RESUMO
The binding interaction of peripheral H1 receptor antagonist drug, fexofenadine hydrochloride to bovine serum albumin (BSA) is investigated by fluorescence spectroscopy in combination with UV-absorption spectroscopy under physiological conditions. The Stern-Volmer plots at different temperatures and the steady state fluorescence suggested a static type of interaction between fexofenadine and BSA. Binding constants were determined to provide a measure of the binding affinity between fexofenadine and BSA. It was found that BSA has one binding site for fexofenadine. On the basis of the competitive site marker experiments and thermodynamic results, it was considered that fexofenadine was primarily bound to the site I of BSA mainly by hydrogen bond and van der Waals force. Utilising Förster resonance energy transfer the distance, r between the donor, BSA and acceptor fexofenadine was obtained. Furthermore, the results of circular dichroism and synchronous fluorescence spectrum indicated that the secondary structure of BSA was changed in the presence of fexofenadine. Molecular docking was applied to further define the interaction of fexofenadine with BSA.
Assuntos
Simulação de Acoplamento Molecular , Soroalbumina Bovina/química , Análise Espectral , Terfenadina/análogos & derivados , Animais , Sítios de Ligação , Conformação Molecular , Simulação de Dinâmica Molecular , Ligação Proteica , Soroalbumina Bovina/metabolismo , Análise Espectral/métodos , Terfenadina/química , Terfenadina/metabolismo , TermodinâmicaRESUMO
The mechanism of the interaction between bovine serum albumin (BSA) and desvenlafaxine was studied using fluorescence, ultraviolet absorption, 3-dimensional fluorescence spectroscopy, circular dichroism, synchronous fluorescence spectroscopy, cyclic voltametry, differential scanning calorimetry, and attenuated total reflection-Fourier transform infrared spectroscopic techniques under physiological condition at pH 7.4. Stern-Volmer calculations authenticate the fluorescence of BSA that was quenched by desvenlafaxine in a collision quenching mode. The fluorescence quenching method was used to evaluate number of binding sites "n" and binding constant KA that were measured, and various thermodynamic parameters were evaluated at different temperatures by using the van't Hoff equation and differential scanning calorimetry technique, which indicated a spontaneous and hydrophobic interaction between BSA and desvenlafaxine. According to the Förster theory we calculate the distance between the donor, BSA and acceptor, desvenlafaxine molecules. Furthermore, circular dichroism and attenuated total reflection-Fourier transform infrared spectroscopy indicate nominal changes in the secondary structure of the protein.
Assuntos
Succinato de Desvenlafaxina/metabolismo , Soroalbumina Bovina/química , Soroalbumina Bovina/metabolismo , Animais , Varredura Diferencial de Calorimetria , Bovinos , Dicroísmo Circular , Succinato de Desvenlafaxina/química , Interações Hidrofóbicas e Hidrofílicas , Modelos Moleculares , Estrutura Secundária de Proteína , Espectrometria de Fluorescência , Espectroscopia de Infravermelho com Transformada de Fourier , TermodinâmicaRESUMO
The goal of this study was to investigate the interactions between meclizine (MEC) and human serum albumin (HSA) under physiological conditions by different spectroscopies and molecular modeling technique. The drug, MEC quenched the intrinsic fluorescence of HSA and the analysis of the results revealed that static quenching mechanism. The binding of MEC quenches the HSA fluorescence; stoichiometry was 1:1 interaction. Thermodynamic quantities were calculated at different temperatures suggested that hydrophobic and van der Waals interaction with HSA-MEC. The molecular distance, r, between donor and acceptor was estimated according to Forster's theory of non-radiation energy transfer. CD and FT-IR studies confirm changes of secondary structure of HSA. Molecular docking studies validate MEC molecule interact to HSA in sub domain IIA.
Assuntos
Meclizina/química , Modelos Moleculares , Conformação Molecular , Albumina Sérica Humana/química , Sítios de Ligação , Dicroísmo Circular , Humanos , Ligantes , Ligação Proteica , Espectrometria de Fluorescência , Espectroscopia de Infravermelho com Transformada de Fourier , TermodinâmicaRESUMO
Interaction of procainamide hydrochloride (PAH) with human serum albumin (HSA) is of great significance in understanding the pharmacokinetic and pharmacodynamic mechanisms of the drug. Multi-spectroscopic techniques were used to investigate the binding mode of PAH to HSA and results revealed the presence of static type of quenching mechanism. The number of binding sites, binding constants and thermodynamic parameters were calculated. The results showed a spontaneous binding of PAH to HSA and hydrophobic interactions played a major role. In addition, the distance between PAH and the Trp-214 was estimated employing the Förster's theory. Site marker competitive experiments indicated that the binding of PAH to HSA primarily took place in subdomain IIA (Sudlow's site I). The influence of interference of some common metal ions on the binding of PAH to HSA was studied. Synchronous fluorescence spectra (SFS), 3D fluorescence spectra and circular dichroism (CD) results indicated the conformational changes in the structure of HSA.
RESUMO
Spectrofluoremetric technique was employed to study the binding behavior of hydralazine with bovine serum albumin (BSA) at different temperatures. Binding study of bovine serum albumin with hydralazine has been studied by ultraviolet-visible spectroscopy, fluorescence spectroscopy and confirmed by three-dimensional, synchronous, circular dichroism, and Raman spectroscopic methods. Effect of ß-cyclodextrin on binding was studied. The experimental results showed a static quenching mechanism in the interaction of hydralazine with bovine serum albumin. The binding constant and the number of binding sites are calculated according to Stern-Volmer equation. The thermodynamic parameters ∆H(o) , ∆G(o) , ∆S(o) at different temperatures were calculated. These indicated that the hydrogen bonding and weak van der Waals forces played an important role in the interaction. Based on the Förster's theory of non-radiation energy transfer, the binding average distance, r, between the donor (BSA) and acceptor (hydralazine) was evaluated and found to be 3.95 nm. Spectral results showed that the binding of hydralazine to BSA induced conformational changes in BSA. The effect of common ions on the binding of hydralazine to BSA was also examined. Copyright © 2016 John Wiley & Sons, Ltd.
Assuntos
Hidralazina/farmacologia , Soroalbumina Bovina/química , Soroalbumina Bovina/metabolismo , beta-Ciclodextrinas/metabolismo , Animais , Sítios de Ligação , Bovinos , Dicroísmo Circular , Transferência de Energia , Ligação de Hidrogênio , Ligação Proteica , Conformação Proteica/efeitos dos fármacos , Análise Espectral RamanRESUMO
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 × 10(3), 9.398 × 10(3) and 16.101 × 10(3) 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.
Assuntos
Dextrometorfano/química , Fluorescência , Soroalbumina Bovina/química , Animais , Bovinos , Dicroísmo Circular , Espectrometria de Fluorescência , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
The information of the quenching reaction of bovine serum albumin with dimethyl fumarate is obtained by multi-spectroscopic methods. The number of binding sites, n and binding constants, KA were determined at different temperatures. The effect of increasing temperature on Stern-Volmer quenching constants (KD) indicates that a dynamic quenching mechanism is involved in the interaction. The analysis of thermodynamic quantities namely, ∆H° and ∆S° suggested hydrophobic forces playing a major role in the interaction between dimethyl fumarate and bovine serum albumin. The binding site of dimethyl fumarate on bovine serum albumin was determined by displacement studies, using the site probes viz., warfarin, ibuprofen and digitoxin. The determination of magnitude of the distance of approach for molecular interactions between dimethyl fumarate and bovine serum albumin is calculated according to the theory of Förster energy transfer. The CD, 3D fluorescence spectra, synchronous fluorescence measurements and FT-IR spectral results were indicative of the change in secondary structure of the protein. The influence of some of the metal ions on the binding interaction was also studied.
Assuntos
Anti-Inflamatórios/metabolismo , Fumarato de Dimetilo/metabolismo , Soroalbumina Bovina/metabolismo , Animais , Sítios de Ligação , Bovinos , Modelos Moleculares , Ligação Proteica , Estrutura Secundária de Proteína/efeitos dos fármacos , Espectrometria de Fluorescência , Espectroscopia de Infravermelho com Transformada de Fourier , TermodinâmicaRESUMO
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 × 10(4), 5.5 × 10(4), and 3.9 × 10(4) M(-1)). Based on the thermodynamic parameters (ΔH(0), ΔG(0), and ΔS(0)), 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.
Assuntos
Dibenzazepinas/química , Dibenzazepinas/metabolismo , Imidazóis/química , Imidazóis/metabolismo , Receptores Histamínicos H1/química , Receptores Histamínicos H1/metabolismo , Soroalbumina Bovina/química , Soroalbumina Bovina/metabolismo , Animais , Bovinos , Dicroísmo Circular , Espectrometria de FluorescênciaRESUMO
The interaction between fosfomycin (FOS) and bovine serum albumin (BSA) has been investigated effectively by multi-spectroscopic techniques under physiological pH 7.4. FOS quenched the intrinsic fluorescence of BSA via static quenching. The number of binding sites n and observed binding constant KA were measured by the fluorescence quenching method. The thermodynamic parameters ΔG0, ΔH0 and ΔS0 were calculated at different temperatures according to the van't Hoff equation. The site of binding of FOS in the protein was proposed to be Sudlow's site I based on displacement experiments using site markers viz. warfarin, ibuprofen and digitoxin. The distance r between the donor (BSA) and acceptor (FOS) molecules was obtained according to the Förster theory. The effect of FOS on the conformation of BSA was analyzed using synchronous fluorescence spectra (SFS), circular dichroism (CD) and 3D fluorescence spectra. A molecular modeling study further confirmed the binding mode obtained by the experimental studies.
RESUMO
The interaction of clindamycin phosphate (CP) with bovine serum albumin (BSA) is studied by using fluorescence spectra, UV-visible absorption, synchronous fluorescence spectra (SFS), CD, 3D fluorescence spectra and lifetime measurements under simulated physiological conditions. CP effectively quenched intrinsic fluorescence of BSA. The binding constants KA values are 2.540×10(5), 4.960×10(5), 7.207×10(5) L mol(-1), the number of binding sites n and corresponding thermodynamic parameters ΔG(o), ΔH(o) and ΔS(o) between CP and BSA were calculated at different temperatures. The interaction between CP and BSA occurs through dynamic quenching and the effect of CP on the conformation of BSA was also analyzed using SFS. The average binding distance r between the donor (BSA) and acceptor (CP) 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 CP.
Assuntos
Antibacterianos/química , Clindamicina/análogos & derivados , Metais/química , Soroalbumina Bovina/química , Animais , Antibacterianos/metabolismo , Sítios de Ligação , Bovinos , Clindamicina/química , Clindamicina/metabolismo , Transferência de Energia , Íons/química , Cinética , Lincosamidas/química , Lincosamidas/metabolismo , Metais/metabolismo , Ligação Proteica , Soroalbumina Bovina/metabolismo , TermodinâmicaRESUMO
The interaction between the human serum albumin (HSA) and drug, fosfomycin disodium salt (FOS) has been studied by different spectroscopic techniques. The experimental results showed a static quenching mechanism in the interaction of FOS with HSA. The number of binding sites, n and observed binding constant K a were measured by fluorescence quenching method. The thermodynamic parameters ΔG°, ΔH° and ΔS° were calculated according to van't Hoff equation. The calculated distance r between FOS and the protein is evaluated according to the theory of Förster energy transfer. A change in the secondary structure of the protein was evident from the circular dichroism measurements, synchronous fluorescence and three-dimensional fluorescence spectra.
Assuntos
Antibacterianos/química , Fosfomicina/química , Simulação de Acoplamento Molecular , Albumina Sérica/química , Análise Espectral , Antibacterianos/metabolismo , Sítios de Ligação , Dicroísmo Circular , Fosfomicina/metabolismo , Humanos , Íons/química , Conformação Molecular , Ligação Proteica , Albumina Sérica/metabolismo , Espectrometria de Fluorescência , TermodinâmicaRESUMO
Atropine sulfate monohydrate (ASM) is an anticholinergic drug, having a wide spectrum of activity. Hence, the kinetics of oxidation of ASM by diperiodatocuperate (DPC) in the presence of micro (10-6) amounts of Ru(III) catalyst has been investigated spectrophotometrically in aqueous alkaline medium at I = 0.50 mol dm-3. The reaction between DPC and ASM exhibits 1:2 stoichiometry (ASM:DPC) i. e., one mole of ASM require two moles of DPC to give products. The main oxidation products were confirmed by spectral studies. The reaction is first order with respect to [DPC] and [Ru(III)], while the order with respect to [ASM] and [OH-] was less than unity. The rates decreased with increase in periodate concentration. The reaction rates revealed that Ru(III) catalyzed reaction was about seven-fold faster than the uncatalyzed reaction. The catalytic constant (KC) was also determined at different temperatures. A plausible mechanism is proposed. The activation parameters with respect to slow step of the mechanism were calculated and the thermodynamic quantities were also determined. Kinetic experiments suggest that [Cu(H2IO6)(H2O)2] is the reactive Cu(III) species and [Ru(H2O)5OH]2+ is the reactive Ru(III) species.
Assuntos
Atropina/química , Cobre/química , Radicais Livres/química , Antagonistas Muscarínicos/química , Ácido Periódico/química , Rutênio/química , Água/química , Álcalis/química , Catálise , Descarboxilação , Cinética , Estrutura Molecular , OxirreduçãoRESUMO
The binding of sulfacetamide sodium (SAS) to bovine serum albumin (BSA) was investigated by spectroscopic methods, namely fluorescence, FT-IR and UV-vis absorption spectral studies. The binding parameters were evaluated by a fluorescence quenching method. The thermodynamic parameters, DeltaH(0), DeltaS(0)and DeltaG(0) were observed to be -49.03 k J mol(-1), -99.9 J K(-1) mol(-1) and -18.96 k J mol(-1), respectively. These indicated that the hydrogen bonding and weak van der Waals forces played major roles in the interaction. Based on Förster's theory of non-radiation energy transfer, the binding average distance, r, between the donor (BSA) and acceptor (SAS) was evaluated and found to be 3.72 nm. The spectral results showed that binding of SAS to BSA induced conformational changes in BSA. The effect of common ions and some of the polymers used in drug delivery for controlled release were also tested on the binding of SAS to BSA.