药物小分子白杨素与人血清白蛋白结合作用的光谱法研究

应用荧光光谱法、共振瑞利散射光谱法和同步荧光法,研究了生理条件下白杨素与人血清白蛋白(HSA)相互作用.研究表明,白杨素与HSA发生作用并形成了新的基态化合物,静态猝灭是导致HSA内源荧光猝灭的主要原因;求得不同温度 (17℃、26℃和35℃) 下白杨素与HSA作用的结合常数分别为2.373×106、1.680×106和1.346×106 L·mol-1;由求得的热力学参数,确定了白杨素与HSA间的结合反应主要由静电引力驱动.根据Frster非辐射能量转移理论,计算出白杨素在蛋白质中的结合位置与214位色氨酸残基间的距离为3.52 nm;同步荧光光谱表明,白杨素使得HSA的二级结构发生了变化.     

Study of the interactions between fluoroquinolones and human serum albumin by affinity capillary electrophoresis and fluorescence method

The interactions between fluoroquinolones and human serum albumin (HSA) were investigated by affinity capillary electrophoresis (ACE) and fluorescence quenching technique. Based on the efficient separation of several fluoroquinolones using a simple phosphate buffer, the binding constants of fluoroquinolones with HSA were determined simultaneously during one set of electrophoresis by ACE method. The thermodynamic parameters were obtained from data at different temperatures, and the negative ΔH and ΔS values showed that both hydrogen bonds and van der Waals interaction played major roles in the binding of fluoroquinolones to HSA. The interactions were also studied by fluorescence quenching technique. The results of fluorescence titration revealed that fluoroquinolones had the strong ability to quenching the intrinsic fluorescence of HSA through the static quenching procedure. The binding site number n, apparent binding constant K_b and the Stern-Volmer quenching constant K_sv were determined. The thermodynamic parameters were also studied by fluorescence method, and the results were consonant with that of ACE.     

Binding of human serum albumin to N-(p-ethoxy-phenyl)-N'-(1-naphthyl)thiourea and synchronous fluorescence determination of human serum albumin.

The binding of N-(p-ethoxy-phenyl)-N'-(1-naphthyl)thiourea (EPNT) to human serum albumin (HSA) was investigated under simulative physiological conditions by fluorescence spectra in combination with UV absorption spectroscopy and a molecular modeling method. A strong fluorescence quenching reaction of EPNT to HSA was observed, and the quenching mechanism was suggested to be static quenching according to the Stern-Volmer equation. The binding constants (K) at different temperatures as well as thermodynamic parameters, enthalpy change (DeltaH) and entropy change (DeltaS), were calculated according to relevant fluorescent data and the vant' Hoff equation. This indicated that a hydrophobic interaction was a predominant intermolecular force for stabilizing the complex, which is in agreement with the results of molecule modeling study. The effects of energy transfer and other ions on the binding constant were considered. In addition, synchronous fluorescence technology was successfully applied to the determination of HSA added into the EPNT solution.     

Spectroscopic characterization of effective components anthraquinones in Chinese medicinal herbs binding with serum albumins

The interactions of serum albumins such as human serum albumin (HSA) and bovine serum albumin (BSA) with emodin, rhein, aloe-emodin and aloin were assessed employing fluorescence quenching and absorption spectroscopic techniques. The results obtained revealed that there are relatively strong binding affinity for the four anthraquinones with HSA and BSA and the binding constants for the interactions of anthraquinones with HSA or BSA at 20 degrees C were obtained. Anthraquinone-albumin interactions were studied at different temperatures and in the presence of some metal ions. And the competition binding of anthraquinones with serum albumins was also discussed. The Stern-Volmer curves suggested that the quenching occurring in the reactions was the static quenching process. The binding distances and transfer efficiencies for each binding reactions were calculated according to the F?ster theory of non-radiation energy transfer. Using thermodynamic equations, the main action forces of these reactions were also obtained. The reasons of the different binding affinities for different anthraquinone-albumin reactions were probed from the point of view of molecular structures.     

Fluorescence study on the interaction of human serum albumin with bromsulphalein

The binding of bromsulphalein (BSP) with human serum albumin was investigated at different temperatures, 298 and 308 K, by the fluorescence spectroscopy at pH 7.24. The binding constant was determined by Stern-Volmer equation based on the quenching of the fluorescence HSA in the presence of bromsulphalein. The effect of various metal ions on the binding constants of BSP with HSA was investigated. The thermodynamic parameters were calculated according to the dependence of enthalpy change on the temperature as follows: DeltaH and DeltaS possess small negative (9.3 kJ mol(-1)) and positive values (22.3 J K(-l)mol(-l)), respectively. The experimental results revealed that BSP has a strong ability to quench the intrinsic fluorescence of HSA through a static quenching procedure. The binding constants between BSP to HSA were remarkable and independent on temperature. The binding constants between HSA and BSP decreased in the presence of various ions, commonly decreased by 30-55%. The hydrophobic force played a major role in the interaction of BSP with HSA. All these experimental results and theoretical data clarified that BSP could bind to HSA and be effectively transported and eliminated in body, which could be a useful guideline for further drug design.     

荧光光谱法研究双醋瑞因与人血清白蛋白的相互作用

在模拟人体生理条件下（pH=7.40）,采用荧光光谱法研究双醋瑞因与人血清白蛋白的相互作用。 采用2种方法计算不同温度下其结合常数KA、结合位点数n,同时对2种计算方法进行了比较;并根据热力学参数确定了双醋瑞因与人血清白蛋白之间的作用力类型。 根据Forster非辐射能量转移原理,确定了双醋瑞因与人血清白蛋白相互结合时供能体 受能体间的作用距离和能量转移效率,并用同步荧光光谱研究了双醋瑞因对人血清白蛋白构象的影响。 结果表明,双醋瑞因与人血清白蛋白之间主要是以静态猝灭为主;结合距离r=2.88 nm,能量转移效率E=0.273 8,二者主要凭借氢键和范德华力进行结合。     

芦荟大黄素与血清白蛋白的相互作用

利用荧光光度法研究了中药有效成分芦荟大黄素与血清白蛋白的相互作用机制 ,求得两者的形成常数 ,讨论了某些金属离子对其形成常数的影响 ,并根据热力学常数确定了它们之间的作用力类型 ,利用F rster非辐射能量转移技术求出了两者的结合位置。     

Binding of brucine to human serum albumin

The feature of brucine binding to human serum albumin (HSA) was investigated via fluorescence and UV/vis absorption spectroscopy. The results revealed that brucine caused the fluorescence quenching of HSA by the formation of brucine–HSA complex. The hydrophobic interaction plays a major role in stabilizing the complex; the binding site number n and apparent binding constant K_A, corresponding thermodynamic parameters the free energy change (ΔG), enthalpy change (ΔH) and entropy change (ΔS) at different temperatures were calculated. The distance r between donor (HSA) and acceptor (brucine) was obtained according to fluorescence resonance energy transfer. The effect of brucine on the conformation of HSA was analyzed using synchronous fluorescence spectroscopy and UV/vis absorption spectroscopy.     

Studies on the binding of vinpocetine to human serum albumin by molecular spectroscopy and modeling

The interaction between vinpocetine(VPC) and human serum albumin(HSA) in physiological buffer(pH 7.40) was investigated by fluorescence,FT-IR,UV-vis absorption and molecular modeling.VPC effectively quenched the intrinsic fluorescence of HSA via static quenching.The binding site number n and apparent binding constant K_a,corresponding thermodynamic parametersΔG,ΔH andΔS at different temperatures were calculated.The synchronous fluorescence and FT-IR spectra were used to investigate the structural change of HSA molecules with addition of VPC.Molecular modeling indicated that VPC could bind to the site I of HSA and hydrophobic interaction was the major acting force,which was in agreement with the binding mode study.     

Characterization of the interaction between 8-bromoadenosine with human serum albumin and its analytical application

This study was designed to examine the interaction of 8-bromoadenosine with human serum albumin (HSA) by fluorescence spectroscopy in combination with molecular modeling under simulative physiological conditions. The results of fluorescence measurements indicate that 8-bromoadenosine has a strong ability to quench the intrinsic fluorescence of HSA through static quenching procedure. The binding constants (K) at different temperatures and thermodynamic parameters, enthalpy changes (ΔH) and entropy changes (ΔS) were calculated according to the fluorescence data. The results showed that the hydrophobic force played the major role in the binding of 8-bromoadenosine to HSA. The fluorescence experimental results were in agreement with the results obtained by molecular modeling study. The effects of some normal positive and negative ions on the binding constants were also discussed. Moreover, the synchronous fluorescence technique was used to characterize the interaction of 8-bromoadenosine to HSA and successfully applied to determine the total proteins in human serum, urine and saliva samples at room temperature under the optimum conditions with a wide linear range and satisfactory results.     

腺苷与人血清白蛋白间相互作用的荧光光谱及分子模型法研究

在模拟人体生理条件下,结合紫外光谱和分子对接模型运用荧光光谱研究了腺苷与人血清白蛋白(HSA)间的键合作用。腺苷有较强的能力猝灭人血清白蛋白的内源荧光,且根据Stern-Volmer方程判断出猝灭机制为静态猝灭。本文运用相应的荧光值和Vant’Hoff热力学方程求得了不同温度下的结合常数(K)以及一些热力学参数,如焓变(ΔH)和熵变(ΔS)。结果表明：键合过程中疏水作用力对新化合物的稳定性起主要作用,这与分子对接模型方法研究的结果基本一致。另外还研究了常见离子对结合常数的影响。     

具抗凝血作用的三种钕配合物与人血清白蛋白的相互作用

采用荧光光谱法,紫外光谱法以及圆二色谱法研究了具抗凝血作用的水杨酸钕((NdL′3.2H2O,L′=水杨酸离子))、华法灵钕(NdL3.2H2O,L=华法灵离子)和华法灵水杨酸钕(NdL2L′.2H2O)3种配合物与人血清白蛋白的相互作用。结果表明:配合物对人血清白蛋白(HSA)的荧光产生猝灭现象;配合物的存在使得HSA紫外吸收光谱的强度增加;配合物的存在也对HSA的构象产生影响。水杨酸钕的猝灭方式为动态与静态猝灭,而华法灵钕和华法灵水杨酸钕的猝灭方式属于两者之间生成了不发荧光的复合物而导致的静态猝灭。并分别确定了它们的结合力类型:华法灵钕与HSA之间主要作用力是静电作用力;水杨酸钕与HSA之间主要作用力为典型的疏水作用力;华法灵水杨酸钕与HSA之间为氢键和范德华力。计算了配合物与人血清白蛋白的结合常数K和结合位点数n。     

光谱法研究哈巴俄苷与人血清白蛋白的结合反应

在不同温度及模拟血液pH值条件下,采用荧光光谱法和紫外-可见吸收光谱法研究了哈巴俄苷(Harpagoside, HAR)与人血清白蛋白(Human serum albumin, HSA)的结合反应.结果表明,HAR有规律地使HSA内源荧光猝灭,猝灭常数随温度升高而降低,其猝灭机制为两者形成复合物而引起的的静态猝灭;不同条件下两者结合常数KA均大于105 L/mol,结合位点数n≈1.由Van′t Hoff方程计算获得了不同条件下HAR与HSA相互作用的热力学参数,由ΔG、ΔH和ΔS均小于0可知,两者结合的主要作用力是氢键和范德华力,且两者结合是吉布斯自由能降低的自发过程.根据F(o)rster非辐射转移理论计,计算了不同条件下HAR与HSA的结合距离r在4.01~4.28 nm范围内,表明两者结合过程发生了非辐射能量转移.同步荧光光谱表征结果表明,HAR使HSA的色氨酸和酪氨酸残基所处的微环境极性增强,疏水性减弱,导致HSA构象发生了一定程度的改变.     

两种组氨酸酰胺衍生物的合成及其与人血清白蛋白的结合

L-组氨酸对生物有机体有着良好的亲和能力,通过修饰其化学结构以期寻找药理活性和生物利用度高的衍生物。本文将L-组氨酸分别与反式肉桂酸和对甲氧基肉桂酸反应,合成了两种组氨酸酰胺类衍生物,利用傅里叶变换红外光谱、质谱、氢谱/碳谱核磁共振谱进行了结构表征。采用分子操作环境(MOE)软件分子对接技术、荧光光谱法、同步荧光光谱法(SFS)、紫外-可见光谱法(UV-Vis),共同研究了两种衍生物分别和人血清白蛋白(HSA)相结合的机理。MOE对接结果显示,这两种衍生物与HSA的模拟结合能分别为-13.82和-16.25 kcal/mol,主要是通过范德华力和疏水作用结合在HSA亚结构域ⅡA(即siteⅠ)的疏水腔内。荧光猝灭数据表明,衍生物与HSA相互作用并形成了新的基态配合物,荧光猝灭过程为静态猝灭;不同温度(300、305和310 K)下衍生物与HSA相互作用的结合常数分别为1.773×104、6.354×10~3、1.260×10~3和5.314×10~4、4.614×10~3、1.420×10~3;由热力学参数得到衍生物与HSA的结合过程是由范德华力驱动;SFS表明,衍生物使得HSA的二级结构发生了变化。结合UV-Vis的结果可以确定,在体外生理条件下,组氨酸酰胺类衍生物均可以通过范德华力与HSA结合,并对HSA内源荧光产生静态猝灭及构象影响,这与分子对接结果一致,从而为组氨酸酰胺类衍生物药物的进一步开发提供了参考。     

光谱法测定伊曲康唑与牛血清和人血清白蛋白相互作用

用荧光光谱和紫外吸收光谱法, 在pH=7.4±0.1的0.1 mol·L-1磷酸缓冲溶液中, 研究了伊曲康唑与牛血清白蛋白(BSA)和人血清白蛋白(HSA)的相互作用. 实验结果表明, 伊曲康唑与牛血清白蛋白和人血清白蛋白作用的猝灭常数均随着温度的升高而降低, 伊曲康唑可以有规律地使血清白蛋白内源荧光猝灭, 其猝灭机理可认为是伊曲康唑与白蛋白形成复合物的静态猝灭. 获得了在不同温度下, 伊曲康唑与血清白蛋白作用的结合常数以及△G、△H和△S等热力学参数. 根据所得结果可推断伊曲康唑与白蛋白的作用力主要为疏水作用力, 同时, 利用荧光共振能量转移理论(FRET)计算得出了伊曲康唑与白蛋白结合位置的距离d. 而且, 利用同步荧光光谱和紫外光谱揭示了该反应中蛋白的结构和其微环境的变化.     

Interaction of human serum albumin with bendroflumethiazide studied by fluorescence spectroscopy

The interactions between bendroflumethiazide (BFTZ) and human serum albumin (HSA) have been studied by fluorescence spectroscopy. Binding constants for drug attachment to the various binding sites of HSA have been measured at different temperatures in physiological buffer solution. The effect of metal ions on BFTZ interaction with HSA was also investigated. The thermodynamic parameters, DeltaH and DeltaS, have been calculated to be 49.28kJmol(-1)>0, and 258.83Jmol(-1)K(-1)>0, respectively. The distance between HSA and BFTZ, r, was determined to be 1.47nm based on F?rster's non-radiative energy transfer theory. The experimental results reveal that BFTZ has a strong ability to quench the intrinsic fluorescence of HSA through a static quenching mechanism. Furthermore, the binding constants between BFTZ and HSA are remarkably independent of temperature, and decrease in the presence of various ions, usually by about 30-55%. Hydrophobic interaction occurs between BFTZ and the sub-domain II A of HSA.     

分子内电荷转移荧光探针1-酮-2-（对二甲氨基苯亚甲基）四氢萘与人血清白蛋白作用

采用荧光及紫外光谱研究了1-酮-2-（对二甲氨基苯亚甲基）-四氢萘（KDTN）与人血清白蛋白（HSA）相互作用的光谱特性。 结果表明,静态猝灭和非辐射能量转移是导致KDTN对HSA荧光猝灭的主要原因。 测得17、27和37 ℃ 3个温度下的结合常数K_A分别为1.633×10⁸、0.7998×10⁸和0.347×10⁸ L/mol,结合位点数n分别为1.7、1.6和1.7;据Forster偶极 偶极非辐射能量转移理论,计算得到KDTN与HSA在3个温度下的作用距离r分别为2.64、2.59和2.64 nm;能量转移效率E分别为0.5100、0.4797和0.4210。 热力学参数表明,二者主要以范德华力或氢键结合;用同步荧光技术研究了KDTN对HSA构象的影响,结果表明,KDTN的加入对HSA构象影响不大。     

Spectroscopic and Molecular Docking Approaches for Investigation of Interaction of Phellopterin with Human Serum Albumin

The mechanism of interaction between human serum albumin (HSA) and natural product phellopterin (PL) from Angelica dahurica was investigated by spectroscopic techniques with molecular docking under simulated physiological conditions. The experimental results showed that the fluorescence of HSA was regularly quenched by PL, and the quenching constants (K_SV) decreased with increasing temperature, which indicated that the quenching mechanism was a static quenching procedure. The binding constants (K_A) were larger than 10^?5 M^?1 and the number of binding sites (n) was approximate to 1 at different temperatures, which indicated that the binding affinity was hige and there was just one main binding site in HSA for PL. According to thermodynamic parameters from Van't Hoff equation, the binding process of PL with HSA was spontaneous and exothermic process due to ΔG < 0, and the electrostatic force played major role in the binding between PL and HSA according to ΔH < 0 and ΔS > 0. The binding distance (r) was calculated to be about 3.35 nm, which implied that the energy transfer from HSA to PL occurred with high possibility according to the theory of Förster's non-radiation energy transfer. The microenvironment and conformation of HSA changed with the addition of PL based on the results of synchronous and three-dimensional fluorescence methods. The molecular docking analysis revealed the binding locus of PL to HSA in subdomain IIIA (Sudlow's site II).     

Interaction of tetrandrine with human serum albumin: a fluorescence quenching study.

The interaction of tetrandrine with human serum albumin (HSA) was studied by measuring fluorescence quenching spectra, synchronous fluorescence spectra and ultra-violet spectra. The fluorescence quenching spectra of HSA in the presence of tetrandrine showed that tetrandrine quenched the fluorescence of HSA. The quenching constants of tetrandrine on HSA were determined using the Stern-Volmer equation. Static quenching and non-radiation energy transfer were the two main reasons leading to the fluorescence quenching of HSA by tetrandrine. According to the F?rster theory of non-radiation energy transfer, the binding distances (r) and the binding constants (K(A)) were obtained. The thermodynamic parameters obtained in this study revealed that the interaction between tetrandrine and HSA was mainly driven by a hydrophobic force. The conformational changes of HSA were investigated by synchronous spectrum studies.     

Synthesis,characterization, HSA interaction,and antibacterial activity of a new water-soluble Pt(II) complex containing the drug cephalexin

Abstract

A new water-soluble platinum(II) complex, [Pt(CEX)Cl(DMSO)]Cl (CEX is cephalexin), was synthesized and characterized by physicochemical, spectroscopic, and computational methods. Multispectroscopic techniques were used to investigate the interaction of Pt(II) complex with human serum albumin (HSA) under the physiological conditions. The results of fluorescence titration indicated that the binding of the Pt(II) complex to HSA induced fluorescence quenching through static quenching mechanism with binding constant of 1.24?×?10⁴?M^?1 at 298?K. The thermodynamic parameters at different temperatures indicated that van der Waals forces, hydrogen bonds, and electrostatic forces play major roles in the stability of Pt(II) complex–HSA association. The displacement experiments using the site probes warfarin and ibuprofen substantiated that Pt(II) complex could bind to both site I and II of HSA. Furthermore, UV–Vis and fluorescence spectra were used to investigate the conformational changes of HSA molecule with the addition of Pt(II) complex. The binding constant of Pt(II) complex is more than two orders of magnitude higher than the corresponding value of cephalexin. These results indicate that the binding affinity of Pt(II) complex is stronger than the free drug. In addition, the antibacterial study showed that the MIC of platinum complex of cephalexin for variety of organisms was lower than free cephalexin.