Showing papers on "Human serum albumin published in 2017"

Biophysical Study on the Interaction between Eperisone Hydrochloride and Human Serum Albumin Using Spectroscopic, Calorimetric, and Molecular Docking Analyses.

Abstract: Eperisone hydrochloride (EH) is widely used as a muscle relaxant for patients with muscular contracture, low back pain, or spasticity. Human serum albumin (HSA) is a highly soluble negatively charged, endogenous and abundant plasma protein ascribed with the ligand binding and transport properties. The current study was undertaken to explore the interaction between EH and the serum transport protein, HSA. Study of the interaction between HSA and EH was carried by UV−vis, fluorescence quenching, circular dichroism (CD), Fourier transform infrared (FTIR) spectroscopy, Forster’s resonance energy transfer, isothermal titration calorimetry and differential scanning calorimetry. Tryptophan fluorescence intensity of HSA was strongly quenched by EH. The binding constants (Kb) were obtained by fluorescence quenching, and results show that the HSA–EH interaction revealed a static mode of quenching with binding constant Kb ≈ 104 reflecting high affinity of EH for HSA. The negative ΔG° value for binding indicated that...

Development of DNA Nanostructures for High-Affinity Binding to Human Serum Albumin

Abstract: The development of nucleic acid therapeutics has been hampered by issues associated with their stability and in vivo delivery. To address these challenges, we describe a new strategy to engineer DNA structures with strong binding affinity to human serum albumin (HSA). HSA is the most abundant protein in the blood and has a long circulation half-life (19 days). It has been shown to hinder phagocytosis, is retained in tumors, and aids in cellular penetration. Indeed, HSA has already been successfully used for the delivery of small-molecule drugs and nanoparticles. We show that conjugating dendritic alkyl chains to DNA creates amphiphiles that exhibit high-affinity (Kd in low nanomolar range) binding to HSA. Notably, complexation with HSA did not hinder the activity of silencing oligonucleotides inside cells, and the degradation of DNA strands in serum was significantly slowed. We also show that, in a site-specific manner, altering the number and orientation of the amphiphilic ligand on a self-assembled DNA ...

Protein corona modulation of hepatocyte uptake and molecular mechanisms of gold nanoparticle toxicity.

Abstract: Protein corona formation over gold nanoparticles (AuNP) can modulate cellular responses by altering AuNP physicochemical properties. The liver plays an essential role in metabolism, detoxification and elimination of xenobiotics and drugs as well as circulating NP clearance. We investigated human hepatic uptake of 40 and 80 nm AuNP with branched polyethylenimine (BPEI), lipoic acid (LA) and polyethylene glycol (PEG) coatings as well as human plasma protein (HP) and human serum albumin (HSA) coronas. AuNP-mediated cytotoxicity, reactive oxygen/reactive nitrogen species (ROS/RNS), and CYP activity in human hepatocytes as well as molecular mechanisms with 40 nm bare and HP BPEI–AuNP were investigated. Time-dependent increase in uptake occurred for all bare AuNP but HP and HSA decreased uptake except for 40 nm HP PEG–AuNP. BPEI–AuNP showed time-and concentration-dependent increase in ROS/RNS which correlated with cytotoxicity at 24 h. HP corona substantially reduced ROS/RNS. The 40 and 80 nm bare, HP o...

Interaction of an antiepileptic drug, lamotrigine with human serum albumin (HSA): Application of spectroscopic techniques and molecular modeling methods.

Abstract: Lamotrigine (an epileptic drug) interaction with human serum albumin (HSA) was investigated by fluorescence, UV-Vis, FTIR, CD spectroscopic techniques, and molecular modeling methods. Binding constant (Kb) of 5.74×103 and number of binding site of 0.97 showed that there is a slight interaction between lamotrigine and HSA. Thermodynamic studies was constructed using the flourimetric titrations in three different temperatures and the resulted data used to calculate the parameters using Vant Hoff equation. Decreased Stern Volmer quenching constant by enhanced temperature revealed the static quenching mechanism. Negative standard enthalpy (ΔH) and standard entropy (ΔS) changes indicated that van der Waals interactions and hydrogen bonds were dominant forces which facilitate the binding of Lamotrigine to HSA, the results were confirmed by molecular docking studies which showed no hydrogen binding. The FRET studies showed that there is a possibility of energy transfer between Trp214 and lamotrigine. Also the binding of lamotrigine to HSA in the studied concentrations was not as much as many other drugs, but the secondary structure of the HSA was significantly changed following the interaction in a way that α-helix percentage was reduced from 67% to 57% after the addition of lamotrigine in the molar ratio of 4:1 to HSA. According to the docking studies, lamotrigine binds to IB site preferably.

Glycosylated Platinum(IV) Complexes as Substrates for Glucose Transporters (GLUTs) and Organic Cation Transporters (OCTs) Exhibited Cancer Targeting and Human Serum Albumin Binding Properties for Drug Delivery

Abstract: Glycosylated platinum(IV) complexes were synthesized as substrates for GLUTs and OCTs for the first time, and the cytotoxicity and detailed mechanism were determined in vitro and in vivo. Galactoside Pt(IV), glucoside Pt(IV), and mannoside Pt(IV) were highly cytotoxic and showed specific cancer-targeting properties in vitro and in vivo. Glycosylated platinum(IV) complexes 5, 6, 7, and 8 (IC50 0.24–3.97 μM) had better antitumor activity of nearly 166-fold higher than the positive controls cisplatin (1a), oxaliplatin (3a), and satraplatin (5a). The presence of a hexadecanoic chain allowed binding with human serum albumin (HSA) for drug delivery, which not only enhanced the stability of the inert platinum(IV) prodrugs but also decreased their reduction by reductants present in human whole blood. Their preferential accumulation in cancer cells compared to noncancerous cells (293T and 3T3 cells) suggested that they were potentially safe for clinical therapeutic use.

Multi-spectroscopic and HPLC Studies of the Interaction Between Estradiol and Cyclophosphamide With Human Serum Albumin: Binary and Ternary Systems

Abstract: Drug resistance is a phenomenon that frequently impairs a proper treatment of infections and cancer with chemotherapy. Multidrug efflux transporters extrude structurally dissimilar organic compounds often providing resistance to multiple toxic chemotherapeutic agents. The quantitative analysis of drug efflux requires measuring the affinity of ligands. In this work, the interaction between cyclophosphamide (Cyc) and estradiol (ES) with human serum albumin (HSA) was studied by fluorescence polarization, circular dichroism and high-performance liquid chromatography (HPLC) under physiological conditions (pH = 7.4). Gradual addition of HSA led to a marked increase in fluorescence polarization. Our assays indicated that the protein was bound to these drugs with different K d. Also, the Hill coefficient showed a simple drug binding process with no cooperativity. Circular dichroism results revealed the occurrence of conformational changes in HSA molecules by the binding of Cyc and ES. The protein binding of the drug was studied by HPLC. Our results indicated that the drug was bound to the protein and that the presence of a second drug affected the interaction and resistance between the first drug and the protein.

Probing the binding affinity of plasma proteins adsorbed on Au nanoparticles

Abstract: Nanoparticle (NP) surfaces are modified immediately by the adsorption of proteins when exposed to human blood, leading to the formation of a protein corona. The adsorption of serum proteins is the key process for exploring the bioapplication and biosafety of NPs. In this study, NP–protein binding affinity (Ka) was investigated. Some serum proteins, such as human serum albumin (HSA), trypsin (TRP), hemoglobin (Hb), myoglobin (MB), immunoglobulin G (IgG), carbonic anhydrase (CA), fibrinogen (FIB), chymotrypsin and r-globulin, were used with gold nanoparticles (AuNPs) to address binding affinity according to isothermal titration calorimetry (ITC) combined with dynamic light scattering (DLS) and fluorescence quenching. The NP protein binding affinities determined by the two methods were in agreement, and depended on the protein properties and size of the NPs. The two methods are convenient, and the results are highly comparable. These methods can be extended to determine the binding affinity of NP protein interactions. The adsorption of proteins upon the AuNP surface is a complex process and depends on several factors, but the binding affinities are higher for proteins with more cysteine residues located on the surface.

Investigating the interaction of juglone (5-hydroxy-1, 4-naphthoquinone) with serum albumins using spectroscopic and in silico methods

Abstract: The interaction between juglone at the concentration range of 10–110 µM and bovine serum albumin (BSA) or human serum albumin (HSA) at the constant concentration of 11 µM was investigated by fluorescence and UV absorption spectroscopy under physiological-like condition. Performing the experiments at different temperatures showed that the fluorescence intensity of BSA/HSA was decreased in the presence of juglone by a static quenching mechanism due to the formation of the juglone–protein complex. The binding constant for the interaction was in the order of 103 M−1, and the number of binding sites for juglone on serum albumins was determined to be equal to one. The thermodynamic parameters including enthalpy (ΔH), entropy (ΔS) and Gibb’s free energy (ΔG) changes were obtained by using the van’t Hoff equation. These results indicated that van der Waals force and hydrogen bonding were the main intermolecular forces stabilizing the complex in a spontaneous association reaction. Moreover, the interaction of BSA/HSA with juglone was verified by UV absorption spectra and molecular docking. The results of synchronous fluorescence, UV–visible and CD spectra demonstrated that the binding of juglone with BSA/HSA induces minimum conformational changes in the structure of albumins. The increased binding affinity of juglone to albumin observed in the presence of site markers (digoxin and ibuprofen) excludes IIA and IIIA sites as the binding site of juglone. This is partially in agreement with the results of molecular docking studies which suggests sub-domain IA of albumin as the binding site.

Hyaluronic Acid Coated Albumin Nanoparticles for Targeted Peptide Delivery to the Retina

Abstract: Recent studies have shown that Connexin43 mimetic peptide (Cx43 MP) can prevent secondary damage following several retinal ischemic and inflammatory disorders by blocking the pathological opening of gap junction hemichannels. However, the poor stability of peptides and the presence of various intraocular barriers limit efficient retinal delivery in the clinical setting. The present study aimed to prolong the bioactivity of Cx43 MP and achieve targeted delivery to the retina by loading the peptide into hyaluronic acid (HA) coated human serum albumin nanoparticles (HSA NPs). Two different loading methods, adsorption and incorporation, were used with the peptide released slowly over a period of up to four months. Compared to uncoated particles, HA coated HSA NPs exhibited enhanced in vitro cellular uptake and ex vivo retinal penetration via HA-CD44 receptor mediated interactions. Furthermore, cell viability and Cx43 MP functionality assays showed that NPs protected Cx43 MP from degradation, sustained its rel...

Thermodynamics and Mechanisms of the Interactions between Ultrasmall Fluorescent Gold Nanoclusters and Human Serum Albumin, γ-Globulins, and Transferrin: A Spectroscopic Approach.

Abstract: Noble metal nanoclusters (NCs) show great promise as nanoprobes for bioanalysis and cellular imaging in biological applications due to ultrasmall size, good photophysical properties, and excellent biocompatibility. In order to achieve a comprehensive understanding of possible biological implications, a series of spectroscopic measurements were conducted under different temperatures to investigate the interactions of Au NCs (∼1.7 nm) with three model plasmatic proteins (human serum albumin (HSA), γ-globulins, and transferrin). It was found that the fluorescence quenching of HSA and γ-globulins triggered by Au NCs was due to dynamic quenching mechanism, while the fluorescence quenching of transferrin by Au NCs was a result of the formation of a Au NC–transferrin complex. The apparent association constants of the Au NCs bound to HSA, γ-globulins, and transferrin demonstrated no obvious difference. Thermodynamic studies demonstrated that the interaction between Au NCs and HSA (or γ-globulins) was driven by hy...

Multi-spectroscopic and molecular modeling studies of interaction between two different angiotensin I converting enzyme inhibitory peptides from gluten hydrolysate and human serum albumin

Abstract: The present study was carried out to characterize Angiotensin-converting enzyme (ACE) inhibitory peptides which are released from the trypsin hydrolysate of wheat gluten protein. The binding of two inhibitory peptide (P4 and P6) to human serum albumin (HSA) under physiological conditions has been investigated by multi-spectroscopic in combination with molecular modeling techniques. Time-resolved and quenching fluorescence spectroscopies results revealed that the quenching of HSA fluorescence by P4 and P6 in the binary and ternary systems caused HSA-peptides complexes formation. The results indicated that both peptides quenched the fluorescence intensity of HSA through a static mechanism. The binding affinities and number of binding sites were obtained for the HSA-peptides complexes. The circular dichroism (CD) data revealed that the presence of both peptides increased the α-helix content of HSA and induced the remarkable folding of the polypeptide of the protein. Therefore, the CD data determined that the protein structure has been stabilized in the percent of ACE inhibitory peptides in binary and ternary systems. The binding distances between HSA and both peptides were estimated by the Forster theory, and it was revealed that nonradiative energy transfer from HSA to peptides occurred with a high probability. ITC experiments reveal that, in the absence and presence of P6, the dominant forces are electrostatic in binary and ternary systems. Furthermore, molecular modeling studies confirmed the experimental results. Molecular modeling investigation suggested that P4 bound to the site IA and IIA of HSA in binary and ternary systems, respectively. This study on the interaction of peptides with HSA should prove helpful for realizing the distribution and transportation of food compliments and drugs in vivo, elucidating the action mechanism and dynamics of food compliments and drugs at the molecular level. It should moreover be of great use for understanding the pharmacokinetic and pharmacodynamic mechanism of the food compliments and drugs.

Serum Albumin Binding and Esterase Activity: Mechanistic Interactions with Organophosphates.

Abstract: The albumin molecule, in contrast to many other plasma proteins, is not covered with a carbohydrate moiety and can bind and transport various molecules of endogenous and exogenous origin. The enzymatic activity of albumin, the existence of which many scientists perceive skeptically, is much less studied. In toxicology, understanding the mechanistic interactions of organophosphates with albumin is a special problem, and its solution could help in the development of new types of antidotes. In the present work, the history of the issue is briefly examined, then our in silico data on the interaction of human serum albumin with soman, as well as comparative in silico data of human and bovine serum albumin activities in relation to paraoxon, are presented. Information is given on the substrate specificity of albumin and we consider the possibility of its affiliation to certain classes in the nomenclature of enzymes.

Structure and Affinity of Cu(I) Bound to Human Serum Albumin.

Abstract: Human serum albumin (HSA) is a major Cu carrier in human blood and in cerebrospinal fluid. A major assumption is that Cu bound to HSA is in the Cu(II) oxidation state; thus, interactions between HSA and Cu(II) have been intensely investigated for over four decades. HSA has been reported previously to support the reduction of Cu(II) to the Cu(I) oxidation state in the presence of the weak reductant, ascorbate; however, the interactions between HSA and Cu(I) have not been explicitly investigated. Here, we characterize both the apparent affinity of HSA for Cu(I) using solution competition experiments and the coordination structure of Cu(I) bound to HSA using X-ray absorption spectroscopy and in silico modeling. We find that HSA binds to Cu(I) at pH 7.4 with an apparent conditional affinity of KCu(I):HSA = 1014.0 using digonal coordination in a structure that is similar to the bis-His coordination modes characterized for amyloid beta (Aβ) and the prion protein. This high affinity and familiar Cu(I) coordination structure suggests that Cu(I) interaction with HSA in human extracellular fluids is unappreciated in the current scientific literature.

Insight into the interaction of antitubercular and anticancer compound clofazimine with human serum albumin: spectroscopy and molecular modelling

Abstract: The binding of clofazimine to human serum albumin (HSA) was investigated by applying optical spectroscopy and molecular docking methods. Fluorescence quenching data revealed that clofazimine binds ...

Allosteric effects of gold nanoparticles on human serum albumin

Abstract: The ability of nanoparticles to alter protein structure and dynamics plays an important role in their medical and biological applications. We investigate allosteric effects of gold nanoparticles on human serum albumin protein using molecular simulations. The extent to which bound nanoparticles influence the structure and dynamics of residues distant from the binding site is analyzed. The root mean square deviation, root mean square fluctuation and variation in the secondary structure of individual residues on a human serum albumin protein are calculated for four protein-gold nanoparticle binding complexes. The complexes are identified in a brute-force search process using an implicit-solvent coarse-grained model for proteins and nanoparticles. They are then converted to atomic resolution and their structural and dynamic properties are investigated using explicit-solvent atomistic molecular dynamics simulations. The results show that even though the albumin protein remains in a folded structure, the presence of a gold nanoparticle can cause more than 50% of the residues to decrease their flexibility significantly, and approximately 10% of the residues to change their secondary structure. These affected residues are distributed on the whole protein, even on regions that are distant from the nanoparticle. We analyze the changes in structure and flexibility of amino acid residues on a variety of binding sites on albumin and confirm that nanoparticles could allosterically affect the ability of albumin to bind fatty acids, thyroxin and metals. Our simulations suggest that allosteric effects must be considered when designing and deploying nanoparticles in medical and biological applications that depend on protein-nanoparticle interactions.

Interaction of mycotoxin zearalenone with human serum albumin

Abstract: Zearalenone (ZEN) is a mycotoxin produced mainly by Fusarium species. Fungal contamination of cereals and plants can result in the formation of ZEN, leading to its presence in different foods, animal feeds, and drinks. Because ZEN is an endocrine disruptor, it causes reproductive disorders in farm animals and hyperoestrogenic syndromes in humans. Despite toxicokinetic properties of ZEN were studied in more species, we have no information regarding the interaction of ZEN with serum albumin. Since albumin commonly plays an important role in the toxicokinetics of different toxins, interaction of ZEN with albumin has of high biological importance. Therefore the interaction of ZEN with human serum albumin (HSA) was investigated using spectroscopic methods, ultrafiltration, and molecular modeling studies. Fluorescence spectroscopic studies demonstrate that ZEN forms complex with HSA. Binding constant (K) of ZEN-HSA complex was quantified with fluorescence quenching technique. The determined binding constant (logK=5.1) reflects the strong interaction of ZEN with albumin suggesting the potential biological importance of ZEN-HSA complex formation. Based on the results of the investigations with site markers as well as docking studies, ZEN occupies a non-conventional binding site on HSA. Considering the above listed observations, we should keep in mind this interaction if we would like to precisely understand the toxicokinetic behavior of ZEN.

Green synthesis of biogenic silver nanoparticles using Solanum tuberosum extract and their interaction with human serum albumin: Evidence of “corona” formation through a multi-spectroscopic and molecular docking analysis

Abstract: Biogenic silver nanoparticles (AgNPs) have been synthesized by using Solanum tuberosum (potato) extract (PE) as a reducing as well as stabilizing agent which is reasonably cheaper, non-toxic and easily available material The green synthesis of silver nanoparticles has been carried out by very simple method and the nanoparticles were characterized by surface plasmon band as well as TEM measurements The PE-AgNPs were highly dispersed in the solution and found to be spherical with around 10nm in size Interaction of these nanoparticles was studied with plasma protein HSA by means of various spectroscopies, such as, UV-visible, fluorescence, DLS, CD and FTIR spectroscopies The HSA was found to form the protein "corona" around the starch-capped PE-AgNPs Absorption spectroscopy revealed that the interaction between HSA and PE-AgNPs resulted in the ground state complex formation Due to the strong absorption of PE-AgNPs, the inner filter effect was corrected for the fluorescence data PE-AgNPs were found to quench the fluorescence of HSA with a small blue shift attributed to the increase in the hydrophobicity near tryptophan residue due to the presence of amylopectin and amylose units in the starch The value of n, Hill's constant, was found to be >1 which determines the existence of a cooperative binding between nanoparticle and albumin Several parameters such as Stern-Volmer and binding constants in addition to the thermodynamic parameters have been analyzed and discussed which established that the complex formation has taken place via static quenching mechanism and the corona formation between albumin and PE-AgNPs was entropy driven process Binding of biogenic PE-AgNPs to the HSA slightly affected the secondary structure of latter with a small decrease in α-helical contents resulting in the partial unfolding of the protein, though the structural motif remained the same Molecular docking simulations revealed various possible binding modes between PE-AgNPs and albumin