Showing papers on "Human serum albumin published in 2011"
TL;DR: The accurate and full basic data in the work is beneficial to clarifying the binding mechanism of TC with HSA in vivo and understanding its effect on protein function during the blood transportation process.
274 citations
TL;DR: The fluorescence data showed that tartrazine could bind to the two SAs to form a complex, and the binding process was a spontaneous molecular interaction procedure, in which van der Waals and hydrogen bond interactions played a major role.
Abstract: Tartrazine is an artificial azo dye commonly used in food products. The present study evaluated the interaction of tartrazine with two serum albumins (SAs), human serum albumin (HSA) and bovine serum albumin (BSA), under physiological conditions by means of fluorescence, three-dimensional fluorescence, UV-vis absorption, and circular dichroism (CD) techniques. The fluorescence data showed that tartrazine could bind to the two SAs to form a complex. The binding process was a spontaneous molecular interaction procedure, in which van der Waals and hydrogen bond interactions played a major role. Additionally, as shown by the UV-vis absorption, three-dimensional fluorescence, and CD results, tartrazine could lead to conformational and some microenvironmental changes of both SAs, which may affect the physiological functions of SAs. The work provides important insight into the mechanism of toxicity of tartrazine in vivo.
219 citations
TL;DR: The production of Oryza sativa recombinant HSA (OsrHSA) from transgenic rice seeds is reported, which displays similar in vitro and in vivo immunogenicity as pHSA and can help to satisfy an increasing worldwide demand for human serum albumin.
Abstract: Human serum albumin (HSA) is widely used in clinical and cell culture applications. Conventional production of HSA from human blood is limited by the availability of blood donation and the high risk of viral transmission from donors. Here, we report the production of Oryza sativa recombinant HSA (OsrHSA) from transgenic rice seeds. The level of OsrHSA reached 10.58% of the total soluble protein of the rice grain. Large-scale production of OsrHSA generated protein with a purity >99% and a productivity rate of 2.75 g/kg brown rice. Physical and biochemical characterization of OsrHSA revealed it to be equivalent to plasma-derived HSA (pHSA). The efficiency of OsrHSA in promoting cell growth and treating liver cirrhosis in rats was similar to that of pHSA. Furthermore, OsrHSA displays similar in vitro and in vivo immunogenicity as pHSA. Our results suggest that a rice seed bioreactor produces cost-effective recombinant HSA that is safe and can help to satisfy an increasing worldwide demand for human serum albumin.
192 citations
TL;DR: The objective of this study was to investigate the plasma‐protein binding of the most abundant bioflavonoid, quercetin, using 14C‐labelled quercets, and to report on the effects of these dietary components in man.
Abstract: Although the bioflavonoids, a large group of polyphenolic natural products, exert chemopreventive effects in cardiovascular disease and cancer, there is little information about the disposition of these dietary components in man. The objective of this study was to investigate the plasma-protein binding of the most abundant bioflavonoid, quercetin, using 14C-labelled quercetin. An ultracentrifugation assay (170,000 g for 16 h at 20 degrees C) was shown to sediment plasma proteins. Binding of quercetin to normal plasma was extensive (99.1+/-0.5%, mean +/- s.d., n = 5). The unbound fraction varied as much as 6-fold, 0.3-1.8%, between subjects. This high binding was independent of quercetin concentration over the range 1.5-15 microM (0.5-5 microg mL(-1)). Human serum albumin was the primary protein responsible for the binding of quercetin in plasma (99.4+/-0.1%). Binding by alpha1-acid glycoprotein (39.2+/-0.5%) and very-low-density lipoproteins (<0.5% of total quercetin) did not make substantial contributions to overall plasma binding. The equilibrium association constant for the binding of quercetin to serum albumin was 267+/-33 x 10(3) M(-1) (n = 15). Thermodynamic data for the binding of quercetin to serum albumin indicated spontaneous, endothermic association. Displacement studies suggested that in man the 'IIA' subdomain binding site of human serum albumin was the primary binding site for quercetin. Association of quercetin with erythrocytes was significantly (P < 0.001) reduced by plasma protein binding. These data indicate poor cellular availability of quercetin because of its extensive binding to plasma proteins.
185 citations
TL;DR: The results suggest that highly tumor-specific albumin nanoparticles have the potential to serve not only as efficient therapeutic agents, but also as photodynamic imaging (PDI) reagents in cancer treatment.
Abstract: Photodynamic therapy (PDT) is an emerging theranostic modality for various cancers and diseases. The focus of this study was the development of tumor-targeting albumin nanoparticles containing photosensitizers for efficient PDT. To produce tumor-targeting albumin nanoparticles, the hydrophobic photosensitizer, chlorin e6 (Ce6), was chemically conjugated to human serum albumin (HSA). The conjugates formed self-assembled nanoparticle structures with an average diameter of 88 nm under aqueous conditions. As expected, the Ce6-conjugated HSA nanoparticles (Ce6-HSA-NPs) were nontoxic in their native state, but upon illumination with the appropriate wavelength of light, they produced singlet oxygen and damaged target tumor cells in a cell culture system. Importantly, when the nanoparticles were injected through the tail vein into tumor-bearing HT-29 mice, Ce6-HSA-NPs compared with free Ce6 revealed enhanced tumor-specific biodistribution and successful therapeutic results following laser irradiation. These results suggest that highly tumor-specific albumin nanoparticles have the potential to serve not only as efficient therapeutic agents, but also as photodynamic imaging (PDI) reagents in cancer treatment.
174 citations
TL;DR: The ensemble is found to have high selectivity toward HSA over a number of polyelectrolytes, proteins and small amino acids, suggested to be a result of the extra stabilization gained from the Pt···Pt and π-π interactions in addition to the electrostatic and hydrophobic interactions found in the polymer-metal complex aggregates.
Abstract: The interaction of conjugated polyelectrolyte, PPE-SO3–, with platinum(II) complexes, [Pt(tpy)(C≡CC6H4−CH2NMe3-4)](OTf)2 (1) and [Pt(tpy)(C≡C–CH2NMe3)](OTf)2 (2), has been studied by UV–vis, and steady-state and time-resolved emission spectroscopy. A unique FRET from PPE-SO3– to the aggregated complex 1 on the polymer chain with Pt···Pt interaction has been demonstrated, resulting in the growth of triplet metal-metal-to-ligand charge transfer (3MMLCT) emission in the near-infrared (NIR) region. This two-component ensemble has been employed in a “proof-of-principle” concept for the sensitive and selective label-free detection of human serum albumin (HSA) by the emission spectral changes in the visible and in the NIR region. The spectral changes have been ascribed to the disassembly of the polymer–metal complex aggregates upon the binding of PPE-SO3– to HSA, which is rich in arginine residues and hydrophobic patches, leading to the decrease in FRET from PPE-SO3– to the aggregated platinum(II) complex. The e...
143 citations
TL;DR: The glycation pattern of HSA was found to vary with different levels of total glycation and included modifications at the 2 major drug binding sites on this protein.
133 citations
TL;DR: It is suggested that difference in dissociation constants of pollutants by calorimetry, spectroscopic and computational approaches could correspond to occurrence of different set of populations of pollutants having different molecular characteristics in ground state and excited state.
Abstract: 1–naphthol (1N), 2–naphthol (2N) and 8–quinolinol (8H) are general water pollutants. 1N and 2N are the configurational enantiomers and 8H is isoelectronic to 1N and 2N. These pollutants when ingested are transported in the blood by proteins like human serum albumin (HSA). Binding of these pollutants to HSA has been explored to elucidate the specific selectivity of molecular recognition by this multiligand binding protein. The association constants (Kb) of these pollutants to HSA were moderate (104–105 M−1). The proximity of the ligands to HSA is also revealed by their average binding distance, r, which is estimated to be in the range of 4.39–5.37 nm. The binding free energy (ΔG) in each case remains effectively the same for each site because of enthalpy–entropy compensation (EEC). The difference observed between ΔCpexp and ΔCpcalc are suggested to be caused by binding–induced flexibility changes in the HSA. Efforts are also made to elaborate the differences observed in binding isotherms obtained through multiple approaches of calorimetry, spectroscopy and bioinformatics. We suggest that difference in dissociation constants of pollutants by calorimetry, spectroscopic and computational approaches could correspond to occurrence of different set of populations of pollutants having different molecular characteristics in ground state and excited state. Furthermore, our observation of enhanced binding of pollutants (2N and 8H) in the presence of hemin signifies that ligands like hemin may enhance the storage period of these pollutants in blood that may even facilitate the ill effects of these pollutants.
133 citations
TL;DR: The results suggest that the connection between complex 1 and HSA is reversible, and therefore the cytotoxic activity of the complex could be preserved during blood circulation.
Abstract: Interactions between platinum complexes and human serum albumin (HSA) play crucial roles in the metabolism, distribution, and efficacy of platinum-based anticancer drugs. Polynuclear monofunctional platinum(II) complexes represent a new class of anticancer agents that display distinct molecular characters of pharmacological action from those of cisplatin. In this study, the interaction between a trinuclear monofunctional platinum(II) complex, [Pt3LCl3](ClO4)3 (L = N,N,N′,N′,N″,N″-hexakis(2-pyridylmethyl)-1,3,5-tris(aminomethyl)benzene) (1), and HSA was investigated using ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, circular dichroism spectroscopy, fluorescence spectroscopy, molecular docking, and inductively coupled plasma mass spectrometry. The spectroscopic and thermodynamic data show that the interaction is a spontaneous process with the estimated enthalpy and entropy changes being 14.6 kJ mol–1 and 145.5 J mol–1 K–1, respectively. The reactive sites of HSA to complex 1 ma...
129 citations
01 Jul 2011
TL;DR: The SVM model was integrated to a free, web-based prediction platform and the potential offered by the combined use of in silico calculation methods and experimental binding data is illustrated.
Abstract: Motivation: Human serum albumin (HSA), the most abundant plasma protein is well known for its extraordinary binding capacity for both endogenous and exogenous substances, including a wide range of drugs. Interaction with the two principal binding sites of HSA in subdomain IIA (site 1) and in subdomain IIIA (site 2) controls the free, active concentration of a drug, provides a reservoir for a long duration of action and ultimately affects the ADME (absorption, distribution, metabolism, and excretion) profile. Due to the continuous demand to investigate HSA binding properties of novel drugs, drug candidates and drug-like compounds, a support vector machine (SVM) model was developed that efficiently predicts albumin binding. Our SVM model was integrated to a free, web-based prediction platform ( http://albumin.althotas.com). Automated molecular docking calculations for prediction of complex geometry are also integrated into the web service. The platform enables the users (i) to predict if albumin binds the query ligand, (ii) to determine the probable ligand binding site (site 1 or site 2), (iii) to select the albumin X-ray structure which is complexed with the most similar ligand and (iv) to calculate complex geometry using molecular docking calculations. Our SVM model and the potential offered by the combined use of in silico calculation methods and experimental binding data is illustrated.
Contact: eszter.hazai@virtuadrug.com
Supplementary information:Supplementary data are available at Bioinformatics online.
126 citations
TL;DR: The co-crystal structures of HSA in complex with six dansylated amino acids that are specific for either drug site 1 or drug site 2 are presented and the structural basis of the site-specificity of different dansyated amino acid compounds is explained.
TL;DR: Using dual-focus fluorescence correlation spectroscopy, the adsorption of three human blood serum proteins onto polymer-coated, fluorescently labeled FePt nanoparticles carrying negatively charged carboxyl groups on their surface is analyzed, suggesting the formation of protein monolayers that enclose the nanoparticles.
Abstract: Using dual-focus fluorescence correlation spectroscopy, we have analyzed the adsorption of three human blood serum proteins, namely serum albumin, apolipoprotein A-I and apolipoprotein E4, onto polymer-coated, fluorescently labeled FePt nanoparticles (~12 nm diameter) carrying negatively charged carboxyl groups on their surface. For all three proteins, a step-wise increase in hydrodynamic radius with protein concentration was observed, strongly suggesting the formation of protein monolayers that enclose the nanoparticles. Consistent with this interpretation, the absolute increase in hydrodynamic radius can be correlated with the molecular shapes of the proteins known from X-ray crystallography and solution experiments, indicating that the proteins bind on the nanoparticles in specific orientations. The equilibrium dissociation coefficients, measuring the affinity of the proteins to the nanoparticles, were observed to differ by almost four orders of magnitude. These variations can be understood in terms of the electrostatic properties of the proteins. From structure-based calculations of the surface potentials, positively charged patches of different extents can be revealed, through which the proteins interact electrostatically with the negatively charged nanoparticle surfaces.
TL;DR: The human serum albumin (HSA) protein–Au nanoparticle interaction is studied to identify the specific binding site of protein with nanoparticles by using the surface energy transfer (SET) method among tryptophan of HSA, ANS-dye-labeled HSA protein, and Au nanoparticles.
Abstract: Here, we study the human serum albumin (HSA) protein–Au nanoparticle interaction to identify the specific binding site of protein with nanoparticles by using the surface energy transfer (SET) method among tryptophan (Trp) of HSA, ANS-dye-labeled HSA protein, and Au nanoparticles. Here, ANS dye is used as a probe located at domain IIIA of HSA. In particular, absorbance, fluorescence quenching, decay time, circular dichroism, dynamic light scattering, and TEM measurements are performed to understand the physical properties of protein-conjugated Au nanoparticles. Using the SET method, the measured distances between the Trp residue of HSA and the binding site of HSA interacting with Au nanoparticles are 42.5, 41.9, and 48.1 A for 1.5, 2.0, and 2.9 nm HSA-conjugated Au nanoparticles, respectively. The measured distances between the binding site of ANS dye (located at domain IIIA) in HSA to the binding site of HSA interacting with Au nanoparticles are 51, 51.5, and 54.7 A for 1.5, 2.0, and 2.9 nm HSA-conjugated...
TL;DR: The experimental results revealed the static quenching mechanism in the interaction of TRP with protein and the hydrogen bond and van der Waals forces played the major role in the binding of TRp to proteins.
TL;DR: When incubated with human melanoma cells (M21+) that express the α(v)β(3) integrin, higher uptake and longer retention of doxorubicin was observed with the RGD-targeted micelles than in the case of untargeted control micells or free doxorbicin, Consequently, the RGDs manifested cytotoxicity at lower doses of drug than control mouselles or free drug.
TL;DR: A partially new model for HSA–VIVO interactions is introduced, in which the two binding sites compete not only with each other, but also with hydrolysis of the metal ion.
TL;DR: Data suggest that covalent linkage of folic acid can specifically increase cancer cell HSA NP uptake into cancer cells but not into HFFs.
TL;DR: Results indicate that choline dhp as a cosolvent may selectively stabilize HSA conformations closer to the crystal structure out of the overall conformational ensemble.
TL;DR: The binding distances between the donor (HSA) and the acceptors (catechins) estimated by the Forster theory revealed that non-radiation energy transfer from HSA to catechins occurred with high possibility and contributed to the current knowledge in the area of protein–ligand binding, particularly catechin–HSA interactions.
TL;DR: PA was found to be more potent than BP with respect to stimulation of T cells from patients with penicillin hypersensitivity, illustrating the functional relevance of diastereoisomeric hapten formation.
Abstract: Covalent binding to proteins to form neoantigens is thought to be central to the pathogenesis of penicillin hypersensitivity reactions. We have undertaken detailed mass spectrometric studies to define the mechanism and protein chemistry of hapten formation from benzylpenicillin (BP) and its rearrangement product, benzylpenicillenic acid (PA). Mass spectrometric analysis of human serum albumin exposed to BP and PA in vitro revealed that at low concentrations (drug protein molar ratio 0.001:1) and during short time incubations BP and PA selectively target different residues, Lys199 and Lys525, respectively. Molecular modeling showed that the selectivity was a function of noncovalent interaction before covalent modification. With increased exposure to higher concentrations of BP and PA, multiple epitopes were detected on albumin, demonstrating that the multiplicity of hapten formation is a function of time and concentration. More importantly, we have demonstrated direct evidence that PA is a hapten accounting for the diastereoisomeric BP antigen formation in albumin isolated from the blood of patients receiving penicillin. Furthermore, PA was found to be more potent than BP with respect to stimulation of T cells from patients with penicillin hypersensitivity, illustrating the functional relevance of diastereoisomeric hapten formation.
TL;DR: The results suggest the reversible covalent modification of EGCg via Schiff-base formation, and that the immobilization of E GCg to HSA, through the formation of a stable complex, prevented the polymerization and decomposition ofEGCg in human serum.
Abstract: Human serum albumin (HSA) contributes to the stabilization of (-)-epigallocatechin gallate (EGCg) in serum. We characterize in the present study the mechanisms for preventing EGCg oxidation by HSA. EGCg was stable in human serum or buffers with HSA, but (-)-epigallocatechin (EGC) was unstable. We show by comparing EGCg and EGC in a neutral buffer that EGCg had a higher binding affinity than EGC. This indicates that the galloyl moiety participated in the interaction of EGCg with HSA and that this interaction was of critical importance in preventing EGCg oxidation. The binding affinity of EGCg for HSA and protein carbonyl formation in HSA were enhanced in an alkaline buffer. These results suggest the reversible covalent modification of EGCg via Schiff-base formation, and that the immobilization of EGCg to HSA, through the formation of a stable complex, prevented the polymerization and decomposition of EGCg in human serum.
TL;DR: The results suggest that serum albumins can act as carrier proteins for tamoxifen and its metabolites in delivering them to target tissues.
TL;DR: Warfarin and phenprocoumon binding to human serum albumin was studied by equilibrium dialysis to establish an understanding of the mechanism of action of these drugs.
Abstract: Warfarin and phenprocoumon binding to human serum albumin was studied by equilibrium dialysis. The first stoichiometric binding constant was 1.89 x 10(5) M-1 for warfarin and 2.40 x 10(5) M-1 for phenprocoumon. The affinity of warfarin was markedly increased on addition of up to 3 mol mol-1 albumin of palmitic, stearic, oleic or linoleic acids with energetic couplings for co-binding of one molecule of each of the fatty acids and one molecule of warfarin of 0.9, 1.1, 0.7 and 0.6 kJ mol-1, respectively. The affinity of phenprocoumon was only increased slightly on addition of palmitate with an energetic coupling of 0.3 kJ mol-1. Six consecutive serum samples were obtained from each of 14 patients undergoing surgery. The serum affinity of the drugs varied considerably corresponding to free drug concentrations between 0.7 and 2.7% for warfarin and between 0.8 and 4.9% for phenprocoumon. The affinity of warfarin but not of phenprocoumon was correlated to the increasing plasma fatty acid concentration. Anticoagulant therapy with phenprocoumon may thus be less sensitive than warfarin to changes in the fatty acid concentration of plasma.
TL;DR: The overall binding of phenothiazines was exothermic with negative δH, which was compensated for by changes in δS, and the values of δG were relatively insensitive to variation in the molecular details of the binding reaction.
Abstract: A flow microcalorimetric study has been carried out to investigate the interactions between phenothiazine derivatives and human plasma, human serum albumin (HSA) and α1acid glycoprotein (AGP) at pH 7·4 and 37°C. The direct analyses of enthalpic titration curves allowed the determination of the binding enthalpy change (δH), the apparent binding constant (K), and the number of the binding sites (n), as well as the evaluation of the apparent free energy (δG), and entropy (δS) changes. The overall binding of phenothiazines was exothermic with negative δH, which was compensated for by changes in δS. The values of δG were relatively insensitive to variation in the molecular details of the binding reaction. HSA possessed two classes of binding sites for phenothiazines. The first (n1 = 1), with high affinity (K1 = 105–106 M−1) was characterized by small negative δH and positive δS values due to hydrophobic interaction. The second class of sites had a low affinity (K2 = 103-104 M−1) and high capacity (n2 = 3–8) and contributed to the negative δH and δS values. The binding and thermodynamic parameters were influenced by the aliphatic side chain moieties on the phenothiazine nucleus. On the other hand, the drugs were bound to AGP at a single common binding site with a binding affinity of the order of 104M−1, characterized by negative δH and δS values, which partially reflected the effect of a van der Waals' interaction. In plasma the drugs were bound as a result of an enthalpy-driven type of reaction having large negative δH and a large binding capacity resulting from the presence of AGP and HSA.
TL;DR: The results show that the Aβ oligomers are recognized by albumin through sites that are evenly partitioned across the three albumin domains and that bind the A β oligomers with similar dissociation constants in the 1-100 nM range, as assessed based on a Scatchard-like model of the albumin inhibition isotherms.
TL;DR: Various neuroprotective actions of the albumin in the brain are summarised to explore newer roles of this endogenously produced multifunctional protein in normal as well as pathological conditions of the brain.
Abstract: Albumin is the most abundant plasma protein synthesised mainly in the liver. It is also a major component of extracellular fluids including cerebrospinal fluid, interstitial fluid and lymph. Albumin has several biochemical properties including regulation of colloid osmotic pressure of plasma, transportation of hormones, fatty acids, drugs and metabolites across plasma, regulation of microvascular permeability, antioxidant activity, anti-thrombotic activity and anti-inflammatory activity. This multifunctional protein has been implicated in many neurological diseases owing to its ability to regulate hemodynamic properties of the brain circulation as well as the direct neuroprotective actions on neuronal and glial cells. In this review, we summarise various neuroprotective actions of the albumin in the brain. In experimental ischemic stroke, exogenous human serum albumin administration has been found to be neuroprotective via reducing brain swelling, prevention of post-ischemic thrombosis, anti-oxidant activity, hemodilution and increasing the perfusion to the ischemic tissue. Also, human serum albumin administration is currently under clinical trials for treatment of cerebral ischemia. In the experimental models of Alzheimer's disease, albumin has been implicated in neuroprotection by inhibiting polymerisation and enhancing the clearance of amyloid β. The direct neuroprotective actions on neuronal and glial cells are mediated via endogenously produced albumin or cellular uptake of blood derived albumin. These neuroprotective effects of albumin are partly attributed to anti-oxidant property and modulation of intracellular signalling of neuronal or glial cells. The recent finding of de novo synthesis of albumin in microglial cells directs us to explore newer roles of this endogenously produced multifunctional protein in normal as well as pathological conditions of the brain.
TL;DR: Examination of the changes that occur in binding of the sulfonylurea drug tolbutamide to HSA as the level of glycation for this protein was increased demonstrates the effects that glycation can have on drug interactions on HSA and should provide a better quantitative understanding of how the protein binding in serum may be affected for individuals with diabetes.
TL;DR: Results clearly show that HSA–MWCNTs selectively attach on the albondin (aka Gp60) receptor located on the HepG2 membrane, followed by an uptake through a caveolin-dependent endocytosis process, which may represent a major step in liver cancer treatment using nanolocalized thermal ablation by laser heating.
Abstract: The main goal of this investigation was to develop and test a new method of treatment for human hepatocellular carcinoma (HCC). We present a method of carbon nanotube-enhanced laser thermal ablation of HepG2 cells (human hepatocellular liver carcinoma cell line) based on a simple multiwalled carbon nanotube (MWCNT) carrier system, such as human serum albumin (HSA), and demonstrate its selective therapeutic efficacy compared with normal hepatocyte cells. Both HepG2 cells and hepatocytes were treated with HSA-MWCNTs at various concentrations and at various incubation times and further irradiated using a 2 W, 808 nm laser beam. Transmission electron, phase contrast, and confocal microscopy combined with immunochemical staining were used to demonstrate the selective internalization of HSA-MWCNTs via Gp60 receptors and the caveolin-mediated endocytosis inside HepG2 cells. The postirradiation apoptotic rate of HepG2 cells treated with HSA-MWCNTs ranged from 88.24% (for 50 mg/L) at 60 sec to 92.34% (for 50 mg/L) at 30 min. Significantly lower necrotic rates were obtained when human hepatocytes were treated with HSA-MWCNTs in a similar manner. Our results clearly show that HSA-MWCNTs selectively attach on the albondin (aka Gp60) receptor located on the HepG2 membrane, followed by an uptake through a caveolin-dependent endocytosis process. These unique results may represent a major step in liver cancer treatment using nanolocalized thermal ablation by laser heating.
TL;DR: Cisplatin, cis-[Pt(Cl(2)(NH(3))(2)], can crosslink residues His67 of domain I and His247 of domain II in human albumin, occupying the major binding site for the essential metal zinc on the protein.
TL;DR: The data of fluorescence spectra displayed that the binding of ARS to HSA is the formation of HSA-ARS complex at 1:1 stoichiometric proportion, which is consistent with guanidine hydrochloride induced HSA unfolding studies and molecular modeling simulations.