光谱法研究染料木素与人血清白蛋白的相互作用

用荧光猝灭光谱、同步荧光光谱和紫外-可见吸收光谱研究了染料木素与人血清白蛋白(HSA)的相互作用。结果表明染料木素对HSA的荧光猝灭作用属于二者形成复合物所引起的静态猝灭;利用Stern-Volmer方程处理实验数据,得到染料木素与HSA之间的结合常数K_A为1.00×106(27 ℃),1.66×106(37 ℃)和5.25×106(47 ℃)。根据Frster非辐射能量转移理论,求出了染料木素与HSA之间的结合距离为2.59 nm(27 ℃),2.65 nm(37 ℃)和2.90 nm(47 ℃)。通过计算热力学参数,可知该药物与人血清白蛋白的相互作用是一个吉布斯自由能降低的自发过程,且二者之间的主要作用力类型为静电引力,同时用同步荧光光谱探讨了染料木素对HSA构象的影响。     

光谱法比较木犀草素及槲皮素与牛血清白蛋白相互作用

在模拟生理pH条件下,采用荧光光谱、紫外-可见吸收光谱、同步荧光光谱和圆二色谱法研究木犀草素及槲皮素与牛血清白蛋白（BSA）的相互作用的异同.结果确定木犀草素及槲皮素对BSA的荧光猝灭是以静态猝灭为主,同时伴随非辐射能量转移猝灭.木犀草素结合BSA的位点与荧光发射基团的距离比槲皮素的小.结合常数Ka表明二者与BSA的结合都属于强的非共价键结合,且结合位点数都约为1.二者均主要通过氢键和范德华力与BSA作用.二者都能影响BSA的酪氨酸残基附近环境的极性,且高浓度下能够引起BSA构象轻微地改变.结果表明黄酮C环上3位羟基的引入会降低其对BSA的亲和力.     

白藜芦醇与人血清白蛋白相互作用的光谱研究

在不同温度下,用荧光猝灭光谱、同步荧光光谱和紫外-可见吸收光谱,研究了白藜芦醇与人血清白蛋白(HSA)相互作用的光谱学行为。根据不同温度下白藜芦醇对HSA的荧光猝灭作用,利用Stern-Volmer方程处理实验数据,结果表明白藜芦醇与HSA的结合常数K_A为2.39×105(25 ℃),1.25×105(35 ℃)和1.10×105(45 ℃)。根据Frster非辐射能量转移理论,求出了白藜芦醇与HSA之间的结合距离为3.02 nm(25 ℃),3.46 nm(35 ℃)和3.79 nm(45 ℃)。实验表明静态猝灭和非辐射能量转移是导致白藜芦醇对HSA荧光猝灭的两大原因,通过计算热力学参数,可知该药物与人血清白蛋白的相互作用是一个吉布斯自由能降低的自发过程,且二者之间的主要作用力类型为疏水作用力。并采用同步荧光光谱探讨了白藜芦醇对HSA构象的影响。     

山姜素与人血清白蛋白相互作用的荧光光谱法研究

利用荧光光谱法和紫外-可见光谱法研究了山姜素与人血清白蛋白(HSA)之间的相互作用。证实了山姜素对HSA的荧光猝灭为动态猝灭过程,并测定了不同温度下的猝灭常数; 根据Fōrster非辐射能量转移理论,计算出山姜素在蛋白质中的结合位置与色氨酸残基间的距离为4.05 nm; 由求得的热力学参数,推断了山姜素与HSA之间主要靠疏水作用力结合;用三维荧光光谱及同步荧光光谱技术探讨了山姜素对HSA构象的影响。     

对-香豆酸与人血清白蛋白相互作用的荧光和表面增强拉曼光谱研究

在模拟生理条件下,应用荧光光谱和表面增强拉曼光谱法对对-香豆酸(p-CA)与人血清白蛋白(HSA)的结合机理进行研究。结果表明,p-CA对HSA的荧光猝灭机制为静态猝灭,并伴有非辐射能量转移。荧光光谱显示,在298,304,310 K下,p-CA与HSA的结合常数(KA)分别为3.41×10~4,2.09×10~4,1.38×10~4L/mol,结合位点数(n)近似为1。表面增强拉曼光谱研究揭示,p-CA的酚基与HSA有效结合。标记竞争实验指出,p-CA在HSA上的结合位点主要在SiteⅠ。反应过程热力学参数表明,二者间的作用主要为静电引力,且根据Frster能量转移理论求得p-CA与HSA间的距离为5.11 nm。同步荧光光谱显示,p-CA的结合没有导致HSA构象发生明显变化。     

荧光和紫外光谱法研究柯里拉京与人血清白蛋白之间的相互作用

在模拟人体血液pH条件(pH 7.4,离子强度0.1mol·L-1),通过荧光猝灭、同步荧光、3D荧光和紫外吸收光谱等方法研究了柯里拉京(Cor)与人血清白蛋白(HSA)之间相互作用机制。结果表明:HSA的荧光能被Cor静态猝灭,两者间结合常数为2.79×103(298K),2.22×104(304K)和8.41×104 L·mol-1(310K)。根据Van’t Hoff方程结果显示,Cor与HSA间的作用主要为疏水作用,其作用过程为自发、吸热。基于Frster能量转移,得知Cor与HSA间结合距离为9.33nm。标记竞争实验指出,Cor优先结合HSA的位点Ⅲ。3D荧光光谱、同步荧光光谱和紫外吸收光谱显示,与Cor作用对HSA构象影响不显著。     

叶酸与人血清白蛋白结合作用的光谱研究

在不同温度下的pH 7.4的Tris-HCl缓冲溶液体系中, 采用荧光光谱、紫外吸收光谱和同步荧光光谱研究了人血清蛋白与叶酸的相互作用。研究表明,这种相互作用使人血清白蛋白发生内源荧光猝灭,属于静态猝灭机制。通过计算得到人血清蛋白与叶酸在17和37 ℃下静态猝灭的猝灭速率常数分别为7.396 6×104和7.2652×104 L·mol-1、结合常数分别为7.50×104和1.98×105 L·mol-1、结合位点数均为1。根据Förster非辐射能量转移机理,求算出给体(HSA)与受体(叶酸)间的作用距离和能量转移效率分别为1.77和0.052 65 nm,并结合热力学参数说明了叶酸分子与人血清白蛋白的作用以疏水作用为主,同时也存在静电引力。利用同步荧光光谱研究了人血清蛋白与叶酸的相互作用中HSA的构象变化,发现色氨酸残基所处环境的疏水性降低,说明叶酸分子进入了人血清白蛋白的疏水腔中。     

防己诺林碱与牛血清白蛋白相互作用的研究

在不同温度下,用荧光猝灭光谱、同步荧光光谱和紫外-可见吸收光谱,研究了防己诺林碱与BSA相互作用的光谱学行为。防己诺林碱对BSA有较强的荧光猝灭作用。根据不同温度下防己诺林碱对BSA的荧光猝灭作用,利用Stern-Volmer方程处理实验数据,表明防己诺林碱对BSA的荧光猝灭作用属于静态猝灭。根据Frster非辐射能量转移理论计算出了防己诺林碱与BSA间的结合距离R(27 ℃ 2.51 nm; 37 ℃ 2.72 nm; 47℃ 2.89 nm)、结合常数K_A(27 ℃ 1.05×105 L·mol-1; 37 ℃ 3.31×105 L·mol-1; 47 ℃ 7.24×105 L·mol-1)及对应温度下的热力学参数。热力学数据表明二者主要靠疏水作用力结合,同时用同步荧光光谱探讨了防己诺林碱对BSA构象的影响。     

L-半胱氨酸修饰的金纳米粒子与牛血清白蛋白相互作用的荧光光谱研究

采用荧光猝灭光谱和同步荧光光谱研究了L-半胱氨酸修饰的金纳米粒子(Cys-GNPs)与牛血清白蛋白(BSA)间的相互作用。根据荧光猝灭相关方程计算了Cys-GNPs与BSA相互作用的结合常数和结合位点数,探讨了其荧光猝灭机制为静态猝灭,并且根据热力学参数确定了二者间的作用力类型,推断出Cys-GNPs和BSA间主要靠疏水作用力结合。同步荧光光谱表明,二者的相互作用没有导致牛血清白蛋白的构象及色氨酸残基的微环境发生明显变化。     

1-脱氧野尻霉素与人血清白蛋白相互作用的荧光光谱

在模拟生理条件下(pH 7.4),采用荧光光谱及傅里叶变换红外光谱研究了1-脱氧野尻霉素(1 -DNJ)与人血清白蛋白(HSA)之间的相互作用方式及机理.结果表明,1-DNJ对HSA的荧光猝灭作用主要为静态猝灭,两者之间形成了1∶1的复合物.通过计算获得了不同温度下的结合常数及结合位点数,并根据1-DNJ与HSA结合的热力学参数,确定了两者之间的主要作用力为疏水作用与静电引力.同步荧光光谱显示1-DNJ对HSA的构象产生了影响,并通过傅里叶变换红外光谱确定了HSA二级结构的变化.     

Study of the Interaction of Fangchinoline with Human Serum Albumin by Fluorescence and UV Spectroscopic Method

The interaction of fangchinoline with human serum albumin (HSA) was studied by use of fluorescence quenching spectra, synchronous fluorescence spectra, and ultraviolet spectra. It was shown that fangchinoline has a strong ability to quench the fluorescence of HSA. The Stern‐Volmer curves based on the quenching of the fluorescence of HSA by fangchinoline indicated that the quenching mechanism of fangchinoline on HSA was static quenching and non‐radiation energy transfer. Based on the Förster theory of non‐radiation energy transfer, the binding distances (r) and the binding constants (K _A) between fangchinoline and HSA were found. The thermodynamic parameters obtained revealed that the interaction between fangchinoline and HSA was mainly driven by hydrophobic force. The conformational changes of HSA were investigated by use of synchronous fluorescence. The result indicates that an ionic electrostatic interaction between fangchinoline and HSA could not be excluded.     

秋水仙碱与人血清白蛋白相互作用的谱学研究

采用紫外、荧光和圆二色光谱研究了秋水仙碱与人血清白蛋白之间的相互作用。结果发现秋水仙碱使人血清白蛋白的紫外吸收增强,特征荧光峰猝灭,并且随温度升高猝灭常数K_SV降低。求算了不同温度下秋水仙碱与人血清白蛋白相互作用的平衡常数与结合位点数。根据Van’t Hoff方程计算出ΔH=-11.66 kJ·mol-1,ΔS=51.507 J·(mol·K)-１,得出二者之间的作用力主要是静电作用力。圆二色光谱测得加入秋水仙碱后人血清白蛋白的α-螺旋降低,二级结构改变,表明秋水仙碱对人血清白蛋白的荧光猝灭机制属于形成配合物所引起的静态猝灭。     

Separate and simultaneous binding effects of aspirin and amlodipine to human serum albumin based on fluorescence spectroscopic and molecular modeling characterizations: A mechanistic insight for determining usage drugs doses

The binding of aspirin (ASA) and amlodipine (AML) to human serum albumin (HSA) in aqueous solution was investigated by multiple techniques such as fluorescence quenching, resonance light scattering (RLS), three-dimensional fluorescence spectroscopy, FT-IR and zeta-potential measurements in an aqueous solution at pH=7.4. For the protein-ligand association reaction, fluorescence measurements can give important clues as to the binding of ligands to proteins, e.g., the binding mechanism, binding mode, binding constants, binding sites, etc. Fluorescence spectroscopy showed that ASA and AML could quench the HSA fluorescence spectra, and this quenching effect became more significant when both ASA and AML coexisted. The results pointed at the interaction between HSA and both drugs as ternary systems decreasing the binding constant and binding stability of the HSA-drug complex as a binary system. Therefore, by reducing the amount of drugs transported to their targets, the free drug concentration of the target would be reduced, lowering the efficacy of the drugs. It was demonstrated that there exists antagonistic behavior between the two drugs when it comes to binding of HSA. Furthermore, the fluorescence results also showed that the quenching mechanism of HSA-drug complexes as binary and ternary systems is a static procedure. The number of binding sites of HSA-ASA, (HSA-AML)ASA, HSA-AML and (HSA-ASA) AML were 1.31, 0.92, 1 and 0.93, respectively. Due to the existence of the antagonistic action between ASA and AML, the binding distance r was reduced. The results of synchronous fluorescence and three-dimensional fluorescence spectra showed that the antagonistic action between ASA and AML would alter the micro-environment around Trp and Tyr residues. Moreover, the simultaneous presence of ASA and AML during binding to HSA should be taken into account in multidrug therapy, as it induces the necessity of a monitoring therapy owing to the possible increase of uncontrolled toxic effects. Molecular dynamic studies showed that the affinity of each of the drugs to HSA was reduced in the presence of significant amounts of the other. In the interaction of HSA with both drugs, the zeta potential of the ternary system is more negative than its binary counterpart. The zeta-potential results suggested induced conformational changes on HSA that confirmed the experimental and theoretical results.     

多光谱和分子模拟技术研究全氟十二酸与人血清白蛋白的相互作用

全氟十二酸(PFDoA)是8～12个碳链的全氟烷酸(PFAAs)中毒性最强的新型环境污染物。已有大量研究表明PFAAs在环境中广泛积累,但对PFDoA与HSA的相互作用还处于起步阶段。本研究力争在模拟生理条件下,采用荧光猝灭法、分子模拟技术和圆二色谱确定HSA与PFDoA的相互作用机理。研究结果表明,PFDoA对HSA的猝灭是动态猝灭与形成PFDoA-HSA基态复合物引起的猝灭共同作用的结果。计算得到的结合距离(r=3.65 nm)表明,PFDoA(受体)与HSA(供体)之间的相互作用发生了非辐射能量转移。取代反应结果表明,PFDoA键合在HSA的site Ⅰ位点上。分子对接进一步研究了PFDoA与HSA作用的详细结合情况,表明PFDoA通过多种作用力结合在HSA的亚域IIA内,例如,PFDoA上的O 1原子主要通过极性键与HSA上的Arg 257和Ser 287残基结合。计算得到的最优对接能量为-25.87 kJ·mol-1,表明PFDoA对HSA有较大的结合亲和力。同步荧光光谱和三维荧光光谱研究了PFDoA对HSA构象的影响,结果显示,与PFDoA结合后,色氨酸的微环境疏水性增加,HSA的构象也发生改变。PFDoA与HSA作用前后圆二色谱二级结构的定量分析结果表明,PFDoA-HSA复合物的形成使螺旋稳定性降低。该研究结果为全氟烷酸与HSA的动力学研究提供了理论依据和可靠数据,并揭示了生物大分子与配体相互作用的化学本质。     

Probing the binding of vitexin to human serum albumin by multispectroscopic techniques

The interaction between vitexin and human serum albumin (HSA) has been studied by using different spectroscopic techniques viz., fluorescence, UV-vis absorption, circular dichroism (CD) and Fourier transform infrared (FT-IR) spectroscopy under simulated physiological conditions. Fluorescence results revealed the presence of static type of quenching mechanism in the binding of vitexin to HSA. The binding constants (K_a) between vitexin and HSA were obtained according to the modified Stern-Volmer equation. The thermodynamic parameters, enthalpy change (ΔH) and entropy change (ΔS) were calculated to be -57.29 kJ mol⁻¹ and -99.01 J mol⁻¹ K⁻¹ via the van't Hoff equation, which indicated that the interaction of vitexin with HSA was driven mainly by hydrogen bond and van der Waals forces. Fluorescence anisotropy data showed that warfarin and vitexin shared a common binding site I corresponding to the subdomain IIA of HSA. The binding distance (r) between the donor (HSA) and the acceptor (vitexin) was 4.16 nm based on the Förster theory of non-radioactive energy transfer. In addition, the results of synchronous fluorescence, CD and FT-IR spectra demonstrated that the microenvironment and the secondary structure of HSA were changed in the presence of vitexin.     

新型羧酸卟啉锌(Ⅱ)配合物与人血清蛋白的作用

卟啉是一种潜在有效的光动力治疗癌症的光敏剂,部分已用于临床实验中。人血清蛋白(HSA)是药物的运输载体,详细研究两者的相互作用对于阐述卟啉类药物的药代动力学行为具有重要的意义。合成了一种新型水溶性羧酸锌(Ⅱ)卟啉配合物(2-Zn),并通过紫外可见吸收光谱、荧光光谱、圆二色(CD)光谱和分子对接模拟研究了其与人血清蛋白(HSA)的相互作用。结果表明：2-Zn以静态猝灭的方式猝灭了HSA的内源荧光,通过计算得到其与HSA在298和310 K下相互作用的猝灭常数分别为1.96×104和1.37×104 L·mol-1、结合常数分别为1.93×104和1.50×104 L·mol-1、结合位点数均为1,两者间的结合作用力以静电作用为主,同时也存在氢键和疏水作用。位点竞争实验表明2-Zn主要结合在位点Ⅱ处;根据Forster非辐射能量理论得到两者的结合距离和能量转移效率分别为4.01 nm和0.163。紫外吸收光谱,同步荧光和CD光谱显示2-Zn与HSA的相互作用影响了HSA 的构象,表现为α-螺旋的含量降低;分子对接模拟结果表明2-Zn通过疏水、静电和氢键作用嵌入HSA分子的亚结构域IIIA(site Ⅱ)的疏水腔内,与位点竞争实验和热力学判据所得的结果相一致。