5,7-二羟基-4''''-甲氧基二氢黄酮与牛血清白蛋白的相互作用研究

应用荧光光谱、紫外吸收光谱和核磁共振波谱研究了5,7-二羟基-4'-甲氧基二氢黄酮(ISO)与牛血清白蛋白(BSA)分子间的相互作用.研究表明:ISO对BSA内源性荧光的猝灭机制属于ISO和BSA形成化合物所引起的静态猝灭;二者的结合常数为7.41×1011L/mol,结合位点数为1.98.ISO与BSA作用的活性部位为其分子内的7-OH和5-OH,且7-OH活性强于5-OH,并且随着ISO浓度增大,BSA的构象发生了变化.     

2,6-二甲基-4-芳基-1,4-二氢吡啶衍生物的合成及其与牛血清白蛋白的相互作用

以芳香醛（1a~1d）、乙酰乙酸甲酯（乙酰乙酸乙酯）、乙酸铵和无水乙醇为原料,采用一锅法合成了5个2,6-二甲基-4-芳基-1,4-二氢吡啶衍生物（2a~2e）,其结构经¹H NMR, IR和MS(EI)表征。应用荧光光谱法和紫外光谱法研究药物分子2a与牛血清白蛋白（BSA）的相互作用。结果表明：药物分子对BSA有较强的猝灭作用,其猝灭机理为静态猝灭,药物分子与BSA间的作用力主要为疏水作用力。     

3，8-二甲基-4′-甲氧基黄酮的合成及其与BSA的相互作用

合成了一种新化合物3,8-二甲基-4’-甲氧基黄酮(DMMOF),通过1H NMR、13C NMR、IR对其进行了表征。在模拟生理条件下,采用原子力显微镜(AFM)、荧光光谱及紫外光谱法研究了DMMOF与牛血清蛋白(BSA)的相互作用。结果表明:DMMOF与BSA粒径大小分别为2.747、2.284 nm,二者混合后为17.705nm;DMMOF对BSA有荧光猝灭作用,通过紫外吸收光谱及Stern-Volmer方程判断其猝灭过程主要为静态猝灭;根据双对数方程计算出不同温度下DMMOF与BSA的结合常数及其相应的结合位点数;由热力学参数方程计算出ΔH、ΔS和ΔG的值分别为-116.86 kJ.mol-1、-279.55 J.mol-1.K-1、-32.14 kJ.mol-1,推断两者之间的作用力类型主要为范德华力和氢键;根据Frster非辐射能量转移理论计算出DMMOF与BSA的结合距离为1.22 nm(306 K)。同时运用同步荧光光谱研究了DMMOF对BSA构象的影响,结果表明DM-MOF的加入并未引起BSA构象的改变,结合紫外吸收光谱推测DMMOF的A环与BSA的134位色氨酸残基及酪氨酸残基发生结合。     

荧光法研究3-氨基苯硼酸与牛血清白蛋白间的相互作用

为了了解分子印迹反应的机理和最适宜的反应条件, 应用荧光猝灭法研究了3-氨基苯硼酸(APBA)与牛血清白蛋白(BSA)的相互作用, 二者的反应受到体系pH值、离子强度等关键因素的影响. 实验结果表明: 适宜的离子强度和pH值为6.25时, APBA与BSA的色氨酸残基的荧光猝灭反应的物质的量比为2∶1, 表观结合常数K_A＝1.0×10¹¹ L²• mol^－2, 说明二者间形成了较强的化学键. 通过上述研究, 明晰了3-氨基苯硼酸与牛血清白蛋白之间的作用机理, 有助于分离或富集蛋白质中BSA组分, 从而能够改进印迹和洗脱的效率.     

用荧光法研究对-二甲氨甲基-杯[8]芳烃与牛血清白蛋白的相互作用

本文研究了对-二甲氨甲基-杯[8]芳烃(CX8)与牛血清白蛋白(BSA)结合反应的荧光光谱和紫外-可见吸收光谱。实验发现CX8对BSA有较强的荧光猝灭作用,且CX8的紫外吸收光谱和BSA的荧光发射光谱有一定程度的重叠;CX8对BSA的猝灭属静态猝灭,疏水作用是两者之间的主要作用。确定了供体-受体间的结合距离r=1.76 nm,能量转移效率E=0.58;得出了结合反应的结合常数、结合位置和结合过程基本热力学性质的变化等。此外,还考察了酸度对BSA和CX8结合反应的影响。     

3,8-二甲基-4'-甲氧基黄酮的合成及其与BSA的相互作用

合成了一种新化合物3,8-二甲基-4'-甲氧基黄酮(DMMOF),通过1H NMR、13C NMR、IR对其进行了表征.在模拟生理条件下,采用原子力显微镜(AFM)、荧光光谱及紫外光谱法研究了DMMOF与牛血清蛋白(BSA)的相互作用.结果表明:DMMOF与BSA粒径大小分别为2.747、2.284 nm,二者混合后为17.705nm; DMMOF对BSA有荧光猝灭作用,通过紫外吸收光谱及Stern-Volmer方程判断其猝灭过程主要为静态猝灭;根据双对数方程计算出不同温度下DMMOF与BSA的结合常数及其相应的结合位点数;由热力学参数方程计算出△H、△S和△G的值分别为-116.86kJ·mol-1、-279.55 J·mol-1·K-1、-32.14 kJ·mol-1,推断两者之间的作用力类型主要为范德华力和氢键;根据F(o)rster非辐射能量转移理论计算出DMMOF与BSA的结合距离为1.22 nm(306 K).同时运用同步荧光光谱研究了DMMOF对BSA构象的影响,结果表明DMMOF的加入并未引起BSA构象的改变,结合紫外吸收光谱推测DMMOF的A环与BSA的134位色氨酸残基及酪氨酸残基发生结合.     

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...     

1,4-二甲基-6,8-二甲氧基-9,10-蒽醌的合成及其与牛血清白蛋白和DNA的相互作用

合成了大黄素类蒽醌衍生物1,4-二甲基-6,8-二甲氧基-9,10-蒽醌(1)并应用紫外光谱、荧光光谱、圆二色谱等方法研究了其与牛血清白蛋白(BSA)和小牛胸腺DNA(ct-DNA)的相互作用.荧光光谱结果表明,化合物1与BSA的相互作用主要以静态猝灭方式使BSA的内源性荧光发生猝灭;圆二色谱表明,化合物1通过疏水作用及形成氢键破坏了α-螺旋结构,导致BSA分子中的α-螺旋含量下降.在pH 7.4时固定DNA的浓度,加入化合物1后,紫外光谱的最大吸收峰发生红移且吸光度加大.荧光光谱表明,化合物1与DNA-4S green NC的结合为竞争性抑制,并可使溶液体系荧光猝灭;圆二色谱表明,随着化合物1的加入,DNA碱基间作用能迅速减弱,表明化合物1与DNA之间为嵌插作用.此外,MTT方法的结果表明,化合物1对结肠癌细胞株HCT116增殖有明显的抑制作用.     

吡喃并[3,2-c]吡啶-5-酮衍生物与血清白蛋白相互作用的光谱和分子对接研究

通过荧光光谱和紫外-可见吸收光谱法,在模拟生理条件下,研究了吡喃并[3,2-c]吡啶-5-酮衍生物-2-氨基-7-甲基-3-氰基-4-(4-甲苯)-吡喃并[3,2-c]吡啶-5-酮(AMP)与牛血清白蛋白(BSA)的相互作用。探讨了AMP对BSA的荧光猝灭过程的猝灭机理。不同温度下的Stern-Volmer曲线和紫外-可见吸收光谱表明:该衍生物主要以静态猝灭的方式使牛血清白蛋白的荧光猝灭。热力学参数表明两者之间的作用力类型主要为疏水作用力。用同步荧光技术考察了这一衍生物对牛血清白蛋白构象的影响。分子对接表明,该衍生物可能位于白蛋白的疏水腔IIA处。     

1,4-二甲基-6,8-二甲氧基-9,10-蒽醌的合成及其与BSA和ct-DNA的相互作用

合成了大黄素类蒽醌衍生物1,4-二甲基-6,8-二甲氧基-9,10-蒽醌(1)并应用紫外光谱、荧光光谱、圆二色谱等方法研究了其与牛血清白蛋白(BSA)和小牛胸腺DNA(ct-DNA)的相互作用。荧光光谱结果表明,化合物1与BSA的相互作用主要以静态猝灭方式使BSA的内源性荧光发生猝灭;圆二色谱表明,化合物1通过疏水作用及形成氢键破坏了α-螺旋结构,导致BSA分子中的α-螺旋含量下降。在p H 7.4时固定DNA的浓度,加入化合物1后,紫外光谱的最大吸收峰发生红移且吸光度加大。荧光光谱表明,化合物1与DNA-4S green NC的结合为竞争性抑制,并可使溶液体系荧光猝灭;圆二色谱表明,随着化合物1的加入,DNA碱基间作用能迅速减弱,表明化合物1与DNA之间为嵌插作用。此外,MTT方法的结果表明,化合物1对结肠癌细胞株HCT116增殖有明显的抑制作用。     

Interaction between Xanthoxylin and Bovine Serum Albumin

在模拟生理条件下,采用荧光光谱法、圆二色光谱法和红外光谱法研究了花椒油素(XT)与牛血清白蛋白（BSA）的相互作用。结果表明花椒油素与牛血清白蛋白之间发生动态和静态联合猝灭,二者间的的猝灭常数(K)在286, 298和310 K分别为3.31 × 105, 到2.03 × 105 和 0.94 × 105 L∙mol-1. 热力学参数表明, 花椒油素与牛血清白蛋白间以疏水作用力为主。圆二色光谱和红外光谱法表明加入花椒油素后,牛血清白蛋白的二级结构发生了变化,其中α-螺旋减少了3.9%。另外,我们还研究了共存离子对两者结合的影响。     

Study of interaction of Potassium Dodecatangestato Cobaltate(III) with Bovine Serum Albumin using Fluorescence Spectroscopy

The binding of potassium dodecatangestato cobaltate(III) (PDC) as a water-soluble polyoxometal with bovine serum albumin (BSA) as a major transporting protein of plasma, has been investigated at pH 7.2, 5?mM phosphate buffer, 27°C and various ionic strength by fluorescence spectroscopy.

The results show that the binding of PDC to BSA quenches BSA emission and the Stern–Volmer linear relationship can be applied for the quenching process.

The values of Stern–Volmer constant, K _sv, which can be considered as a binding constant for formation of 1:1 complex at 0.01, 0.1 and 0.2?M NaCl are 8.56 × 10⁵, 5.72 × l0⁵ and 9.60 × 10⁵, respectively. The interpretation of the results represents that binding affinity depends on both electrostatic forces and conformational stability of BSA. A step-by-step aggregation model, which has been developed by Borissevich et al., was used to determine the average aggregation number of BSA, ?J?, from the fluorescence quenching. The results show that the binding of PDC to BSA does not induce any considerable aggregation in BSA molecules. Therefore, it can be concluded that there are no considerable conformational changes in BSA molecules during its interaction with PDC.     

Studies of the interaction between apigenin and bovine serum albumin by spectroscopic methods

The interaction between apigenin (Ap) and bovine serum albumin (BSA) in physiological buffer (pH = 7.4) is investigated by fluorescence quenching technique and UV-vis absorption spectra. The results reveal that Ap could strongly quench the intrinsic fluorescence of BSA. The quenching mechanism of Ap for BSA varies with the change of Ap concentration. when Ap concentration is lower, it is a static quenching procedure, when Ap concentration is higher, a combined quenching (both static and dynamic) would operate. The apparent binding constants Ka and number of binding sites n of Ap with BSA are obtained by fluorescence quenching method. The thermodynamic parameters, enthalpy change (Δ_r H ^m and entropy change (Δ_r S ^m ), are calculated to be −15.382 kJ mol⁻¹ K⁻¹ < 0 and 104.888 J mol⁻¹ K⁻¹ > 0, respectively, which indicate that the interaction of Ap with BSA is driven mainly by hydrogen bonding and hydrophobic interactions. The distance r between BSA and Ap is calculated to be 1.89 nm based on F?rster’s non-radiative energy transfer theory. The results of synchronous fluorescence spectra show that binding of Ap with BSA cannot induce conformational changes in BSA.     

Studies of the interaction between daidzein and 3′-daidzein sulfonic sodium with bovine serum albumin by spectroscopic methods

The interaction between daidzein and 3′-daidzein sulfonic sodium with bovine serum albumin (BSA) in physiological buffer (pH = 7.4) is investigated by fluorescence quenching technique and UV/vis absorption spectra. The results reveal that both daidzein and 3′-daidzein sulfonic sodium could strongly quench the intrinsic fluorescence of BSA. The quenching mechanism of both the daidzein and 3′-daidzein sulfonic sodium for BSA is static quenching procedure. The apparent binding constants K _a and number of binding sites n of daidzein and 3′-daidzein sulfonic sodium with BSA are obtained by fluorescence quenching method. The thermodynamic parameters, enthalpy change (Δ_r H ^m ), and entropy change (Δ_r S ^m ), are calculated, respectively, which indicate that the interaction of daidzein with BSA is driven mainly by hydrogen bonding and van der Waals, and 3′-daidzein sulfonic sodium with BSA is driven mainly by hydrophobic forces. The distance r between BSA with daidzein and 3′-daidzein sulfonic sodium are calculated to be 4.02 nm and 3.08 nm, respectively, based on F?rster’s non-radiative energy transfer theory. The results of synchronous fluorescence spectra show that binding of daidzein and 3′-daidzein sulfonic sodium with BSA cannot induce conformational changes in BSA.     

Study on Interactions of Phenolic Acid-Like Drug Candidates with Bovine Serum Albumin by Capillary Electrophoresis and Fluorescence Spectroscopy

The interactions of the phenolic acids cinnamic acid (CNA), ferulic acid (FA), caffeic acid (CA) and chlorogenic acid (CLA) with bovine serum albumin (BSA) were investigated and compared using affinity capillary electrophoresis (ACE) and the fluorescence quenching methods. ACE gives binding constants (K _b) and thermodynamic parameters. The thermodynamic parameters show that each of four phenolic acids bind to BSA mainly by hydrogen bonds, electrostatic and hydrophobic interactions. The fluorescence quenching method provided quenching constant K _sv, binding site number n and K _b. The fluorescence results indicate that BSA fluorescence quenching is mainly a static quenching process. The binding constants (K _b) of CNA, FA, CA and CLA were from 2.52×10⁴ to 7.90×10⁴ L⋅mol⁻¹ from ACE experiments and 1.19×10⁴ to 5.21×10⁴ L⋅mol⁻¹ from fluorescence, their increase corresponded to the increase in the number of hydroxyl groups. These results imply that molecular structure and the number of hydroxyl groups of phenolic acids play act key roles in the affinity of natural phenolic acids towards BSA.     

Spectroscopic Studies on the Interaction of Asiatic Acid with Bovine Serum Albumin

Fluorescence spectroscopy, Fourier transform infrared (FT‐IR) spectroscopy, circular dichroism (CD) and FT‐Raman spectroscopy were employed to analyze the binding of the asiatic acid (AA) to bovine serum albumin (BSA) under simulative physiological conditions. Fluorescence data revealed that the fluorescence quenching of BSA by AA was the result of the formation of BSA‐AA complex. The fluorescence quenching mechanism of BSA by AA was a static quenching procedure. According to the Van′t Hoff equation, the thermodynamic parameters enthalpy change (ΔH⁰) and entropy change (ΔS⁰) for the reaction were evaluated to be ?12.55 kJ·mol^?1 and 67.08 kJ·mol^?1, respectively, indicating that hydrophobic and electrostatic interactions played a major role in stabilizing the complex. The influence of AA on the conformation of BSA has also been analyzed on the basis of FT‐IR, CD and FT‐Raman spectra.     

Mechanism and conformational studies of farrerol binding to bovine serum albumin by spectroscopic methods

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.     

Synthesis,crystal structure,DNA/bovine serum albumin binding and antitumor activity of two transition metal complexes with 4‐acylpyrazolone derivative

Two new complexes, namely [Cu₆L₆] ( 1 ) and [Zn(HL)₂] ( 2 ) (H₂L = N‐(1‐phenyl‐3‐methyl‐4‐propenylidene‐5‐pyrazolone)‐2‐furancarboxylic acid hydrazide), have been synthesized and characterized. Single crystal X‐ray analysis indicates that complex 1 has a hexanuclear structure and complex 2 exhibits a mononuclear structure. The DNA/bovine serum albumin (BSA) binding properties of complexes 1 and 2 were investigated by absorption spectroscopy and fluorescence quenching. Both complexes could effectively intercalate to DNA with calculated quenching constants of 2.6 × 10⁵ and 1.25 × 10⁵ M^?1, respectively. The quenching mechanism of the intrinsic fluorescence of BSA by the complexes was found to be a static one. The cytotoxicities of 1 and 2 were investigated in two human tumor cell lines, human esophageal cancer cells (Eca‐109) and cervical cancer cells (HeLa). Complex 1 exhibits higher antitumor activity than 2 . Furthermore, 1 can inhibit HeLa cells by inducing apoptosis and G0/G1 phase cell cycle arrest. All results demonstrate that 1 and 2 both have DNA/BSA binding capacity and antitumor activity.     

Effect of Hydrogenation on Ring C of Flavonols on Their Affinity for Bovine Serum Albumin

In this paper, the effect of hydrogenation on ring C of flavonols on the affinity for bovine serum albumin was investigated. Two differently substituted B-ring hydroxylation flavonols (myricetin and quercetin) and their dihydrides (dihydromyricetin and dihydroquercetin) were used to study their affinities for BSA by quenching the intrinsic BSA fluorescence in solution. From the spectra, the bimolecular quenching constants, the binding constants, the number of binding sites and the binding distances were calculated. The hydroxylation on ring B and hydrogenation on ring C of flavonols significantly affected the binding/quenching process; in general, the hydroxylation increased the affinity and the hydrogenation decreased the affinity. For myricetin and quercetin, the binding constants (K _a) for BSA were 1.84×10⁸ L⋅mol⁻¹ and 3.83×10⁷ L⋅mol⁻¹. For dihydromyricetin, the binding constant was 1.36×10⁴ L⋅mol⁻¹, while dihydroquercetin hardly quenched the BSA intrinsic fluorescence. These results showed that hydrogen bonding and conjugative effects may play an important role in binding of flavonols to BSA. These results also showed that the properties of flavonols are related to their chemical structure.