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.     

6-苄氨基嘌呤与牛血清白蛋白作用荧光特性的研究

应用荧光光谱法研究了6-苄氨基嘌呤（6-BA）与牛血清白蛋白（BSA）相互作用的荧光特性。测得了6-BA与BSA在10、27、40℃温度下的结合常数KA为：0.21×10^5、1.37×10^5、5.53×10^5L/mol,结合位点数n为：1.0、1.2、1.3。6-BA对BSA内源荧光的猝灭机理主要为静态猝灭,6-BA主要以疏水作用与BSA相互作用,BSA的荧光主要源于色氨酸残基,6-BA对BSA的构象有影响。     

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.     

Studies of interaction between colchicine and bovine serum albumin by fluorescence quenching method

We investigated the interaction between colchicine and bovine serum albumin (BSA) by fluorescence and UV–Vis absorption spectroscopy. In the mechanism discussion, it was proved that the fluorescence quenching of BSA by colchicine is a result of the formation of colchicine–BSA complex; van der Waals interactions and hydrogen bonds play a major role in stabilizing the complex. The modified Stern–Volmer quenching constant K_a and corresponding thermodynamic parameters ΔH, ΔG, ΔS at different temperatures were calculated. The distance r between donor (BSA) and acceptor (colchicine) was obtained according to fluorescence resonance energy transfer (FRET).     

金丝桃苷与牛血清白蛋白相互作用的研究

采用荧光共振能量转移法研究了金丝桃苷与牛血清白蛋白的相互作用.金丝桃苷对牛血清白蛋白(BSA)的荧光猝灭类型是静态猝灭,25℃时的结合位点数为0.5451.并依据F(o)ster非辐射能量转移理论,研究了给体(牛血清白蛋白)--受体(金丝桃苷)间的结合距离R.和能量转移效率E分别为2.04nm和0.66.同时,采用同步...     

Study on the interaction between antibacterial drug and bovine serum albumin: A spectroscopic approach

The binding of sulfamethoxazole (SMZ) to bovine serum albumin (BSA) was investigated by spectroscopic methods viz., fluorescence, FT-IR and UV–vis absorption techniques. The binding parameters have been evaluated by fluorescence quenching method. The thermodynamic parameters, ΔH°, ΔS°and ΔG° were observed to be −58.0 kJ mol⁻¹, −111 J K⁻¹ mol⁻¹ and −24 kJ mol⁻¹, respectively. These indicated that the hydrogen bonding and weak van der Waals forces played a major role in the interaction. Based on the Forster's theory of non-radiation energy transfer, the binding average distance, r, between the donor (BSA) and acceptor (SMZ) was evaluated and found to be 4.12 nm. Spectral results showed the binding of SMZ to BSA induced conformational changes in BSA. The effect of common ions and some of the polymers used in drug delivery for control release was also tested on the binding of SMZ to BSA. The effect of common ions revealed that there is adverse effect on the binding of SMZ to BSA.     

卡络磺钠与牛血清蛋白荧光光谱的研究

采用荧光光谱法研究了卡络磺钠CSS (Carbazochrome Sodium Sulfonate)与牛血清蛋白(BSA)结合反应的特征, 测定了结合常数(K=1.32×105 L/mol) 和结合位点数(n=1.28). 依据Foster非辐射能量转移理论, 确定了给体-受体间的结合距离(r=4.896 nm)和能量转移效率, 采用同步荧光技术考察了CSS对BSA构象的影响.     

Binding of the bioactive component isothipendyl hydrochloride with bovine serum albumin

The binding of isothipendyl hydrochloride (IPH) to bovine serum albumin (BSA) was investigated by fluorescence spectroscopy combined with UV-visible absorption and circular dichroism (CD) techniques under simulative physiological conditions for the first time. The quenching mechanism of fluorescence BSA by IPH was discussed. The binding parameters have been evaluated by fluorescence quenching method. The thermodynamic parameters, ΔH°, ΔS° and ΔG° calculated at different temperatures indicated that the hydrophobic force played a major role in the interaction of IPH to BSA. The distance, r between donor (BSA) and acceptor (IPH) was obtained according to the Förster's theory of non-radiation energy transfer and was found to be 2.21 nm. Experimental results showed that the α-helicity of BSA decreased from 66.4% (in free BSA) to 39.1% (in bound BSA). The effect of common ions on the binding constant was also investigated.     

荧光猝灭法研究胆红素与牛血清白蛋白的相互作用

在模拟生理条件下,利用荧光猝灭法研究了胆红素(BR)和牛血清白蛋白(BSA) 的相互作用.结果表明胆红素对BSA有较强的荧光猝灭作用,两者形成了新的复合物,属于静态荧光猝灭,发生了分子内的非辐射能量转移.计算了不同温度下的结合位点数n,结合常数KA,以及对应的热力学参数ΔG,ΔH和ΔS.根据Foster非辐射能量转移理论确定了胆红素和BSA间的结合距离r.此外,利用同步荧光光谱,分析了胆红素对牛血清白蛋白构象的影响.     

胡椒酸丁二醇单脂与牛血清白蛋白相互作用的研究

运用荧光及紫外-可见吸收光谱法研究了胡椒酸丁二醇单酯(简称BPM)与牛血清白蛋白(BSA)的相互作用。实验结果表明,胡椒酸丁二醇单酯与BSA形成基态复合物导致BSA内源性荧光猝灭,猝灭机理主要为静态猝灭和非辐射能量转移,其猝灭速率常数为Kq为1.077×1013L/(mol.s)(25℃)、0.946×1013L/(mol.s)(37℃)。利用荧光猝灭反应测得结合常数KA为2.6×106(25℃)、3.4×106(37℃),结合位点数n为1.30(25℃)、1.33(37℃)。根据Frster能量转移理论得到结合距离r=2.92nm(25℃)、2.66nm(37℃)和能量转移效率E=0.45(25℃)、0.43(37℃)。通过热力学参数计算,确定胡椒酸丁二醇单酯与BSA的相互作用是熵增加和吉布斯自由能降低的自发过程,主要作用力是疏水作用力。     

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.     

二氢氯噻与牛血清白蛋白的相互作用特征

利用荧光技术研究了在生理酸度条件下,二氢氯噻与牛血清白蛋白相互作用,发现二氢氯噻对牛血清白蛋白有较强的荧光猝灭作用,用Stern-Volmer和Line weaver-Burk方程处理荧光猝灭数据,得到了反应的结合常数、结合热力学性质等参数。根据热力学参数确定了该药物与血清白蛋白之间的作用力类型,在此基础上依据福斯特F rster非辐射能量转移理论探讨了二氢氯噻与BSA相互结合时其供体-受体间的距离。与人血清蛋白[1]比较,牛血清白蛋白与二氢氯噻的结合较弱,体现了二氢氯噻与血清蛋白结合的动物间的差异性。同时考察了中药活性成分和金属离子对结合的影响,结果显示甘草次酸对结合的影响较大,提示同时给药时应该注意它们之间的血清药物相互作用。     

荧光光谱法研究克仑特罗与蛋白质的结合作用

应用荧光光谱法研究了水溶液中盐酸克仑特罗与牛血清白蛋白分子间的结合反应 ,测定了结合常数 (K =2 .84× 1 0 3 L mol)和结合位点数 (n =5 .65)。依据F ster非辐射能量转移理论 ,确定了授体 受体间的结合距离 (r=1 .69nm)和能量转移效率 ,采用同步荧光技术考察了盐酸克仑特罗对牛血清白蛋白构象的影响。利用盐酸克仑特罗对蛋白质荧光猝灭 ,对作用机理做了初步探讨     

Study on the interaction between salvianic acid A sodium and bovine serum albumin by spectroscopic methods

The interaction between salvianic acid A sodium (SAS) and bovine serum albumin (BSA) was investigated using fluorescence and ultraviolet spectroscopy at different temperatures under imitated physiological conditions. The experimental results showed that the fluorescence of BSA was quenched by SAS through a static quenching procedure. The binding constants of SAS with BSA were 2.03, 1.17 and 0.71×10(5) L mol(-1) at 291, 298 and 305 K, respectively. Negative values of ΔG, ΔH, and ΔS indicate that the interaction between SAS and BSA is driven by hydrogen bonds and van der Waals forces. According to F?rster non-radiation energy transfer theory, the binding distance between BSA and SAS was calculated to be about 2.92 nm. The effect of SAS on the conformation of BSA was analyzed using synchronous fluorescence spectroscopy. In addition, the effect of some metal ions Cu(2+), Ca(2+), Mg(2+), and Zn(2+) on the binding constant between SAS and BSA was examined.     

Study on the interaction between methyl violet and bovine serum albumin by spectral analyses

In this article the interaction between methyl violet (MV) and bovine serum albumin (BSA) was studied with spectroscopy. The results indicated that the fluorescence intensity of BSA was quenched strongly by MV through a static quenching procedure. The association constants, the number of binding sites and basic thermodynamic parameters were obtained based on fluorescence quenching data. The effect of MV on the conformation of BSA had been investigated with synchronous fluorescence spectroscopy and circular dichroism (CD) spectrum.     

Spectrometric study of the interaction between Alpinetin and bovine serum albumin using chemometrics approaches

The binding interaction of Alpinetin (APT) with bovine serum albumin (BSA) was studied by fluorescence, UV-visible and synchronous fluorescence spectroscopy (SFS) under simulated physiological conditions. The measured complex spectra were resolved by multivariate curve resolution-alternating least squares (MCR-ALS), yielding a host of data and information, which otherwise would have been impossible to obtain. The extracted profiles corresponded to the spectra of the single species in the APT/BSA mixture. In addition, the presence of the APT-BSA complex was demonstrated, and it was shown that the associated quenching of the fluorescence from the BSA protein resulted from the formation of APT-BSA complex via a static mechanism. The binding constant (K_a(ave) = 2.34 × 10⁶ L mol⁻¹) and the number of sites (n = 1) were obtained by fluorescence methods as were the thermodynamic parameters (ΔH⁰, ΔS⁰ and ΔG⁰). This work suggested that the principal binding between APT to BSA was facilitated by hydrophobic interactions. The thermodynamic parameters for APT were compared to those from the structurally similar Chrysin and Wogonin molecules. It appeared that the entropy parameters were relatively more affected by the small structural changes. SFS from the interaction of BSA and APT showed that the ligand affected the conformation of BSA. The competitive interaction of APT and site makers with BSA indicated site I as the binding area of APT in BSA.     

桔皮苷与牛血清白蛋白相互作用的研究

运用荧光光谱、紫外光谱法研究了桔皮苷与牛血清白蛋白(BSA)的相互作用。桔皮苷分子与BSA作用导致BSA内源荧光猝灭,猝灭机理主要为静态猝灭,并存在非辐射能量转移。测定了不同温度下该反应的结合常数、结合位点数及结合热力学参数。结果表明:桔皮苷与BSA之间主要为氢键或范德华作用力,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;测得了供体与受体间结合距离r和能量转移效率E;并用同步荧光技术考察了桔皮苷对BSA构象的影响。     

Spectroscopic analysis of the interaction between bilirubin and bovine serum albumin

The interactions between bilirubin (BR) and bovine serum albumin (BSA) have been studied by fluorescence spectroscopy. The association constant between BR and BSA was obtained by fluorescence enhancement titration. Furthermore, fluorescence quenching was studied at different temperatures, and the binding constant was also determined by the method of fluorescence quenching. The two methods yielded similar results. It indicated that the former method could be successfully applied to the determination of BR. The results showed that the binding of BR to BSA induced conformational changes in BSA. Based on the theory of F?rster energy transfer, the distance between BR and protein were calculated. According to the thermodynamic parameters, the main binding force could be judged. The experimental results revealed that BSA and BR had strong interactions. The mechanism of quenching belonged to static quenching and the main sort of binding force was van der Waals interactions and hydrogen bonds.     

Synthesis,characterization, and thermodynamic studies of the interaction of some new water-soluble Schiff-base complexes with bovine serum albumin

Some new water-soluble Schiff-base complexes Na₂[M(5-SO₃-2,3-salpyr)(H₂O) _n ]?·?2H₂O (5-SO₃-2,3-salpyr?=?N,N′-bis(5-sulphosalicyliden)-2,3-diaminopyridine and M?=?Zn, Cu, Ni) were synthesized and characterized by elemental analysis, IR, ¹H NMR, magnetic susceptibility measurement, thermal analysis, and UV-Vis spectroscopy. The mechanism of binding of Na₂[M(5-SO₃-2,3-salpyr)(H₂O) _n ]?·?2H₂O with bovine serum albumin (BSA) was investigated by fluorescence spectroscopy. The fluorescence titration revealed that the intrinsic fluorescence of BSA was quenched by Na₂[M(5-SO₃-2,3-salpyr)], which was rationalized in terms of the static quenching mechanism. The values of the Stern–Volmer constants, quenching rate constants, binding constants, binding sites, and average aggregation number of BSA were determined by this method. Thermodynamic parameters were calculated by the van’t Hoff equation. The data clearly indicate that the binding is entropy driven and enthalpically disfavored. Based on the Förster theory of non-radiative energy transfer, the efficiency of energy transfer, and the distance between the donor (Trp residues) and the acceptor (Na₂[M(5-SO₃-2,3-salpyr)]) were evaluated. Also the synchronous fluorescence spectra showed that the microenvironment of the tryptophan residues was not changed. Finally, our results indicate that the complexes can bind to BSA and be efficiently transported in the body, which could be helpful for further drug design.     

硫唑嘌呤与牛血清白蛋白相互作用的热力学研究

用荧光光谱法和紫外-可见光谱法研究了在模拟人体生理条件下,硫唑嘌呤和牛血清白蛋白（BSA）结合反应的特征,发现硫唑嘌呤对BSA有较强的荧光猝灭作用,且硫唑嘌呤的紫外吸收光谱和BSA的荧光光谱有一定程度的重叠,由此可得出其作用距离和结合过程的基本热力学参数。