Investigations on the Interaction between Cuprous Oxide Nanocubes and Bovine Serum Albumin with Comprehensive Spectroscopic Methods

The interaction between cuprous oxide (Cu(2)O) nanocubes and bovine serum albumin (BSA) was investigated from a spectroscopic angle under simulative physiological conditions. Under pH 7.4, Cu(2)O could effectively quench the intrinsic fluorescence of BSA via static quenching. The apparent binding constant (K(A)) was 3.23, 1.91, and 1.20?×?10(4) M(-1) at 298, 304, and 310 K, respectively, and the number of binding sites was 1.05. According to the Van't Hoff equation, the thermodynamic parameters (ΔH° = -63.39 kJ mol(-1), ΔS° = -126.45 J?mol(-1) K(-1)) indicated that hydrogen bonds and van der Waals forces played a major role in stabilizing the BSA-Cu(2)O complex. Besides, the average binding distance (r(0)?= 2.76 nm) and the critical energy transfer distance (R(0) = 2.35 nm) between Cu(2)O and BSA were also evaluated according to F?rster's non-radioactive energy transfer theory. Furthermore, UV-visible and circular dichroism results showed that the addition of Cu(2)O changed the secondary structure of BSA and led to a decrease in α-helix. All results showed that BSA underwent substantial conformational changes induced by Cu(2)O, which can be very helpful in the study of nanomaterials in the application of biomaterials.     

Spectroscopic Investigation of the Interaction Between Copper (II) 2-oxo-propionic Acid Salicyloyl Hydrazone Complex and Bovine Serum Albumin

The interaction between copper (II) 2-oxo-propionic acid salicyloyl hydrazone (Cu^IIL) and bovine serum albumin (BSA) under physiological conditions was investigated by the methods of fluorescence spectroscopy, UV-Vis absorption, and circular dichroism spectroscopy. Fluorescence data showed that the fluorescence quenching of BSA by Cu^IIL was the result of the formation of the BSA–Cu^IIL complex. The apparent binding constants (K _a) between Cu^IIL and BSA at four different temperatures were obtained according to the modified Stern–Volmer equation. The thermodynamic parameters, enthalpy change (ΔH) and entropy change (ΔS), for the reaction were calculated to be ?80.79 kJ mol^?1 and ?175.48 J mol^?1 K^?1 according to van’t Hoff equation. The results indicated that van der Waals force and hydrogen bonds were the dominant intermolecular force in stabilizing the complex. The binding distance (r) between Cu^IIL and the tryptophan residue of BSA was obtained to be 4.1 nm according to Förster’s nonradioactive energy transfer theory. The conformational investigation showed that the application of Cu^IIL increased the hydrophobicity of amino acid residues and decreased the α-helical content of BSA (from 62.71% to 37.31%), which confirmed some microenvironmental and conformational changes of BSA molecules.     

Investigation of the Interaction of Naringin Palmitate with Bovine Serum Albumin: Spectroscopic Analysis and Molecular Docking

Background

Bovine serum albumin (BSA) contains high affinity binding sites for several endogenous and exogenous compounds and has been used to replace human serum albumin (HSA), as these two compounds share a similar structure. Naringin palmitate is a modified product of naringin that is produced by an acylation reaction with palmitic acid, which is considered to be an effective substance for enhancing naringin lipophilicity. In this study, the interaction of naringin palmitate with BSA was characterised by spectroscopic and molecular docking techniques.

Methodology/Principal Findings

The goal of this study was to investigate the interactions between naringin palmitate and BSA under physiological conditions, and differences in naringin and naringin palmitate affinities for BSA were further compared and analysed. The formation of naringin palmitate-BSA was revealed by fluorescence quenching, and the Stern-Volmer quenching constant (K_SV) was found to decrease with increasing temperature, suggesting that a static quenching mechanism was involved. The changes in enthalpy (ΔH) and entropy (ΔS) for the interaction were detected at −4.11±0.18 kJ·mol⁻¹ and −76.59±0.32 J·mol⁻¹·K⁻¹, respectively, which indicated that the naringin palmitate-BSA interaction occurred mainly through van der Waals forces and hydrogen bond formation. The negative free energy change (ΔG) values of naringin palmitate at different temperatures suggested a spontaneous interaction. Circular dichroism studies revealed that the α-helical content of BSA decreased after interacting with naringin palmitate. Displacement studies suggested that naringin palmitate was partially bound to site I (subdomain IIA) of the BSA, which was also substantiated by the molecular docking studies.

Conclusions/Significance

In conclusion, naringin palmitate was transported by BSA and was easily removed afterwards. As a consequence, an extension of naringin applications for use in food, cosmetic and medicinal preparations may be clinically and practically significant, especially in the design of new naringin palmitate-inspired drugs.     

荷叶中紫云英苷和牛血清白蛋白相互作用的光谱学研究

本文采用荧光光谱法、紫外光谱法研究在生理条件(pH=7.4)下荷叶中紫云英苷(AST)与牛血清白蛋白(BSA)的相互作用。结果表明AST可与BSA结合并通过静态猝灭作用机制对BSA内源性荧光进行猝灭。在温度为298K及308K时,测得其猝灭速率常数(Kq)分别为4.31×1013L/mol/s和3.72×1013L/mol/s;结合常数(Kd)分别为2.009×105L/mol和0.927×105L/mol;结合位点数(n)分别为0.943和0.893。依据298K时测定的反应自由能变(△G0=-30.25kJ/mol),反应焓变(△H0=-59.02kJ/mol)及反应熵变(△S0=-96.54J/mol/K),结果发现AST与BSA间的结合反应可自发进行且其作用力主要表现为氢键和范德华力。此外,根据Frster非辐射能量转移理论得到AST与BSA之间的结合距离(r)为4.13nm,表明非辐射能量可从BSA转移至AST。     

Investigation of the Interaction of Sorafenib with Alpha-Lactalbumin: Spectroscopic and Molecular Modeling

Russian Journal of Bioorganic Chemistry - In this work binding properties and conformational changes in alpha lactalbumin (α-LA) upon interaction with sorafenib were investigated by...     

Spectroscopic Studies on the Interaction of Fluorine Containing Triazole with Bovine Serum Albumin

The binding of one fluorine including triazole (C₁₀H₉FN₄S, FTZ) to bovine serum albumin (BSA) was studied by spectroscopic techniques including fluorescence spectroscopy, UV–Vis absorption, and circular dichroism (CD) spectroscopy under simulative physiological conditions. Fluorescence data revealed that the fluorescence quenching of BSA by FTZ was the result of forming a complex of BSA–FTZ, and the binding constants (K _a) at three different temperatures (298, 304, and 310 K) were 1.516?×?10⁴, 1.627?×?10⁴, and 1.711?×?10⁴?mol L^?1, respectively, according to the modified Stern–Volmer equation. The thermodynamic parameters ΔH and ΔS were estimated to be 7.752 kJ mol^?1 and 125.217 J?mol^?1?K^?1, respectively, indicating that hydrophobic interaction played a major role in stabilizing the BSA–FTZ complex. It was observed that site I was the main binding site for FTZ to BSA from the competitive experiments. The distance r between donor (BSA) and acceptor (FTZ) was calculated to be 7.42 nm based on the Förster theory of non-radioactive energy transfer. Furthermore, the analysis of fluorescence data and CD data revealed that the conformation of BSA changed upon the interaction with FTZ.     

Biophysical Study on the Interaction of Ceftriaxone Sodium with Bovine Serum Albumin Using Spectroscopic Methods

The interaction of ceftriaxone sodium (CS), a cephalosporin antibiotic, with the major transport protein, bovine serum albumin (BSA), was investigated using different spectroscopic techniques such as fluorescence, circular dichroism (CD), and UV–vis spectroscopy. Values of binding parameters for BSA–CS interaction in terms of binding constant and number of binding sides were found to be 9.00 × 10³, 3.24 × 10³, and 2.30 × 10³ M^?1 at 281, 301, and 321 K, respectively. Thermodynamic analysis of the binding data obtained at different temperatures showed that the binding process was spontaneous and was primarily mediated by van der Waals force or hydrogen bonding. CS binding to BSA caused secondary structural alterations in the protein as revealed by CD results. The distance between CS and Trp of BSA was determined as 3.23 nm according to the Förster resonance energy transfer theory. © 2012 Wiley Periodicals, Inc. J Biochem Mol Toxicol 26:487‐492, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/jbt.21446     

EPR Spectroscopic Study of the Interaction of E. coliCells with Ascorbic Acid and Sodium Nitrite

Ascorbic acid, an effective modulator and regulator of cell metabolism, was shown to induce the production of nitric oxide inE. colicells. This process was detected by EPR spectroscopy as the generation of a spectral signal typical of nitrosyl–iron–sulfur centers (Fe–S–NO) under anaerobic conditions. Incubation of E. colicells in the presence of ascorbic acid under aerobic conditions was shown to be accompanied by sodium nitrite formation. It is suggested that ascorbic acid is capable of supporting the system of energy supply to cells in hypoxia caused by reduced oxygen content or treatment with sodium nitrite.     

罗丹明类荧光分子探针与血清白蛋白之间相互作用的研究

本研究旨在对罗丹明类荧光探针ZM-6与人血清白蛋白(HSA)的相互作用进行研究。采用了荧光光谱法、三维荧光光谱法、同步荧光光谱法以及CD光谱法在模拟生理条件下对二者的相互作用以及HSA的构象进行了研究。研究结果表明,探针与ZM-6之间的猝灭机理主要是静态猝灭方式。根据热力学数据确定了二者之间的作用力,类型为范德华力和氢键。二者之间的结合距离为4.45 nm。同时得出,ZM-6对HSA的构象产生了影响。此研究对于探针分子的设计以及修饰提供有效的数据以及理论支持。     

Interaction of Antimalarial Drug Quinacrine with Nucleic Acids of Variable Sequence Studied by Spectroscopic Methods

Abstract

The interaction of antimalarial drug quinacrine (QA) with polynucleotides is studied by UV- visible absorption, fluorescence and surface-enhanced Raman spectroscopy(SERS). The polynucleotides employed for such a study were calf thymus DNA, poly(A).poly(T), poly(A).poly(U), poly(C).poly(G) and poly(dG-dC).poly(dG-dC). Absorption and fluorescence spectra of QA complexes indicate that an interaction with the biomolecule is taking place, although different interaction mechanisms are probable depending on the sequence. The SERS spectra also reflect spectral changes which depend on the polymer sequence and that can be correlated to those observed by fluorescence, with the advantage of the detailed structural information provided by this vibrational technique. QA interacts with polynucleotides through its diprotonated form and by ring stacking. The strength of such interaction is extremely sequence dependent, thus suggesting different interaction mechanisms in each case. The SERS technique allows the simultaneous study of those polynucleotide moieties that are directly involved in the interaction thanks to the short-range character of the SERS spectroscopy. The interaction of QA with the above nucleic acids lead to a different change in the chain stability and flexibility which is further related to the different denaturation tendency of the polymer in the presence of the metal surface.     

The Interaction of Human Serum with the Plant Hormone Indole-3-Acetic Acid

It is well known that human serum inhibits the longitudinal root growth in Lupinus albus L and Triticum sativum Lam. This inhibitory effect has been ascribed to the IAA content in human serum, which unfortunately has never been measured quantitatively. Experiments are presented in which Triticum roots are grown in media with pooled human serum and varying concentrations of IAA. In the presence of 10^?5M p-chlorophenoxy-isobutyric acid (PCIB) and serum, minute IAA additions promoted the growth. This feature hardly could be expected were the serum inhibition in itself an IAA effect. In view of this finding, renewed but unsuccessful attempts were made to demonstrate a similar promotion in media without serum. To explain the observed response curves, it must be further assumed that serum components bind IAA reversibly. In experiments without PCIB in the medium the response curves were similar at a lower level of growth, except that no growth promotion by IAA was discernible. It is concluded, that the inhibiting effect of human serum on the growth of plant roots is not due to free IAA, although IAA in all probability occurs in that fluid.     

Investigation of the Interaction between Nilotinib and Alpha-Lactalbumin by Spectroscopic Methods and Docking Studies

Russian Journal of Bioorganic Chemistry - The interaction of Nilotinib (NIL) with alpha lactalbumin (α-LA) were studied by spectrofluorimetry, UV-Vis spectroscopy, circular dichroism (CD) and...     

The Molar Combining Ratio of Anti-Albumin Fab' Fragments to Homologous and Heterologous Serum Albumins

The number of antibody combining sites on bovine (BSA), goat (GSA) and sheep (SSA) serum albumins was studied using rabbit and chicken antibodies. In homologous reactions, the profiles of quantitative precipitations with chicken antibody were similar to those with rabbit antibody reported previously (12), and the antigenic valence in the extreme antibody excess zone was found to be 6–7 for each albumin. The univalent Fab' fragments of rabbit and chicken antibodies were prepared. The stoichiometry of the soluble complex formed with the Fab' fragment and fluorescence labeled albumin was analyzed by gel filtration, and the number of Fab' fragment molecules capable of binding to an albumin molecule was estimated. In a homologous reaction with both rabbit and chicken Fab' fragments, the Fab' to albumin combining ratio revealed from the molecular weight of the soluble complex was 14:1. In the heterologous reactions, the combining ratio was 5:1 for rabbit Fab' fragment to BSA, and 9:1 for chicken Fab' fragment to BSA. From the heterologous reactions between GSA and SSA, it was demonstrated that the combining ratios were 10–11:1 with rabbit Fab' fragment and 11–13:1 with chicken Fab' fragment.     

Spectroscopic Evidence for Complexing of Acetic Acid with Bovine Serum Albumin, Gramicidin, and Dimethylformamide

Acetic acid has a major effect on the absorption spectra of bovine serum albumin, gramicidin, and dimethylformamide in the region, 255 to 200 mμ. Increasing the concentration of acetic acid causes progressively decreasing absorbency accompanied by a large and progressively increasing red shift of the absorption maximum. The decrease in absorbency is interpreted in terms of a reversible complexing of acetic acid with these molecules and the red shift in terms of a non-specific solvent effect.     

Synergistic Effects of Trace Amounts of Water in the Enantiodiscrimination Processes by Lipodex E: A Spectroscopic and Computational Investigation

Nuclear magnetic resonance (NMR) investigations on mixtures containing octakis(3‐O‐butanoyl‐2,6‐di‐O‐pentyl)‐γ‐cyclodextrin (Lipodex E) and each enantiomer of methyl‐2‐chloropropionate (MCP) ascertained the role of trace amounts of water in the enantiodiscrimination processes. Water is deeply included into the cyclodextrin and favors the formation of the inclusion complex with (S)‐MCP, whereas (R)‐MCP is only slightly affected, thus causing a significant increase of NMR differentiation. Molecular dynamics simulations were performed to shed light on the possible behavior of Lipodex E in different conditions (i.e., solvent, inclusion complexes), providing energetic and atomistic details that are in agreement with NMR observations. Chirality 27:95–103, 2014. © 2014 Wiley Periodicals, Inc.     

Analysis of Binding Interaction Between Antibacterial Ciprofloxacin and Human Serum Albumin by Spectroscopic Techniques

To develop an efficient method for extracting and purifying the active ingredient, arctiin, from Fructus arctii and to investigate the protective effect of arctiin against glucose-induced rat aortic endothelial cell (RAEC) injury was investigated. Using a L9 (34) orthogonal array and two-step column chromatography (with AB-8 macroporous resin) arctiin extraction was optimized using a reflux method with 70 % ethanol. The RAECs were then treated with different concentrations of arctiin (1, 10, or 100 μg/ml). The effects of arctiin on cell viability in a high glucose medium, malondialdehyde (MDA) levels, and lactate dehydrogenase were measured using commercially available assays. After extraction, the purity of arctiin reached 95.7 %. In rats, arctiin was shown to stimulate the proliferation of RAECs in a high glucose medium in a dose-dependent manner. Exposure of RAECs to high glucose resulted in a significant increase in MDA and release of lactate dehydrogenase. This was accompanied by significant increase in nitric oxide release and expression of antiendothelial nitric oxide synthase. This technique resulted in relatively pure arctiin extraction. Furthermore, the results from this study suggest that arctiin could potentially function as a protector against vascular endothelial cell injury and further investigation is warranted.     

药物重定位的计算分析方法

全新结构药物的研发存在周期长、耗资大、风险高的问题.通过各种技术预测已有药物的新适应症,即药物重定位,可以缩短药物研发时间、降低研发成本和风险.由于疾病种类和已知药物的数量繁多,完全通过实验筛选已知药物的新用途仍然具有很高的成本.随着组学和药物信息学数据的积累,药物重定位进入到了理性设计和实验筛选相结合的阶段,药物重定位的计算预测已经成为计算生物学和系统生物学的重要研究方向.本文将目前药物重定位计算分析的策略归纳为药物-靶标关系分析、药物-药物关系分析和药物-疾病关系分析,对已报道的技术方法及其成功应用实例进行了综述.     

Interaction of Serum Albumin and Fatty Acid Molecules with Graphenes of Shungite Carbon Nanoparticles in Aqueous Dispersion Assessed by Raman Spectroscopic Analysis of Water in the High Wavenumber Region

Biophysics - Raman spectroscopy was used to analyze the positions of extrema, amplitudes, and widths of the main Raman spectral lines in the wavenumber range 3200–3600 cm–1 attributed...     

Probing the Interaction of a Therapeutic Flavonoid,Pinostrobin with Human Serum Albumin: Multiple Spectroscopic and Molecular Modeling Investigations

Interaction of a pharmacologically important flavonoid, pinostrobin (PS) with the major transport protein of human blood circulation, human serum albumin (HSA) has been examined using a multitude of spectroscopic techniques and molecular docking studies. Analysis of the fluorescence quenching data showed a moderate binding affinity (1.03 × 10⁵ M⁻¹ at 25°C) between PS and HSA with a 1∶1 stoichiometry. Thermodynamic analysis of the binding data (ΔS = +44.06 J mol⁻¹ K⁻¹ and ΔH = −15.48 kJ mol⁻¹) and molecular simulation results suggested the involvement of hydrophobic and van der Waals forces, as well as hydrogen bonding in the complex formation. Both secondary and tertiary structural perturbations in HSA were observed upon PS binding, as revealed by intrinsic, synchronous, and three-dimensional fluorescence results. Far-UV circular dichroism data revealed increased thermal stability of the protein upon complexation with PS. Competitive drug displacement results suggested the binding site of PS on HSA as Sudlow’s site I, located at subdomain IIA, and was well supported by the molecular modelling data.     

Spectroscopic and Molecular Modeling Studies on the Interaction Between a Fluorine-Containing Triazole Derivative and Human Serum Albumin

The interaction between 4-(4-fluorobenzylideneamino)-5-propyl-4H-1,2,4-triazole-3-thiol (FBTZ) and human serum albumin (HSA) under simulative physiological conditions was investigated by fluorescence, UV–vis absorption and circular dichroism (CD) spectroscopy as well as molecular modeling method. Fluorescence spectroscopic data showed that the fluorescence quenching of HSA was a result of the formation of FBTZ–HSA complex. According to the modified Stern–Volmer equation, the effective quenching constants (K _a) of FBTZ to HSA were obtained at three different temperatures. The enthalpy change (ΔH) and entropy change (ΔS) were calculated on the basis of van′t Hoff equation, and the results showed that hydrogen-bonding and van der Waals forces were the dominant intermolecular forces to stabilize the complex. Site marker competitive replacement experiments demonstrated that the binding of FBTZ to HSA primarily took place in sub-domain IIA (Sudlow’s site I). The binding distance (r) between FBTZ and the tryptophan residue of HSA was estimated according to the theory of fluorescence resonance energy transfer. The conformational investigation showed that the presence of FBTZ induced some changes of secondary structure of HSA. Molecular modeling study further confirmed the binding mode obtained by experimental study.