诺氟沙星与环糊精的超分子体系

研究了诺氟沙星与β-环糊精(简称β-CD)及其两种衍生物羟丙基-β-环糊精(简称Hp-β-CD)、甲基-β-环糊精(简称Me-β-CD)形成的超分子体系.利用荧光光谱法测定了超分子体系的包结常数和包结比,及其热力学参数.诺氟沙星与3种环糊精均形成1∶1稳定的包合物,诺氟沙星与β-CD、Me-β-CD及Hp-β-CD作用...     

茜草色素蒽棕与DNA的相互作用机理研究

在pH为7.41的生理条件下,以溴化乙锭(EB)作为荧光探针,通过紫外可见光谱法(UV-Vis)和荧光光谱法对茜草色素类食用色素蒽棕(Ant)与鲱鱼精脱氧核糖核酸(DNA)分子之间的相互作用机理做了初步探讨。通过循环伏安法研究蒽棕在玻碳电极上的电化学规律,根据蒽棕与DNA作用的循环伏安曲线及EB对Ant与DNA作用的影响,推断Ant与DNA相互作用的主要方式为嵌插。结果显示:蒽棕与DNA分子之间相互作用的结合比为n(Ant):n(DNA)=3.68:1,25℃时的结合常数K=2.084×103L/mol,Ant-DNA复合物的表观摩尔吸光系数ε=2.21×104L·mol-1·cm-1。探讨了盐效应对蒽棕与DNA分子相互作用的影响以及它们之间的作用方式,发现蒽棕电化学变化规律同EB相似,这些实验结果证明茜草类食用色素中的蒽棕能够与DNA分子发生相互作用,相互作用方式存在嵌插。     

甲基百里酚蓝-铜（Ⅱ）络合物与白蛋白的相互作用

在模拟动物体生理条件下,采用荧光光谱、紫外-可见光谱法研究了甲基百里酚蓝-铜(Ⅱ)络合物与牛血清白蛋白(BSA)的相互作用.实验表明,MTB-Cu(Ⅱ)络合物与BSA之间为一形成复合物的静态猝灭过程.根据Stern-Volmer方程和Lineweaver-Burk方程求出了其结合常数(295K:3.449×105L·mol-1;310K:2.792×105L·mol-1)和热力学参数(△H=-10.71kJ·mol-1;△S=69.69J·K-1/69.71J·K-1;△G=-31.27kJ·mol-1/-32.32kJ·mol-1).证明二者主要以静电力作用,该过程是一个熵增加、Gibbs自由能降低的自发超分子过程.依据Foerster理论求出了结合距离r=2.25nm,阐明了猝灭机制是通过能量转移产生的.     

荧光法研究四(对甲氧基苯基)钴卟啉与牛血清白蛋白的相互作用

合成了四(对甲氧基苯基)钴卟啉,利用荧光光谱法研究了四(对甲氧基苯基)钴卟啉与牛血清白蛋白的相互作用,由实验数据计算求得该卟啉与牛血清白蛋白的双分子猝灭过程速率常数Kq=9.619×1012L·mol-1.s-1、结合常数KA=3.475×103L·mol-1、结合数n=0.6893,结果表明:四(对甲氧基苯基)钴卟啉与牛血清白蛋白之间发生了较强的静态荧光猝灭作用。     

一种分子内电荷转移荧光探针与牛血清白蛋白相互作用的研究

应用荧光光谱法研究了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(KDTN)与牛血清白蛋白(BSA)的相互作用。研究表明,KDTN能与牛血清白蛋白形成稳定的络合物从而猝灭BSA的荧光,疏水作用是结合反应的主要作用力,二者的结合常数为3.2742×104L.mol-1,结合位点数n=0.9389(30℃时)。同时考察了KDTN的加入对BSA构象的影响。     

诺氟沙星与卵清蛋白相互作用的研究

应用荧光光谱法和紫外光谱法研究了诺氟沙星(NRF)与卵清蛋白(OVA)的相互作用,计算了诺氟沙星与卵清蛋白之间的结合常数和结合位点数.实验发现卵清蛋白的最大发射峰位于338 nm,当向该溶液中滴加诺氟沙星时,该发射峰强度明显减弱,且向长波长方向稍有移动.实验表明:随着温度升高,卵清蛋白的猝灭曲线斜率降低,证实了诺氟沙星与卵清蛋白的相互作用为单一的静态猝灭过程,同时随着溶液pH值的增大,诺氟沙星对卵清蛋白的猝灭程度逐渐降低.根据热力学参数确定了诺氟沙星与卵清蛋白之间主要以静电作用力相结合.最后利用紫外光谱法证明了诺氟沙星对卵清蛋白构象产生了影响.     

靶向分子羧甲基多糖与DNA作用机理研究

以溴化乙锭(EB)为荧光探针, 结合紫外光谱法研究了壳聚糖、羧甲基壳聚糖、羧甲基纤维素与DNA的相互作用, 药物分子与DNA作用程度可用作用常数D来表示, 实验表明: 几种生物多糖与DNA分子的作用强弱顺序为: 壳聚糖＞羧甲基壳聚糖＞羧甲基纤维素;多糖主要以嵌插方式与DNA作用, 使EB-DNA荧光猝灭.     

光谱法研究3H-吲哚季铵盐探针分子与牛血清底的相互作用

合成了一种新型的荧光探针分子2-(对-十二烷基氨基)苯基-3, 3-二甲基-5-乙酯基-3H-吲哚基-甲基-二-十六烷基碘化铵, 并运用荧光光谱探讨它与牛血清蛋白的作用. 结果表明, 探针分子与牛血清蛋白(BSA)的结合作用可使3H-吲哚的荧光强度增强, 而对蛋白质却具有猝灭性质, 其结合常数和结合位点数分别为Ka=1.995×105 dm3*mol-1和n=1.12.     

含喹啉基团的杯芳烃衍生物的合成及其Zn2+和Cu2+配合物光谱性质的研究

杯[4]芳烃下缘引入荧光基团,合成了一种具有荧光特性的新型杯[4]芳烃衍生物(25,27-二2-甲基喹啉杯[4]芳烃,简称MQBC)。通过红外光谱、元素分析、核磁共振氢谱、质谱等波谱分析确定其结构。研究了MQBC的紫外光谱和荧光光谱,并对其Zn2 和Cu2 配合物的荧光性质进行了分析。MQBC与Zn2 和Cu2 作用主要源于其杯式腔体下缘的氧原子提供孤对电子参与配位,紫外光谱实验发现MQBC与Zn2 作用后,226 nm处的吸收强度减弱,315 nm处吸收强度增强,同时测定了结合常数(K=2 064 L.mol-1)与结合比(n=1),MQBC有用于对微量Zn2 检测的前景。荧光光谱实验发现MQBC存在分子内光诱导电子转移过程(PET),导致其荧光较弱;当其与Zn2 和Cu2 生成配合物后,光诱导电子转移受阻,荧光增强。文章初步探讨了光诱导电子受阻作用机理,研究了Zn2 和Cu2 浓度对荧光强度的影响。     

荧光光谱法研究锌(Ⅱ)存在下诺氟沙星与牛血清白蛋白的结合作用

在模拟生理条件下,用荧光光谱法研究了诺氟沙星对牛血清白蛋白以及锌(Ⅱ)对诺氟沙星和牛血清白蛋白荧光光谱特性的影响。实验结果表明,诺氟沙星和锌(Ⅱ)都可以使牛血清白蛋白的荧光强度发生猝灭。根据荧光猝灭双倒数图计算诺氟沙星和牛血清白蛋白之间的结合常数为6.80×105,结合位点数为1.21。由此可见,诺氟沙星和牛血清白蛋白之间有很强的结合作用,这为诺氟沙星在体内被蛋白质储存和转运提供了条件。并且在锌(Ⅱ)存在下,诺氟沙星与牛血清白蛋白的结合作用有所增强。荧光猝灭双倒数图计算的结果表明,诺氟沙星和牛血清白蛋白之间的结合常数和结合位点数均随锌(Ⅱ)浓度的增大而增大。通过对锌(Ⅱ)、诺氟沙星和牛血清白蛋白的结合反应的研究,进一步探讨了诺氟沙星、锌(Ⅱ)在生物体内与蛋白质相互作用的机理。     

Investigation of the inclusion behavior between p-sulfoniccalix[8]arene and norfloxacin by fluorescence spectroscopy

The host-guest complexation between p-sulfoniccalix[8]arene (SC₈A) and norfloxacin (NFLX) in aqueous solution was investigated by fluorescence spectroscopy. Strong fluorescence intensity of the NFLX aqueous solution alone and obvious fluorescence quenching of NFLX solution in the presence of SC₈A were observed. The fluorescence lifetimes of NFLX and SC₈A-NFLX inclusion complex were determined and the effect of temperature on SC₈A-NFLX inclusion complex was studied. The static quenching of the inclusion was obtained, that is the SC₈A can form a nonfluorescent ground-state inclusion complex with NFLX. As the results show, the combined ratio (n) was 1:1 and association constant K was 1.17×10⁵ L/mol. Based on the experimental results, the mechanism of the inclusion complex was explored. The space matching, electrostatic force and hydrogen bond play important effects in the inclusion process. Subsequently, the addition of bovine serum albumin (BSA) solution led to the recovery of fluorescence intensity. It is indicated that BSA can liberate the NFLX into the solution by destructing the SC₈A-NFLX inclusion complex. Hence SC₈A may be used for controlled-release drug delivery in the pharmaceutical industry.     

桑色素与牛血红蛋白相互作用的光谱研究

利用紫外可见吸收光谱和荧光光谱研究了在生理pH条件下桑色素与牛血红蛋白(BHb)的相互作用。实验结果表明:桑色素分子与BHb发生反应生成基态复合物,导致BHb内源荧光的猝灭,该猝灭属于静态猝灭。测定了不同温度下该反应的表观结合常数、结合位点数及结合热力学参数,热力学参数的变化表明上述作用过程是一个熵增加、自由能降低的自发分子间作用过程,桑色素与BHb之间以疏水和静电作用力为主;根据F-rster能量转移理论,测得供体与受体间结合距离r和能量转移效率E;并用同步荧光光谱法探讨了桑色素对BHb构象的影响。     

荧光光谱法研究山梨醇与牛血清白蛋白的相互作用

采用荧光和紫外吸收光谱法,研究了利尿脱水药山梨醇(Sorbitol)与牛血清白蛋白(BSA)的相互作用。在正常生理条件下,山梨醇对牛血清白蛋白有较强的猝灭作用,根据不同的药物浓度、温度及紫外吸收光谱的变化,判断其猝灭方式可能为静态猝灭,考察了不同温度、药物浓度等多种条件下Sorbitol对BSA荧光猝灭的影响。通过Stern-Volmer方程和Lineweaver-Burk方程的简化形式,求出在不同温度下反应的结合常数KD分别为7.4×10-5(25℃)和1.7×10-4(37℃)、结合位点数n为1。根据反应热力学参数确定了它们之间相互作用的主要形式为电荷作用力。采用同步荧光考察了山梨醇对BSA构象的影响,发现随药物浓度的增大,色氨酸残基的最大发射波长不变,而酪氨酸残基所处环境的疏水性改变,从而导致BSA的构象发生了变化。     

Multiple Spectroscopic,Docking and Cytotoxic Study of a Synthesized 2,2′ Bipyridin Phenyl Isopentylglycin Pt(II) Nitrate Complex: Human Serum Albumin and Breast Cancer Cell Line of MDA-MB231 as Targets

In the present study, the biological activities of a new synthesized Pt(II)-complex, 2,2′ bipyridinphenyl isopentylglycin Pt(II) nitrate was investigated via its interaction with the most important blood carrier protein of human serum albumin (HSA), using fluorescence and Far-UV circular dichroism (CD) spectroscopic techniques and also molecular docking. Moreover, cytotoxicity activity of the complex was studied against breast cancer cell line of MDA MB231 using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The Pt(II)-complex has a strong ability to quench the intrinsic fluorescence of HSA through a static quenching mechanism. According fluorescence quenching data, the binding parameters of the interaction were calculated and showed that hydrophobic interaction has an important role. The molecular docking results in coherent with fluorescence measurements illustrated that Pt(II) complex can bind to HSA at one position that located in the hydrophobic cavity of groove between drug site I and II. Also, experimental data on driving force in binding site was confirmed whereas theoretical results demonstrated Pt(II) complexinteract to HSA by hydrophobic interaction. Far-UV-CD results showed that Pt(II)-complex induced an increasing in the content of α-helical structure of the protein and stabilized it. Also, MTT assay represented growth inhibitory effect of the complex toward the breast cancer cell line.     

左氧氟沙星与牛血清白蛋白相互作用的液滴荧光法研究

采用液滴荧光技术与紫外-可见光度法研究了生理pH值条件下左氧氟沙星和牛血清白蛋白的相互作用机制。左氧氟沙星对牛血清白蛋白产生荧光猝灭,且猝灭过程是由于复合物形成而引起的静态猝灭。根据Frster偶极-偶极非辐射能量转移理论算出供体-受体的结合距离为2.68nm。由Linewear-Burk方程求出不同温度下反应时复合物的形成常数KLB和结合位点数n及对应温度下结合反应的热力学参数,证明二者主要靠疏水作用力结合。同时采用同步荧光分析技术,对蛋白质与药物结合时构象的变化进行了探讨。     

荧光光谱法研究咖啡因与肌红蛋白的相互作用

采用荧光光谱法在生理pH 7.4条件下研究了药物咖啡因与肌红蛋白分子间的相互作用,表明这种相互作用能使肌红蛋白的内源荧光猝灭.通过猝灭常数,结合常数和结合位点数的计算,证明此猝灭为静态猝灭机制.咖啡因和肌红蛋白形成1∶1稳定配合物,形成常数(18℃)KA=1.82×104 L·mol-1;根据热力学参数确定了它们之间的主要作用力为疏水力和静电力.利用同步荧光光谱法研究了咖啡因对肌红蛋白构象的影响.咖啡因能使肌红蛋白的构象发生改变,导致蛋白质分子中色氨酸和酪氨酸残基所处微环境由原来的疏水环境不同程度地向亲水环境转变.     

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.     

Spectroscopic studies on the interaction between ZnSe nanoparticles with bovine serum albumin

The interaction between ZnSe nanoparticles (NPs) and bovine serum albumin (BSA) was studied by UV–vis, fluorescence spectroscopic techniques. The results showed that the fluorescence of BSA was strongly quenched by ZnSe NPs and the quenching mechanism was discussed to be a static quenching procedure, which was proved by quenching constant (K_q). The recorded UV–vis data and the fluorescence data quenching by the ZnSe NPs showed that the interaction between them leads to the formation of ZnSe–BSA complex. Based on the synchronous fluorescence spectra, it was established that the conformational change of BSA was induced by the interaction of ZnSe with the tyrosine micro-region of the BSA molecules. Furthermore, the temperature effects on the structural and spectroscopic properties of individual ZnSe NPs and protein and their bioconjugates (ZnSe–BSA) were also researched. It was found that, compared to the monotonic decrease of the individual ZnSe NPs fluorescence intensity, the temperature dependence of the ZnSe–BSA emission had a much more complex behavior, which was highly sensitive to the conformational changes of the protein.     

Effect of temperature and pH on interaction between bovine serum albumin and cetylpyridinium bromide: Fluorescence spectroscopic approach

The fluorescence spectroscopic technique has been efficiently employed to investigate the interaction between bovine serum albumin (BSA) and cetylpyridinium bromide (CPB) under different pH and temperature conditions. The binding constant, number of binding sites, thermodynamic parameters such as ΔG, ΔH, ΔS, and nature of binding forces between BSA and CPB were obtained by measuring the steady state fluorescence quenching of BSA by CPB. The experimental results showed that the fluorescence quenching of BSA by CPB was a result of the formation of CPB-BSA complex. The static quenching was confirmed from the Stern-Volmer quenching constant at different temperatures. The effect of CPB on the conformation of BSA was analyzed using synchronous and three-dimensional fluorescence spectroscopy. pH dependence complex formation between BSA-CPB is due to the interaction between cationic side chain of CPB and the net charge developed on BSA. The distance ‘r’ between BSA and CPB was obtained according to the fluorescence resonance energy transfer.