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。     

Spectroscopic and nano-molecular modeling investigation on the binary and ternary bindings of colchicine and lomefloxacin to Human serum albumin with the viewpoint of multi-drug therapy

Combination of several drugs is often necessary especially during long-term therapy. The competitive binding drugs can cause a decrease in the amount of drug bound to protein and increase the biological active fraction of the drug. The aim of this study is to analyze the interactions of Lomefloxacin (LMF) and Colchicine (COL) with human serum albumin (HSA) and to evaluate the mechanism of simultaneous binding of LMF and COL to protein. Fluorescence analysis was used to estimate the effect of drugs on the protein fluorescence and to define the binding and quenching properties of drugs-HSA complexes. The binding sites for LMF and COL were identified in tertiary structure of HSA with the use of spectrofluorescence analysis. The analysis of fluorescence quenching of HSA in the binary and ternary systems show that LMF does not affect the complex formed between COL and HSA. On the contrary, COL decreases the interaction between LMF and HSA. The results of synchronous fluorescence, resonance light scattering and circular dichroism spectra of binary and ternary systems show that binding of LMF and COL to HSA can induce micro-environmental and conformational changes in HSA. The simultaneous presence of LMF and COL in binding to HSA should be taken into account in the multi-drug therapy, and necessity of using a monitoring therapy owning to the possible increase of the uncontrolled toxic effects. Molecular modeling of the possible binding sites of LMF and COL in binary and ternary systems to HSA confirms the spectroscopic results.     

Characterize the interaction between polyethylenimine and serum albumin using surface plasmon resonance and fluorescence method

Polyethylenimine (PEI) is a type of cationic polymer which is efficient in DNA transfer. The characters of PEI binding to bovine serum albumin and human serum albumin (HSA) were described by fluorescence quenching, surface plasmon resonance (SPR) and circular dichroism (CD) spectroscopy. The fluorescence quenching results showed that the binding processes occurred on the surface of the protein molecules. The accurate binding constants between PEI and the two proteins were obtained by SPR spectroscopy. The CD spectra results showed that the confirmations of the two proteins were affected with the addition of PEI.     

Optical, Structural and Thermodynamic Studies of the Association of an Anti-leucamic Drug Imatinib Mesylate with Transport Protein

The interaction of an anti-leukemic drug, imatinib mesylate (IMT) with human serum albumin (HSA) was investigated by fluorescence, synchronous fluorescence, three-dimensional fluorescence, circular dichroism and UV–vis absorption techniques under physiological condition. The process of binding of IMT on HSA was observed to be through a spontaneous molecular interaction procedure. IMT effectively quenched the intrinsic fluorescence of HSA via static quenching. The values of binding constant, number of molecules that interact simultaneously with the binding site and thermodynamic parameters were evaluated by carrying out the interactions at three different temperatures. Based on thermodynamic parameters and displacement studies with site probes, it was proposed that the drug bound at Sudlow’s site I of subdomain IIA. The change in the conformation of HSA was evident from synchronous, three-dimensional fluorescence and circular dichroism studies. The distance between the donor (protein) and acceptor (drug) was calculated based on the Foster’s theory of resonance energy stransfer and it was found to be 1.30 nm. The effect of different metal ions on the binding of the drug to protein was also investigated.     

小檗碱与人血清白蛋白的相互作用

利用紫外光谱和荧光光谱技术研究了中药有效成分小檗碱与人血清白蛋白(HSA)的相互作用机制。利用荧光猝灭反应测得它们之间结合常数K=1.168×105 L·mol-1,结合位点数n=5.26。依据Frster非辐射能量转移机制,测得供体-受体间结合距离R=3.44 nm和能量转移效率E=0.303。认为小檗碱在HSA的位置阻断了酪氨酸残基与色氨酸残基之间的能量转移,并使它们的荧光猝灭,并与色氨酸结合生成了较弱的荧光发光体。     

Determining the binding affinity and binding site of bensulfuron-methyl to human serum albumin by quenching of the intrinsic tryptophan fluorescence

Bensulfuron-methyl (BM) is a highly active sulfonylurea herbicide for use on paddy rice. Steady state fluorescence, UV/vis absorption, circular dichroism (CD), time-resolved fluorescence and molecular modeling methods have been exploited to determine the binding affinity and binding site of BM to human serum albumin (HSA). From the synchronous fluorescence, UV/vis, CD and three-dimensional fluorescence spectra, it was evident that the interaction between BM and HSA induced a conformational change in the protein. Steady state and time-resolved fluorescence data illustrates that the fluorescence quenching of HSA by BM was the formation of HSA-BM complex at 1:1 molar ratio. Site marker competitive experiments demonstrated that the binding of BM to HSA primarily took place in subdomain IIIA (Sudlow’s site II), this corroborates the hydrophobic probe ANS displacement and molecular modeling results. Thermodynamic analysis displays hydrophobic, electrostatic and hydrogen bonds interactions are the major acting forces in stabilizing the HSA-BM complex.     

维生素B6与人血清白蛋白的相互作用

人血清白蛋(HSA)在2 96nm的光激发下能发射35 0nm的荧光(即λex=2 96 ,λem =35 0nm)。当HSA中加入适量的维生素B6 (B6 )后,HSA的荧光被部分猝灭,从τ0 (不加B6 时HSA的荧光寿命———分子激发态的寿命)与τi (加入B6 后的寿命)相等(近似)得知这种猝灭是静态猝灭。根据理论,可求出HSA与B6 间的结合常数K =2 6 7×10 4 L·mol- 1 。又从实验上可观察到HSA (它的激发态)可向B6 转移能量,由此可求出HSA和B6 间的临界距离R0 =1 872nm。测定了HSA和(HSA B6 )的园二色(CD)谱,发现所测得的CD谱都很相似(基本上是一样的)。从测得的[θ]值可以算出各个样品所含的四种结构(α螺旋、β折叠片、β卷角,无规卷曲)的百分含量也大体相同。     

光谱法和分子对接模拟技术研究左氧氟沙星与人血清白蛋白的相互作用

左氧氟沙星(LVFX)是临床上普遍使用的一种抗生素,对革兰氏阳性菌及革兰氏阴性菌引起的各种感染都有一定的作用。人血清白蛋白(HSA)是血液循环系统中最丰富的运输蛋白,能与多种内源及外源性物质结合,起着储存和转运的作用。因此详细研究LVFX与HSA间的相互作用对了解LVFX的药代动力学行为具有重要意义。运用光谱法和分子对接模拟技术研究左氧氟沙星和人血清白蛋白的相互作用。结果表明,LVFX对HSA的荧光淬灭作用为形成复合物导致的静态猝灭,结合常数为9.44×104 L·mol-1 (294 K)和2.72×104 L·mol-1 (310 K),结合位点数均为1,两者间的主要作用力为氢键和范德华力。取代实验表明,LVFX在HSA的Site Ⅰ,ⅡA 子域上有一个结合位点。根据Frster理论得到的LVFX和色氨酸(Trp)残基间的结合距离为3.66 nm,这一结果与分子对接模拟技术得到的结果相一致。紫外差谱,三维荧光光谱和红外光谱都进一步表明LVFX能够改变HSA的结构。采用傅里叶变换红外光谱法对LVFX与HSA作用前后HSA二级结构的变化进行了定量分析,结果表明,当加入LVFX后HSA的α-螺旋结构有所降低,β-折叠结构、β-转角结构和无规则卷曲有所上升,说明LVFX能使HSA的二级结构变得松散。     

光谱法和分子对接模拟技术研究异烟肼对人血清白蛋白和过氧化氢酶的特异性结合及抑制作用

异烟肼(Isoniazid, INH)是最常用的一线抗结核药物之一。据报道,人体内高浓度的异烟肼可导致癫痫, 肝功能衰竭, 甚至死亡。因此,研究异烟肼对人血清白蛋白(HSA)和过氧化氢酶(CAT)的结构和活性的潜在结合影响有利于评估其毒性和副作用。在模拟生理条件下,利用多种荧光光谱和分子对接技术研究INH与HSA和CAT之间的相互作用。所有荧光数据均进行了内滤光校正以获得更准确的结合参数。结果表明,INH-HSA和INH-CAT体系的猝灭常数(K_sv)随着温度的升高而降低,表明INH对HSA及CAT的荧光猝灭机理为静态猝灭。利用紫外-可见吸收光谱、同步荧光光谱、和圆二色(CD)光谱法研究了INH对HSA和CAT构象的影响。结果发现,INH可改变色氨酸残基的微环境并降低HSA和CAT中α-螺旋结构,导致蛋白质结构发生伸展,进而可能影响其生理功能。分子对接结果表明,INH与HSA的结合位点位于HSA的site Ⅰ,ⅡA子域。INH可以进入CAT中β-折叠的桶状空腔,从而抑制CAT的活性。Hill系数结果表明,INH与左氧氟沙星(LVFX,一种安全有效的二线抗结核药物,与其他抗结核药物联合使用可以提高抗结核疗效)之间存在药物协同性,促进INH与HSA的相互作用。另外,CD光谱测定表明INH与LVFX的协同作用改变HSA的二级结构,使α-螺旋结构降低约7.9%。该研究探讨了INH与HSA和CAT之间的结合作用和毒性机制,为INH的安全使用提供重要依据。     

多光谱技术结合分子模拟研究头孢唑林和头孢曲松与人血清白蛋白的相互作用

头孢唑林(CFZ)属第一代β-内酰胺类半合成头孢菌素,对革兰氏阳性菌和革兰氏阴性菌均有较强的抗菌作用。头孢曲松(CRO)属第三代β-内酰胺类广谱抗生素,对敏感致病菌导致的疾病及手术后期感染预防有一定作用。人血清白蛋白(HSA)作为生物体内循环系统中含量最丰富的蛋白质,可以与多种内源性和外源性化合物可逆性结合,起到储存和转运的作用。因此,研究CFZ和CRO与HSA的相互作用对了解CFZ和CRO的药代动力学行为具有重要意义。在模拟生理条件下,采用多种光谱法和分子对接技术研究CFZ和CRO与HSA的相互作用。结果表明,在298和310 K条件下,CFZ和CRO与HSA分别形成复合物导致内源荧光猝灭,猝灭机制均为静态猝灭。在消除内滤光影响下,HSA-CFZ和HSA-CRO体系的猝灭常数(K_SV)和结合常数(K_a)均随着温度的升高而降低,结合位点数约为1。根据Fster能量转移定律,CFZ和CRO与HSA结合距离分别为2.41和1.40 nm。希尔系数(n_H)值小于1,表明CFZ和CRO分别与HSA结合后存在药物间负协同作用。热力学参数(ΔH_HSA-CFZ=-22.67 kJ·mol-1, ΔH_HSA-CRO=-39.56 kJ·mol-1, ΔS_HSA-CFZ=-4.90 J·mol-1·K-1, ΔS_HSA-CRO=-37.28 J·mol-1·K-1) 揭示,CFZ和CRO能自发地通过氢键和范德华力与HSA相结合。三维荧光光谱和圆二色谱法(CD)显示CFZ和CRO使HSA的微环境和构象发生改变。分子对接技术显示CFZ和CRO均结合在HSA的site Ⅰ结合位点上,与取代实验结果一致。本研究有助于了解CFZ和CRO在机体内的作用机制及对HSA结构和功能的影响。     

Binding studies of costunolide and dehydrocostuslactone with HSA by spectroscopy and atomic force microscopy

Human serum albumin (HSA), a major plasma protein and plasma-derived therapeutic, interacts with a wide variety of drugs and native plasma metabolites. In this study the interactions of costunolide (CE) and dehydrocostuslactone (DE) with HSA were investigated by molecule modeling, atomic force microscopy (AFM), and different optical techniques. In the mechanism discussion, it was proved that fluorescence quenching of HSA by both of the drugs is a result of the formation of drug-HSA complexes. Binding parameters for the reactions were determined according to the Stern-Volmer equation and static quenching. The results of thermodynamic parameters ΔG⁰, ΔH⁰, and ΔS⁰ at different temperatures indicated that hydrogen bonding interactions play a major role in the drug-HSA associations process. The binding properties were further studied by quantitative analysis of CD, FTIR, and Raman spectra. Furthermore, AFM results showed that the dimension of HSA molecules became more swollen after binding with the drugs.     

多西环素与人血清白蛋白相互作用的研究

将经典光谱法与内滤光校正、取代实验和分子对接等技术相结合,较全面地研究了多西环素(DC)与人血清白蛋白(HSA)之间的相互作用。通过荧光猝灭实验测得在298和310 K时,DC与HSA的结合常数分别为2.73×105和0.74×105 L·mol-1,二者有一个结合位点,表明DC与HSA间具有较强的结合作用,属于静态猝灭。根据Vant’Hoff公式计算的热力学参数(ΔH=-83.55 kJ·mol-1,ΔS=-176.31 J·mol-1·K-1)表明,两者间主要作用力为氢键和范德华力。根据Fster能量转移定律求得DC与HSA的Trp-214之间的结合距离为4.98 nm。取代反应结果表明,DC键合在HSA的亚域IIA内。三维荧光光谱结果显示,DC使HSA疏水性增加,改变了HSA的构象。DC与HSA作用前后红外光谱二级结构的定量分析结果表明,DC能使HSA结构松散。分子对接技术进一步表明DC通过氢键和范德华力等键合在HSA的亚域IIA疏水腔中,结合距离与光谱法计算结果相近。实验结果为研究药物小分子与人血清白蛋白的相互作用提供了理论依据和可靠数据。     

4-硫-5-碘尿苷的合成及其与人血清白蛋白间的相互作用

基于硫碱基(thio-base)的易烷基化、易氧化、强紫外长波(UVA)吸收等独特的性质,以及核苷类化合物的抗肿瘤活性,设计合成了一种新化合物4-硫-5-碘尿苷,通过NMR、IR、UV、MS对其结构进行了表征。在模拟生理条件下,利用荧光光谱法、紫外-可见吸收光谱法以及圆二色谱法研究了4-硫-5-碘尿苷与人血清白蛋白(HSA)的相互作用。结果表明,4-硫-5-碘尿苷对HSA荧光具有静态猝灭作用。运用Stern-Volmer方程计算了体系的猝灭常数,利用Lineweaver-Burk方程计算了二者的结合常数,并且确定了4-硫-5-碘尿苷与HSA之间的主要作用力类型为疏水作用力,根据能量转移理论求得4-硫-5-碘尿苷与HSA的结合距离及能量转移率。此外,通过圆二色谱法考察了4-硫-5-碘尿苷对HSA作用前后的构型结构的影响。     

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.     

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。     

Interaction of Sulfadiazine with Model Water Soluble Proteins: A Combined Fluorescence Spectroscopic and Molecular Modeling Approach

The binding behavior of antibacterial drug sulfadiazine (SDZ) with water soluble globular proteins like bovine as well as human serum albumin (BSA and HSA, respectively) and lysozyme (LYS) was monitored by fluorescence titration and molecular docking calculations. The experimental data reveal that the quenching of the intrinsic protein fluorescence in presence of SDZ is due to the strong interaction in the drug binding site of the respective proteins. The Stern-Volmer plot shows positive deviation at higher quencher concentration for all the proteins and was explained in terms of a sphere of action model. The calculated fluorophore-quencher distances vary within 4?~?11 Å in different cases. Fluorescence experiments at different temperature indicate thermodynamically favorable binding of SDZ with the proteins with apparently strong association constant (~10⁴–10⁵ M^?1) and negative free energy of interaction within the range of ?26.0?~??36.8 kJ mol^?1. The experimental findings are in good agreement with the respective parameters obtained from best energy ranked molecular docking calculation results of SDZ with all the three proteins.     

Binding of Puerarin to Human Serum Albumin: A Spectroscopic Analysis and Molecular Docking

Puerarin is a widely used compound in Chinese traditional medicine and exhibits many pharmacological activities. Binding of puerarin to human serum albumin (HSA) was investigated by ultraviolet absorbance, fluorescence, circular dichroism and molecular docking. Puerarin caused a static quenching of intrinsic fluorescence of HSA, the quenching data was analyzed by Stern–Volmer equation. There was one primary puerarin binding site on HSA with a binding constant of 4.12 × 10⁴ M⁻¹ at 298 K. Thermodynamic analysis by Van Hoff equation found enthalpy change () and entropy change () were −28.01 kJ/mol and −5.63 J/mol K respectively, which indicated the hydrogen bond and Van der waas interaction were the predominant forces in the binding process. Competitive experiments showed a displacement of warfarin by puerarin, which revealed that the binding site was located at the drug site I. Puerarin was about 2.22 nm far from the tryptophan according to the observed fluorescence resonance energy transfer between HSA and puerarin. Molecular docking suggested the hydrophobic residues such as tyrosine (Tyr) 150, Tyr 148, Tyr 149 and polar residues such as lysine (Lys) 199, Lys 195, arginine 257 and histidine 242 played an important role in the binding reaction.     

光谱法研究碳量子点与人血清白蛋白的相互作用

近年来,纳米材料对环境和人类健康的潜在风险已经引起了人们的广泛关注。纳米颗粒尺寸小、反应活性高,当其进入机体后很可能与体内的生物大分子相互作用,使其原来的理化性质发生改变,更容易被细胞识别、吞噬,进而对组织、器官等产生危害;作用过程中生物大分子也会受到纳米颗粒的影响,可能导致其生理结构受到损伤,并干扰其特定功能的正常执行;因此研究纳米材料与蛋白质的相互作用对探究其生物安全性具有重要意义。实验通过多种光谱手段研究了碳量子点（CQDs）对人血清白蛋白（HSA）结构与功能性质的影响以及两者的相互作用机制。荧光光谱与紫外-可见吸收光谱结果显示,CQDs通过与HSA结合形成复合物导致蛋白质荧光猝灭;结合常数K_A与结合位点数n的计算结果表明CQDs在HSA上只有一个结合位点,且同步荧光和位点竞争实验发现,这个结合位点接近HSA中ⅡA亚结构域上的色氨酸残基;根据Förster共振能量转移(FRET)理论计算出两者的作用距离r=2.89 nm<8 nm,表明HSA与CQDs之间通过非辐射能量转移导致蛋白质内源性荧光猝灭;根据Van’t Hoff方程计算得到HSA-CQDs体系的热力学参数,由热力学参数计算结果推断相互作用过程中主要有氢键和范德华力参与;根据共振光散射（RLS）、三维荧光光谱和圆二色光谱（CD）结果显示,相互作用会导致HSA的二级、三级结构发生改变,蛋白质中α-螺旋结构含量增加,HSA进一步卷曲折叠,使色氨酸残基所处微环境的疏水性增大;而结构变化还进一步影响着蛋白质的聚集状态和一些生理功能,使得相互作用后HSA的聚集程度和类酯酶活性降低,不利于蛋白质的团聚,自由基清除能力略有提高。该研究可为纳米材料的生物与环境安全评价提供参考依据,也为探究纳米颗粒-蛋白质相互作用提供了一套较为系统的光谱分析方法。     

多光谱法和分子模拟技术研究氟罗沙星与人血清白蛋白的相互作用

氟罗沙星(FLRX) 是一种含氟喹诺酮类抗菌素,有关它对人血清白蛋白(HSA)的影响及作用机理,特别是对HSA二级结构的影响及内滤光(影响荧光数据的准确性)校正的研究报道较少。采用多光谱法和分子模拟技术探究了FLRX 与HSA的相互作用。荧光光谱结果表明,FLRX对HSA的猝灭是由于形成结合常数在105 L·mol-1水平上的1∶1 FLRX-HSA基态复合物引起的静态猝灭作用。由Van’t Hoff方程确定的FLRX与HSA结合过程中的ΔH=-107.99 kJ·mol-1和ΔS=-240.99 J·mol-1·K-1,表明FLRX与HSA之间的主要作用力是氢键和范德华力。同步荧光光谱、红外光谱和三维荧光光谱结果表明,静态猝灭过程所产生的中间复合物使HSA的构象发生改变。通过对HSA与FLRX作用前后红外光谱酰胺Ⅰ带进行傅里叶去卷积和分峰拟合,获得代表HSA二级结构的不同子峰,对各子峰进行二级结构归属,根据各子峰的积分面积计算出各二级结构的相对百分含量。结果表明：FLRX与HSA结合后,α-螺旋从51.5%减小到33.2%,β-折叠从30.3%减小到20.7%,β-转角从15.6%增加到33.6%。取代实验显示FLRX与HSA的结合位点在HSA的site Ⅰ(亚域ⅡA)。分子对接实验结果表明,FLRX可以通过氢键、疏水作用和范德华力等多种作用力很好的结合在亚域ⅡA的疏水腔中。实验获得的可信数据将有助于阐明FLRX与HSA的作用机制,也有助于理解FLRX在储运过程中对蛋白质功能的影响。     

双酚A与人血清白蛋白作用特征的热力学研究

利用荧光光谱和吸收光谱法研究了双酚A与人血清白蛋白结合反应的特征,实验结果表明,双酚A对人血白蛋白有较强的荧光猝灭作用,根据荧光猝灭数据和非辐射能量转移机理,由StermVolmer和Lineweaver-Burk方程处理实验数据,得到了结合反应的结合常数、结合位置和结合过程的基本热力学参数.