Interaction Between Ranitidine Hydrochloride and Bovine Serum Albumin in Aqueous Solution

The interaction between ranitidine hydrochloride (RAN) and bovine serum albumin (BSA) in aqueous solution was investigated by means of fluorescence, synchronous fluorescence, and UV-Vis spectroscopy. The fluorescence of BSA was quenched remarkably by RAN and the quenching mechanism was concluded to be static quenching. The binding constants K and the number of binding sites n were calculated at three different temperatures. The RAN–BSA binding distance was determined to be less than 8 nm, suggesting that energy transfer may occur from BSA to RAN. The interaction process is spontaneous. Based on the obtained thermodynamic parameters, electrostatic forces may play a major role in this process. In addition, the effect of RAN on the conformation of BSA was analyzed using synchronous fluorescence spectra.     

荧光光谱法研究除草醚与牛血清白蛋白的相互作用

运用荧光光谱和紫外吸收光谱研究水溶液中除草醚(NP)与牛血清白蛋白(BSA)的相互作用.结果表明,NP与BSA形成基态复合物导致BSA内源荧光猝灭,猝灭机理主要为静态猝灭和非辐射能量转移.运用位点模型计算298 K、308 K、318 K时结合常数K_A分别为6.97×10~4、5.25×10~4 、4.96×10~4 L·mol~(-1),结合位点数n分别为0.98、0.92、0.96.根据热力学参数确定其作用力以疏水作用和静电作用为主;运用F(o)rster偶极-偶极非辐射能量转移原理,测定了NP与BSA的结合距离r为2.19 nm;用同步荧光技术初步考察了NP对BSA构象的影响.     

Probing BSA binding to citrate-coated gold nanoparticles and surfaces

The interaction of bovine serum albumin (BSA) with gold colloids and surfaces was studied using zeta-potential and quartz crystal microbalance (QCM) measurements, respectively, to determine the surface charge and coverage. The combination of these two measurements suggests that BSA binding to gold nanoparticles and gold surfaces occurs by an electrostatic mechanism when citrate is present. The binding of BSA to bare gold is nearly two times greater than the binding of BSA to a citrate-coated gold surface, suggesting that protein spreading (denaturation) on the surface may occur followed by secondary protein binding. On the other hand, binding to citrate-coated gold surfaces can be fit to a Langmuir isotherm model to obtain a maximum surface coverage of (3.7 +/- 0.2) x 10(12) molecules/cm(2) and a binding constant of 1.0 +/- 0.3 microM(-1). The zeta-potential measurements show that the stabilization of colloids by BSA has a significant contribution from a steric mechanism because the colloids are stable, even at their isoelectric point (pI approximately 4.6). To be consistent with the observed phenomena, the electrostatic interactions between BSA and citrate must consist of salt-bridges, for example, of the carboxylate-ammonium type, between the citrate and the lysine on the protein surface. The data support the role of strong electrostatic binding but do not exclude contributions from steric or hydrophobic interactions with the surface adlayer.     

Interaction Between <Emphasis Type="Italic">Trans</Emphasis>-resveratrol and Serum Albumin in Aqueous Solution

The interaction between trans-resveratrol (TR) with bovine serum albumin (BSA) in aqueous solution was investigated by means of fluorescence, synchronous fluorescence and infrared spectroscopy. The fluorescence of BSA can be quenched remarkably by TR in aqueous solution. A notable red-shift of the maximum emission of BSA from 340 to 353 nm together with appearance of an isoemissive point at 395 nm were observed. The results indicate that TR binds to BSA, forming a TR–BSA complex. The TR–BSA binding distance was determined to be less than 7 nm, suggesting that energy transfer from BSA to TR may occur. The interaction process is spontaneous. Based on the obtained thermodynamic parameters, electrostatic forces may play a major role in this process. Both synchronous fluorescence and FT-IR spectra confirmed the interaction, and indicate the conformational changes of BSA.     

Study of the conjugation reaction between bovine serum albumin and gentamicin with Ponceau S as fluorescence probe

Abstract  

Ponceau S (PS) can quench the fluorescence of bovine serum albumin (BSA) in aqueous solution of pH 7.40. The static fluorescence-quenching process between BSA and PS was confirmed and the binding constant, the number of binding sites, and thermodynamic data for the interaction between BSA and PS were obtained. The results showed that the number of binding sites was 1 and that electrostatic attraction was important in the binding of BSA to PS. On the basis of the theory of F?rster resonance energy transfer, the binding distance (r < 7 nm) between PS and BSA was obtained. Site marker competitive experiments indicated that binding of PS to BSA primarily occurred in sub-domain IIA (site I). There was no obvious fluorescence intensity change on combining BSA and gentamicin (GM), so the conjugation reaction between BSA and GM cannot be studied by spectroscopy. It was observed that when GM was added to the BSA–PS system, the relative fluorescence intensity of the system recovered gradually with increasing concentration of GM, which showed there was a conjugation reaction between GM and BSA and that binding of GM to BSA primarily occurred in sub-domain IIA (site I).     

碱性橙与蛋白间的特异性与非特异性作用荧光光谱比较

将碱性橙与抗体的作用、碱性橙与牛血清白蛋白(BSA)间的作用分别作为特异性作用和非特异性作用模型,采用荧光光谱法固定激发波长为280 nm,扫描不同温度下碱性橙与抗体和牛血清白蛋白两种相互作用,在300～600 nm的发射波长,比较了两种相互作用的差异.结果表明,碱性橙与抗体结合为单一的静态猝灭过程,二者之间的作用力主要为静电作用力;在溶液中,二者以摩尔比1∶1结合,结合常数为3.88×104 L/mol(25.C),3.73×104 L/mol(37.C)和2.35×104 L/mol (45.C);碱性橙距抗体分子色氨酸残基最短距离(r)为5.52 nm.碱性橙与BSA的结合也为静态猝灭,作用力为静电作用力.但碱性橙与抗体作用过程中形成了激基复合物,与BSA则不形成激基复合物.     

Interaction Between Fluorinated Amphiphilic Copolymer P(HFMA)-g-P(SPEG) and BSA

A novel fluorinated amphiphilic copolymer P(HFMA)-g-P(SPEG) was synthesized. The interactions between P(HFMA)-g-P(SPEG) and bovine serum albumin (BSA) were studied by synchronous fluorescence and intrinsic fluorescence spectroscopy. It was concluded through synchronous fluorescence that P(HFMA)-g-P(SPEG) mainly bound to tryptophan residues of BSA. Intrinsic fluorescence results revealed that BSA and P(HFMA)-g-P(SPEG) had strong interactions. The mechanism of quenching belonged to dynamic quenching and the main sort of binding force was hydrophobic force. The hydrophobic interaction between P(HFMA)-g-P(SPEG) and BSA was conformed by micropolarity and TEM photographs.     

Spectroscopic studies on the interaction between nicotinamide and bovine serum albumin

The interaction of nicotinamide (NA) and bovine serum albumin (BSA) was studied by fluorescence and absorption spectroscopy at different temperatures. The results revealed that NA caused the fluorescence quenching of BSA through a static quenching procedure. The binding constants K(A), and the number of binding sites n, corresponding thermodynamic parameters DeltaG, DeltaH, DeltaS between NA and BSA at different temperatures were calculated. The primary binding pattern between NA and BSA was interpreted as hydrophobic interaction. In addition, the effect of NA on the conformation of BSA was analyzed using synchronous fluorescence spectroscopy. The binding average distance, r between the donor (BSA) and acceptor (NA) was determined based on the F?rster's theory and it was found to be 3.1 nm.     

大黄酸铜(Ⅱ)配合物与血清白蛋白的相互作用

采用荧光光谱法和紫外光谱法研究了大黄酸铜配合物与牛血清白蛋白之间的相互作用.大黄酸铜配合物能显著猝灭牛血清白蛋白的内源荧光并以静态猝灭为主;计算了298 K和309 K温度下结合常数、结合位点,根据热力学参数判断大黄酸铜配合物与牛血清白蛋白之间具有较强的疏水作用力;依据F?rster的偶极-偶极非辐射能量转移理论,计算出大黄酸铜在蛋白质中结合位置与色氨酸残基间的距离为3.21 nm, 表明大黄酸铜的部分片段能够插入蛋白质分子内部;用同步荧光光谱和圆二色光谱技术探讨了大黄酸铜对牛血清白蛋白构象的影响.     

Spectrophotofluorimetric Study of the Interaction between Trazodone Hydrochloride and Bovine Serum Albumin

Abstract

The binding of trazodone hydrochloride (TZH), an antidepressant drug, to bovine serum albumin (BSA) has been investigated by fluorescence spectroscopic analysis. The fluorescence emission of BSA (λ_em=350 nm) was quenched by TZH while that of this ligand was enhanced (λ_em=443 nm). The spectral behavior was consistent with the static quenching mechanism, and the apparent binding constant, K _a (1.05×10⁴ l mol^?1) as well as binding site number, n (～1), were estimated. Thermodynamic parameters obtained from the measured data at different temperatures showed that the binding of TZH to BSA involved predominantly hydrophobic interactions as well as smaller contributions from electrostatic forces. Phenylbutazone and ibuprofen were utilized as competitive markers for sites I and II, respectively, in the interaction of TZH with BSA. This competitive displacement procedure indicated that the likely binding was site I, i.e., subdomain IIA, and this was supported by the observation that up to 50% of this site marker, phenylbutazone, could be exchanged with TZH whilst only a few percent of ibuprofen were so affected.     

Study of interaction of Potassium Dodecatangestato Cobaltate(III) with Bovine Serum Albumin using Fluorescence Spectroscopy

The binding of potassium dodecatangestato cobaltate(III) (PDC) as a water-soluble polyoxometal with bovine serum albumin (BSA) as a major transporting protein of plasma, has been investigated at pH 7.2, 5?mM phosphate buffer, 27°C and various ionic strength by fluorescence spectroscopy.

The results show that the binding of PDC to BSA quenches BSA emission and the Stern–Volmer linear relationship can be applied for the quenching process.

The values of Stern–Volmer constant, K _sv, which can be considered as a binding constant for formation of 1:1 complex at 0.01, 0.1 and 0.2?M NaCl are 8.56 × 10⁵, 5.72 × l0⁵ and 9.60 × 10⁵, respectively. The interpretation of the results represents that binding affinity depends on both electrostatic forces and conformational stability of BSA. A step-by-step aggregation model, which has been developed by Borissevich et al., was used to determine the average aggregation number of BSA, ?J?, from the fluorescence quenching. The results show that the binding of PDC to BSA does not induce any considerable aggregation in BSA molecules. Therefore, it can be concluded that there are no considerable conformational changes in BSA molecules during its interaction with PDC.     

Study of the interaction between N-confused porphyrin and bovine serum albumin by fluorescence spectroscopy

The fluorescence and ultraviolet spectroscopy were explored to study the interaction between N-confused porphyrins (NCP) and bovine serum albumin (BSA) under imitated physiological condition. The experimental results indicated that the fluorescence quenching mechanism between BSA and NCP was static quenching procedure at low NCP concentration at 293 and 305 K or a combined quenching (static and dynamic) procedure at higher NCP concentration at 305 K. The binding constants, binding sites and the corresponding thermodynamic parameters ΔH, ΔS, and ΔG were calculated at different temperatures. The comparison of binding potency of the three NCP to BSA showed that the substituting groups in benzene ring could enhance the binding affinity. From the thermodynamic parameters, we concluded that the action force was mainly hydrophobic interaction. The binding distances between NCP and BSA were calculated using F?rster non-radiation energy transfer theory. In addition, the effect of NCP on the conformation of BSA was analyzed using synchronous fluorescence spectroscopy.     

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.     

Aggregation Capacity and Complexation Properties of a System Based on an Imidazole-Containing Amphiphile and Bovine Serum Albumin

A complex of physicochemical methods was used to study the aggregation characteristics of an imidazolium-containing amphiphile and its ability for complex formation with bovine serum albumin (BSA). Tensiometry showed that adding BSA to the surfactant decreases the aggregation threshold of the system by a factor of 50. Dynamic light scattering established, that the size of the surfactant–BSA complexes depends on the size of the polypeptide (6–10 nm) and is independent on the concentrations of the surfactant and BSA. The Stern?Volmer constants and surfactant?protein binding constants were calculated from fluorescence spectroscopy data.     

锌(Ⅱ)对于甲基百里酚蓝与牛血清白蛋白相互作用的影响

采用荧光光谱、紫外-可见光谱研究了有/无金属Zn2+存在下甲基百里酚蓝(MTB)与牛血清白蛋白(BSA)的相互作用.实验结果表明,无论Zn2+离子存在与否,MTB与BSA之间均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与热力学参数,发现Zn2+离子存在时,MTB与BSA间的作用力由静电力转为氢键和Van der Waals力作用为主,认为金属Zn2+以"离子架桥"的方式参与MTB与BSA的结合过程,从而ΔH对ΔG的贡献增大.     

The investigation of the interaction between NCP-EDA and bovine serum albumin by spectroscopic approaches

The fluorescence and ultraviolet spectroscopies were explored to study the interaction between N-confused porphyrins-edaravone diad (NCP-EDA) and bovine serum albumin (BSA) under simulative physiological condition at different temperatures. The experimental results show that the fluorescence quenching mechanism between NCP-EDA and BSA is a combined quenching (dynamic and static quenching). The binding constants, binding sites and the corresponding thermodynamic parameters (ΔG, ΔH, and ΔS) of the interaction system were calculated at different temperatures. According to F?rster non-radiation energy transfer theory, the binding distance between NCP-EDA and BSA was calculated to be 3.63 nm. In addition, the effect of NCP-EDA on the conformation of BSA was analyzed using synchronous fluorescence spectroscopy.     

Study of the interaction between 2,5-di-[2-(4-hydroxy-phenyl)ethylene]-terephthalonitril and bovine serum albumin by fluorescence spectroscopy

A new compound, 2,5-di-[2-(4-hydroxy-phenyl)ethylene]-terephthalonitrile (DHPEPN), was synthesized. The interaction between bovine serum albumin (BSA) and DHPEPN in Tris-HCl buffer solution (pH 7.4) was investigated using fluorescence and UV-vis absorption spectroscopy. The mechanism of BSA fluorescence quenched by DHPEPN is discussed according to the Stern-Volmer equation. The binding constant and the thermodynamic parameters ΔH, ΔS, ΔG at different temperatures were calculated. The results indicate that the van der Waals interaction and hydrogen bonding play major roles in the binding process. The distance between BSA and DHPEPN is estimated to be 3.59 nm based on the F?rster resonance energy transfer theory. The spectral changes of synchronous fluorescence and three-dimensional fluorescence suggest that both of the microenvironment of DHPEPN and the conformation of BSA are changed during binding between DHPEPN and BSA.     

绞股蓝皂苷与牛血清白蛋白相互作用的荧光光谱研究

用荧光光谱技术研究了绞股蓝皂苷与牛血清白蛋白(BSA)在pH=7.40的Tris-HCl缓冲溶液中的相互作用;通过计算确定了绞股蓝皂苷与BSA的结合位点数和结合常数,利用热力学分析探讨了绞股蓝皂苷与BSA之间的结合方式;同时采用同步荧光技术考察了绞股蓝皂苷对BSA构象的影响.结果表明,绞股蓝皂苷对牛血清白蛋白的荧光猝灭过程为静态猝灭;二者主要靠疏水作用和静电引力结合.     

Investigation of the Interaction between Nitrite Ion and Bovine Serum Albumin Using Spectroscopic and Molecular Docking Techniques

The interaction between nitrite ion and bovine serum albumin (BSA), in an aqueous environment, was studied using spectroscopic methods, including fluorescence quenching technique, synchronous fluorescence, UV? Vis spectrophotometry and Resonance Rayleigh Scattering (RRS), and molecular docking technique. The experimental results showed that nitrite ion effectively quenched the intrinsic fluorescence of BSA with the static quenching. The ion‐BSA binding constant was determined to be 3.69×10³ L mol^?1. As the results showed the stoichiometry of binding nitrite ion to BSA was 1 : 1. Furthermore the thermodynamic parameters and nature of the binding force were calculated. The negative ΔH^o and ΔS^o values of reaction between nitrite ion and BSA indicated the predominant forces in the ion‐BSA interactions are hydrogen bonding interactions. Based on the Förster’s theory of non‐radiative energy transfer, the binding distance between nitrite ion and the inner tyrosine and tryptophan residue of BSA were determined to be 2.16 nm. Furthermore binding site of this ion on BSA was carried out by molecular docking technique.     

Spectroscopic Studies on the Binding of Kaempferol‐3,7‐α‐L‐rhamnopyranoside to Bovine Serum Albumin

The binding of kaempferol‐3,7‐α‐L‐rhamnopyranoside (KRR) with bovine serum albumin (BSA) was investigated by different spectroscopic methods under simulative physiological conditions. Analysis of ?uorescence quenching data of BSA by KRR at different temperatures using Stern‐Volmer methods revealed the formation of a ground state KRR‐BSA complex with moderate binding constant of the order 10⁴ L·mol^?1. The existence of some metal ions could weaken the binding of KRR on BSA. The changes in the van't Hoff enthalpy (ΔH⁰) and entropy (ΔS⁰) of the interaction were estimated to be ?26.53 kJ·mol^?1 and 3.33 J·mol^?1·K^?1 and both hydrophobic and electrostatic forces contributed to stabilizing the BSA‐KRR complex. According to the F?ster theory of non‐radiation energy transfer, the distance r between the donor (BSA) and the acceptor (KRR) was obtained (r=2.83 nm). Site marker competitive experiments showed that KRR could bind to Site I of BSA. In addition, synchronous fluorescence, UV‐Vis absorption and circular dichroism (CD) results indicated that the KRR binding could cause conformational changes of BSA.