盐酸胺碘酮的电化学测定及与牛血清白蛋白的相互作用

建立了测定盐酸胺碘酮(Am)的新的电化学分析方法。采用电化学方法结合紫外、红外光谱分析,研究了Am与牛血清白蛋白(BSA)的相互作用。实验发现,在pH=5.0的B-R缓冲溶液中,Am在0.87V处有一灵敏的氧化峰,其氧化峰电流Ipa与Am的浓度在1.8×10-7～6.7×10-5 mol/L范围呈良好的线性关系,检出限(S/N=3)为6.0×10-8 mol/L。当BSA加入Am溶液后,Am的氧化峰电流降低,其氧化峰电流的降低值△Ipa与BSA的浓度在2.4×10-7～2.2×10-5 mol/L范围内呈良好线性关系,BSA的检出限(S/N=3)为9.0×10–8 mol/L。电化学研究表明,Am与BSA之间形成1∶1的结合物,结合常数为9.9×106 L/mol。紫外光谱表明Am的加入使BSA的吸收峰发生红移且有增色效应。傅立叶红外光谱表明Am与BSA分子中氨基酸残基的硫及氮原子形成键合作用。     

阿替洛尔的电化学行为及与牛血清白蛋白的相互作用

建立了石墨烯修饰玻碳电极测定阿替洛尔的电化学分析新方法。采用电化学方法结合紫外、荧光光谱分析,研究了阿替洛尔(ATN)与牛血清白蛋白(BSA)的相互作用。实验发现,在pH 10.0的Na2CO3-NaHCO3缓冲溶液中,ATN在0.78 V处有一灵敏的氧化峰,氧化峰电流Ip与ATN的浓度在4.8～30.0μmol/L范围内呈良好的线性关系(r=0.9926,n=11),方法检出限为3μmol/L。当BSA加入ATN溶液后,ATN氧化峰电流降低,氧化峰电流的降低值ΔIp与BSA的浓度在2.6～31.0μmol/L范围内呈良好线性关系。紫外光谱表明ATN的加入使BSA的吸收峰发生蓝移。荧光光谱表明,ATN对BSA的内源荧光有显著的猝灭作用,猝灭机制为静态猝灭。     

阿托伐他汀钙与牛血清白蛋白的相互作用

采用电化学方法并结合紫外、红外光谱分析, 研究了近生理pH 实验条件下新型抗血脂紊乱药物阿托伐他汀钙(AC)与牛血清白蛋白(BSA)的相互作用, 探讨了BSA对AC峰电流的增敏和减敏效应. 实验发现, 在pH为7.17的NaH₂PO₄-Na₂HPO₄缓冲溶液中, AC在静汞电极上产生一个还原峰, 加入BSA后峰电位发生移动且峰电流发生变化. 电化学研究结果表明, 部分疏水性AC小分子的芳香基团通过疏水作用镶嵌到BSA疏水微区内部, 使AC与BSA之间通过疏水作用力形成一种1:1的结合物, 结合常数为1.67×10⁵. 紫外吸收光谱结果表明,AC的加入使BSA的紫外吸收峰发生红移且有减色效应, 导致BSA 构象改变、α-螺旋含量减小. 红外光谱结果显示, AC与BSA分子中氨基酸残基的硫及氮原子形成键合作用.     

甲氨蝶呤与牛血清白蛋白相互作用的光谱和分子对接研究

利用紫外-可见吸收光谱法、傅立叶红外光谱法和分子对接技术研究了抗癌药物甲氨蝶呤与牛血清白蛋白的相互作用。紫外光谱发现,在298 K和308 K,甲氨蝶呤与牛血清白蛋白结合常数分别为5.28×105L/mol和6.14×105L/mol,通过热力学计算得到反应的焓变和熵变。热力学函数说明甲氨蝶呤与牛血清白蛋白之间的作用力主要为疏水作用力。红外光谱表明甲氨蝶呤与牛血清白蛋白分子中氨基酸残基的硫及氮原子形成键合作用。结合AutoDock 4.2分子对接软件模拟研究了二者的键合模式和键合机制,表明甲氨蝶呤与牛血清白蛋白的相互作用力主要是疏水作用。     

异烟肼与牛血清白蛋白相互作用的光谱和电化学研究

本文用自制L-天冬氨酸修饰电极(PLA/GCE),采用循环伏安法研究了牛血清白蛋白(BSA)与异烟肼(INH)的相互作用,并与荧光光谱法、紫外-可见光谱法进行了比较。使用循环伏安法和荧光光谱法,测得异烟肼与牛血清白蛋白的结合常数K分别为1.544×10~4、1.479×10~4 L/mol,结合位点数均接近1.1。实验测得异烟肼对牛血清白蛋白是静态猝灭。异烟肼的浓度与牛血清白蛋白的荧光强度的降低在2.5×10~(-7)~4.5×10~(-4) mol/L范围内呈线性关系,检出限为1.0×10~(-7) mol/L。BSA的浓度与异烟肼的氧化峰电流的下降在1.0×10~(-9)~5.0×10~(-5) mol/L范围内呈线性关系,检出限为5.0×10~(-10) mol/L。该方法可用于样品中异烟肼和牛血清白蛋白的测定。     

秋水仙碱与牛血清白蛋白相互作用的电化学研究

以电化学方法对秋水仙碱与牛血清白蛋白的相互作用进行了研究。在0.3 mol/L H2SO4底液中,秋水仙碱在玻碳电极上产生一不可逆的氧化峰,峰电位为1.18 V(vs.SCE),加入表面活性剂四丁基氯化铵后,秋水仙碱的峰信号得到明显提高。在上述条件下,加入BSA后秋水仙碱的氧化峰电位正移,峰电流下降,峰电流下降值与BSA加入的浓度在1.5×10-7～2×10-6mol/L(r=0.9978)范围内有良好的线性关系,检出限达4.0×10-8mol/L。进一步探讨了秋水仙碱与BSA的结合数和结合常数,得到结合数为1,结合常数为2.40×105L/mol。     

Fe3+存在下磺胺甲恶唑与牛血清白蛋白相互作用的光谱学研究

在模拟生理条件下,应用荧光光谱、紫外吸收光谱以及傅立叶变换红外光谱研究Fe3+存在下磺胺甲恶唑(Sulfamethoxazole,SMZ)与牛血清白蛋(Bovine Serum Albumin,BSA)的相互作用.结果表明,Fe3+存在时SMZ与BSA结合常数增大,作用力类型由疏水作用力转变为氢键和范德华力.无论Fe3...     

壳聚糖镍与牛血清白蛋白相互作用的研究

采用紫外吸收、荧光和红外光谱,研究了壳聚糖镍与牛血清白蛋白(BSA)的相互作用。结果表明:随着壳聚糖镍浓度的增加,BSA的紫外光谱表现增色效应和较小的蓝移;壳聚糖镍可以猝灭BSA的内源荧光,其猝灭机理属于静态猝灭。在室温下,壳聚糖镍与BSA的的结合常数KA为7.08×106。     

肼黄与牛血清白蛋白相互作用的光谱研究

本文用荧光光谱法和紫外-可见吸收光谱法研究了肼黄与牛血清白蛋白(BSA)结合反应的光谱行为,发现肼黄因对BSA有较强的荧光猝灭作用,且肼黄的紫外吸收光谱和BSA的荧光发射光谱有一定程度的重叠,据此得出了其结合反应的结合常数、结合位点数和基本热力学参数等,并研究了二者的相互作用机理。     

Spectroscopic investigation of interaction between mangiferin and bovine serum albumin

The mechanism of interaction between mangiferin (MA) and bovine serum albumin (BSA) in aqueous solution was investigated by fluorescence spectra, synchronous fluorescence spectra, absorbance spectra and Fourier transform infrared (FT-IR) spectroscopy. The binding constants and binding sites of MA to BSA at different reaction times were calculated. And the distance between MA and BSA was estimated to be 5.20 nm based on Föster's theory. In addition, synchronous fluorescence and FT-IR measurements revealed that the secondary structures of the protein changed after the interaction of MA with BSA. As a conclusion, the interaction between the anti-diabetes Chinese medicine MA and BSA may provide some significant information for the mechanism of the traditional chinese medicine MA on the protein level to cure diabetes or other diseases.     

Fluorometric investigation on the interaction of oleanolic acid with bovine serum albumin

The interactions between oleanolic acid and bovine serum albumin (BSA) have been studied by fluorescence, circular dichroism (CD), UV–vis absorption and Fourier transform infrared spectroscopy (FTIR) under physiological conditions. Spectroscopic analysis of the emission quenching at different temperatures has revealed that the quenching mechanism of bovine serum albumin by oleanolic acid is static quenching mechanism. The binding sites number n and binding constants K are obtained at various temperatures. The distance r between oleanolic acid and the protein is evaluated according to the theory of Forster energy transfer. The results by FTIR, CD and UV–vis absorption spectra experiment indicate that the secondary structures of protein have been perturbed in the presence of oleanolic acid. The thermodynamic parameters ΔH⁰, ΔG⁰, and ΔS⁰ are calculated according to van’t Hoff equation, which indicates that the hydrogen bonds and van der-waals are the intermolecular forces stabilizing the complex. Molecular modeling studies the interaction BSA with oleanolic acid.     

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.     

荧光光谱法研究4-硝基苯胺与牛血清白蛋白的相互作用

在模拟动物生理条件下利用荧光光谱法从分子水平上研究了4-硝基苯胺同牛血清白蛋白(BSA)的相互作用.4-硝基苯胺对BSA的荧光有较强猝灭作用.用Stern-Volmer方程和双对数方程分别处理实验数据发现BSA与4-硝基苯胺发生反应生成了新的复合物,猝灭机理以静态碎灭为主.根据双对数方程求出了不同温度下反应时复合物的形...     

光谱法研究染料木素与牛血清白蛋白的相互作用

采用荧光和紫外-可见吸收光谱,研究了染料木素与牛血清白蛋白(BSA)的相互作用.结果表明染料木素对BSA有较强的荧光猝灭作用;根据Stern-Volmer方程得到染料木素与BSA之间的结合常数KA为4.37×106(27 ℃)、6.45×10b(37℃)和6.76×106(47℃).根据Forster非辐射能量转移理论,求出了染料木素与BSA之间的结合距离为2.64 nm(27℃)、2.68mm(37℃)和2.71 nm(47℃).热力学数据表明该药物与牛血清白蛋白的相互作用是一个吉布斯自由能降低的自发过程,且二者之间的主要作用力类型为静电引力,同时用同步荧光光谱探讨了染料木素对BSA构象的影响.     

Electrochemical and Spectroscopic Studies on the Interaction of Gallocyanine with DNA

The interaction of gallocyanine (GC) with double‐stranded DNA (dsDNA) in pH 3.5 Tris‐HCl buffer solution was investigated by electrochemical methods and spectrophotometric methods as well. In the potential scan range of ‐0.25 ? +0.18 V(vs. SCE), GC had a couple of well‐defined redox peaks at ‐0.022 V and ‐0.069 V on a cyclic voltammogram at the scan rate of 100.0 mV/s, respectively. After the addition of dsDNA into the GC solution, the redox‐peak currents decreased obviously and the peak potentials shifted positively. The results demonstrated that GC binding to DNA was caused by intercalation. Electrochemical parameters such as the electron number (n), the charge transfer coefficient (α) and the electrochemical reaction standard rate constant (k_s) were calculated and compared in the absence and presence of dsDNA. Almost unchanged values of the electrochemical parameters after adding dsDNA showed that non‐electroactive complexes were formed when GC interacted with DNA. The results indicated that the decrease of the redox‐peak currents was caused by the decrease of the free concentration of GC in the reaction solution. The binding constant and binding ratio were investigated by spectrophotometric methods. DNA concentration can be determined by the decrease of the peak current of GC. The linear range for dsDNA was in the range of 1.45 × 10^?7 ? 1.45 × 10^?6mol/Land 1.45 × 10^?6 ? 1.45 × 10^?5 mol/L, respectively with the linear regression equation as Δi_P (10^?7 A) = 0.037 + 0.018C (10^?7mol/L), and Δi_P (10^?7 A) = 0.25 + 0.041C (10^?6mol/L), respectively, and the detection limit (3σ) was 1.13 × 10^?7 mol/L.     

荧光光谱法研究辛硫磷与牛血清白蛋白的相互作用

用荧光光谱法研究了在生理pH条件下杀虫剂辛硫磷与牛血清白蛋白(BSA)的相互作用. 结果表明: 辛硫磷对BSA的荧光有较强的猝灭作用, 该猝灭属于静态猝灭. 根据猝灭结果求得了不同温度下辛硫磷与牛血清白蛋白结合作用的结合位点数、结合常数及反应热力学参数, 并据此确定它们之间主要的相互作用力为疏水作用力. 用同步荧光光谱法探讨了辛硫磷对BSA构象的影响.     

Effect of acetonitrile on the hydration of human serum albumin films: a calorimetric and spectroscopic study

A new experimental approach based on the combination of calorimetric and FTIR spectroscopic measurements was proposed to study simultaneously the sorption of water and organic solvent, and corresponding changes in the structure of protein films in the water activity range from 0 to 1.0. Enthalpy changes (ΔH_tot) on the interaction of water with the dried human serum albumin (HSA) in the presence and absence of acetonitrile (AN) have been measured using a Setaram BT-2.15 calorimeter at 298 K. Spectroscopic data on water and organic solvent vapor sorption by the HSA films and the corresponding changes in the protein secondary structure were determined by means of a Bruker Vector-22 FTIR spectrometer. By using a water activity-based comparison we characterised the effect of acetonitrile on the hydration and structure of the HSA films. Acetonitrile (AN) sorption isotherm resembles a smooth curve. HSA film binds about 250 mol AN/mol protein at the lowest water activities. As the water activity increases from 0 to 0.8, the sorption of AN gradually decreases from 250 to 150 mol AN/mol HSA. At a_w > 0.8, the sorption of AN sharply decreases to zero. Acetonitrile decreases markedly the water content at a given a_w. This behavior suggests that the suppression in the uptake of water is due to a competition for water-binding sites on the HSA films by acetonitrile. Changes in the secondary structure of HSA were determined from infrared spectra by analyzing the structure of amide I band. Acetonitrile increases the intensity of the 1654 cm⁻¹ band that was assigned to the α-helix structure. Changes in the intensity of the 1654 cm⁻¹ band agree well with the decrease in water uptake in the presence of AN. An explanation of the acetonitrile effect on the hydration and structure of the HSA films was provided on the basis of hypothesis on water-assisted disruption of polar contacts in the initially dried protein.     

Electrochemical Reduction of Nitrobenzene in Ionic Liquid BMImAc

Ionic liquid,1-butyl-3-methylimidazolium acetate（BMImAc）,was used in the electrochemical reduction of nitrobenzene.The electro-reduction of nitrobenzene on platinum electrode was studied by cyclic voltammetry（CV）,in situ Fourier transform infrared（FTIR） spectroscopy and constant-potential electrolysis.The experimental results show that electrochemical reduction process of nitrobenzene was controlled by diffusion,the main reduction product was azobenzen at-1.45 V,and the influences of scan rate and temperature on the electrochemical behaviors were obviously.A reduction mechanism of nitrobenzene in an ionic liquid was a probable ‘nitrobenzene→nitrosobenzene→azobenzene→aniline＇ main reductive reaction route.     

Microcalorimetric studies on the interactions of lanthanide ions with bovine serum albumin

The interactions of lanthanide ions (Ln³⁺) with bovine serum albumin (BSA) under mimetic physiological conditions (310.15 K, pH 6.7, 0.1MNaCl) were studied by microcalorimetry. For the first time, based on Two Sets of Independent Sites Model, molar enthalpies (Δ_r H _m1, Δ_r H _m2) and coordination number (n ₁, n ₂) of the two sets of binding sites with different affinity were obtained directly from the microcalorimetric results. It was shown that the interactions are endothermic and entropy-driving processes. By combining with fluorescence spectroscopy, other thermodynamic parameters (Δ_r G _m1, Δ_r S _m1) were determined for high-affinity specific sites.