A study of the binding of C.I. Direct Yellow 9 to human serum albumin using optical spectroscopy and molecular modeling

The mechanism of interaction between C.I. Direct Yellow 9 and human serum albumin was studied using spectroscopic methods including fluorescence spectra, UV–vis, Fourier transform infrared (FT-IR) and circular dichroism (CD). The quenching mechanism was investigated in terms of the association constants, number of binding sites and basic thermodynamic parameters. The distance between the human serum albumin donor and the acceptor dye was 3.64 nm as derived from fluorescence resonance energy transfer. Alteration of the secondary protein structure in the presence of the dye was confirmed by UV, FT-IR and CD spectroscopy. Molecular modeling revealed that a dye–protein complex was stabilized by hydrophobic forces and hydrogen bonding, via amino acid residues.     

抗生素痢菌净与人血清白蛋白的相互作用

用荧光、同步荧光、三维荧光和紫外-可见吸收光谱法,研究了在生理条件下痢菌净(MEQ)与人血清白蛋白(HSA)相互作用的光谱学行为。分析了MEQ对HSA的荧光猝灭机制,计算了不同温度下的猝灭常数KSV、结合常数Kb、结合位点数n、热力学参数(如:ΔH、ΔS、ΔG)和结合距离r,并探研了MEQ对HSA构象的影响。结果表明:MEQ对HSA荧光猝灭方式是动态猝灭;结合位点数1;结合距离4.2 nm;MEQ对HSA构象的影响不大。MEQ与HSA间结合作用较弱,作为肠、胃或体外消炎药时,不易被血清白蛋白储存和转运,药物在体内的残留量较少、残留时间较短、所产生的副作用也较小。     

Characterization of the Interaction between Eupatorin and Bovine Serum Albumin by Spectroscopic and Molecular Modeling Methods

This study investigated the interaction between eupatorin and bovine serum albumin (BSA) using ultraviolet-visible (UV-vis) absorption, fluorescence, synchronous fluorescence, circular dichroism (CD) spectroscopies, and molecular modeling at pH 7.4. Results of UV-vis and fluorescence spectroscopies illustrated that BSA fluorescence was quenched by eupatorin via a static quenching mechanism. Thermodynamic parameters revealed that hydrophobic and electrostatic interactions played major roles in the interaction. Moreover, the efficiency of energy transfer, and the distance between BSA and acceptor eupatorin, were calculated. The effects of eupatorin on the BSA conformation were analyzed using UV-vis, CD, and synchronous fluorescence. Finally, the binding of eupatorin to BSA was modeled using the molecular docking method.     

Investigation of the Binding Behavior between the S-heterocyclic Aromatic Palladium(II) Complex and Human Serum Albumin: Spectroscopic Approach

The interaction of 1, 10-phenanthroline octhyldithiocarbamato palladium(II) nitrate ([Pd(Oct-dtc)(phen)]NO₃) with human serum albumin (HSA) has been investigated by various spectroscopic techniques under physiological conditions. Here, HSA was titrated with the Pd(II) complex, followed by UV–Vis absorption spectroscopy to estimate a binding constant (K_b) and other thermodynamic parameters. The results indicate that the Pd (II) complex has a high affinity for bind HSA. Thermodynamic analysis showed that the enthalpy (ΔH°) and entropy changes (ΔS°) are positive and Gibbs free energy change (ΔG°) is negative which indicated that hydrophobic interactions played the predominant role in the binding process. Fluorescence spectroscopy were used to show the mechanism and binding parameters of this interaction. Utilizing the Stern–Volmer equation, the Pd(II) complex quenched the intrinsic fluorescence of HSA via a static quenching procedure. The specific binding distances between the tryptophan (donor) proteins and Pd(II) complex (acceptor) were estimated by Forster resonance energy transfer. The CD results also showed the conformational changes on serum albumin upon binding with the Pd(II) complex.     

对硝基氯苯与牛血清白蛋白的相互作用研究

在模拟动物体生理条件下,用荧光光谱、三维荧光光谱、同步荧光光谱、紫外-可见吸收光谱等方法研究了在不同温度下,对硝基氯苯(PCNB)与牛血清白蛋白(BSA)结合反应的光谱行为。试验发现,PCNB对BSA有较强的荧光猝灭作用。用Stern-Volmer和Lineweaver-Burk方程及热力学方程分别处理试验数据,发现BSA与PCNB发生反应生成了新的复合物,属于静态荧光猝灭,得到了它们相互作用的生成常数KLB(1.557×104L/mol)、热力学参数(ΔHθ=-89.962kJ/mol,ΔSθ=-217.98J/K,ΔGθ=-23.93kJ/mol)和结合位点数(1.080)等。位点竞争实验结果显示PCNB与BSA的作用位置主要在BSA的SiteⅠ(Sub-domainⅡA)位。证明二者主要靠氢键和范德华力结合,同时用三维荧光光谱及同步荧光光谱法探讨了PCNB对BSA构象的影响,为研究PCNB的毒性和生物学效应提供了重要信息。     

Synthesis,Characterization, Cytotoxicity and Detailed HSA Interaction of New Zinc(II) Complexes Containing Dithiocarbamate and Heterocyclic N-donor Ligands

[Zn(ph-dtc)(bpy)]Cl (1) and [Zn(ph-dtc)(phen)]Cl (2) (where bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline and ph-dtc = phenylacetichydrazidedithiocarbamate) were synthesized and characterized by elemental analysis and spectroscopic methods (FT–IR, UV–Vis and ¹H NMR). Zn(II) complexes were examined in biological tests in vitro using MCF-7 breast cancer cell line. Both complexes showed significant cytotoxic activity against human breast cancer MCF-7 cells. The interaction of above compounds with Human Serum Albumin (HSA) was investigated by means of various spectroscopic (at pH ～ 7.4 in Tris–HCl buffer medium) and molecular docking methods. The fluorescence data showed that 1 and 2 quench the intrinsic fluorescence of HSA through a static quenching procedure. The binding constants (K_b) and the number of binding sites (n ～ 1) were calculated. The thermodynamic analysis suggested that hydrophobic interaction played major roles in the binding of 1 or 2 to HSA. The distance r between protein and the above-mentioned compounds was obtained according to fluorescence resonance energy transfer. The conformational changes of protein secondary structure in the presence of Zn(II) complexes were proven using UV–Vis absorption and circular dichroism techniques. Also, docking results confirmed the spectroscopic results.     

血竭总黄酮与血清白蛋白的作用

应用荧光光谱法研究不同离子强度、温度、酸度条件下,血竭总黄酮(tFSD)与血清白蛋白的相互作用。研究表明:tFSD能不同程度地猝灭牛血清白蛋白(BSA)和人血清白蛋白(HSA)的荧光强度,BSA的荧光强度猝灭得更显著;在288~298K间,随着温度的升高,BSA-tFSD和HSA-tFSD两荧光体系的猝灭程度降低,推测tFSD对BSA、HSA的荧光猝灭作用不是动态猝灭,而是静态猝灭;在pH6.0~pH10.0间,随着pH的提高,tFSD对BSA(HSA)的荧光猝灭程度上升,说明tFSD与BSA(HSA)之间以非静电作用为主,并形成了不发荧光的复合物。     

光谱法研究一种喹唑啉酮衍生物与牛血清白蛋白的相互作用

应用荧光光谱及紫外可见光谱的方法研究了2-异丙氧基-3-苯基-3H-喹唑啉-4-酮(PHQ)与牛血清白蛋白(BSA)的相互作用。实验结果表明,PHQ能强烈猝灭牛血清白蛋白的荧光强度,其荧光猝灭机理为动态猝灭。在此基础上计算了二者相互作用的结合常数、结合位点数及ΔHθ,ΔGθ,ΔSθ等热力学参数等。结果表明PHQ与BSA以1∶1结合,其反应主要是熵驱动的,相互作用力主要为疏水作用力。根据Frster无辐射能量转移理论计算了给体(BSA)与受体(PHQ)之间的结合距离。     

氟碳化合物与环糊精包合物的制备及其对牛血清白蛋白的影响

以氟碳化合物FC-77作为模型药物,制备FC-77与β-环糊精（卢一cD）包合物。考察包合物与牛血清白蛋白（BSA）的相互作用。通过紫外-可见光谱、红外光谱、热重分析等方法研究包合物的物理化学性能。通过荧光光谱法研究包合物对BSA的荧光猝灭作用。结果为Fc-77与β-cD之间存在强烈的相互作用,从而增加了FC-77的稳定性和水中的溶解性。荧光猝灭结果显示FC-77分子能进入BSA的疏水区域。结论是以β-CD为介质,能显著改善FC-77的理化性能,使FC-77粉末化,便于制成多种剂型,扩大给药方式。     

两种金属卟啉与牛血清白蛋白作用的研究

采用荧光光谱法和紫外-可见吸收光谱法研究了两种金属卟啉与牛血清白蛋白(BSA)的结合作用。实验结果表明:卟啉配合物对BSA有较强的荧光猝灭作用,按照Stern-Volmer方程和Lineweaver-Burk双倒数方程分析和处理试验数据,得到反应的结合常数、结合位点数和热力学参数等;探讨了金属卟啉的分子结构对结合反应的影响。利用同步荧光技术考察了金属卟啉对BSA构象的影响,发现金属卟啉的加入使BSA构象发生变化,色氨酸残基所处环境的疏水性降低。     

荜茇宁与牛血清白蛋白相互作用的研究

用荧光光谱及紫外光谱法研究生理条件下荜茇宁与生物大分子牛血清白蛋白(BSA)的相互作用.实验结果表明,荜茇宁与BSA形成基念复合物从而猝火BSA的内源性荧光,猝灭原因主要为静态猝灭和非辐射能量转移.根据Forster 偶极-偶极非辐射能量转移理论,确定荜茇宁与BSA有较强的相互作用,可以被蛋白质所储存和运输.荜茇宁与B...     

Novel Polymeric Metal Complexes of 2,7-Bis[2-(2′-Pyridyl) Benzimidazole]- 9,9′-Dioctylfluorene with Cu(II)and Zn(II): Synthesis and Luminescence Properties

Abstract  A novel ligand, 2,7-bis[2-(2′-Pyridyl)benzimidazole]- 9,9′-dioctylfluorene (BPDOF) and its polymeric complexes with copper(II) and zinc(II) were successfully synthesized and characterized by ¹H NMR, FT-IR, elemental analysis, UV-vis, conductivity measurements and gel permeation chromatography. The UV–vis absorption, fluorescence spectra, and thermal properties of these complexes were investigated at room temperature. The experimental results show that polymeric metal complexes BPDOF-Cu(II) and BPDOF-Zn(II) emit purple/green luminescence at 430 and 509 nm in DMF solution and emit green luminescence at 495 and 527 nm in the solid state. Thermal properties measurement and analysis show that they have good thermal stabilities. Graphical Abstract  Synthesis route: 2,7-bis[2-(2′-Pyridyl) benzimidazole]- 9,9′-dioctylfluorene (BPDOF) was synthesized using 2-(2′-Pyridyl)benzimidazole and 2,7-dibromo-9,9′-dioctylfluorene by Ullmann condensation. Polymeric metal complexes of the corresponding were synthesized with CuCl₂ · 2H₂O, ZnCl₂.      

分子模拟和光谱法研究华法林与人血清白蛋白的结合机制

华法林(WF)是临床常用口服抗凝药物,有关它与人血清白蛋白(HSA)结合位点处的热点残基、作用力类型以及对HSA构象影响报道较少.通过在模拟人体生理条件下,利用分子模拟、内源荧光光谱、三维荧光光谱和同步荧光光谱,研究了WF与HSA之间作用机理.WF能使HSA构象发生改变,导致Tyr残基微环境极性降低、Trp残基周围亲水...     

Quenching of Protein Fluorescence by Fullerenol C60(OH)36 Nanoparticles

The effect of the interaction between fullerenol C₆₀(OH)₃₆ (FUL) and alcohol dehydrogenase (ADH) from Saccharomyces cerevisiae and human serum albumin (HSA) was studied by absorption spectroscopy, fluorescence spectroscopy, and time-resolved fluorescence spectroscopy. As shown in the study, the fluorescence intensities of ADH and HSA at excitation wavelengths λ_ex = 280 nm (Trp, Tyr) and λ_ex = 295 nm (Trp) are decreased with the increase in the FUL concentration. The results of time-resolved measurements indicate that both quenching mechanisms, dynamic and static, are present. The binding constant K_b and the number of binding sites were obtained for HSA and ADH. Thus, the results indicated the formation of FUL complexes and proteins. However, the binding of FUL to HSA is much stronger than that of ADH. The transfer of energy from the protein to FUL was also proved.     

The binding of C.I. Acid Red 2 to human serum albumin: Determination of binding mechanism and binding site using fluorescence spectroscopy

The mechanism of interaction between C.I. Acid Red 2 and human serum albumin was studied using different spectroscopic methods. The binding constants for the formation of a complex between the dye and albumin were 2.557, 2.461 and 2.383 × 10⁵ M^?1 at 298, 304 and 310 K, respectively. The associated changes in enthalpy and entropy were ?4.512 kJ mol^?1 and 88.38 J mol^?1 K^?1, indicating that hydrophobic interactions as well as H-bonding were the dominant intermolecular forces stabilizing the complex. Site marker competitive experiments revealed that the binding of the dye to albumin occurred in subdomain IIA; the distance between dye and albumin was 3.91 nm according to fluorescence resonance energy transfer theory. Changes in the albumin secondary structure imparted by the dye were confirmed using synchronous fluorescence, electronic absorption, circular dichroism and three-dimensional fluorescence spectroscopy.     

甲基对硫磷与牛血清白蛋白相互作用的光谱研究

[目的]为了解释有机磷农药—甲基对硫磷对牛血清白蛋白(BSA)的作用与致毒机理。[方法]采用紫外和荧光光谱法研究甲基对硫磷与BSA的相互作用。[结论]甲基对硫磷能与BSA相互作用,其作用程度和方式与浓度、酸度和离子强度等因素有关。甲基对硫磷对BSA的荧光猝灭方式为静态猝灭,通过计算得到结合位点数(n)和结合常数(K),且结合距离(r)小于7 nm。二者的作用力为氢键或范德华力。甲基对硫磷使BSA构象发生变化,且对酪氨酸残基的影响较大。     

光谱法研究迷迭香酸和牛血清白蛋白的相互作用

利用荧光和圆二色光谱研究了迷迭香酸(RA)与牛血清白蛋白(BSA)之间的相互作用.通过荧光猝灭测得在301、308和315 K时,RA与BSA的结合常数K分别为4.18×10~4、3.62×10~4和2.52×10~4 L/mol,表明RA与BSA间具有较强的结合作用,属于静态猝灭.热力学参数计算结果表明RA与BSA相互作用力以范德华力及氢键作用力为主.圆二色光谱、红外及拉曼光谱、荧光同步光谱研究表明相互作用后BSA的二级结构发生微小变化.此外,常见金属离子对结合有较为显著的影响.     

N-乙酰-L-半胱氨酸修饰的CdTe量子点与人血清白蛋白的相互作用

以N,乙酰-L-半胱氨酸为修饰剂,制备了水溶性的CdTe量子点（NAc—CdTeQDs）。利用荧光光谱法和等温滴定量热法（11℃）研究了NAC-CdTeQDs与人血清白蛋白（HsA）的相互作用。结果表明,NAC—CdTeQDs对HSA内源荧光具有较强的动态猝灭作用,且猝灭作用是扩散控制的。     

Characterization of interaction between C.I. Acid Green 1 and human serum albumin: Spectroscopic and molecular modeling method

The binding characteristics of human serum albumin with C.I. Acid Green 1 were studied by employing fluorescence, resonance light scattering, ultraviolet–visible, circular dichroism, Fourier transform infrared techniques and molecular modeling. Spectroscopic analysis has revealed that quenching of human serum albumin by C.I. Acid Green operates by a static quenching mechanism. The results by Fourier transform infrared, circular dichroism and ultraviolet–visible absorption spectra experiment indicated that the secondary structures of protein were changed in the presence of C.I. Acid Green 1. Molecular modeling revealed that a dye–protein complex was stabilized by hydrophobic forces, Van-der-Waals force and hydrogen bonding, via amino acid residues. Furthermore, influences of coexisting substances on the binding constant of C.I. Acid Green 1-human serum albumin complexes were investigated.     

Luminescent polyethylene with side-chain triarylboranes: Synthesis and fluoride sensing properties

The direct copolymerization of ethylene with an electron-deficient borane monomer (1) using a single-site catalytic system, Me₂Si(η⁵-C₅Me₄)(η¹-N-^tBu)TiCl₂ (CGC)/methylaluminoxane (MAO) efficiently leads to the novel class of luminescent polyethylene with pendent triarylborane groups. The catalytic system provides high-molecular-weight copolymers with controlled incorporation of 1. Characterization by multinuclear NMR spectroscopy reveals that the copolymers constitute a well-defined polymer structure with base-free tricoordinate boron centers. While UV-vis absorption and PL spectra of copolymers display almost identical absorption and emission features with those of 1, the copolymer (8.8 mol% of 1) shows the enhanced emission quenching efficiency with 70% amplification effect upon addition of fluoride ion in solution. Particularly, the thin film of the copolymer exhibits the high fluorescence quenching response in the presence of a very low concentration of fluoride ion (4.5 μM) in THF.