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1.
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.  相似文献   

2.
The interaction between 2,4-dichlorophenol (DCP) and bovine serum albumin (BSA) was investigated by fluorescence spectroscopy combined with UV-vis absorption and circular dichroism (CD) spectroscopy under simulative physiological conditions. The experiment results show that the fluorescence intensity of BSA is dramatically decreased owing to the formation of a DCP–BSA complex. The corresponding effective quenching constants (K a) between DCP and BSA at four different temperatures (292, 298, 304 and 310 K) were determined to be 10.08×104, 9.082×104, 8.177×104, and 7.260×104 L?mol?1, respectively. The thermodynamics parameters enthalpy change (ΔH) and entropy change (ΔS) were calculated to be ?13.64 kJ?mol?1 and 49.08 J?mol?1?K?1, which suggested that hydrophobic interaction was the predominant intermolecular force. Site marker competitive experiments indicated that the binding of DCP to BSA primarily takes place in subdomain IIA. The binding distance (r) between DCP and the tryptophan residue of BSA ias 4.09 nm according to Förster’s theory of non-radioactive energy transfer. The conformational investigation demonstrated that the presence of DCP decreased the α-helical content of BSA and induced a slight unfolding of the polypeptides of protein, which confirmed the occurrence some micro environmental and conformational changes of BSA molecules.  相似文献   

3.
The interaction of bovine serum albumin (BSA) with raloxifene was assessed via fluorescence spectroscopy. The number of binding sites and the apparent binding constants between raloxifene and BSA were analyzed using the Tachiya model and Stern-Volmer equation, respectively. The apparent binding constant and the number of binding sites at 298 K were 2.33×105 L?mol?1 and 1.0688 as obtained from the Stern-Volmer equation and 2.00×105 L?mol?1 and 2.6667 from the Tachiya model. The thermodynamic parameters ΔH and ΔS were calculated to be 69.46 kJ?mol?1 and 121.12 J?K?1?mol?1, respectively, suggesting that the force acting between raloxifene and BSA was mainly a hydrophobic interaction. The binding distance between the donor (BSA) and acceptor (raloxifene) was 4.77 nm according to Förster’s nonradiational energy transfer theory. It was also found that common metal ions such as K+, Cu2+, Zn2+, Mg2+ and Ca2+ decreased the apparent association constant and the number of binding sites between raloxifene and BSA.  相似文献   

4.
The mechanism of the interaction between bovine serum albumin (BSA) and [Pt(phen) (histidine)]+ complex was studied employing ultraviolet (UV) absorption, circular dichroism (CD), FT-IR, differential pulse voltammetry (DPV), and fluorescence spectral methods. Fluorescence data showed that the intrinsic fluorescence of BSA was strongly quenched by Pt(II) complex in terms of an untypical static quenching process. The corresponding number of binding sites (n) and binding constant (K b) of BSA and complex at 283, 298, and 310 K were calculated to be 0.61?×?106, 19?×?106, and 42?×?106 M?1, respectively. The results showed that the increasing temperature improves the stability of the complex–BSA system, which results in a higher binding constant and the number of binding sites of the complex–BSA system. The positive ΔH and positive ΔS indicated that hydrophobic forces might play a major role in the binding between complex and BSA. Based on Forster’s theory of non-radiation energy transfer, the binding distance (r) between the donor (BSA) and acceptor (Pt(II) complex) was evaluated. The results of CD, UV–vis, DPV, and FT-IR spectroscopy showed that the binding of Pt(II) complex to BSA induced conformational changes in BSA  相似文献   

5.
There is much interest in the interactions between the active constituents of traditional Chinese medicine and biomolecules. By use of frontal analysis on an affinity column we have examined the binding interaction of berberine chloride (BC), a major active constituent of coptis, with bovine serum albumin (BSA) in 40 mM phosphate buffer, pH 7.0. Adsorption of BC on immobilized BSA was in accordance with the Langmuir isotherm, suggesting BC is binding to a single type of site on the immobilized BSA. The binding constant was 4.79 × 104 L mol?1 at 30 °C, less than the value of 6.61 × 104 L mol?1 obtained by fluorescence spectroscopy under the same buffer and temperature conditions. The effects of temperature on the retention, binding constant, and active binding sites, and on the percentage protein binding of BC, were also investigated. Thermodynamic measurements indicated that the increase in entropy was an important process promoting the interaction between BC and BSA.  相似文献   

6.

Background

Rivaroxaban is a direct inhibitor of coagulation factor Xa and is used for venous thromboembolic disorders. The rivaroxaban interaction with BSA was studied to understand its PK and PD (pharmacokinetics and pharmacokinetics) properties. Multi-spectroscopic studies were used to study the interaction which included UV spectrophotometric, spectrofluorometric and three dimensional spectrofluorometric studies. Further elucidation of data was done by molecular simulation studies to evaluate the interaction behavior between BSA and rivaroxaban.

Results

Rivaroxaban quenched the basic fluorescence of BSA molecule by the process of static quenching since rivaroxaban and BSA form a complex that results in shift of the absorption spectra of BSA molecule. A decline in the values of binding constants was detected with the increase of temperatures (298–308 K) and the binding constants were in range from 1.32 × 105 to 4.3 × 103 L mol?1 indicating the instability of the BSA and rivaroxaban complex at higher temperatures. The data of number of binding sites showed uniformity. The site marker experiments indicated site I (sub-domain IIA) as the principal site for rivaroxaban binding. The thermodynamic study experiments were carried at the temperatures of 298/303/308 K. The ?G0, ?H0 and ?S0 at these temperatures ranged between ? 24.67 and ? 21.27 kJ mol?1 and the values for ?H0 and ?S0 were found to be ? 126 kJ mol?1 and ?S ? 340 J mol?1 K?1 The negative value of ?G0 indicating spontaneous binding between the two molecules. The negative values in ?H0 and ?S0 indicated van der Waals interaction and hydrogen bonding were involved during the interaction between rivaroxaban and BSA.

Conclusions

The results of molecular docking were consistent with the results obtained from spectroscopic studies in establishing the principal binding site and type of bonds between rivaroxaban and BSA.
  相似文献   

7.
A new nickel(II) complex, [Ni(o-van-L-met)(phen)(CH3OH)] (o-van-L-met = Schiff base derived from o-vanillin and l-methionine, phen = 1,10–phenanthroline), has been synthesized and characterized by elemental analyses, IR spectra, and single-crystal X-ray diffraction. The crystal structure shows nickel is six-coordinate in a distorted octahedral geometry. In this crystal, molecules form a 2-D plane structure via hydrogen bonds and π–π interactions. The interaction of the complex with calf thymus DNA (CT-DNA) was investigated by absorption, fluorescence, circular dichroism (CD), spectroscopies, and viscosity measurement. The complex binds to CT-DNA in an intercalative mode with a binding constant of (4.7 ± 0.5) × 104 M?1. The interaction of the complex with bovine serum albumin (BSA) was also studied by the multispectroscopic methods. Results illustrated that the nickel(II) complex can effectively quench the intrinsic fluorescence of BSA via a static quenching mechanism and cause conformational changes. The binding constant Kb was (6.3 ± 1.6) × 104 M?1 and the binding site number n was 0.96 ± 0.04; its bind site was located within subunit IIA of BSA.  相似文献   

8.
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 ΔHo and ΔSo 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.  相似文献   

9.
The interaction of ginkgolic acid (15:1, GA) with human serum albumin (HSA) was investigated by FT–IR, CD and fluorescence spectroscopic methods as well as molecular modeling. FT–IR and CD spectroscopic showed that complexation with the drug alters the protein’s conformation by a major reduction of α-helix from 54 % (free HSA) to 46–31 % (drug–complex), inducing a partial protein destabilization. Fluorescence emission spectra demonstrated that the fluorescence quenching of HSA by GA was by a static quenching process with binding constants on the order of 105 L·mol?1. The thermodynamic parameters (ΔH = ?28.26 kJ·mol?1, ΔS = 11.55 J·mol?1·K?1) indicate that hydrophobic forces play a leading role in the formation of the GA–HSA complex. The ratio of GA and HSA in the complex is 1:1 and the binding distance between them was calculated as 2.2 nm based on the Förster theory, which indicates that the energy transfer from the tryptophan residue in HSA to GA occurs with high probability. On the other hand, molecular docking studies reveal that GA binds to Site II of HSA (sub-domain IIIA), and it also shows that several amino acids participate in drug–protein complexation, which is stabilized by H-bonding.  相似文献   

10.
The interaction between CdTe quantum dots (QDs) and bovine serum albumin (BSA) was systematically investigated by fluorescence, UV‐vis absorption and circular dichroism (CD) spectroscopy under physiological conditions. The experimental results showed that the fluorescence of BSA could be quenched by CdTe QDs with a static quenching mechanism, indicating that CdTe QDs could react with BSA. The quenching constants according to the modified Stern‐Volmer equation were obtained as 1.710×106, 1.291×106 and 1.010×106 L·mol?1 at 298, 304, and 310 K, respectively. ΔH, ΔS and ΔG for CdTe QDs‐BSA system were calculated to be ?33.68 kJ·mol?1, 6.254 J·mol?1·K?1 and ?35.54 kJ·mol?1 (298 K), respectively, showing that electrostatic interaction in the system played a major role. According to F?rster theory, the distance between Trp‐214 in BSA and CdTe QDs was given as 2.18 nm. The UV‐vis, synchronous fluorescence and CD spectra confirmed further that the conformations of BSA after addition of CdTe QDs have been changed.  相似文献   

11.
The interaction of trans-resveratrol and BSA was investigated by means of fluorescence quenching, resonance light scattering, ultraviolet spectroscopy and Fourier Transform Infrared Spectroscopy. Binding of trans-resveratrol to BSA quenches the BSA fluorescence and both static and dynamic quenching occur with complex formation. The apparent binding constants of trans-resveratrol and BSA at 20, 30 and 40?°C are 1.95×106, 1.70×106 and 1.65×106 L?mol?1, respectively. The binding site values are (1.25±0.02). According to the Förster theory of non-radiation energy transfer, the binding distances between trans-resveratrol and BSA are 3.47, 3.73 and 3.99 nm at 20, 30 and 40?°C, respectively. The negative enthalpy change and positive entropy change indicated that the interaction of trans-resveratrol and BSA was driven mainly by electrostatic forces. The process of binding was spontaneous whereby the Gibbs energy change was negative.  相似文献   

12.
The interaction of surfactin, a typical biosurfactant, with bovine serum albumin (BSA) was investigated by surface tension, fluorescence, freeze-fractured transmission electron microscopy (FF-TEM) and circular dichroism (CD) measurements. The surface tension curves of pure surfactin solution and surfactin/BSA solutions have different phenomena, where two obvious inflections determined as the critical aggregation concentration (cac) and the critical micelle concentration (cmc) appear for surfactin/BSA solutions. The higher BSA concentration, the higher cac and cmc values for surfactin/BSA solution. Fluorescence spectra show that the structure change of BSA is dependent on both surfactin and BSA concentration. The micropolarity, FF-TEM and CD results further demonstrate the interaction between BSA and surfactin. The excess free energy (ΔG0) of surfactin/BSA interactions have been obtained as ?6.13 and 5.32 kJ/mol for 1.0 × 10?6 and 3.8 × 10?6 mol/L BSA concentration, respectively. The binding ratio (R) determined for surfactin/BSA systems are higher than that reported for dirhamnolipid to BSA. Above all, it can be concluded that the hydrophobic interaction and the hydrogen bonds between surfactin and BSA play the key role for the high binding ratio for surfactin to BAS.  相似文献   

13.
The binding of kaempferol‐3,7‐αL‐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.  相似文献   

14.
Lei  Genhu  Yang  Rong  Zeng  Xiaolei  Shen  Yehua  Zheng  Xiaohui  Wei  Yinmao 《Chromatographia》2007,66(11):847-852

There is much interest in the interactions between the active constituents of traditional Chinese medicine and biomolecules. By use of frontal analysis on an affinity column we have examined the binding interaction of berberine chloride (BC), a major active constituent of coptis, with bovine serum albumin (BSA) in 40 mM phosphate buffer, pH 7.0. Adsorption of BC on immobilized BSA was in accordance with the Langmuir isotherm, suggesting BC is binding to a single type of site on the immobilized BSA. The binding constant was 4.79 × 104 L mol−1 at 30 °C, less than the value of 6.61 × 104 L mol−1 obtained by fluorescence spectroscopy under the same buffer and temperature conditions. The effects of temperature on the retention, binding constant, and active binding sites, and on the percentage protein binding of BC, were also investigated. Thermodynamic measurements indicated that the increase in entropy was an important process promoting the interaction between BC and BSA.

  相似文献   

15.
The interaction of plumbagin (PLU) with human serum albumin (HSA) in physiological buffer (pH=7.4) was studied by fluorescence spectroscopy. Results obtained from analysis of the fluorescence spectra indicated that PLU has a strong ability to quench the intrinsic fluorescence of HSA through a static quenching procedure. Fluorescence quenching data revealed that the quenching constants (K) are 4.43×104, 3.26×104 and 1.69×104 L?mol?1 at 293, 303 and 313 K, respectively. The thermodynamic parameters ΔH° and ΔS° were calculated to be ?36.63 kJ?mol?1, and ?35.702 J?mol?1?K?1 respectively, which suggested that van der Waals interactions and hydrogen bonds play a major role in the interaction of PLU with HSA. The distance between donor (HSA) and acceptor (PLU) was calculated to be 3.76 nm based on Förster’s non-radiative energy transfer theory. The results of synchronous fluorescence spectra showed that binding of PLU to HSA can induce conformational changes in HSA.  相似文献   

16.
In this work, the interaction of memantine with human serum albumin (HSA) immobilized on porous silica particles was studied using a biochromatographic approach. The determination of the enthalpy change at different pH values suggested that the protonated group in the memantine–HSA complex exhibits a heat protonation with a magnitude around 65 kJ mol?1. This value agrees with the protonation of a guanidinium group, and confirmed that an arginine group may become protonated in the memantine–HSA complex formation. The thermodynamic data showed that memantine–HSA binding, for low temperature (<293 K), is dominated by a positive entropy change. This result suggests that dehydration at the binding interface and charge–charge interactions contribute to the memantine–HSA complex formation. Above 293 K, the thermodynamic data ΔH and ΔS became negative due to van der Waals interactions and hydrogen bonding which are engaged at the complex interface. The temperature dependence of the free energy of binding is weak because of the enthalpy–entropy compensation caused by a large heat capacity change, ΔC p = ? 3.79 kJ mol?1 K?1 at pH = 7. These results were used to determine the potential binding site of this drug on HSA.  相似文献   

17.
A new Pt(II) complex, [Pt(Caff)(His)(Cl)] (Caff is Caffeine (3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6-dione) and His is l-Histidine), was synthesized and characterized using different physicochemical methods. The interaction of this complex with calf thymus DNA (ct-DNA) was investigated by absorption, emission, circular dichroism (CD), and viscosity measurements and molecular docking techniques. The calculated binding constant, Kb, was 5.3 × 103 M?1. In fluorimetric studies, the enthalpy and entropy of the reaction between the complex and ct-DNA showed that the reaction is exothermic (?H = ?184.07 kJ mol?1, ?S = ?551.97 J mol?1 K?1). CD spectra of DNA in the presence of different amounts of the complex showed little changes in both the negative and positive band intensities, which imply a non-intercalative mode between the DNA and the platinum complex. Furthermore, the study of molecular docking also indicated that the complex binds to DNA via a groove binding mode.  相似文献   

18.
The interaction of HE–Eu(III) complex (HE?=?hematoxylin) with Herring-sperm DNA (hsDNA) has been studied by absorption spectra, fluorescence, and viscosity measurements in physiological buffer (pH?=?7.40). The binding constant of HE–Eu(III) complex to hsDNA was obtained by double reciprocal method at 298 and 310?K and the corresponding thermodynamic parameters (Δr Hm??=?8.55?×?104?J?mol?1, Δr Gm??=??3.01?×?104?J?mol?1, Δr Sm??=?387.95?J?mol?1?K?1) were calculated, showing that the interaction between HE–Eu(III) complex and hsDNA was driven mainly by entropy. The value of K indicated that the binding mode of HE–Eu(III) complex with DNA was not classical intercalation. These results were further supported by viscosity method and competitive binding experiment. Scatchard analysis suggests that the interaction mode was a mixed binding, which contains partial intercalation and groove binding.  相似文献   

19.
Fluorescence spectroscopy, Fourier transform infrared (FT‐IR) spectroscopy, circular dichroism (CD) and FT‐Raman spectroscopy were employed to analyze the binding of the asiatic acid (AA) to bovine serum albumin (BSA) under simulative physiological conditions. Fluorescence data revealed that the fluorescence quenching of BSA by AA was the result of the formation of BSA‐AA complex. The fluorescence quenching mechanism of BSA by AA was a static quenching procedure. According to the Van′t Hoff equation, the thermodynamic parameters enthalpy change (ΔH0) and entropy change (ΔS0) for the reaction were evaluated to be ?12.55 kJ·mol?1 and 67.08 kJ·mol?1, respectively, indicating that hydrophobic and electrostatic interactions played a major role in stabilizing the complex. The influence of AA on the conformation of BSA has also been analyzed on the basis of FT‐IR, CD and FT‐Raman spectra.  相似文献   

20.
The interaction between a water-soluble cationic fluorescent conjugated polymer (WCFP) and bovine serum albumin (BSA) was studied using UV?CVis absorption, fluorescence and circular dichroism spectroscopies. The results show that the fluorescence of BSA is strongly quenched by the WCFP under physiological conditions (pH?=?7.4). The quenching mechanism was found to be static, which was confirmed by the quenching rate constant (Kq) and UV?CVis absorption spectra. The thermodynamic parameters (?H ??, ?S ?? and ?G ??) calculated from the complexation constant, determined according to Lineweaver?CBurk equations are 38.6?kJ·mol?1, 228?J·mol?1·K?1 and ?29.4?kJ·mol?1 at 298?K. The principal interaction was proposed to be electrostatic.  相似文献   

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