Interaction Of Human Serum Albumin Research Articles

Unfolding of human serum albumin by gemini and single-chain surfactants: A comparative study

Abstract The interactions of human serum albumin (HSA) with four cationic gemini surfactants and four single-chain surfactants have been investigated from the measurements of fluorescence spectroscopy, dynamic lights scattering (DLS), zeta potential, and circular dichroism (CD). The fluorescence results show the binding strength of surfactants to HSA, along with the blue shift under the maximum emission wavelength (λmax) which is sensitive to the protein conformations. It has been found that the hydrodynamic diameters of the protein aggregates are enlarged and the electrokinetic potentials of them get positive with increasing the concentration of the surfactants. The conformational transformation of the secondary structures of surfactant–HSA aggregates has been confirmed through the quantitative analysis of the CD spectra. The isothermal titration microcalorimetry (ITC) has been employed to further analyze the binding process of single-chain surfactants to HSA. The comprehensive results obtained from various approaches have shown that both hydrophobic and electrostatic interactions are present in the cationic surfactant–HSA systems. Compared with the corresponding single-chain surfactants, the gemini ones have much stronger binding ability to induce the unfolding of HSA. These investigations on the interactions between HSA and surfactants with the altered chain architecture in different concentration regimes can facilitate the application of surfactant-protein systems in pharmaceutical, biotechnology and related fields.

The interaction of human serum albumin with selected lanthanide and actinide ions: Binding affinities, protein unfolding and conformational changes.

Human serum albumin (HSA), the most abundant soluble protein in blood plays critical roles in transportation of biomolecules and maintenance of osmotic pressure. In view of increasing applications of lanthanides- and actinides-based materials in nuclear energy, space, industries and medical applications, the risk of exposure with these metal ions is a growing concern for human health. In present study, binding interaction of actinides/lanthanides [thorium: Th(IV), uranium: U(VI), lanthanum: La(III), cerium: Ce(III) and (IV)] with HSA and its structural consequences have been investigated. Ultraviolet-visible, Fourier transform-infrared, Raman, Fluorescence and Circular dichroism spectroscopic techniques were applied to study the site of metal ions interaction, binding affinity determination and the effect of metal ions on protein unfolding and HSA conformation. Results showed that these metal ions interacted with carbonyl (CO..:)/amide(N..-H) groups and induced exposure of aromatic residues of HSA. The fluorescence analysis indicated that the actinide binding altered the microenvironment around Trp214 in the subdomain IIA. Binding affinity of U(VI) to HSA was slightly higher than that of Th(IV). Actinides and Ce(IV) altered the secondary conformation of HSA with a significant decrease of α-helix and an increase of β-sheet, turn and random coil structures, indicating a partial unfolding of HSA. A correlation was observed between metal ion's ability to alter HSA conformation and protein unfolding. Both cationic effects and coordination ability of metal ions seemed to determine the consequences of their interaction with HSA. Present study improves our understanding about the protein interaction of these heavy ions and their impact on its secondary structure. In addition, binding characteristics may have important implications for the development of rational antidote for the medical management of health effects of actinides and lanthanides.

A comprehensive investigation of the differential interaction of human serum albumin with gold nanoparticles based on the variation in morphology and surface functionalization

A systematic investigation on the effect of gold nanoparticle morphology and surface functionalization on the differential interaction of HSA was performed.

Studies on Binding of Widely used Drugs with Human Serum Albumin at Different Temperatures and PHs

The study on the interaction of human serum albumin (HSA) with three widely used drugs (diclofenac sodium (DIC), furosemide (FUR) and dexamethasone phosphate (DEX)) was investigated by fluorescence method. Fluorescence emission spectra of HSA in presence of the studied drugs was recorded at excitation wavelength 278 nm and showed that the studied drugs act as quenchers. A decrease in fluorescence emission at 340 nm was attributed to changes in environment of the protein fluorophore caused due to presence of the ligand. The modified Stern–Volmer equation was used as a mathematical model to calculate the binding constants between the drug and HSA. The binding constants for the studied drugs with HSA were found inversely related with temperature. The thermodynamic parameters, the changes of standard Gibbs free energy (ΔG°), enthalpy change (DH°) and entropy change (DS°) for the drug-HSA interaction were calculated according to van't Hoff equation. Among the thermodynamic parameters, the values of ΔG° were: -25.83, -25.29 and -25.09 kJ/mol for the drugs DIC, FUR and DEX, respectively, and the values of ΔH° and ΔS° were negative suggested that the hydrogen bonding and van der Waals forces were the predominant intermolecular forces in stabilizing the drug-HSA complex formed. The effect of pH on the binding of the studied drugs to human serum albumin in phosphate buffer solutions (pH 6.0-8.0) has been investigated in this study. The results showed that the binding of each studied drug was decreased with pH studied and the results were attributed according to the ionic forms of both protein and drug in the pH range studied. Finally, the distances between the donor (HSA) and the acceptor (drug) were estimated to be 2.98, 3.52 and 5.30 nm for the drugs DIC, FUR and DEX, respectively, based on Förster’s resonance energy transfer theory (FRET).

Four Cu(ii) complexes based on antitumor chelators: synthesis, structure, DNA binding/damage, HSA interaction and enhanced cytotoxicity.

Four novel copper(ii) complexes [Cu(II)(Bp4mT)(μ-Cl)]2 (), [Cu(II)(μ-Bp4mT)Br]2 (), [Cu(II)(HBpT)Cl] (), and [Cu(II)(HBpT)Br] () (Bp4mT = 2-benzoylpyridine-4-methylthiosemicarbazone, HBpT = 2-benzoylpyridine thiosemicarbazone), were synthesized and characterized using single-crystal X-ray diffraction, elemental analysis, infrared, and ultraviolet-visible spectroscopy. X-ray analysis revealed that complexes and based on the Bp4mT ligand presented dimeric structures in which the Cu(ii) ions were located in a five-coordinated distorted square-pyramidal geometry, whereas both and complexes were mononuclear with the Cu(ii) ions exhibiting a tetracoordinated square planar configuration. Their interactions with calf thymus DNA (CT-DNA) were investigated using viscosity measurements and fluorescence spectroscopy. Multispectroscopic evidence has shown interactions between these complexes and human serum albumin (HSA). All these complexes have exhibited efficient oxidative cleavage of supercoiled DNA in the presence of hydrogen peroxide, presumably via an oxidative mechanism. Furthermore, in vitro cytotoxicity studies of against human liver hepatocellular carcinoma cells (HepG-2), human large cell lung carcinoma cells (NCI-H460), and human cervical carcinoma cells (HeLa) indicated their promising antitumor activity with quite low IC50 values in the range of 0.08-1.98 μM, which are 83 times lower than those of cisplatin. The mechanistic studies revealed that four complexes, which induced early apoptosis, were involved in reactive oxygen species generation and DNA cleavage for their antitumor activities.

Human Serum Albumin Interactions with Bioactive 3H-Imidazo[4,5-A]Acridin-11(6H)-Ones Studied by Fluorescence Spectroscopy

The key intermediates 3H-imidazo[4′,5′:3,4]benzo[c]isoxazoles were synthesized by the reaction of N-alkyl-5-nitrobenzimidazoles with aryl acetonitriles under basic conditions. These compounds were converted to 3H-imidazo[4,5-a]acridin-11(6H)-ones by the Tanasescu reaction in excellent yields. The structures of all newly synthesized compounds were confirmed by IR, 1H NMR, and mass spectroscopic data. The interactions of 3H-imidazo[4,5-a]acridin-11-ones with human serum albumin (HSA) have been studied by fluorescence spectroscopy. The binding of 3H-imidazo[4,5-a]acridin-11(6H)-ones quenches the HSA fluorescence, revealing a 1 : 1 interaction with a binding constant of about 4.50 × 104 – 1.25 × 105 M-1. A decrease in the fluorescence intensity at 339.41 nm, when excited at 280 nm, is attributed to changes in the environment of protein fluorophores caused by the presence of the ligands. Differences in the interactions of 3H-imidazo[4,5-a]acridin-11(6H)-one derivatives with HSA were observed using the spectrofluorimetry technique. Thermodynamic characteristics and the parameters of HSA binding with these compounds are in accordance with the antibacterial activity of various derivatives of 3H-imidazo[4,5-a]acridin-11(6H)-one.

Fluorescence and Docking Studies of the Interaction between Human Serum Albumin and Pheophytin.

In the North of Brazil (Pará and Amazonas states) the leaves of the plant Talinum triangulare (popular: cariru) replace spinach as food. From a phytochemical point of view, they are rich in compounds of the group of pheophytins. These substances, related to chlorophyll, have photophysical properties that give them potential application in photodynamic therapy. Human serum albumin (HSA) is one of the main endogenous vehicles for biodistribution of molecules by blood plasma. Association constants and thermodynamic parameters for the interaction of HSA with pheophytin from Talinum triangulare were studied by UV-Vis absorption, fluorescence techniques, and molecular modeling (docking). Fluorescence quenching of the HSA’s internal fluorophore (tryptophan) at temperatures 296 K, 303 K, and 310 K, resulted in values for the association constants of the order of 104 L∙mol−1, indicating a moderate interaction between the compound and the albumin. The negative values of ΔG° indicate a spontaneous process; ΔH° = 15.5 kJ∙mol−1 indicates an endothermic process of association and ΔS° = 0.145 kJ∙mol−1∙K−1 shows that the interaction between HSA and pheophytin occurs mainly by hydrophobic factors. The observed Trp fluorescence quenching is static: there is initial non-fluorescent association, in the ground state, HSA:Pheophytin. Possible solution obtained by a molecular docking study suggests that pheophytin is able to interact with HSA by means of hydrogen bonds with three lysine and one arginine residues, whereas the phytyl group is inserted in a hydrophobic pocket, close to Trp-214.

Synthesis, cytotoxicity assessment, and interaction and docking of novel palladium(II) complexes of imidazole derivatives with human serum albumin

Imidazole analogs are the agents that attract both bioinorganic chemist and drug designer. Numerous methods have been proposed for synthesis of imidazole derivatives. In this study, a series of heterocyclic system with p-conjugated system such as 2-aryl-imidazo[4,5-f][1,10]phenanthroline analogs were synthesized. Then, three new palladium(II) complexes containing 2-(Furan-2-yl)-1H-Imidazo[4,5-f][1,10]Phenanthroline (FIP) and 2-(thiophen-2-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (TIP) ligands were synthesized. The structures of the compounds, [Pd(Phen)(TIP)](NO3)2, [Pd(Phen)(FIP)](NO3)2, and [Pd(FIP)2]Cl were determined by spectroscopic methods and elemental analysis. Biological activity of the complexes synthesized was assessed against chronic myelogenous leukemia cell line, K562. Also, the interactions of human serum albumin with complexes were investigated using isothermal titration in the Tris buffer, pH 7.4. According to the results obtained, it was found that there is a set of six binding sites for these complexes on HSA with positive cooperativity in the binding process. Docking technique was also applied to confirm the experimental results. The results showed that smaller complexes have higher interaction affinity.

Effect of morphine, oxycodone and thebaine on resonance light scattering properties of human serum albumin: Investigation possibility of morphine determination in the presence of the two other drugs

This work reports on the resonance light scattering (RLS) technique for studying the interaction of human serum albumin (HSA) with three opiates drugs (i.e. morphine (MO), oxycodone (OX) and thebaine (TH)). RLS is very sensitive to the interaction caused by weak binding forces such as intermolecular electrostatic attraction, hydrogen bonding, hydrophobic interaction, and aggregation interaction of biological macromolecules. The results of this work showed that the investigated drugs, with similar chemical structures, have different affinities to interact with HSA and enhance its RLS signal in following order: MO>OX>TH. Furthermore, the results showed that using the proposed method, MO could be determined in the presence of TH (up to ten-fold concentration ratio), OX (up to seven-fold concentration ratio) and both of OX and TH (up to three-fold concentration ratio) in the concentration range of 0.1–10.0μgmL−1 with detection limit of 43μgL−1.

Interaction of human serum albumin with novel imidazole derivatives studied by spectroscopy and molecular docking.

This study was a detailed characterization of the interaction of a series of imidazole derivatives with a model transport protein, human serum albumin (HSA). Fluorescence and time-resolved fluorescence results showed the existence of a static quenching mode for the HSA-imidazole derivative interaction. The binding constant at 296 K was in the order of 10(4) M(-1), showing high affinity between the imidazole derivatives and HSA. A site marker competition study combined with molecular docking revealed that the imidazole derivatives bound to subdomain IIA of HSA (Sudlow's site I). Furthermore, the results of synchronous, 3D, Fourier transform infrared, circular dichroism and UV-vis spectroscopy demonstrated that the secondary structure of HSA was altered in the presence of the imidazole derivatives. The specific binding distance, r, between the donor and acceptor was obtained according to fluorescence resonance energy transfer.

Weak interactive forces govern the interaction between a non-ionic surfactant with human serum albumin

The effect of the non-ionic surfactant Tween 40 (TW40) on Human Serum Albumin (HSA) has been studied by spectroscopic and isothermal titration calorimetric (ITC) methods. Our steady-state and time-resolved spectroscopic results reveal the perturbation of the native protein conformation upon interaction with TW40. The interaction of TW40 with HSA does not occur in a sequential manner unlike another anionic surfactant, sodium dodecyl sulfate (SDS). Our major conclusion is that the HSA–TW40 interaction is mainly driven by weak forces like van der Waal/hydrogen bonding interactions. This is also generalized from the results of interaction of HSA with another non-ionic surfactant TW80.

Anesthetic 2,2,2-trifluoroethanol induces amyloidogenesis and cytotoxicity in human serum albumin

Trifluoroethanol (TFE) mimics the membrane environments as it simulates the hydrophobic environment and better stabilizes the secondary structures in peptides owing to its hydrophobicity and hydrogen bond-forming properties. Its dielectric constant approximates that of the interior of proteins and is one-third of that of water. Human serum albumin (HSA) is a biological transporter. The effect of TFE on HSA gives the clue about the conformational changes taking place in HSA on transport of ligands across the biological membranes. At 25% (v/v) and 60% (v/v) TFE, HSA exhibits non-native β-sheet, altered tryptophan fluorescence, exposed hydrophobic clusters, increased thioflavin T fluorescence and prominent red shifted Congo red absorbance, and large hydrodynamic radii suggesting the aggregate formation. Isothermal titration calorimetric results indicate weak binding of TFE and HSA. This suggests that solvent-mediated effects dominate the interaction of TFE and HSA. TEM confirmed prefibrillar at 25% (v/v) and fibrillar aggregates at 60% (v/v) TFE. Comet assay of prefibrillar aggregates showed DNA damage causing cell necrosis hence confirming cytotoxic nature. On increasing concentration of TFE to 80% (v/v), HSA showed retention of native-like secondary structure, increased Trp and ANS fluorescence, a transition from β-sheet to α-helix. Thus, TFE at high concentration possess anti- aggregating potency.

Spectral and molecular modeling studies on the influence of β-cyclodextrin and its derivatives on aripiprazole-human serum albumin binding

The binding mechanism of aripiprazole (APZ) with human serum albumin (HSA) in the absence and presence of three cyclodextrins (CyDs) (β-cyclodextrin, hydroxypropyl-β-cyclodextrin, and (2,6-di-O-methyl)-β-cyclodextrin) was studied by fluorescence, ultraviolet–visible absorption, nuclear magnetic resonance, and circular dichroism (CD) spectroscopy. The CD results revealed some degree of recovery of refolding caused by APZ after the addition of CyD. The Stern–Volmer quenching constant and binding constant of the APZ–HSA interaction were smaller in the presence of the three CyDs. The ultraviolet–visible absorption results indicated that APZ formed 1:1 complex with the three CyDs. The 1H NMR spectra of CyD showed chemical shift and resolution loss of proton after the addition of HSA. Molecular modeling studies showed that both APZ and CyD bind to HSA. The process was initiated through inclusion of free APZ molecules by CyD and the increase in steric hindrance of CyD–HSA binding.

Spectroscopic study on the interaction of resveratrol and pterostilbene with human serum albumin

The interaction of human serum albumin (HSA) with two stilbene compounds, resveratrol and pterostilbene was investigated using fluorescence, UV–visible absorption, Fourier transform infrared spectroscopic methods and molecular modeling technique. The intrinsic fluorescence of HSA was quenched significantly by resveratrol and pterostilbene. Analysis of fluorescence quenching data of HSA by the two compounds using Stern–Volmer and modified Stern–Volmer methods showed the formation of ground state complexes of HSA with resveratrol and pterostilbene. The binding analysis showed that the binding constant for resveratrol as 4.47×106 and 0.299×102M−1s−1 for pterostilbene revealing the high binding affinity of resveratrol to HSA. The conformational changes of HSA were investigated using synchronous fluorescence and Fourier transform infrared spectroscopy. The efficiency of energy transfer and the distance between HSA and resveratrol/pterostilbene were calculated. The binding of resveratrol/pterostilbene was modeled by molecular docking, which is in accordance with the experimental data.

Probing the binding interaction of human serum albumin with three bioactive constituents of Eriobotrta japonica leaves: Spectroscopic and molecular modeling approaches

Corosolic acid (CRA), maslinic acid (MA), and tormentic acid (TA) are three kind of bioactive constituents of Eriobotrta japonica leaves. In this study, plasma protein binding model prediction suggested that the binding ability to HSA was CRA>MA>TA. Furthermore, fluorescence spectroscopy confirmed this prediction. The results from emission and time resolved fluorescence studies revealed that the emission quenching of HSA with CRA, MA, and TA were all initiated by static quenching mechanism. From molecular docking results and site marker competitive experimental results it was possible to make good estimates about CRA, MA, and TA mainly bound to subdomain IIA of HSA. 3D fluorescence, FT-IR and CD spectra indicated that the local conformation of HSA molecules was affected by the presence of CRA, MA, and TA, but at different extents.

Supramolecular interaction of 6-shogaol, a therapeutic agent of Zingiber officinale with human serum albumin as elucidated by spectroscopic, calorimetric and molecular docking methods

Background6-Shogaol, one of the main bioactive constituents of Zingiber officinale has been shown to possess various therapeutic properties. Interaction of a therapeutic compound with plasma proteins greatly affects its pharmacokinetic and pharmacodynamic properties. PurposeThe present investigation was undertaken to characterize the interaction between 6-shogaol and the main in vivo transporter, human serum albumin (HSA). MethodsVarious binding characteristics of 6-shogaol–HSA interaction were studied using fluorescence spectroscopy. Thermal stability of 6-shogaol–HSA system was determined by circular dichroism (CD) and differential scanning calorimetric (DSC) techniques. Identification of the 6-shogaol binding site on HSA was made by competitive drug displacement and molecular docking experiments. ResultsFluorescence quench titration results revealed the association constant, Ka of 6-shogaol–HSA interaction as 6.29 ± 0.33 × 104 M−1 at 25 ºC. Values of the enthalpy change (−11.76 kJ mol−1) and the entropy change (52.52 J mol−1 K−1), obtained for the binding reaction suggested involvement of hydrophobic and van der Waals forces along with hydrogen bonds in the complex formation. Higher thermal stability of HSA was noticed in the presence of 6-shogaol, as revealed by DSC and thermal denaturation profiles. Competitive ligand displacement experiments along with molecular docking results suggested the binding preference of 6-shogaol for Sudlow's site I of HSA. ConclusionAll these results suggest that 6-shogaol binds to Sudlow's site I of HSA through moderate binding affinity and involves hydrophobic and van der Waals forces along with hydrogen bonds.

Spectroscopy study and co-administration effect on the interaction of mycophenolic acid and human serum albumin

Mycophenolic acid (MPA), an immunosuppressor, is always administered in combination with several drugs in clinical therapy, which may alter the binding of MPA to human serum albumin (HSA) and could influence its pharmacological activities. Thus, this study evaluated the interaction between HSA and MPA, as well as investigated the effect of co-administrated drugs on the MPA–protein binary system using fluorescence spectroscopy. Results revealed that MPA has a strong capability to quench the fluorescence of HSA, and the acting forces for the binding are hydrogen bonds and van der Waals forces. Competition on combined administration showed that balofloxacin significantly affects the MPA–HSA interaction, as reflected by the remarkable decrease in fluorescence intensity. Furthermore, cefminox sodium has competitive capability with MPA to some extent, whereas methyl prednisone and amlodipine besylate have a minor influence on the binary system. However, simvastatin has no appreciable effect on the MPA–HSA interaction. In addition, three-dimensional fluorescence spectra and circular dichroism spectroscopy, which were employed to determine the conformation, showed that the binding of MPA with HSA can induce conformation changes in HSA.

Studies on drug-human serum albumin binding: the current state of the matter.

Human serum albumin (HSA) is the major plasma protein with vital functions acting as depot and career for many endogenous (fatty acids, bilirubin, etc.) and exogenous substances (drugs, nutrients, etc.) in the blood. Binding to HSA controls the free, active concentration of the drug and may affect considerably the overall pharmacodynamic and pharmacokinetic profile. Studies on drug - protein binding are important from both theoretical and practical point of view as they allow better understanding of the processes underlying drug disposition and elimination and the effect of several pathological states or co-administered drugs on drug delivery and efficacy. The present review focuses on the current state of drug - HSA binding studies. The major functions and consequences of drug - protein binding are described. The X-ray structure of HSA is discussed focusing on the location and the architecture of the primary drug and fatty acids binding sites. Some of the most commonly used methods for drug - HSA binding assay are presented together with examples for their application. The most extensive studied topics in the area are discussed including quantitative characterization of drug - HSA complexation, identification of the binding sites, stereoselectivity of drug - HSA interactions, and thermodynamic characterization of the binding process. A short section is devoted to in silico prediction of drug - HSA binding as an important step in drug design and development.

Cordycepin and N6-(2-hydroxyethyl)-adenosine from Cordyceps pruinosa and their interaction with human serum albumin.

Cordyceps pruinosa (CP) is often used as Traditional Chinese Medicine, but the substance basis of its medicinal properties is unclear. In this study, two compounds were isolated from CP cultures by column chromatography, and identified as cordycepin and N6-(2-hydroxyethyl)-adenosine (HEA) by Nuclear Magnetic Resonance. In order to understand the efficacy of these two substances as potential therapeutic agents, it is necessary to explore their binding with proteins. The molecular mechanisms of interaction between cordycepin, HEA and human serum albumin (HSA) were studied using UV and fluorescence spectroscopy. The bingding constants between HSA and cordycepin were 4.227, 3.573 and 3.076 × 103·at 17, 27 and 37°C respectively, and that of HSA and HEA were 27.102, 19.409 and 13.002 × 103·at the three tempretures respectively. Both cordycepin and HEA can quench the intrinsic fluorescence of HSA via static quenching, and they can bind with HSA to form complexes with a single binding site. The interaction forces between cordycepin and HSA were determined as electrostatic and hydrophobic, and those of HEA and HSA were hydrogen bonding and van der Waals forces. Using Foster's equation, the distance between fluorophores of cordycepin and HSA, and HEA and HSA are estimated to be 5.31 nm and 4.98 nm, respectively. In this study, cordycepin was isolated for the first time from CP, and will provide a new source of cordycepin and expand the use of this taxon. The interaction mechanisms between cordycepin and HSA was studied for the first time, which will provide a useful guide for the clinical application of cordycepin. The pharmacological importance of this study is to understand the interaction of HSA with cordycepin and HEA, which will be essential for the future designing of drugs based on the two compounds.

Characteristic of silicon doped diamond like carbon thin films on surface properties and human serum albumin adsorption

Diamond-like carbon (DLC) coatings are useful for creating biocompatible surfaces for medical implants. DLC and silicon doped DLC have been synthesised using plasma enhanced chemical vapour deposition (PECVD). The effects of surface morphology on the interaction of human serum albumin (HSA) with doped and undoped DLC films have been investigated using a range of surface analysis techniques using Raman spectroscopy and atomic force microscopy (AFM). Raman spectra of doped DLC show that silicon doped DLC reduces the growth range of the ID/IG ratio, with a significant red-shift of the G peak position. Following exposure to protein, for undoped DLC the peaks at 1664cm−1 and around 1241cm−1 can be attributed to amide I and III, respectively, with an increase in the surface morphology of the surfaces giving some indication of the protein structure on the surfaces. Results indicate that HSA exhibit the majority of β-sheet during the adsorption on the surfaces. The results showed that the silicon incorporation DLC tends to increase of surface roughness and the adsorbed level of HSA is higher with higher levels of silicon doping of the DLC. Therefore, doping DLC may provide a method of controlling the adsorption of protein.