环丙沙星与牛血清白蛋白相互作用的研究

研究了不同酸度条件下,环丙沙星(CPFX)与牛血清白蛋白(BSA)间的相互作用,讨论了药物对BSA构象的影响,证实了二者间相互作用为单一的动态猝灭过程,求出了猝灭常数,并依据能量转移理论确定了药物与蛋白的最近距离.     

环丙沙星与牛血清白蛋白相互作用的研究

研究了不同酸度条件下,环丙沙星(CPFX)与牛血清白蛋白(BSA)间的相互作用,讨论了药物对BSA构象的影响,证实了二者间相互作用为单一的动态猝灭过程,求出了猝灭常数,并依据能量转移理论确定了药物与蛋白的最近距离.     

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。     

秦皮甲素、秦皮乙素与血清白蛋白的相互作用

用荧光光谱法研究了中药有效成分秦皮甲素、秦皮乙素与牛血清白蛋白(BSA)、人血清白蛋白(HSA)的相互作用。结果表明：秦皮甲素、秦皮乙素对血清白蛋白的荧光有较强的猝灭作用,其荧光猝灭为单一的静态猝灭过程,其作用机制属能量转移机制。求得不同温度下反应的结合常数K。由反应焓变、熵变确定它们间的结合主要是静电引力。依据非辐射能量转移机理,求出了其结合位置和能量转移效率。     

阿霉素与牛血清白蛋白结合作用的研究

结合荧光光谱和吸收光谱研究了阿霉素与牛血清白蛋白间的结合作用，确定了 阿霉素对牛血清白蛋白的荧光猝灭过程的猝灭机理，测定了不同酸度条件下该结合 反应的结合常数、结合位点数，依据能量转移理认确定了药物和蛋白间的结合距离 。通过比较阿霉素和去糖基阿霉素与牛血清白蛋白的相互作用，结合阿霉素对蛋白 构象的影响，讨论了药物与蛋白的结合模式。     

洛美沙星与人血清白蛋白的相互作用机理

利用荧光及紫外光谱法研究了水溶液中洛美沙星(LMX)与人血清白蛋白(HSA)的相互作用机理. 结果表明洛美沙星对人血清白蛋白的荧光有较强的猝灭作用, 其猝灭类型主要为静态猝灭. 在不同温度下求得了洛美沙星与人血清白蛋白的结合常数K, 发现随反应温度上升K值下降. 由热力学参数确定了洛美沙星与人血清白蛋白的结合作用主要为色散力. 用同步荧光技术考察了洛美沙星对人血清白蛋白构象的影响, 又根据Fōrster理论, 测得了洛美沙星与人血清白蛋白之间的能量转移效率, 相互结合距离. 进一步证明了该反应是单一静态猝灭过程, 阐述了其猝灭机理是通过能量转移产生的.     

速灭威与牛血清白蛋白作用的研究

在pH=7.4的生理条件下,应用荧光光谱法研究了速灭威与牛血清白蛋白间相互作用。结果表明:速灭威对牛血清白蛋白的荧光有较强的猝灭作用,测定不同温度下的猝灭常数,证实了速灭威对牛血清白蛋白的荧光猝灭过程机理为静态猝灭。根据猝灭结果计算了不同温度下的结合位点数、结合常数。应用同步荧光光谱法探讨了速灭威对牛血清白蛋白构象的影响。依据f ster非辐射能量转移理论确定受体间的结合距离和能量转移效率。     

用荧光猝灭和荧光加强两种理论研究喹诺酮类新药与白蛋白的作用

应用荧光加强和荧光猝灭两种理论公式, 对四种喹诺酮类药物与人血清和牛血清白蛋白的作用作进行了对比研究, 对药物与白蛋白的结合特点和通常的表征量(解离常数、 猝灭常数、 猝灭效率、 能量转移效率、 给体 受体作用距离等)进行了深入地分析; 在白蛋白与药物结合类型上, 四种药物对HSA和BSA的猝灭实验结果表明, 这种由给体-受体结合引起的猝灭作用类型不是由生物大分子血清白蛋白单方面决定的, 而是由血清白蛋白与药物、 即给体与受体两者的分子结构和相互匹配共同决定的.     

光谱法测定伊曲康唑与牛血清和人血清白蛋白相互作用

用荧光光谱和紫外吸收光谱法, 在pH=7.4±0.1的0.1 mol·L-1磷酸缓冲溶液中, 研究了伊曲康唑与牛血清白蛋白(BSA)和人血清白蛋白(HSA)的相互作用. 实验结果表明, 伊曲康唑与牛血清白蛋白和人血清白蛋白作用的猝灭常数均随着温度的升高而降低, 伊曲康唑可以有规律地使血清白蛋白内源荧光猝灭, 其猝灭机理可认为是伊曲康唑与白蛋白形成复合物的静态猝灭. 获得了在不同温度下, 伊曲康唑与血清白蛋白作用的结合常数以及△G、△H和△S等热力学参数. 根据所得结果可推断伊曲康唑与白蛋白的作用力主要为疏水作用力, 同时, 利用荧光共振能量转移理论(FRET)计算得出了伊曲康唑与白蛋白结合位置的距离d. 而且, 利用同步荧光光谱和紫外光谱揭示了该反应中蛋白的结构和其微环境的变化.     

用荧光猝灭和荧光加强两种理论研究头孢类药物与白蛋白的作用

应用荧光加强和荧光猝灭两种理论公式，对七种头孢类抗菌药物与人血清和牛血清白蛋白的作用作进行了对比研究，对药物与白蛋白的结合特点和通常的表征量：解离常数、猝灭常数、猝灭效率、能量转移效率、给体-受体作用距离等，进行了深入地分析。     

Study of the interaction between daunorubicin and human serum albumin,and the determination of daunorubicin in blood serum samples

The interactions between daunorubicin and human serum albumin (HSA) were studied using the spectrofluorimetric method. The binding constants of daunorubicin with HSA were obtained at different temperatures. The effects of various metal ions on the binding constants of daunorubicin with HSA were also studied. The optimum conditions of fluorometric determination of daunorubicin were studied and the developed method was successfully applied to the determination of daunorubicin in serum samples.     

Fluorescence study on the interaction of human serum albumin with bromsulphalein

The binding of bromsulphalein (BSP) with human serum albumin was investigated at different temperatures, 298 and 308 K, by the fluorescence spectroscopy at pH 7.24. The binding constant was determined by Stern-Volmer equation based on the quenching of the fluorescence HSA in the presence of bromsulphalein. The effect of various metal ions on the binding constants of BSP with HSA was investigated. The thermodynamic parameters were calculated according to the dependence of enthalpy change on the temperature as follows: DeltaH and DeltaS possess small negative (9.3 kJ mol(-1)) and positive values (22.3 J K(-l)mol(-l)), respectively. The experimental results revealed that BSP has a strong ability to quench the intrinsic fluorescence of HSA through a static quenching procedure. The binding constants between BSP to HSA were remarkable and independent on temperature. The binding constants between HSA and BSP decreased in the presence of various ions, commonly decreased by 30-55%. The hydrophobic force played a major role in the interaction of BSP with HSA. All these experimental results and theoretical data clarified that BSP could bind to HSA and be effectively transported and eliminated in body, which could be a useful guideline for further drug design.     

Dependence of the constants of binding for nanomarkers of the fluorescein family with human serum albumin on Ph

The effective constants of binding for probes of the fluorescein family (fluorescein and its halogen derivatives, eosin and erythrosin) with human serum albumin (HSA) at different pH were determined. It was found that the introduction of halogen groups into the structural formula of fluorescein changes the character of the dependence on pH of the effective constant of binding of a nanomarker with HSA: the nonlinear dependence of the effective constants of binding with its protein typical for fluorescein, eosin, and erythrosine is characterized by an almost linear reduction with increasing pH dependence of the effective constants of their binding with human serum albumin. It was shown that the presence of more electronegative atoms in the structural formula of nanomarker leads to decrease of values of effective constants of nanomarker binding with HSA.     

Interaction of tetrandrine with human serum albumin: a fluorescence quenching study.

The interaction of tetrandrine with human serum albumin (HSA) was studied by measuring fluorescence quenching spectra, synchronous fluorescence spectra and ultra-violet spectra. The fluorescence quenching spectra of HSA in the presence of tetrandrine showed that tetrandrine quenched the fluorescence of HSA. The quenching constants of tetrandrine on HSA were determined using the Stern-Volmer equation. Static quenching and non-radiation energy transfer were the two main reasons leading to the fluorescence quenching of HSA by tetrandrine. According to the F?rster theory of non-radiation energy transfer, the binding distances (r) and the binding constants (K(A)) were obtained. The thermodynamic parameters obtained in this study revealed that the interaction between tetrandrine and HSA was mainly driven by a hydrophobic force. The conformational changes of HSA were investigated by synchronous spectrum studies.     

Exploring the binding mechanism of dihydropyrimidinones to human serum albumin: spectroscopic and molecular modeling techniques

The binding mechanism of molecular interaction between 5-(ethoxycarbonyl)-6-methyl-4-phenyl-3,4-dihydropyrimidin-2(1H)-one (a dihydropyrimidinones derivative, EMPD) and human serum albumin (HSA) was studied using spectroscopic methods and modeling technique. The quenching mechanism was investigated in terms of the binding constants and the basic thermodynamic parameters. The results of spectroscopic measurements suggested that EMPD have a strong ability to quench the intrinsic fluorescence of HSA through static quenching procedure. The drug-protein complex was stabilized by hydrophobic forces and hydrogen bonding as indicated from the thermodynamic parameters and synchronous fluorescence spectra, which was consistent with the results of molecular docking and accessible surface area calculation. Competitive experiments indicated that a displacement of warfarin by EMPD, which revealed that the binding site of EMPD to HSA was located at the subdomains IIA. The distance between the donor and the acceptor was 4.85nm as estimated according to F?rster's theory of non-radiation energy transfer. The effect of metal ions on the binding constants was also investigated. The results indicated that the binding constants between EMPD and HSA increased in the presence of common metal ions.     

Interaction of human serum albumin with bendroflumethiazide studied by fluorescence spectroscopy

The interactions between bendroflumethiazide (BFTZ) and human serum albumin (HSA) have been studied by fluorescence spectroscopy. Binding constants for drug attachment to the various binding sites of HSA have been measured at different temperatures in physiological buffer solution. The effect of metal ions on BFTZ interaction with HSA was also investigated. The thermodynamic parameters, DeltaH and DeltaS, have been calculated to be 49.28kJmol(-1)>0, and 258.83Jmol(-1)K(-1)>0, respectively. The distance between HSA and BFTZ, r, was determined to be 1.47nm based on F?rster's non-radiative energy transfer theory. The experimental results reveal that BFTZ has a strong ability to quench the intrinsic fluorescence of HSA through a static quenching mechanism. Furthermore, the binding constants between BFTZ and HSA are remarkably independent of temperature, and decrease in the presence of various ions, usually by about 30-55%. Hydrophobic interaction occurs between BFTZ and the sub-domain II A of HSA.     

Spectroscopic Investigation of the Interactions of Cryptotanshinone and Icariin with Two Serum Albumins

The interactions of two drugs, cryptotanshinone (CTS) and icariin, with bovine serum albumin (BSA) and human serum albumin (HSA) have been investigated using multiple spectroscopic techniques under imitated physiological conditions. CTS and icariin can quench the fluorescence intensity of BSA/HSA by a static quenching mechanism with complex formation. The binding constants of CTS–BSA, CTS–HSA, icariin–BSA and icariin–HSA complexes were observed to be 1.67 × 10⁴, 4.04 × 10⁴, 4.52 × 10⁵ and 4.20 × 10⁵ L·mol^?1, respectively at 298.15 K. The displacement experiments suggested icariin/CTS are primarily bound to tryptophan residues of the proteins within site I and site II. The thermodynamic parameters calculated on the basis of the temperature dependence of the binding constants revealed that the binding of CTS–BSA/HSA mainly depends on van der Waals interaction and hydrogen bonds, and yet the binding of icariin–HSA/BSA strongly relies on the hydrophobic interactions. The binding distances between BSA/HSA and CTS/icariin were evaluated by the Föster non-radiative energy transfer theory. The results of synchronous fluorescence, 3D fluorescence, FT-IR and CD spectra indicates that the conformations of proteins were altered with the addition of CTS or icariin. In addition, the effects of some common ions on the binding constants of CTS/icariin to proteins are also discussed.     

Synthesis and interaction studies of benzimidazole derivative with human serum albumin

A benzimidazole derivative, 1-(2-picolyl)-3-(2-picolyl) benzimidazole iodide (PPB), was synthesized. Fourier transform infrared spectroscopy (FT-IR), UV–visible, three-dimensional (3D) fluorescence, synchronous fluorescence (SF) and fluorescence spectroscopic methods were used to determine the PPB binding mode and the effects of PPB on protein stability and secondary structure. Fluorescence results revealed the presence of static type of quenching mechanism in the binding of PPB to human serum albumin (HSA). The binding constants between PPB and HSA were obtained according to Scatchard equation. The number of binding sites, the binding constants and the thermodynamic parameters were measured. The results showed a spontaneous binding of PPB to HSA through hydrogen bonds and van der Waals forces. In addition, the distance between PPB and the Trp 214 was estimated via employing the Förster's non-radiative energy transfer theory, and was found to be 3.49 nm, which indicated that PPB can bind to HSA with high probability. Site marker competitive experiments indicated that the binding of PPB to HSA primarily took place in subdomain IIA.     

白杨素与不同构型人血清白蛋白的作用机制

采用多种光谱学手段研究了白杨素(CHR)和不同构型人血清白蛋白(HSA)相互作用的分子机制.研究表明,白杨素能使蛋白质荧光发射峰发生静态淬灭,同时,白杨素的紫外吸收谱带也发生了明显的位移,说明与蛋白质的结合可使白杨素分子中的酚羟基发生解离.蛋白质还可以引起白杨素荧光发射峰强度的明显增强.利用荧光淬灭和荧光增强两种模式计算得到的白杨素和人血清白蛋白在生理条件下(pH 7.4)的结合常数(KA)分别为(9.97±0.24)×104和(9.75±0.11)×104L mol-1,其结合比例为1:1.随着pH值的降低,蛋白质与白杨素的结合常数逐渐减小,这与蛋白质的构型变化有关.根据不同异构体血清蛋白质的结构特征,判定白杨素在蛋白质分子上的结合位置位于IIA亚域的Site I活性位点.结合分子模拟,讨论了白杨素与蛋白质分子的结合机制.     

Stabilizing proteins for affinity capillary electrophoresis using ionic liquid aqueous two phase systems: Pharmaceuticals and human serum albumin

Recently, ionic liquids (ILs) are finding ever broader scope within pharmaceutical and bioanalytical applications. In the current work, ACE binding measurements of tryptophan (Try)‐HSA, chlorambucil (CHL)‐HSA, and dacarbazine (DTIC)‐HSA complexes were estimated in the absence or presence of several short chain imidazolium ILs within the range of concentrations of 10.0–1000.0 μmol/L that are far below the critical micelle concentrations of ILs. Results indicated that the value of binding constant of Trp‐HSA was dramatically deviated in the presence of 1000.0 μmol/L 1‐decyl‐3‐methylimidazolium bromide (DMIMBr) IL. However, interestingly, there is no any deviation for the Trp‐HSA binding constant with 100.0 μmol/L 1‐butyl‐3‐methylimidazolium bromide (BMIMBr) IL as an adjuvant additive in 67.0 mmol/L phosphate buffer at pH 7.4. This finding was further used to estimate the binding constants of important but weakly binding substances of CHL and DTIC antitumors with HSA; their binding constants were also estimated by HPAC giving data in good agreement with that revealed by ACE. These achievements were attributed to the significant improvement of HSA stability by combination with BMIMBr IL through hydrogen bond, electrostatic, and π–π forces. In addition, the use of 100.0 μmol/L BMIMBr extended the stability of native HSA solution stored under the ambient lab conditions up to 25 days with significant improvements in the precision of ACE binding data.