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.     

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.     

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.     

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.     

Study on the interactions of mapenterol with serum albumins using multi‐spectroscopy and molecular docking

The interactions of mapenterol with bovine serum albumin (BSA) and human serum albumin (HSA) have been investigated systematically using fluorescence spectroscopy, absorption spectroscopy, circular dichroism (CD) and molecular docking techniques. Mapenterol has a strong ability to quench the intrinsic fluorescence of BSA and HSA through static quenching procedures. At 291 K, the binding constants, K_a, were 1.93 × 10³ and 2.73 × 10³ L/mol for mapenterol–BSA and mapenterol–HAS, respectively. Electrostatic forces and hydrophobic interactions played important roles in stabilizing the mapenterol–BSA/has complex. Using site marker competitive studies, mapenterol was found to bind at Sudlow site I on BSA/HSA. There was little effect of K⁺, Ca²⁺, Cu²⁺, Zn²⁺ and Fe³⁺ on the binding. The conformation of BSA/HSA was changed by mapenterol, as seen from the synchronous fluorescence spectra. The CD spectra showed that the binding of mapenterol to BSA/HSA changed the secondary structure of BSA/HSA. Molecular docking further confirmed that mapenterol could bind to Sudlow site I of BSA/HSA. According to Förster non‐radiative energy transfer theory (FRET), the distances r₀ between the donor and acceptor were calculated as 3.18 and 2.75 nm for mapenterol–BSA and mapenterol–HAS, respectively. Copyright © 2015 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.     

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.     

Probing the behavior of bovine serum albumin upon binding to atenolol: insights from spectroscopic and molecular docking approaches

Molecular interaction of atenolol, a selective β₁ receptor antagonist with the major carrier protein, bovine serum albumin (BSA), was investigated under imitated physiological conditions (pH 7.4) by means of fluorescence spectroscopy, UV absorption spectroscopy, Fourier transform infrared spectroscopy (FT-IR), and molecular modeling studies. The steady-state fluorescence spectra manifested that static type, due to formation of the atenolol-BSA complex, was the dominant mechanism for fluorescence quenching. The characteristic information about the binding interaction of atenolol with BSA in terms of binding constant (K_b) were determined by the UV–vis absorption titration, and were found to be in the order of 10³ M^?1 at different temperatures, indicating the existence of a weak binding in this system. Thermodynamic analysis revealed that the binding process was primarily mediated by van der Waals force and hydrogen bonds due to the negative sign for enthalpy change (ΔH⁰), entropy change (ΔS⁰). The molecular docking results elucidated that atenolol preferred binding on the site II of BSA according to the findings observed in competitive binding experiments. Moreover, via alterations in synchronous fluorescence, three-dimensional fluorescence and FT-IR spectral properties, it was concluded that atenolol could arouse slight configurational and micro-environmental changes of BSA.     

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.     

Fluorescence spectroscopic studies on the interaction of Gemini surfactant 14‐6‐14 with bovine serum albumin

The interaction of the cationic Gemini surfactant hexamethylene‐1,3‐bis (tetradecyldimethylammonium bromide) (14‐6‐14) with bovine serum albumin (BSA) has been investigated by fluorescence quenching spectra and three‐dimensional (3D) fluorescence spectra. The Stern–Volmer quenching constants K_SV and the corresponding thermodynamic parameters ΔH, ΔG and ΔS have been estimated by the fluorescence quenching method. The results indicated that hydrophobic forces were the predominant intermolecular forces between BSA and the surfactant. Competitive experiments and the number of binding sites calculation show that 14‐6‐14 can be inserted in site‐II (in subdomain IIIA) of BSA. The effect of 14‐6‐14 on the conformation of BSA was evaluated by synchronous fluorescence spectroscopy and 3D fluorescence spectral methods. The results show that the conformation of BSA was changed dramatically in the presence of 14‐6‐14, by binding to the Trp and Try residues of BSA. The investigation provides interaction between BSA and 14‐6‐14 as a model for molecular design and industrial research. Copyright © 2011 John Wiley & Sons, Ltd.     

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.     

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.     

Combined spectroscopies and molecular docking approach to characterizing the binding interaction between lisinopril and bovine serum albumin

To further understand the mode of action and pharmacokinetics of lisinopril, the binding interaction of lisinopril with bovine serum albumin (BSA) under imitated physiological conditions (pH 7.4) was investigated using fluorescence emission spectroscopy, synchronous fluorescence spectroscopy, Fourier transform infrared spectroscopy (FTIR), circular dichroism (CD) and molecular docking methods. The results showed that the fluorescence quenching of BSA near 338 nm resulted from the formation of a lisinopril–BSA complex. The number of binding sites (n) for lisinopril binding on subdomain IIIA (site II) of BSA and the binding constant were ~ 1 and 2.04 × 10⁴ M^–1, respectively, at 310 K. The binding of lisinopril to BSA induced a slight change in the conformation of BSA, which retained its α‐helical structure. However, the binding of lisinopril with BSA was spontaneous and the main interaction forces involved were van der Waal's force and hydrogen bonding interaction as shown by the negative values of ΔG⁰, ΔH⁰ and ΔS⁰ for the binding of lisinopril with BSA. It was concluded from the molecular docking results that the flexibility of lisinopril also played an important role in increasing the stability of the lisinopril–BSA complex. Copyright © 2015 John Wiley & Sons, Ltd.     

Binding of caffeine with caffeic acid and chlorogenic acid using fluorescence quenching,UV/vis and FTIR spectroscopic techniques

The interactions of caffeine (CF) with chlorogenic acid (CGA) and caffeic acid (CFA) were investigated by fluorescence quenching, UV/vis and Fourier transform infrared (FTIR) spectroscopic techniques. The results of the study indicated that the fluorescence quenching between caffeine and hydroxycinnamic acids could be rationalized in terms of static quenching or the formation of non‐fluorescent CF–CFA and CF–CGA complexes. From fluorescence quenching spectral analysis, the quenching constant (K_SV), quenching rate constant (k_q), number of binding sites (n), thermodynamic properties and conformational changes of the interaction were determined. The quenching constants (K_SV) between CF and CGA, CFA are 1.84 × 10⁴ and 1.04 × 10⁴ L/mol at 298 K and their binding site n is ~ 1. Thermodynamic parameters determined using the Van't Hoff equation indicated that hydrogen bonds and van der Waal's forces have a major role in the reaction of caffeine with caffeic acid and chlorogenic acid. The 3D fluorescence, UV/vis and FTIR spectra also showed that the binding of CF with CFA and CGA induces conformational changes in CFA and CGA. 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.     

Investigations on the interactions of DiAmsar with serum albumins: Insights from spectroscopic and molecular docking techniques

Diamine‐sarcophagine (DiAmsar) binding to human serum albumin (HSA) and bovine serum albumin (BSA) was investigated under simulative physiological conditions. Fluorescence spectra in combination with Fourier transform infrared (FT‐IR), UV‐visible (UV–vis) spectroscopy, cyclic voltammetry (CV), and molecular docking method were used in the present work. Experimental results revealed that DiAmsar had an ability to quench the HSA and BSA intrinsic fluorescence through a static quenching mechanism. The Stern–Volmer quenching rate constant (K_sv) was calculated as 0.372 × 10³ M^‐1 and 0.640 × 10³ M^‐1 for HSA and BSA, respectively. Moreover, binding constants (K_a), number of binding sites (n) at different temperatures, binding distance (r), and thermodynamic parameters (?H°, ?S°, and ?G°) between DiAmsar and HSA (or BSA) were calculated. DiAmsar exhibited good binding propensity to HSA and BSA with relatively high binding constant values. The positive ?H° and ?S° values indicated that the hydrophobic interaction is main force in the binding of the DiAmsar to HSA (or BSA). Furthermore, molecular docking results revealed the possible binding site and the microenvironment around the bond. Copyright © 2014 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.     

Fluorescence spectrometric study on the interaction of tamibarotene with bovine serum albumin

The interaction between tamibarotene and bovine serum albumin (BSA) was studied using fluorescence quenching technique and ultraviolet–visible spectrophotometry. The results of experiments showed that tamibarotene could strongly quench the intrinsic fluorescence of BSA by a dynamic quenching mechanism. The apparent binding constant, number of binding site and corresponding thermodynamic parameters at different temperatures were calculated respectively, and the main interaction force between tamibarotene and BSA was proved to be hydrophobic force. Synchronous fluorescence spectra showed that tamibarotene changed the molecular conformation of BSA. When BSA concentration was 1.00 × 10^?6 mol L^?1, the quenched fluorescence ΔF had a good linear relationship with the concentration of tamibarotene in the range 1.00 × 10^?6 to 12.00 × 10^?6 mol L^?1 with the detection limit of 6.52 × 10^?7 mol L^?1. Copyright © 2010 John Wiley & Sons, Ltd.     

Effects of N‐Acetyl‐L‐Cysteine‐Capped CdTe Quantum Dots on Bovine Serum Albumin and Bovine Hemoglobin: Isothermal Titration Calorimetry and Spectroscopic Investigations

The interactions of N‐acetyl‐L‐cysteine‐capped CdTe quantum dots (QDs) with bovine serum albumin (BSA) and bovine hemoglobin (BHb) were investigated by isothermal titration calorimetry (ITC), fluorescence, synchronous fluorescence, fluorescence lifetime, ultraviolet–visible absorption, and circular dichroism techniques. Fluorescence data of BSA–QDs and BHb–QDs revealed that the quenching was static in every system. While CdTe QDs changed the microenvironment of tryptophan in BHb, the microenvironment of BSA kept unchanged. Adding CdTe QDs affected the skeleton and secondary structure of the protein (BSA and BHb). The ITC results indicated that the interaction between the protein (BSA and BHb) and QDs‐612 was spontaneous and the predominant force was hydrophobic interaction. In addition, the binding constants were determined to be 1.19 × 10⁵ L mol^?1 (BSA–QDs) and 2.19 × 10⁵ L mol^?1 (BHb–QDs) at 298 K. From these results, we conclude that CdTe QDs have a larger impact on the structure of BHb than BSA.     

Underlying molecular interaction of bovine serum albumin and linezolid: a biophysical outlook

Linezolid, one of the reserve antibiotic of oxazolidinone class has wide range of antimicrobial activity. Here we have conducted a fundamental study concerning the dynamics of its interaction with bovine serum albumin (BSA), and the post binding modification of the later by employing different spectroscopic (absorption, fluorescence and circular dichroism (CD) spectroscopy) and molecular docking tools. Gradual quenching of the tryptophan (Trp) fluorescence upon addition of linezolid to BSA confirms their interaction. Analysis of fluorescence quenching at different temperature indicates that the interaction is made by static complex formation and the BSA has one binding site for the drug. The negative Gibbs energy change (ΔG⁰), and positive values of enthalpy change (ΔH⁰) and entropy change (ΔS⁰) strongly suggest that it is an entropy driven spontaneous and endothermic reaction. The reaction involves hydrophobic pocket of the protein, which is further stabilized by hydrogen bonding and electrostatic interactions as evidenced from 8-anilino-1-napthalene sulfonic acid, sucrose and NaCl binding studies. These findings also support the molecular docking study using AutoDock 4.2. The influence of this interaction on the secondary structure of the protein is negligible as evidenced by CD spectroscopy. So, from these findings, we conclude that linezolid interacts with BSA in 1:1 ratio through hydrophobic, hydrogen bonding and ionic interactions, and this may not affect the secondary structure of the protein.