Study of the interaction between sodium salts of (2E)‐3‐(4'‐halophenyl)prop‐2‐enoyl sulfachloropyrazine and bovine serum albumin by fluorescence spectroscopy

Three sodium salts of (2E)‐3‐(4'‐halophenyl)prop‐2‐enoyl sulfachloropyrazine (CCSCP) were synthesized and their structures were determined by ¹H and ¹³C NMR, LC‐MS and IR. The binding properties between CCSCPs and bovine serum albumin (BSA) were studied using fluorescence spectroscopy in combination with UV–vis absorbance spectroscopy. The results indicate that the fluorescence quenching mechanisms between BSA and CCSCPs were static quenching at low concentrations of CCSCPs or combined quenching (static and dynamic) at higher CCSCP concentrations of 298, 303 and 308 K. The binding constants, binding sites and corresponding thermodynamic parameters (ΔH, ΔS, ΔG) were calculated at different temperatures. All ΔG values were negative, which revealed that the binding processes were spontaneous. Although all CCSCPs had negative ΔH and positive ΔS, the contributions of ΔH and ΔS to ΔG values were different. When the 4'‐substituent was fluorine or chlorine, van der Waals interactions and hydrogen bonds were the main interaction forces. However, when the halogen was bromine, ionic interaction and proton transfer controlled the overall energetics. The binding distances between CCSCPs and BSA were determined using the Förster non‐radiation energy transfer theory and the effects of CCSCPs on the conformation of BSA were analyzed by synchronous fluorescence spectroscopy. Copyright © 2012 John Wiley & Sons, Ltd.     

Combined spectroscopies and molecular docking approach to characterizing the binding interaction of enalapril with bovine serum albumin

The binding interaction between bovine serum albumin (BSA) and enalapril (ENPL) at the imitated physiological conditions (pH = 7.4) was investigated using UV–vis absorption spectroscopy (UV–vis), fluorescence emission spectroscopy (FES), synchronous fluorescence spectroscopy (SFS), Fourier transform infrared spectroscopy (FT‐IR), circular dichroism (CD) and molecular docking methods. It can be deduced from the experimental results from the steady‐state fluorescence spectroscopic titration that the intrinsic BSA fluorescence quenching mechanism induced by ENPL is static quenching, based on the decrease in the BSA quenching constants in the presence of ENPL with increase in temperature and BSA quenching rates >10¹⁰ L mol^?1 sec^?1. This result indicates that the ENPL–BSA complex is formed through an intermolecular interaction of ENPL with BSA. The main bonding forces for interaction of BSA and ENPL are van der Waal's forces and hydrogen bonding interaction based on negative values of Gibbs free energy change (ΔG ⁰), enthalpic change (ΔH ⁰) and entropic change (ΔS ⁰). The binding of ENPL with BSA is an enthalpy‐driven process due to |ΔH °| > |T ΔS °| in the binding process. The results of competitive binding experiments and molecular docking confirm that ENPL binds in BSA sub‐domain IIA (site I) and results in a slight change in BSA conformation, but BSA still retains its α‐helical secondary structure.     

Study on the interaction between anti‐tuberculosis drug ethambutol and bovine serum albumin: multispectroscopic and cyclic voltammetric approaches

The binding of bovine serum albumin (BSA) to ethambutol (EMB) was investigated using spectroscopic methods, viz., fluorescence, Fourier transform infrared (FTIR), ultraviolet (UV)/vis absorption and cyclic voltammetry techniques. Spectroscopic analysis of the emission quenching at different temperatures revealed that the quenching mechanism of serum albumin by EMB is static, which was also confirmed by lifetime measurements. The number of binding sites, n, and binding constant, K, were obtained at various temperatures. The distance, r, between EMB and the protein was evaluated according to the Förster energy transfer theory. Based on displacement experiments using site probes, viz., warfarin, ibuprofen and digitoxin, the site of binding of EMB in BSA was proposed to be Sudlow's site I. The effect of EMB on the conformation of BSA was analyzed by using synchronous fluorescence spectra (SFS) and 3D fluorescence spectra. The results of fluorescence, UV/vis absorption and FTIR spectra showed that the conformation of BSA was changed in the presence of EMB. The thermodynamic parameters including enthalpy change (ΔH⁰), entropy change (ΔS⁰) and free energy change (ΔG⁰) for BSA–EMB were calculated according to the van't Hoff equation and are discussed.     

Characterization of intermolecular interaction between cyanidin‐3‐glucoside and bovine serum albumin: Spectroscopic and molecular docking methods

The intermolecular interaction between cyanidin‐3‐glucoside (Cy‐3‐G) and bovine serum albumin (BSA) was investigated using fluorescence, circular dichroism and molecular docking methods. The experimental results revealed that the fluorescence quenching of BSA at 338 nm by Cy‐3‐G resulted from the formation of Cy‐3‐G–BSA complex. The number of binding sites (n) for Cy‐3‐G binding on BSA was approximately equal to 1. The experimental and molecular docking results revealed that after binding Cy‐3‐G to BSA, Cy‐3‐G is closer to the Tyr residue than the Trp residue, the secondary structure of BSA almost not change, the binding process of Cy‐3‐G with BSA is spontaneous, and Cy‐3‐G can be inserted into the hydrophobic cavity of BSA (site II′) in the binding process of Cy‐3‐G with BSA. Moreover, based on the sign and magnitude of the enthalpy and entropy changes (ΔH⁰ = – 29.64 kcal/mol and ΔS⁰ = – 69.51 cal/mol K) and the molecular docking results, it can be suggested that the main interaction forces of Cy‐3‐G with BSA are Van der Waals and hydrogen bonding interactions. Copyright © 2013 John Wiley & Sons, Ltd.     

Combined multispectroscopic and molecular docking investigation on the interaction between delphinidin‐3‐O‐glucoside and bovine serum albumin

Anthocyanin is one of the flavonoid phytopigments with specific health benefits. The interaction between delphinidin‐3‐O‐glucoside (D3G) and bovine serum albumin (BSA) was investigated by fluorescence spectroscopy, synchronous fluorescence spectroscopy, three‐dimensional fluorescence spectroscopy, ultraviolet‐visible absorption spectroscopy, circular dichroism spectroscopy and molecular modeling. D3G effectively quenched the intrinsic fluorescence of BSA via static quenching. The number of binding sites and binding constant K_a were determined, and the hydrogen bonds and van der Waals forces played major roles in stabilizing the D3G–BSA complex. The distance r between donor and acceptor was obtained as 2.81 nm according to Förster's theory. In addition, the effects of pH and metal ions on the binding constants were discussed. The results studied by synchronous fluorescence, three‐dimensional fluorescence and circular dichroism experiments indicated that the secondary structures of the protein has been changed by the addition of D3G and the α‐helix content of BSA decreased (from 56.1% to 52.4%). Furthermore, the study of site marker competitive experiments and molecular modeling indicated that D3G could bind to site I of BSA, which was in the large hydrophobic cavity of subdomain IIA. Copyright © 2014 John Wiley & Sons, Ltd.     

Fluorescent bovine serum albumin interacting with the antitussive quencher dextromethorphan: a spectroscopic insight

The interaction of dextromethorphan hydrobromide (DXM) with bovine serum albumin (BSA) is studied by using fluorescence spectra, UV–vis absorption, synchronous fluorescence spectra (SFS), 3D fluorescence spectra, Fourier transform infrared (FTIR) spectroscopy and circular dichroism under simulated physiological conditions. DXM effectively quenched the intrinsic fluorescence of BSA. Values of the binding constant, K_A, are 7.159 × 10³, 9.398 × 10³ and 16.101 × 10³ L/mol; the number of binding sites, n, and the corresponding thermodynamic parameters ΔG°, ΔH° and ΔS° between DXM and BSA were calculated at different temperatures. The interaction between DXM and BSA occurs through dynamic quenching and the effect of DXM on the conformation of BSA was analyzed using SFS. The average binding distance, r, between the donor (BSA) and acceptor (DXM) was determined based on Förster's theory. The results of fluorescence spectra, UV–vis absorption spectra and SFS show that the secondary structure of the protein has been changed in the presence of DXM. Copyright © 2015 John Wiley & Sons, Ltd.     

Spectroscopic investigation of water‐soluble alloyed QDs with bovine serum albumin

We present here a systematic investigation on the interaction between a water‐soluble alloyed semiconductor quantum dot and bovine serum albumin using various spectroscopic techniques i.e. fluorescence quenching, resonance light scattering and synchronous fluorescence spectroscopy. The analysis of fluorescence spectrum and fluorescence intensity indicates that the intrinsic fluorescence of bovine serum albumin (BSA) gets quenched by both static and dynamic quenching mechanism. The Stern‐Volmer quenching constants, energy transfer efficiency parameters, binding parameters and corresponding thermodynamic parameters (ΔH⁰, ΔS⁰ and ΔG⁰) have been evaluated by using van 't Hoff equation at different temperatures. A positive entropy change with a positive enthalpy change was observed suggesting that the binding process was an entropy‐driven, endothermic process associated with the hydrophobic effect. The intermolecular distance (r) between donor (BSA) and acceptor (CdSeS/ZnS quantum dots) was estimated according to Förster's theory of non‐radiative energy transfer. The synchronous fluorescence spectra revealed a blue shift in the emission maxima of tryptophan which is indicative of increasing hydrophobicity. Negative ΔG⁰ values implied that the binding process was spontaneous. It was found that hydrophobic forces played a role in the quenching process. Copyright © 2016 John Wiley & Sons, Ltd.     

A study on the interaction between 3‐spiro‐piperidones and bovine serum albumin using spectroscopic approaches

The interaction between 3‐spiro‐2′‐pyrrolidine‐3′‐spiro‐3″‐piperidine‐2,3″‐dione (PPD) and bovine serum albumin (BSA) in aqueous solution was studied using fluorescence and UV–vis spectroscopy. Fluorescence emission data revealed that BSA (1.00 × 10^‐5 mol/L) fluorescence was statically quenched by PPD at various concentrations, which implies that a PPD–BSA complex was formed. The binding constant (K_A), the number of binding sites (n) and the specific binding site of the PPD with BSA were determined. Energy‐transfer efficiency parameters were determined and the mechanism of the interaction discussed. The thermodynamic parameters, ΔG, ΔH and ΔS, were obtained according to van't Hoff's equation, showing the involvement of hydrophobic forces in these interactions. The effect of PPD acting on the BSA conformation was detected by synchronous fluorescence. Copyright © 2012 John Wiley & Sons, Ltd.     

Study of fluorescence interaction and conformational changes of bovine serum albumin with histamine H1‐receptor–drug epinastine hydrochloride by spectroscopic and time‐resolved fluorescence methods

The fluorescence, ultraviolet (UV) absorption, time resolved techniques, circular dichroism (CD), and infrared spectral methods were explored as tools to investigate the interaction between histamine H₁ drug, epinastine hydrochloride (EPN), and bovine serum albumin (BSA) under simulated physiological conditions. The experimental results showed that the quenching of the BSA by EPN was static quenching mechanism and also confirmed by lifetime measurements. The value of n close to unity indicated that one molecule of EPN was bound to protein molecule. The binding constants (K) at three different temperatures were calculated (7.1 × 10⁴, 5.5 × 10⁴, and 3.9 × 10⁴M⁻¹). Based on the thermodynamic parameters (ΔH⁰, ΔG⁰, and ΔS⁰), the nature of binding forces operating between drug and protein was proposed. The site of binding of EPN in the protein was proposed to be Sudlow's site I based on displacement experiments using site markers viz, warfarin, ibuprofen, and digitoxin. Based on the Förster's theory of non‐radiation energy transfer, the binding average distance, r between the donor (BSA) and acceptor (EPN) was evaluated and found to be 4.48 nm. The UV–visible, synchronous fluorescence, CD, and three‐dimensional fluorescence spectral results revealed the changes in secondary structure of the protein upon its interaction with EPN. © 2015 Wiley Periodicals, Inc. Biopolymers 103: 646–657, 2015.     

Spectroscopic and molecular modelling analysis of the interaction between ethane‐1,2‐diyl bis(N,N‐dimethyl‐N‐hexadecylammoniumacetoxy)dichloride and bovine serum albumin

Several spectroscopic approaches namely fluorescence, time‐resolved fluorescence, UV‐visible, and Fourier transform infra‐red (FT‐IR) spectroscopy were employed to examine the interaction between ethane‐1,2‐diyl bis(N,N‐dimethyl‐N‐hexadecylammoniumacetoxy)dichloride (16‐E2‐16) and bovine serum albumin (BSA). Fluorescence studies revealed that 16‐E2‐16 quenched the BSA fluorescence through a static quenching mechanism, which was further confirmed by UV–visible and time‐resolved fluorescence spectroscopy. In addition, the binding constant and the number of binding sites were also calculated. The thermodynamic parameters at different temperatures (298 K, 303 K, 308 K and 313 K) indicated that 16‐E2‐16 binding to BSA is entropy driven and that the major driving forces are electrostatic interactions. Decrease of the α‐helix from 53.90 to 46.20% with an increase in random structure from 22.56 to 30.61% were also observed by FT‐IR. Furthermore, the molecular docking results revealed that 16‐E2‐16 binds predominantly by electrostatic and hydrophobic forces to some residues in the BSA sub‐domains IIA and IIIA. Copyright © 2015 John Wiley & Sons, Ltd.     

Molecular interactions of thymol with bovine serum albumin: Spectroscopic and molecular docking studies

Thymol is the main monoterpene phenol present in the essential oils which is used in the food industry as flavoring and preservative agent. In this study, the interaction of thymol with the concentration range of 1 to 6 μM and bovine serum albumin (BSA) at fixed concentration of 1 μM was investigated by fluorescence, UV‐vis, and molecular docking methods under physiological‐like condition. Fluorescence experiments were performed at 5 different temperatures, and the results showed that the fluorescence quenching of BSA by thymol was because of a static quenching mechanism. The obtained binding parameters, K, were in the order of 10⁴ M^?1, and the binding number, n, was approximately equal to unity indicating that there is 1 binding site for thymol on BSA. Calculated thermodynamic parameters for enthalpy (ΔH), entropy (ΔS), and Gibb's free energy (ΔG) showed that the reaction was spontaneous and hydrophobic interactions were the main forces in the binding of thymol to BSA. The results of UV‐vis spectroscopy and Arrhenius' theory showed the complex formation in the interaction of thymol and BSA. Negligible conformational changes in BSA by thymol were observed in fluorescence experiments, and the same results were also obtained from UV‐vis studies. Results of molecular docking indicated that the subdomain IA of BSA was the binding site for thymol.     

Study on the synthesis of sulfonamide derivatives and their interaction with bovine serum albumin

Three sulfonamide derivatives (SAD) were first synthesized from p‐hydroxybenzoic acid and sulfonamides (sulfadimidine, sulfamethoxazole and sulfachloropyridazine sodium) and were characterized by elemental analysis, ¹H NMR and MS. The interaction between bovine serum albumin (BSA) and SAD was studied using UV/vis absorption spectroscopy, fluorescence spectroscopy, time‐resolved fluorescence spectroscopy and circular dichroism spectra under imitated physiological conditions. The experimental results indicated that SAD effectively quenched the intrinsic fluorescence of BSA via a static quenching process. The thermodynamic parameters showed that hydrogen bonding and van der Waal's forces were the predominant intermolecular forces between BSA and two SADs [4‐((4‐(N‐(4,6‐dimethylpyrimidin‐2‐yl)sulfamoyl)phenyl)carbamoyl)phenyl acetate and 4‐((4‐(N‐(5‐methylisoxazol‐3‐yl)sulfamoyl)phenyl)carbamoyl)phenyl acetate], but hydrophobic forces played a major role in the binding process of BSA and 4‐((4‐(N‐(6‐chloropyridazin‐3‐yl)sulfamoyl)phenyl) carbamoyl)phenyl acetate. In addition, the effect of SAD on the conformation of BSA was investigated using synchronous fluorescence spectroscopy and circular dichroism spectra. Molecular modeling results showed that SAD was situated in subdomain IIA of BSA. Copyright © 2014 John Wiley & Sons, Ltd.     

Intermolecular interaction of fosinopril with bovine serum albumin (BSA): The multi‐spectroscopic and computational investigation

The intermolecular interaction of fosinopril, an angiotensin converting enzyme inhibitor with bovine serum albumin (BSA), has been investigated in physiological buffer (pH 7.4) by multi‐spectroscopic methods and molecular docking technique. The results obtained from fluorescence and UV absorption spectroscopy revealed that the fluorescence quenching mechanism of BSA induced by fosinopril was mediated by the combined dynamic and static quenching, and the static quenching was dominant in this system. The binding constant, K_b, value was found to lie between 2.69 × 10³ and 9.55 × 10³ M^?1 at experimental temperatures (293, 298, 303, and 308 K), implying the low or intermediate binding affinity between fosinopril and BSA. Competitive binding experiments with site markers (phenylbutazone and diazepam) suggested that fosinopril preferentially bound to the site I in sub‐domain IIA on BSA, as evidenced by molecular docking analysis. The negative sign for enthalpy change (ΔH⁰) and entropy change (ΔS⁰) indicated that van der Waals force and hydrogen bonds played important roles in the fosinopril‐BSA interaction, and 8‐anilino‐1‐naphthalenesulfonate binding assay experiments offered evidence of the involvements of hydrophobic interactions. Moreover, spectroscopic results (synchronous fluorescence, 3‐dimensional fluorescence, and Fourier transform infrared spectroscopy) indicated a slight conformational change in BSA upon fosinopril interaction.     

Multispectroscopic exploration and molecular docking analysis on interaction of eriocitrin with bovine serum albumin

Eriocitrin is a flavanone glycoside, which exists in lemon or lime citrus fruits. It possesses antioxidant, anticancer, and anti‐allergy activities. In order to investigate the pharmacokinetics and pharmacological mechanisms of eriocitrin in vivo, the interaction between eriocitrin and bovine serum albumin (BSA) was studied under the simulated physiological conditions by multispectroscopic and molecular docking methods. The results well indicated that eriocitrin and BSA formed a new eriocitrin‐BSA complex because of intermolecular interactions, which was demonstrated by the results of ultraviolet‐visible (UV‐vis) absorption spectra. The intrinsic fluorescence of BSA was quenched by eriocitrin, and static quenching was the quenching mechanism. The number of binding sites (n) and binding constant (K_b) at 310 K were 1.22 and 2.84 × 10⁶ L mol^?1, respectively. The values of thermodynamic parameters revealed that the binding process was spontaneous, and the main forces were the hydrophobic interaction. The binding distance between eriocitrin and BSA was 3.43 nm. In addition, eriocitrin changed the conformation of BSA, which was proved by synchronous fluorescence and circular dichroism (CD) spectra. The results of site marker competitive experiments suggested that eriocitrin was more likely to be inserted into the subdomain IIA (site I), which was further certified by molecular docking studies.     

Characterization of interactions of simvastatin,pravastatin, fluvastatin,and pitavastatin with bovine serum albumin: multiple spectroscopic and molecular docking

The binding interactions of simvastatin (SIM), pravastatin (PRA), fluvastatin (FLU), and pitavastatin (PIT) with bovine serum albumin (BSA) were investigated for determining the affinity of four statins with BSA through multiple spectroscopic and molecular docking methods. The experimental results showed that SIM, PRA, FLU, and PIT statins quenched the intrinsic fluorescence of BSA through a static quenching process and the stable stains–BSA complexes with the binding constants in the order of 10⁴ M^?1 at 298 K were formed through intermolecular nonbond interaction. The values of ΔH⁰, ΔS⁰ and ΔG⁰ in the binding process of SIM, PRA, FLU, and PIT with BSA were negative at the studied temperature range, suggesting that the binding process of four statins and BSA was spontaneous and the main interaction forces were van der Waals force and hydrogen-bonding interactions. Moreover, the binding of four statins with BSA was enthalpy-driven process due to |ΔH°|>|TΔS°| under the studied temperature range. From the results of site marker competitive experiments and molecular docking, subdomain IIIA (site II) was the primary binding site for SIM, PRA, FLU, and PIT on BSA. The results of UV–vis absorption, synchronous fluorescence, 3D fluorescence and FT-IR spectra proved that the slight change in the conformation of BSA, while the significant changes in the conformation of SIM, PRA, FLU, and PIT drug in statin–BSA complexes, indicating that the flexibility of statin molecules plays an important role in increasing the stability of statin–BSA complexes.     

Study on the interaction between pelargonidin‐3‐O‐glucoside and bovine serum albumin using spectroscopic,transmission electron microscopy and molecular modeling techniques

The aim of this study is to evaluate the binding behavior between pelargonidin‐3‐O‐glucoside (P3G) and bovine serum albumin (BSA) using multi‐spectroscopic, transmission electron microscopy (TEM) and molecular docking methods under physiological conditions. Fluorescence spectroscopy and time‐resolved fluorescence showed that the fluorescence of BSA could be quenched remarkably by P3G via a static quenching mechanism, and there is a single class of binding site on BSA. In addition, the thermodynamic functions ΔH and ΔS were –21.69 kJ/mol and 24.46 J/mol/K, indicating that an electrostatic interaction was a main acting force. The distance between BSA and P3G was 2.74 nm according to Förster's theory, illustrating that energy transfer occurred. In addition, the secondary structure of BSA changed with a decrease in the α‐helix content from 66.2% to 64.0% as seen using synchronous fluorescence, UV/vis, circular dichroism and Fourier transform infrared spectroscopies, whereas TEM images showed that P3G led to BSA aggregation and fibrillation. Furthermore, site marker competitive experiments and molecular docking indicated that P3G could bind with subdomain IIA of BSA. The calculated results of the equilibrium fraction showed that the concentration of free P3G in plasma was high enough to be stored and transported from the circulatory system to its target sites to provide therapeutic effects. Copyright © 2015 John Wiley & Sons, Ltd.     

Interactions between m‐phenylenediamine and bovine serum albumin measured by spectroscopy

This study explored interactions between m‐phenylenediamine (MPD) and bovine serum albumin (BSA) by spectrophotometry. The Stern‐Volmer equation and UV‐vis spectra examination at different temperatures and pH were used to explore different quenching mechanisms. Under simulated physiological conditions, the binding distance between MPD and BSA was 5.18 nm with a ratio of 1:1. The quenching effect of MPD on BSA intrinsic fluorescence depended strongly on pH, and maximum quenching was observed at alkaline pH. Moreover, the thermodynamic parameters of the MPD‐BSA system showed that the predominant acting force between MPD and BSA was a hydrophobic force. The impact of MPD on the conformation of BSA and the effects of co‐ions on binding interactions were also examined. Copyright © 2012 John Wiley & Sons, Ltd.     

In vitro study on binding interaction of quinapril with bovine serum albumin (BSA) using multi-spectroscopic and molecular docking methods

The binding interaction between quinapril (QNPL) and bovine serum albumin (BSA) in vitro has been investigated using UV absorption spectroscopy, steady-state fluorescence spectroscopic, synchronous fluorescence spectroscopy, 3D fluorescence spectroscopy, Fourier transform infrared spectroscopy, circular dichroism, and molecular docking methods for obtaining the binding information of QNPL with BSA. The experimental results confirm that the quenching mechanism of the intrinsic fluorescence of BSA induced by QNPL is static quenching based on the decrease in the quenching constants of BSA in the presence of QNPL with the increase in temperature and the quenching rates of BSA larger than 10¹⁰ L mol^?1 s^?1, indicating forming QNPL–BSA complex through the intermolecular binding interaction. The binding constant for the QNPL–BSA complex is in the order of 10⁵ M^?1, indicating there is stronger binding interaction of QNPL with BSA. The analysis of thermodynamic parameters together with molecular docking study reveal that the main binding forces in the binding process of QNPL with BSA are van der Waal’s forces and hydrogen bonding interaction. And, the binding interaction of BSA with QNPL is an enthalpy-driven process. Based on Förster resonance energy transfer, the binding distance between QNPL and BSA is calculated to be 2.76 nm. The results of the competitive binding experiments and molecular docking confirm that QNPL binds to sub-domain IIA (site I) of BSA. It is confirmed there is a slight change in the conformation of BSA after binding QNPL, but BSA still retains its secondary structure α-helicity.     

Spectroscopic and molecular docking studies on the interaction between N‐acetyl cysteine and bovine serum albumin

The interaction between N‐acetyl cysteine (NAC) and bovine serum albumin (BSA) was investigated by UV–vis, fluorescence spectroscopy, and molecular docking methods. Fluorescence study at three different temperatures indicated that the fluorescence intensity of BSA was reduced upon the addition of NAC by the static quenching mechanism. Binding constant (K_b) and the number of binding sites (n) were determined. The binding constant for the interaction of NAC and BSA was in the order of 10³ M^?1, and the number of binding sites was obtained to be equal to 1. Enthalpy (ΔH), entropy (ΔS), and Gibb's free energy (ΔG) as thermodynamic values were also achieved by van't Hoff equation. Hydrogen bonding and van der Waals force were the major intermolecular forces in the interaction process and it was spontaneous. Finally, the binding mode and the binding sites were clarified using molecular docking which were in good agreement with the results of spectroscopy experiments. © 2015 Wiley Periodicals, Inc. Biopolymers 103: 638–645, 2015.     

Good use of fruit wastes: eco‐friendly synthesis of silver nanoparticles,characterization, BSA protein binding studies

A simple and eco‐friendly methodology for the green synthesis of silver nanoparticles (AgNPs) using a mango seed extract was evaluated. The AgNPs were characterized by ultraviolet‐visible spectrophotometry, Fourier transform infrared spectroscopy, transmission electron microscopy, energy dispersive X‐ray spectroscopy, and X‐ray diffraction. The interaction between the green synthesized AgNPs and bovine serum albumin (BSA) in an aqueous solution at physiological pH was examined by fluorescence spectroscopy. The results confirmed that the AgNPs quenched the fluorophore of BSA by forming a ground state complex in aqueous solution. This fluorescence quenching data were also used to determine the binding sites and binding constants at different temperatures. The calculated thermodynamic parameters (ΔG°, ΔH° and ΔS°) suggest that the binding process occurs spontaneously through the involvement of electrostatic interactions. The synchronous fluorescence spectra showed a blue shift, indicating increasing hydrophobicity. Copyright © 2015 John Wiley & Sons, Ltd.