Showing papers on "Human serum albumin published in 2006"
TL;DR: Experimental results showed that the binding of GEM to BSA or HSA induced conformational changes in BSA and HSA, and confirmed that the secondary structure of protein was altered by GEM.
477 citations
TL;DR: Thermodynamic analysis and computational modeling indicated that GEA could bind to the site I of HSA and hydrophobic interaction was the major acting force for the second type of binding site, which was in agreement with the thermodynamic analysis.
339 citations
TL;DR: It is shown that FA sites 2, 4 and 5 bind FA with high affinity, while sites 1, 3, 6 and 7 exhibit low affinity for FA, thus providing the first complete determination of relative affinities of all seven long-chain FA sites on HSA.
315 citations
TL;DR: The conformational changes in two physiologically important isomers of HSA (N and B isomers) upon ciprofloxacin binding were evaluated by measuring far, near-UV CD, and fluorescence properties of the CFX-HSA complex.
302 citations
TL;DR: It was found that liposomal vehicle is capable of loading more curcumin in to cells than HSA or aqueous-DMSO, and lymphoma cells show preferential uptake ofCurcumin to lymphocytes.
268 citations
TL;DR: The interaction of morin with human serum albumin (HSA) has been investigated by using fluorescence, UV absorption and Fourier transform infrared spectroscopic approaches for the first time, and an obvious reduction of the protein alpha-helix and beta-sheet structures was induced.
211 citations
TL;DR: Examination of the interaction of human serum albumin with quercetin, kaempferol and delphinidin in aqueous solution at physiological conditions showed that flavonoids are located along the polypeptide chains through H-bonding interactions with overall affinity constant, and major reduction of HSA α-helix is indicative of a partial protein unfolding upon flavonoid interaction.
163 citations
TL;DR: This review focuses on the combination of biochromatography and circular dichroism as an effective approach for the characterization of albumin binding sites and their enantioselectivity.
161 citations
TL;DR: It is concluded that an increased level of oxidized HSA may impair HSA function in a number of pathological conditions.
Abstract: Human serum albumin (HSA) exists in both reduced and oxidized forms, and the percentage of oxidized albumin increases in several diseases. However, little is known regarding the pathophysiological significance of oxidation due to poor characterization of the precise structural and functional properties of oxidized HSA. Here, we characterize both the structural and functional differences between reduced and oxidized HSA. Using LC-ESI-TOFMS and FTMS analysis, we determined that the major structural change in oxidized HSA in healthy human plasma is a disulfide-bonded cysteine at the thiol of Cys34 of reduced HSA. Based on this structural information, we prepared standard samples of purified HSA, e.g. nonoxidized (intact purified HSA which mainly exists in reduced form), mildly oxidized and highly oxidized HSA. Using these standards, we demonstrated several differences in functional properties of HSA including protease susceptibility, ligand-binding affinity and antioxidant activity. From these observations, we conclude that an increased level of oxidized HSA may impair HSA function in a number of pathological conditions.
150 citations
TL;DR: Data obtained by fluorescence spectroscopy, CD, and FTIR experiments along with the docking studies suggest that EGCG binds to residues located in subdomains IIa and IIIa of HSA, suggesting that apart from an initial hydrophobic association, the complex is held together by van der Waals interactions and hydrogen bonding.
Abstract: (-)-Epigallocatechin-3-gallate (EGCG), the major constituent of green tea has been reported to prevent many diseases by virtue of its antioxidant properties. The binding of EGCG with human serum albumin (HSA) has been investigated for the first time by using fluorescence, circular dichroism (CD), Fourier transform infrared (FTIR) spectroscopy, and protein-ligand docking. We observed a quenching of fluorescence of HSA in the presence of EGCG. The binding parameters were determined by a Scatchard plot and the results were found to be consistent with those obtained from a modified Stern-Volmer equation. From the thermodynamic parameters calculated according to the van't Hoff equation, the enthalpy change deltaH degrees and entropy change deltaS degrees were found to be -22.59 and 16.23 J/mol K, respectively. These values suggest that apart from an initial hydrophobic association, the complex is held together by van der Waals interactions and hydrogen bonding. Data obtained by fluorescence spectroscopy, CD, and FTIR experiments along with the docking studies suggest that EGCG binds to residues located in subdomains IIa and IIIa of HSA. Specific interactions are observed with residues Trp 214, Arg 218, Gln 221, Asn 295 and Asp 451. We have also looked at changes in the accessible surface area of the interacting residues on binding EGCG for a better understanding of the interaction.
139 citations
TL;DR: It was shown that TCZ has quite a strong ability to quench the fluorescence launching from HSA by reacting with it and forming a certain kind of new compound.
Abstract: The interaction of tricyclazole (TCZ) with beta-cyclodextrin (beta-CD) and human serum albumin (HSA) were studied by fluorescence spectrum, UV-visible spectrum and second-order scattering technology. It was shown that TCZ has quite a strong ability to quench the fluorescence launching from HSA by reacting with it and forming a certain kind of new compound. The quenching and the energy transfer mechanisms were discussed, respectively. The binding constants and thermodynamic parameters at four different temperatures, the binding locality, and the binding power were obtained. The conformation of HSA was discussed by synchronous and three-dimensional fluorescence techniques. The inclusion reaction between beta-CD and TCZ was explored by scattering method, the inclusion constants and the thermodynamic parameters at 297 K and 311 K were figured out, respectively. The mechanism of inclusion reaction was speculated and linkage among the toxicity of TCZ, the exterior environment and its concentration was attempted to explain on molecule level.
TL;DR: Development of a rationally designed potentiator of cancer chemotherapy, via inhibition of Bcl-X(L) function, 73R, potentiates the activity of paclitaxel and UV irradiation in vitro and potentiated the antitumor efficacy of pac litaxel in a mouse xenograft model.
Abstract: Development of a rationally designed potentiator of cancer chemotherapy, via inhibition of Bcl-X(L) function, is described. Lead compounds generated by NMR screening and directed parallel synthesis displayed sub-microM binding but were strongly deactivated in the presence of serum. The dominant component of serum deactivation was identified as domain III of human serum albumin (HSA); NMR solution structures of inhibitors bound to both Bcl-X(L) and HSA domain III indicated two potential optimization sites for separation of affinities. Modifications at both sites resulted in compounds with improved Bcl-X(L) binding and greatly increased activity in the presence of human serum, culminating in 73R, which bound to Bcl-X(L) with a K(i) of 0.8 nM. In a cellular assay 73R reversed the protection afforded by Bcl-X(L) overexpression against cytokine deprivation in FL5.12 cells with an EC(50) of 0.47 microM. 73R showed little effect on the viability of the human non small cell lung cancer cell line A549. However, consistent with the proposed mechanism, 73R potentiated the activity of paclitaxel and UV irradiation in vitro and potentiated the antitumor efficacy of paclitaxel in a mouse xenograft model.
TL;DR: In vitro mutagenesis and interaction studies with recombinant, soluble, purified receptors and IgG and albumin show clear evidence that the conserved H166 is a key player in the FcRn‐albumin interaction.
Abstract: The MHC class I-related neonatal Fc receptor (FcRn) serves in the homeostatic regulation of IgG and albumin by increasing their half-lives. FcRn may bind IgG and albumin simultaneously, and in a pH-dependent manner, with ligand binding at pH 6.0–6.5 and release at pH 7.0–7.4. The FcRn-IgG interaction has been extensively characterized at the amino acid level and shown to depend on conserved histidine residues in the IgG-Fc part that interact with negatively charged residues in the α-2 domain of FcRn. The recently discovered FcRn-albumin interaction remains to be elucidated. Guided by the pH dependence of the FcRn-albumin interaction, we compared the sequence of the FcRn α-2 domain from eleven different species, and identified histidine residues that were conserved in all (H166) or seven (H161) of these. Both residues are located directly opposite to the IgG interaction site in the folded molecule. We did in vitro mutagenesis (H161A or H166A) in combination with interaction studies (ELISA and surface plasmon resonance) with recombinant, soluble, purified receptors and IgG and albumin to investigate the role of the two histidine residues. Our results show clear evidence that the conserved H166 is a key player in the FcRn-albumin interaction.
TL;DR: In this paper, the thermal denaturation process of bovine and human both fatty acid containing and fatty acid free albumins in aqueous solution was studied by use of differential scanning calorimetry.
Abstract: The thermal denaturation process of bovine and human both fatty acid containing and fatty acid free albumins in aqueous solution was studied by use of differential scanning calorimetry. Human serum albumins were found to be more stable than their bovine counterparts. Fatty acid free albumins were characterized as generally less stable, more susceptible to aggregation, their unfolding endothermic transition was less cooperative and with the smaller degree of reversibility. Deconvolution analysis with using a non-two-state model with two component transitions showed essential differences in the thermodynamic parameters between all studied albumins, particularly regarding the high-temperature component transition.
TL;DR: Results from structural analysis suggest that purified rHSA possesses an identical conformation to plasma derived human albumin (pdHA) and no difference from pdHA has been observed in neo-antigenicity.
TL;DR: It is found by HPLC analysis that HNE is rapidly quenched by human serum albumin (HSA) because of the covalent adduction to the different accessible nucleophilic residues of the protein.
Abstract: Several pieces of evidence indicate that albumin modified by HNE is a promising biomarker of systemic oxidative stress and that HNE-modified albumin may contribute to the immune reactions triggered by lipid peroxidation-derived antigens. In this study, we found by HPLC analysis that HNE is rapidly quenched by human serum albumin (HSA) because of the covalent adduction to the different accessible nucleophilic residues of the protein, as demonstrated by electrospray ionization mass spectrometry (ESI-MS) direct infusion experiments (one to nine HNE adducts, depending on the molar ratio used, from 1 : 0.25 to 1 : 5 HSA : HNE). An LC-ESI-MS/MS approach was then applied to enzymatically digested HNE-modified albumin, which permitted the identification of 11 different HNE adducts, 8 Michael adducts (MA) and 3 Schiff bases (SB), involving nine nucleophilic sites, namely: His67 (MA), His146 (MA), His242 (MA), His288 (MA), His510 (MA), Lys 195 (SB), Lys 199 (MA, SB), Lys525 (MA, SB) and Cys34 (MA). The most reactive HNE-adduction site was found to be Cys34 (MA) followed by Lys199, which primarily reacts through the formation of a Schiff base, and His146, giving the corresponding HNE Michael adduct. These albumin modifications are suitable tags of HNE-adducted albumin and could be useful biomarkers of oxidative and carbonylation damage in humans. Copyright © 2006 John Wiley & Sons, Ltd.
TL;DR: The protein conformation was altered with major reduction of α-helix from 60 to 55% to 40 to 40% and increase of β-structure from 22 to 15% (free HSA) to 33 to 23% in the drug- Protein secondary, structure are attributed to partial, unfolding of HSA on drug complexation.
Abstract: We report different analytical methods used to study the effects of 3′-azido-3′-deoxythymidine, aspirin, taxol, cisplatin, atrazine, 2,4-dichlorophenoxyacetic, biogenic, polyamines, chlorophyll, chlorophyllin, poly(ethylene glycol), vanadyl cation, vanadate anion, cobalt-hexamine cation, and As2O3, on the stability and secondary structure of human serum albumin (HSA) in aqueous solution, using capillary electrophoresis. Fourier transform infrared, ultraviolet visible, and circular dichroism (CD) spectroscopic methods. The concentrations of HSA used were 4% to 2% or 0.6 to 0.3 mM, while different ligand concentrations were 1μM to 1 mM. Structural data showed drugs are mostly located along the polypeptide chains with both specific and nonspecific interactions. The stability of drug-protein complexes were in the order KVO2+ 1.2×108M−1>KAZT 1.9×106M−1>KPEG 4.1×105M−1>Katrazine 3.5×104M−1>Kchlorophyll 2.9×104M−1>K2,4-D2.5×104 M−1>Kspermine 1.7×104M−1>Ktaxol 1.43×104M−1>KCo3+>1.1×104M−1>Kaspirin 1.04×104i−1>Kchlorophyllin 7.0×103M−1×KVO3−6.0×103M−1>Kspermidine 5.4 ×103M−1>Kputrescine 3.9×103M−1>KAs2O3, 2.2×103M−1>Kcisplatin 1.2×102M−1. The protein conformation was altered (infrared and CD results) with major reduction of α-helix from 60 to 55% (free HSA) to 40 to 40% and increase of β-structure from 22 to 15% (free HSA) to 33 to 23% in the drug-protein complexes. The alterations of protein secondary, structure are attributed to partial, unfolding of HSA on drug complexation.
TL;DR: Relaxation rates of Gd-BOPTA showed a strong dependency on HSA, and the influence of serum protein concentration should be considered in both research studies and in clinical use.
Abstract: Objectives Exogenous magnetic resonance (MR) contrast media (CM) are used to improve detection and delineation of physiological and pathologic structures. Temporary binding between CM and proteins such as human serum albumin (HSA) may alter the relaxation-enhancing properties of specific contrast agents. In this study, the presence and strength of HSA interaction with different CM was investigated. Material and methods Three contrast agents were chosen: Gd-DTPA, Gd-BT-DO3A, and Gd-BOPTA, each of which is known to have a different protein interaction. Samples were prepared using 7 different HSA concentrations, all at a constant CM concentration of 0.5 mmol/L. The relaxation rates, R1 and R2, of each sample were measured at 1.5 T. Virtual docking studies were performed to estimate the number of high affinity-binding sites of Gd-BOPTA and the surface of the HSA dimer. Results Gd-BOPTA caused the greatest increase in R1 and R2, which followed an exponential dependency with increasing HSA concentration. Between the range of 0 and 7 g/dL of HSA, Gd-DTPA and Gd-BT-DO3A showed a relative change in both relaxation rates of approximately 13% and 22% for R1 and 26% and 30% for R2, respectively. In contrast, Gd-BOPTA demonstrated a relative increase of approximately 108% and 363% for R1 and R2, respectively. Changes of HSA concentration within physiological range (3.5-5.5 g/dL) resulted in an increase of R1 and R2 of approximately 40% when using Gd-BOPTA. The docking study revealed that approximately 10 small hydrophobic pockets exist on the HSA surface where the aromatic tail of Gd-BOPTA can fit in and a stronger noncovalent binding can occur compared with Gd-DTPA and Gd-BT-DO3A. Conclusion Relaxation rates of Gd-BOPTA showed a strong dependency on HSA. In contrast, Gd-DTPA and Gd-BT-DO3A demonstrated little or no relevant dependency. On the basis of these results, the influence of serum protein concentration should be considered in both research studies and in clinical use.
TL;DR: It is concluded that a simple, three-component free-energy rule adequately describes protein adsorption from aqueous solution, at least for materials bearing varying surface concentrations of anionic (not cationic) functional groups.
TL;DR: It is highly possible that the stereoselective binding site of Human serum albumin exists at the interface of the subdomains, as suggested by various experimental data.
TL;DR: It is suggested that the net negative charge of HSA is decreased in fever, which results in the decrease of H SA-associated cations and plasma osmolarity, and consequently, heat removal via the increase in urine volume.
Abstract: Thermal conformational changes of human serum albumin (HSA) in phosphate buffer, 10 mM at pH = 7 are investigated using differential scanning calorimetric (DSC), circular dichroism (CD) and UV spectroscopic methods. The results indicate that temperature increment from 25 degrees C to 55 degrees C induces reversible conformational changes in the structure of HSA. Conformational change of HSA are shown to be a three-step process. Interestingly, melting temperature of the last domain is equal to the maximum value of fever in pathological conditions, i.e. 42 degrees C. These conformational alterations are accompanied by a mild alteration of secondary structures. Study of HSA-SDS (sodium dodecyl sulphate) interaction at 45 degrees C and 35 degrees C reveals that SDS affects the HSA structure at least in three steps: the first two steps result in more stabilization and compactness of HSA structure, while the last one induces the unfolding of HSA. Since HSA has a more affinity for SDS at 45 degrees C compared to 35 degrees C, It is suggested that the net negative charge of HSA is decreased in fever, which results in the decrease of HSA-associated cations and plasma osmolarity, and consequently, heat removal via the increase in urine volume.
TL;DR: Amyloid fibril formation is also allowed in a protein with a high degree of structural complexity, and the existence of other protein aggregated species than fibrils is inferred, some of which seem to be formed by a structural rearrangement of the properfibrils.
Abstract: Under in vitro solution conditions where the native state is destabilized, many proteins present an abnormal structure and metabolism associated with a strong tendency to self-aggregation into a polymeric amyloid fibril structure, suggesting that this ability is a generic feature of the polypeptide chains. Such structures play a key role in different pathogenesis of neurodegenerative diseases such as Alzheimer, Parkinson, or Creutzfeldt-Jakob. Here, we report the formation of amyloid fibrils in the plasma protein human serum albumin under different in vitro conditions monitored using a combination of spectrophotometric and microscopic tecnhiques. Amyloid fibril formation, therefore, is also allowed in a protein with a high degree of structural complexity. We also infer from experimental data the existence of other protein aggregated species than fibrils, some of which seem to be formed by a structural rearrangement of the proper fibrils.
TL;DR: The results of spectroscopic measurements suggested that N-(p-chlorophenyl)-N'-(1-naphthyl) thiourea should have a strong ability to quench the intrinsic fluorescence of both bovine serum albumin and human serumalbumin through static quenching procedure, and the hydrophobic interaction was the predominant intermolecular force stabilizing the complex.
TL;DR: Analysis of the tryptic peptides from the samples indicates that the oxidations are highly selective, and insights into the factors that in vivo drive the selective carbonylation of specific proteins in systems under oxidative stress are provided.
TL;DR: The plasma protein binding studies conducted on four gyrase inhibitors in rat and human plasma exhibited no interspecies difference via ultra filtration method, which proves that both the techniques have their own merits and demerits and should be exploited judiciously as per the requirement.
TL;DR: The ability of HSA to form ternery complexes with other neutral molecules such as warfarin, which also binds within the subdomain IIA pocket, increases the understanding of the binding dynamics of exogenous drugs to HSA.
Abstract: Genistein and daidzein, the major isoflavones present in soybeans, possess a wide spectrum of physiological and pharmacological functions. The binding of genistein to human serum albumin (HSA) has been investigated by equilibrium dialysis, fluorescence measurements, CD and molecular visualization. One mole of genistein is bound per mole of HSA with a binding constant of 1.5 +/- 0.2 x 10(5) m(-1). Binding of genistein to HSA precludes the attachment of daidzein. The ability of HSA to bind genistein is found to be lost when the tryptophan residue of albumin is modified with N-bromosuccinimide. At 27 degrees C (pH 7.4), van't Hoff's enthalpy, entropy and free energy changes that accompany the binding are found to be -13.16 kcal x mol(-1), -21 cal x mol(-1) K(-1) and -6.86 kcal x mol(-1), respectively. Temperature and ionic strength dependence and competitive binding measurements of genistein with HSA in the presence of fatty acids and 8-anilino-1-naphthalene sulfonic acid have suggested the involvement of both hydrophobic and ionic interactions in the genistein-HSA binding. Binding measurements of genistein with BSA and HSA, and those in the presence of warfarin and 2,3,5-tri-iodobenzoic acid and Forster energy transfer measurements have been used for deducing the binding pocket on HSA. Fluorescence anisotropy measurements of daidzein bound and then displaced with warfarin, 2,3,5-tri-iodobenzoic acid or diazepam confirm the binding of daidzein and genistein to subdomain IIA of HSA. The ability of HSA to form ternery complexes with other neutral molecules such as warfarin, which also binds within the subdomain IIA pocket, increases our understanding of the binding dynamics of exogenous drugs to HSA.
TL;DR: To test the efficiency of HSA removal from human serum, proteins in the serum and eluted portion were analyzed by two-dimensional gel electrophoresis and the depletion efficiencies for HSA were above 87% for all studied concentrations.
TL;DR: Binding of fatty acid anions to different high-affinity sites and the sensitivity of these sites to amino acid substitutions elsewhere in the protein are important factors that could effect simultaneous binding of other ligands, e.g. in patients treated with albumin-binding drugs.
TL;DR: F Fourier transform infrared measurements have shown that the secondary structures of the protein have been changed by the interaction of formononetin with HSA, and it is argued that the drug is located in a restricted environment of protein.
TL;DR: The results of fluorescence titration revealed that palmatine hydrochloride could strongly quench the intrinsic fluorescence of HSA by static quenching and nonradiative energy transferring.