum albumin: Molecular modeling and spectroscopic methods

The affinity between two plant-growth regulators (PGRs) and human serum albumin (HSA) was investigated by molecular modeling techniques and spectroscopic methods. The results of molecular modeling simulations revealed that paclobutrazol (PAC) could bind on both site I and site II in HSA where the interaction was easier, while uniconazole (UNI) could not bind with HSA. Furthermore, the results of fluorescence spectroscopy, three-dimensional (3D) fluorescence spectroscopy and circular dichroism (CD) spectroscopy suggested that PAC had a strong ability to quench the intrinsic fluorescence of HSA. The binding affinity (K_b) and the amounts of binding sites (n) between PAC and HSA at 291 K were estimated as 2.37 × 10⁵ mol L⁻¹ and 1, respectively, which confirm that PAC mainly binds on site II of HSA. An apparent distance between the Trp214 and PAC was 4.41 nm. Additionally, the binding of PAC induced the conformational changes of disulfide bridges of HSA with the decrease of α-helix content. These studies provide more information on the potential toxicological effects and environmental risk assessment of PGRs.     

光谱法与分子模拟表征2种呫吨酮类化合物键合人血清白蛋白

目的:表征2种呫吨酮类化合物(1-hydroxy-7-methoxyxanthone,HM;dehydrocycloguanandin,DC)与人血清白蛋白(human serum albumin,HSA)的键合作用。方法:在模拟生理条件下,应用计算机模拟技术,并结合荧光光谱法和紫外吸收光谱法研究药物与蛋白的相互作用。结果:分子模拟显示了DC及HM与HSA的键合区域和键合模式,表明维持药物与蛋白质的相互作用力主要是疏水作用,兼有位于不同氨基酸残基的氢键。荧光光谱实验结果表明:这2种呫吨酮类化合物对HSA的荧光在一定的浓度范围内都有猝灭作用,猝灭方式均为静态猝灭。紫外光谱图表明它们对蛋白微环境有影响。根据荧光滴定数据,求出了不同温度下(296,303,310 K)反应的结合常数及反应热力学参数。通过竞争实验确定了这2种药物在蛋白上的不同结合位点。结论:在分子水平上揭示了这2种呫吨酮类化合物与HSA有不同的、较强的键合作用。