1,4-二氢吡啶衍生物的合成及其与牛血清白蛋白的相互作用

以对甲苯磺酸为催化剂,一锅法合成了一系列1,4-二氢吡啶衍生物,并对其进行了红外光谱、质谱和核磁共振表征。采用荧光光谱法、紫外光谱法对2,6-二甲基-4-苯乙烯-1,4-二氢吡啶-3,5-二甲酸乙酯(1a)与BSA在不同温度的相互作用进行了研究。在298K时,Kq为2.43×10~(12)L·mol~(-1)·s~(-1),Ka为4.15×10~3L·mol~(-1),n为0.82,ΔS为65.12J·mol~(-1)·K~(-1),ΔH为-1.24k J·mol~(-1)。研究表明,1a对BSA具有荧光猝灭作用,且1a与BSA的主要作用力可能是疏水作用力(ΔS0)。     

New phosphonate-substituted tricarbocyanines and their interaction with bovine serum albumin

New tricarbocyanine dyes with phosphonate groups (2, 3) were synthesized and their binding constants to bovine serum albumin (BSA) were determined. The binding constants of the synthesized tricarbocyanines and cardiogreen (1) (K_b ~ 10⁵ M^–1) are similar, indicating an insignificant contribution of the Coulomb interaction to the complex formation, which is determined by the polymethine chain interaction with BSA. The fluorescence lifetimes attest to the formation of two types of complexes: the lifetime of the dye complex with BSA with a major contribution (~80%) is 740–800 ps, and a lifetime of ~210 ps corresponds to the complex of dye aggregates with BSA.     

Green synthesis and characterization of Fe doped ZnO nanoparticles and their interaction with bovine serum albumin

Herein we report an eco-friendly and cost efficient synthesis of Fe doped ZnO (TPFZO) nanoparticles using the extract of Thespesia polpulanea flowers as a stabilizing agent. The synthesized NPs have been characterized by XRD, FT-IR, UV-DRS, SEM, EDAX and TEM studies. The synthesized NPs were found to have the crystallite size in the range of 30–60 ​nm. The calculated band gap energies for ZO and TPFZO nanoparticles were 3.00 ​eV and 1.97 ​eV respectively. The size distribution of the ZO and TPFZO obtained from TEM were observed to be lying in the range 50–120 ​nm and 4–22 ​nm respectively. The interaction of TPFZO NPs with bovine serum albumin (BSA) has been studied using fluorescence and absorption titration methods. The results indicated that the nanoparticles quenched the BSA fluorescence at 340 ​nm via static quenching mode having a bimolecular quenching rate constant value of 6.21 ​× ​10¹³ Lmol⁻¹s⁻¹.     

Fluorescence study on the interaction of bovine serum albumin with two coumarin derivatives

The interactions between bovine serum albumin (BSA) and two substituted hydroxychromone derivatives of coumarin, 3-hydroxy-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-on (C₃) and 1,3-dihydroxy-7,8,9,10-tetrahy-dro-6H-benzo[c]chromen-6-on (C_1.3), were investigated by fluorescence quenching spectra and UV-vis absorption spectra. It was proved that the fluorescence quenching of BSA by C₃ and C_{1, 3} was mainly a result of the formation of C₃ and C_1.3-BSA complexes. The Stern-Volmer quenching constants, binding constants, binding sites and the corresponding thermodynamic parameters ΔH ^o, ΔS ^o and ΔG ^o at different temperatures were calculated. The results indicated that van der Waals interactions and hydrogen bonds were the predominant intermolecular forces in stabilizing each complex. The detection limits of C₃ and C_1.3 were 5.08 × 10⁻⁷ and 1.11 × 10⁻⁷ M in the presence of BSA, respectively.     

壳寡糖及酰化壳寡糖与钕(Ⅲ)配合物的合成及其与牛血清白蛋白相互作用的对比研究

用壳寡糖及酰化壳寡糖与氯化钕反应,合成了壳寡糖-钕和酰化壳寡糖-钕配合物,利用红外光谱(IR)、紫外光谱(UV)手段对其结构进行了表征。在模拟生理条件下,本文采用紫外光谱和荧光光谱研究了两种配合物与牛血清白蛋白(BSA)的相互作用,计算了配合物与BSA的结合常数、结合位点数。荧光光谱结果表明,配合物均可有规律地猝灭BSA的内源荧光,猝灭方式为静态猝灭,壳寡糖-钕和酰化壳寡糖-钕分别与BSA的结合常数为1.33×104L·mol-1和6.95×104L·mol-1,结合位点数为1.05和1.3,说明配合物与BSA均具有较强的结合作用,能够被BSA储存和运输,并且酰化壳寡糖-钕与BSA的结合能力强于壳寡糖-钕。最后采用紫外光谱法对其作用机理进一步确认。因此,酰化壳寡糖-钕可以被BSA存储和运输,有望成为蛋白质荧光探针。     

Thyroxine binding properties of glycosylated bovine serum albumin.

Thyroid hormone, thyroxine (T4) binding properties of glycosylated bovine serum albumin (G-BSA), and intact BSA were studied by the fluorescence method. The apparent binding constants for intact BSA were 0.8 (0.16) x 10(6) M-1 at pH 5.0 and 2.18 (0.06) x 10(6) M-1 at pH 9.5 at 25 degrees C. T4 binding for G-BSA was independent of pH and the apparent binding constant was 1.4 x 10(6) M-1. Thermodynamic parameters were also evaluated from the Van't Hoff plots of the apparent binding constants at pH 7.4 and 8.5. At both pH's, the free energy, enthalpy and entropy changes were almost the same for both G-BSA and BSA.     

Biocompatible polymer vesicles from biamphiphilic triblock copolymers and their interaction with bovine serum albumin

The self-assembly of the biamphiphilic triblock copolymer poly(ethylene oxide)-b-poly(caprolactone)-b-poly(acrylic acid) into polymer vesicles is studied. The vesicles provide both biocompatibility and biodegradability. Moreover, the biamphiphilic nature of the triblock copolymer provides different surface properties in the interior and in the outer interface of the vesicles. Preparation of the aggregates by direct dissolution of the copolymer in a solution of albumin does not alter the morphology of the aggregates, and thus, they have the potential to immobilize protein molecules. Since a part of the protein is encapsulated in the interior of the vesicles, they can be used as nanocontainers. A further fraction of the protein is bound to the outer interface, which is primarily composed of the poly(acrylic acid) tails. Immobilization of protein on the outer interface can stabilize the colloidal particles and also provide them with a biofunctional component.     

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.     

Binding interaction of gatifloxacin with bovine serum albumin.

The binding of gatifloxacin to bovine serum albumin (BSA) in aqueous solution was studied using fluorescence spectroscopy and absorbance spectra, Further, the interactions influenced by Fe3+ and Cu2+ were also explored in this work. Based on Scatchard's site-binding model and florescence quenching, practical formulas for small molecule ligands to bio-macromolecules have been proposed. The binding parameters were measured according to suggested models, and the binding distance and the transfer efficiency of energy between gatifloxacin and BSA were also obtained in view of the F?rster theory of non-radiation energy transfer. The effect of gatifloxacin on the conformation of BSA has also been analyzed using synchronous fluorescence spectroscopy.     

Photosensitizing properties of octacarboxy metallophthalocyanines in aqueous medium and their interaction with bovine serum albumin

Photosensitizing properties of aluminium, silicon, zinc and germanium octacarboxy phthalocyanines ((OH)AlOCPc, (OH)₂SiOCPc, ZnOCPc and (OH)₂GeOCPc) were studied in aqueous medium and in the presence of bovine serum albumin (BSA). Triplet quantum yields increased with increasing atomic number of the central metals of the metallophthalocyanine. The efficiency of singlet oxygen generation via energy transfer from the excited triplet state of the octacarboxy metallophthalocyanines (MOCPcs) to ground state oxygen increased markedly in the presence of BSA. The triplet state lifetimes of the MOCPc complexes in the presence of BSA were found to be longer than in the absence of BSA, ranging from 110 to 580 μs. These complexes bind readily to BSA. Stern–Volmer quenching constant K_SV as well as the binding constant k_b values were calculated. The probable mechanism of quenching of BSA fluorescence by the MOCPc complexes is by static quenching.     

Synthesis and cytotoxicity of pentacyclic triterpenes-aniline nitrogen mustard derivatives

To discover novel nitrogen mustards, the reported mustard pharmacophore was combined with natural pentacyclic triterpenes, which are characterized with pharmacological and structural diversity. Thus, six conjugates were synthesized with 1,2,3-triazole linking N,N-bis (2-chloroethyl)-1,4-phenylenediamine and oleanolic acid, ursolic acid, or glycyrrhetinic acid, and their biological activity was evaluated against tumor cell lines HeLa, BGC-823, BEL-7404, and NCI-H460 using the MTT assay. As a result, these conjugates showed some selective cytotoxicity to NCI-H460, though all their activity potency was moderate or weak in the four cell lines.     

Synthesis and physicochemical characterization of two gadolinium(III) TTDA-like complexes and their interaction with human serum albumin

Two novel derivatives of TTDA (3,6,10-tri(carboxymethyl)-3,6,10-triazadodecanedioic acid), TTDA-BOM and TTDA-N'-BOM, each having a benzyloxymethyl group, were synthesized. (17)O NMR longitudinal and transverse relaxation rates and chemical shifts of aqueous solutions of their Gd(III) complexes were measured at variable temperature with a magnetic field strength of 9.4 T. The water exchange rate (k(ex)(298)) values for [Gd(TTDA-BOM)(H(2)O)](2-) (117 x 10(6) s(-1)) and [Gd(TTDA-N'-BOM)(H(2)O)](2-) (131 x 10(6) s(-1)) are significantly higher than those of [Gd(DTPA)(H(2)O)](2-) (4.1 x 10(6) s(-1)) and [Gd(BOPTA)(H(2)O)](2-) (3.45 x 10(6) s(-1)). The rotational correlation time (tau) values for [Gd(TTDA-BOM)(H(2)O)](2-) (119 ps) and [Gd(TTDA-N'-BOM)(H(2)O)](2-) (125 ps) are higher than those of [Gd(DTPA)(H(2)O)](2-) (103 ps) and [Gd(TTDA)(H(2)O)](2-) (104 ps). The stepwise stoichiometric binding constants of [Gd(TTDA-BOM)(H(2)O)](2)(-) and [Gd(TTDA-N'-BOM)(H(2)O)](2)(-) bound to HSA are obtained by ultrafiltration studies. Fluorescent probe displacement studies exhibit that [Gd(TTDA-BOM)(H(2)O)](2-) and [Gd(TTDA-N'-BOM)(H(2)O)](2-) can displace dansylsarcosine from HSA with inhibition constants (K(i)) of 1900 and 1600 microM, respectively; however, they are not able to displace warfarin. These results indicate that [Gd(TTDA-BOM)(H(2)O)](2-) and [Gd(TTDA-N'-BOM)(H(2)O)](2-) have a weak binding to site II on HSA. In addition, the mean bound relaxivity (r(1b)) and bound relaxivity (r(1)(b)) values for the [Gd(TTDA-BOM)(H(2)O)](2-)/HSA and [Gd(TTDA-N'-BOM)(H(2)O)](2-)/HSA adducts are obtained by ultrafiltration and relaxivity studies, respectively. The bound relaxivity of these adducts values are significantly higher than those of [Gd(BOPTA)(H(2)O)](2-)/HSA and [Gd(DTPA-BOM(3))(H(2)O)](2-)/HSA. These results also suggest that bound relaxivity is site dependent. In binding sites studies of Gd(III) chelates to HSA, a significant decrease of the relaxation rates (R(1obs)) was observed for the [Eu(TTDA-BOM)(H(2)O)](2-) complex which was added to the [Gd(TTDA-N'-BOM)(H(2)O)](2-)/HSA solution, and this indicated that these Gd(III) complexes share the same HSA binding site. Finally, as measured by the Zn(II) transmetalation process, the kinetic stability of these Gd(III) complexes are significantly higher than that of [Gd(DTPA-BMA)(H(2)O)].     

18β-Glycyrrhetinic acid interaction with bovine serum albumin

The interaction of 18β-glycyrrhetinic acid (GA): The metabolite of glycyrrhizic acid which is the main active component of a commonly used traditional Chinese medicine (TCM) Glycyrrhiza Uralensis Fisch with bovine serum albumin (BSA) has been investigated. Fluorescence emission spectra of serum albumin in the presence of GA, recorded at the excitation wavelength 280 nm, clearly show that GA act as quencher and have different quenching mechanism at a pH below or above the isoelectric point (pI). The binding sites number n and apparent binding constant K were measured. The thermodynamic parameters ΔH°, ΔG°, ΔS° at different temperatures were calculated. The effects of some common metal ions on binding are considered. Synchronous fluorescence and UV–vis spectra were used to study protein conformation. Energy transfer between GA and HSA was calculated by Förster's theory and the binding site was suggested to be site II. The binding of monoammonium glycyrrhizinate (GL) to BSA is also compared.     

四羧基酞菁钴配合物的合成及其与牛血清蛋白的相互作用

在诸多治疗癌症的方法中,光动力治疗(photodynamin therapy)因其独特的优点而日益受到重视,成为近年来研究的热点之一.动力学治疗所使用的光敏剂称为抗癌光敏剂,是PDT疗法的关键.     

Study of the interaction of indirubin with bovine serum albumin

This study examined the interaction of indirubin with bovine serum albumin (BSA) at three temperatures (286, 297, 308 K) at pH 7.40. In the presence of indirubin, the drug-BSA binding mode, binding constant and the protein structure changes in aqueous solution were determined by fluorescence quenching methods including Fourier transform infrared (FT-IR) spectroscopy and UV-Vis spectroscopy. The FT-IR change indicates that indirubin binds to BSA. The change in protein secondary structure accompanying ligand binding has been proved by fluorescence spectra data. The thermodynamic parameters, the enthalpy change (DeltaH), and the entropy change (DeltaS) calculated by the van't Hoff equation possess small negative (-2.744 kJ.mol(-1)) and positive values (112.756 J.mol(-1).K(-1)), respectively, which indicated that hydrophobic interactions play the main role in the binding of indirubin to BSA. Furthermore, the displacement experiment shows that indirubin can bind to the subdomain IIA and the distance between the tryptophan residues in BSA and indirubin bound to site I was estimated to be 2.24 nm according to F?ster's equation on the basis of fluorescence energy transfer.     

槲皮素-铝配合物的制备及其与BSA的结合作用

在甲醇溶液中合成了槲皮素-铝配合物(Que-Al),并用紫外-可见吸收光谱和红外光谱进行了表征;运用荧光光谱探讨了Que-Al与牛血清白蛋白(BSA)的相互作用;求得了结合常数KA和热力学参数△H、△G、和△S.结果表明,Que-Al对BSA具有荧光猝灭作用,其猝灭方式为动态猝灭;Que-Al与BSA之间的作用力主要为疏水作用力.     

Aggregation of two carboxylic derivatives of porphyrin and their affinity to bovine serum albumin

Aggregation of two porphyrin derivatives with carboxylic groups, 4-oxo-4-((4-(10,15,20-triphenyl-21H,23H-porphin-5-yl)phenyl)amino)butanoic acid (MAC) and 4,4',4',4'-[21H,23H-porphine-5,10,15,20-tetrayltetrakis(4,1-phenyleneimino)]tetrakis(4-oxo-butanoic acid) (TA4C), and their affinity to bovine serum albumin were investigated via absorption spectrometry, (1)H NMR and fluorescence spectrometry. MAC and its complexes with beta-cyclodextrin could form aggregates in an aqueous solution while TA4C was self-associated loosely. From the absorbance profiles of MAC in the titration of bovine serum albumin, hypochromicity was observed without any shift of the maximum absorbance wavelength. In both absorption spectra of TA4C in aqueous solutions and in solid state, three Q bands appeared in the visible region. In the measurements of absorption and fluorescence spectra upon titration of BSA, some spectral changes of TA4C were observed. The whole procedure of titration could be divided into three successive stages. The three-banded profiles of TA4C might be explained according to a loose dimer model.     

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。     

大豆苷元与牛血清白蛋白的相互作用研究

采用荧光和紫外-可见吸收光谱,研究了大豆苷元与牛血清白蛋白(BSA)的相互作用.结果表明大豆苷元对BSA有较强的荧光猝灭作用;根据Stern-Volmer方程得到大豆苷元与BSA之间的结合常数KA为0.385×105 (30℃)、0.405×105(40℃)和0.431×105(50℃).根据F(o)rster非辐射能量转移理论,求出了大豆苷元与BSA之间的结合距离为2.34 nm(30℃)、2.48 nm(40℃)和2.71 nm(50℃).热力学数据表明大豆苷元与BSA之间的作用力主要为疏水作用力,同时用同步荧光光谱探讨了大豆苷元对BSA构象的影响.     

The interaction of dansyl amino acids with bovine serum albumin

The interaction of 5-dimethylaminonaphthalene-1-sulfonyl (DNS or dansyl) amino acids with bovine serum albumin (BSA) was investigated by means of fluorescence measurements. Fluorometric titrations revealed that BSA has one high affinity site (binding constant,K _a=10⁵10⁶ M^–1), and other sites of lower affinity (K _a=10³10⁴ M^–1) for the probes. Static excitation and emission spectra, lifetimes, time resolved emission spectra, and anisotropy data indicated that the binding is stabilized mainly through fixation by the high affinity binding site. The binding constant significantly decreased with the increase of the spacer distance between the dansyl and anionic groups of the probe molecule. This observation was explained by considering the change of the electrostatic interaction between the anionic group of the probe and a cationic residue in the vicinity of the site.