Showing papers on "Human serum albumin published in 2008"
TL;DR: This review gives an account of the different drug delivery systems which make use of albumin as a drug carrier with a focus on those systems that have reached an advanced stage of preclinical evaluation or that have entered clinical trials.
1,913 citations
TL;DR: This review brings together recent insights on albumin antioxidant properties and describes the role of albumin in ligand binding and free radical‐trapping activities, concerning protein antioxidation.
925 citations
TL;DR: In this article, the interaction between icariin and human serum albumin (HSA) in physiological buffer (pH 7.4) was investigated by fluorescence and UV-Vis absorption spectroscopy.
282 citations
TL;DR: It is shown that although the AlbudAb/IL-1ra fusion has a similar in vitro potency, its in vivo efficacy can be dramatically improved due to its extended serum half-life.
Abstract: We have used phage display to isolate a range of human domain antibodies (dAbs) that bind to mouse, rat and/or human serum albumin (SA) and can be expressed at very high levels in bacterial, yeast or mammalian cell culture. In contrast to non-SA-binding dAbs, which have terminal half-lives of less than 45 min, the half-lives of these 12 kDa 'AlbudAbs' can match the half-life of SA itself. To demonstrate the use of AlbudAbs for extending the half-lives of therapeutic drugs, we created a fusion of the interleukin-1 receptor antagonist (IL-1ra) with an AlbudAb. Soluble IL-1ra is potent inhibitor of IL-1 signalling that is approved for the treatment of rheumatoid arthritis but has a relatively short in vivo half-life. Here we show that although the AlbudAb/IL-1ra fusion has a similar in vitro potency, its in vivo efficacy can be dramatically improved due to its extended serum half-life. AlbudAbs could potentially be used to generate a range of long half-life versions of many different drugs in order to improve their dosing regimen and/or clinical effect.
254 citations
TL;DR: The results provide the first crystal structure of a natural bilirubin pigment bound to serum albumin, challenge some of the present conceptions about HSA–bilirubsin interactions, and provide a sound structural framework for finally resolving the long-standing question of where 4Z,15Z-bilirUBin-IXα binds to the protein.
235 citations
TL;DR: Comparisons of X-ray crystal structures of free and fatty-acid bound human serum albumin suggest that zinc binding to this site and fatty acid binding to one of the five major sites may be interdependent, and interactive binding of zinc and long-chain fatty acids to albumin may have physiological implications.
Abstract: Although details of the molecular mechanisms for the uptake of the essential nutrient zinc into the bloodstream and its subsequent delivery to zinc-requiring organs and cells are poorly understood, it is clear that in vertebrates the majority of plasma zinc (9–14 μM; approx. 75–85%) is bound to serum albumin, constituting part of the so-called exchangeable pool. The binding of metal ions to serum albumins has been the subject of decades of studies, employing a multitude of techniques, but only recently has the identity and putative structure of the major zinc site on albumin been reported. Intriguingly, this site is located at the interface between two domains, and involves two residues from each of domains I and II. Comparisons of X-ray crystal structures of free and fatty-acid bound human serum albumin suggest that zinc binding to this site and fatty acid binding to one of the five major sites may be interdependent. Interactive binding of zinc and long-chain fatty acids to albumin may therefore have physiological implications.
234 citations
TL;DR: It could be shown that the kinetics of particle degradation was dependent on the degree of particle stabilisation, which will influence drug release after cellular accumulation of HSA nanoparticles.
208 citations
TL;DR: The development of a novel serum albumin binding protein showing an extremely high affinity (K(D)) for HSA in the femtomolar range is described and a capture experiment involving human serum indicated that the selectivity for serumalbumin had not been compromised from the affinity engineering.
Abstract: We describe the development of a novel serum albumin binding protein showing an extremely high affinity (K(D)) for HSA in the femtomolar range. Using a naturally occurring 46-residue three-helix bundle albumin binding domain (ABD) of nanomolar affinity for HSA as template, 15 residues were targeted for a combinatorial protein engineering strategy to identify variants showing improved HSA affinities. Sequencing of 55 unique phage display-selected clones showed a strong bias for wild-type residues at nine positions, whereas various changes were observed at other positions, including charge shifts. Additionally, a few non-designed substitutions appeared. On the basis of the sequences of 12 variants showing high overall binding affinities and slow dissociation rate kinetics, a set of seven 'second generation' variants were constructed. One variant denoted ABD035 displaying wild-type-like secondary structure content and excellent thermal denaturation/renaturation properties showed an apparent affinity for HSA in the range of 50-500 fM, corresponding to several orders of magnitude improvement compared with the wild-type domain. The ABD035 variant also showed an improved affinity toward serum albumin from a number of other species, and a capture experiment involving human serum indicated that the selectivity for serum albumin had not been compromised from the affinity engineering.
200 citations
TL;DR: Molecular docking showed that the MTX binds HSA to a non-classical drug binding site and synchronous fluorescence, thermodynamic parameters and molecular modeling, which entails that hydrophobic interactions, hydrogen bonding and electrostatic forces, stabilizes the interaction.
182 citations
TL;DR: It is concluded that BSA and HSAFAF reduce the Km values of only those enzymes inhibited by long-chain unsaturated fatty acids.
Abstract: Bovine serum albumin (BSA) and fatty acid-free human serum albumin (HSAFAF) reduce the K(m) values for UGT2B7 substrates by sequestering inhibitory long-chain fatty acids released by incubations of human liver microsomes (HLM) and HEK293 cells expressing this enzyme. However, the scope of the "albumin effect" is unknown. In this investigation we characterized the effects of albumin on the kinetics of 4-methylumbelliferone (4MU) glucuronidation by UDP-glucuronosyltransferase (UGT) 1A1, 1A6, and 1A9, and propofol (PRO) glucuronidation by UGT1A9 and HLM. BSA and HSAFAF, but not human serum albumin, reduced the K(m) values for 4MU and PRO glucuronidation by UGT1A9. For example, HSAFAF (2%) reduced the K(m) values for 4MU and PRO glucuronidation from 13.4 to 2.9 and 41 to 7.2 microM, respectively. Similarly, HSAFAF (2%) reduced the K(m) for PRO glucuronidation by HLM from 127 to 10.6 muM. Arachidonic, linoleic, and oleic acids and a mixture of these decreased the rates of 4MU and PRO glucuronidation by UGT1A9. K(m) values for these reactions were increased 3- to 6-fold by the fatty acid mixture. Inhibition was reversed by the addition of BSA (2%). Extrapolation of kinetic constants for PRO glucuronidation by HLM in the presence of HSAFAF predicted in vivo hepatic clearance within 15%. Fatty acids had no effect on 4MU glucuronidation by UGT1A1 and UGT1A6 but, paradoxically, all forms of albumin altered the kinetic model for 4MU glucuronidation by UGT1A6 (from Michaelis-Menten to two-site). Only BSA caused a similar effect on 4MU glucuronidation by UGT1A1. It is concluded that BSA and HSAFAF reduce the K(m) values of only those enzymes inhibited by long-chain unsaturated fatty acids.
159 citations
TL;DR: The reagent 7-chloro-4-nitrobenz-2-oxa-1,3-diazole was determined not to be suitable as a chromophoric probe for sulfenic acid in human serum albumin (HSA-SOH) because of lack of specificity.
Abstract: Sulfenic acid is formed upon oxidation of thiols and is a central intermediate in the redox modulation of an increasing number of proteins. Methods for quantifying or even detecting sulfenic acid are scarce. Herein, the reagent 7-chloro-4-nitrobenz-2-oxa-1,3-diazole was determined not to be suitable as a chromophoric probe for sulfenic acid in human serum albumin (HSA−SOH) because of lack of specificity. Thionitrobenzoate (TNB) reacted with HSA exposed to hydrogen peroxide, but not control or thiol-blocked HSA. The reaction was biphasic. The first phase was ∼20-fold faster than the second phase and first order in HSA−SOH and TNB (105 ± 11 M-1 s-1, 25 °C, pH 7.4), allowing quantitative data on HSA−SOH formation and reactivity to be obtained. Exposure of reduced HSA (0.5 mM) to hydrogen peroxide (4 mM, 37 °C, 4 min) yielded 0.18 ± 0.02 mol of HSA−SOH per mol of HSA. HSA−SH reacted with hydrogen peroxide at 2.7 ± 0.7 M-1 s-1 (37 °C, pH 7.4), while HSA−SOH reacted at 0.4 ± 0.2 M-1 s-1, yielding sulfinic acid ...
TL;DR: The mechanism of induced stepwise conformational change of protein on carbon nanotube surfaces would be helpful to better understand the protein-surface interaction at the molecular level.
TL;DR: Binding of puerarin to human serum albumin was investigated by ultraviolet absorbance, fluorescence, circular dichroism and molecular docking, which suggested the hydrophobic residues such as tyrosine (Tyr) 150, Tyr 148, Tyr 149 and polar residuessuch as lysine (Lys) 199, Lys 195, arginine 257 and histidine 242 played an important role in the binding reaction.
Abstract: Puerarin is a widely used compound in Chinese traditional medicine and exhibits many pharmacological activities. Binding of puerarin to human serum albumin (HSA) was investigated by ultraviolet absorbance, fluorescence, circular dichroism and molecular docking. Puerarin caused a static quenching of intrinsic fluorescence of HSA, the quenching data was analyzed by Stern–Volmer equation. There was one primary puerarin binding site on HSA with a binding constant of 4.12 × 104 M−1 at 298 K. Thermodynamic analysis by Van Hoff equation found enthalpy change (
$$\Delta H^{O} $$
) and entropy change (
$$\Delta S^{O} $$
) were −28.01 kJ/mol and −5.63 J/mol K respectively, which indicated the hydrogen bond and Van der waas interaction were the predominant forces in the binding process. Competitive experiments showed a displacement of warfarin by puerarin, which revealed that the binding site was located at the drug site I. Puerarin was about 2.22 nm far from the tryptophan according to the observed fluorescence resonance energy transfer between HSA and puerarin. Molecular docking suggested the hydrophobic residues such as tyrosine (Tyr) 150, Tyr 148, Tyr 149 and polar residues such as lysine (Lys) 199, Lys 195, arginine 257 and histidine 242 played an important role in the binding reaction.
TL;DR: This is the first study demonstrating a specific trastuzumab-based targeting of HER2 overexpressing breast cancer cells with doxorubicin-loaded nanoparticles, and the results indicate that these cell-type specific drug- loaded nanoparticles could achieve an improvement in cancer therapy.
TL;DR: It was concluded that colchicine may probably cause displacement of phenylbutazone from its complex with serum albumin (SA) and Static and dynamic quenching for the binary and ternary systems showed that phenyl butazone does not affect the complex formed between colchichine and BSA, and colchicaine has no effect on the Phe–BSA complex.
TL;DR: It was demonstrated that linker with 5 amino acid residues was sufficient to separated HSA and IFN-alpha2b effectively, as fusion protein with this linker migrated as single band on non-reducing SDS-PAGE.
TL;DR: In this study, an aqueous solution of 13-nm gold nanoparticles covalently bonded with human serum albumin (HSA) was used for sensing lysozyme (Lys) and it was found that the sensitivity of HSA-AuNPs for Lys was highly dependent on the HSA concentration.
Abstract: In this study, an aqueous solution of 13-nm gold nanoparticles (AuNPs) covalently bonded with human serum albumin (HSA) was used for sensing lysozyme (Lys). HSA molecules were good stabilizing agents for AuNPs in high-salt solution and exhibited the ability to bond with Lys electrostatically. The aggregation of HSA-AuNPs was achieved upon the addition of high-pI proteins, such as Lys, α-chymotrypsinogen A, and conalbumin. Not the same was achieved, however, when low-pI proteins such as ovalbumin, bovine serum albumin, and α-lactalbumin were added. Matrix-assisted desorption/ionization mass spectrometry was used to demonstrate the interaction between HSA-AuNPs and Lys. It was found that the sensitivity of HSA-AuNPs for Lys was highly dependent on the HSA concentration. The Lys-induced aggregation of HSA-AuNPs was suggested based on the London−van der Waals attractive force. We further improved the selectivity of the probe by adjusting the pH solution to 8.0. Under the optimum conditions, the selectivity of...
TL;DR: The combination of the polymer monolithic column and the aptamer affinities makes theaptamer-modified monolithic columns useful for protein detection and separation.
Abstract: A capillary chromatography technique was developed for the separation and detection of proteins, taking advantage of the specific affinity of aptamers and the porous property of the monolith. A biotinylated DNA aptamer targeting cytochrome c was successfully immobilized on a streptavidin-modified polymer monolithic capillary column. The aptamer, having a G-quartet structure, could bind to both cytochrome c and thrombin, enabling the separation of these proteins from each other and from the unretained proteins. Elution of strongly bound proteins was achieved by increasing the ionic strength of the mobile phase. The following proteins were tested using the aptamer affinity monolithic columns: human immunoglobulin G (IgG), hemoglobin, transferrin, human serum albumin, cytochrome c, and thrombin. Determination of cytochrome c and thrombin spiked into dilute serum samples showed no interference from the serum matrix. The benefit of porous properties of the affinity monolithic column was demonstrated by selective capture and preconcentration of thrombin at low ionic strength and subsequent rapid elution at high ionic strength. The combination of the polymer monolithic column and the aptamer affinities makes the aptamer-modified monolithic columns useful for protein detection and separation.
TL;DR: In this paper, the interaction of rofecoxib with human serum albumin (HSA) under physiological condition was investigated by fluorescence, UV-vis absorbance and Fourier transfer infrared (FT-IR) spectroscopy.
Abstract: The interaction of rofecoxib with human serum albumin (HSA) under physiological condition was investigated by fluorescence, UV–vis absorbance and Fourier transfer infrared (FT-IR) spectroscopy. Fluorescence data revealed that the fluorescence quenching of HSA by rofecoxib was the result of the formed complex of HSA–rofecoxib, and the site binding constants ( K a ) were 4.840 × 10 4 , 3.450 × 10 4 , and 2.325 × 10 4 M −1 at 298, 304, and 310 K, respectively. The thermodynamic parameters, enthalpy change (Δ H ) and entropy change (Δ S ) for the reaction were calculated to be −46.90 kJ mol −1 and −67.59 J mol −1 K −1 according to van’t Hoff equation. The spectroscopic measurements and the thermodynamic parameters suggested that van der Waals interaction and hydrogen bonds were the predominant intermolecular forces to stabilize the complex. The distance r = 5.1 nm between donor (Trp 214 ) and accepter (rofecoxib) was obtained according to the Forster theory of non-radiative energy transfer. FT-IR spectra and UV–vis absorbance showed that the change of protein secondary structures resulted from the rofecoxib binding to several amino acids on the hydrophobic pocket of HSA. Furthermore, it is observed from the probe of competitive experiments that the binding location of rofecoxib with HSA could be the same as the warfarin site I of HSA, which was also revealed by fluorescence anisotropy.
TL;DR: Several specific binding sites for anionic, neutral, and cationic ligands were described, and the extent of binding depends on the ligand and albumin concentration, albumin-binding affinity, and presence of competing ligands.
TL;DR: The synthesis and testing of a new synthetic plasma expander that can replace not only the osmotic and volume expansion properties of HSA but, uniquely, its binding and transport properties is reported here.
TL;DR: In this paper, the mechanism of interaction between C.I.Direct Yellow 9 and human serum albumin was studied using spectroscopic methods including fluorescence spectra, UV-vis, Fourier transform infrared (FT-IR) and circular dichroism (CD).
TL;DR: Free, unbound antibiotic concentrations differed substantially between plasma and protein supplements and correlated well with antimicrobial efficacy, therefore, free, active concentrations should be measured in the test system instead of correcting for literature protein binding values.
Abstract: During antibiotic drug development, media are frequently spiked with either serum/plasma or protein supplements to evaluate the effect of protein binding Usually, previously reported serum or plasma protein binding values are applied in the analysis The aim of this study was to evaluate this approach by experimentally measuring free, unbound concentrations for antibiotics with reportedly high protein binding and their corresponding antimicrobial activities in media containing commonly used protein supplements Free, unbound ceftriaxone and ertapenem concentrations were determined in bacterial growth medium with and without bovine/human serum albumin, as well as adult bovine serum and human plasma using in vitro microdialysis The corresponding antimicrobial activity was determined in MIC and time-kill curve experiments using Escherichia coli ATCC 25922 and Streptococcus pneumoniae ATCC 6303 as test strains A semimechanistic maximum effect model was simultaneously fitted to the data and respective EC(50) (concentration at half-maximum effect) values compared Protein binding differed significantly for ceftriaxone (P < 005) between human plasma (768 +/- 110%) and commercially available bovine (202 +/- 83%) or human serum albumin (569 +/- 166%) Similar results were obtained for ertapenem (human plasma, 738 +/- 116%; bovine serum albumin, 124 +/- 48%; human serum albumin, 178 +/- 115%) The MICs and EC(50)s of both strains were significantly increased (P < 005) for ceftriaxone when comparing human and bovine serum albumin, whereas the EC(50)s were not significantly different for ertapenem Free, unbound antibiotic concentrations differed substantially between plasma and protein supplements and correlated well with antimicrobial efficacy Therefore, free, active concentrations should be measured in the test system instead of correcting for literature protein binding values
TL;DR: Though the concentration of albumin in plasma is very high, its reactivity with soman (phosphonylation and phosphotriesterase activity) is too slow to play a major role in detoxification of the highly toxic organophosphorus compound soman.
Abstract: Human plasma and fatty acid free human albumin were incubated with soman at pH 8.0 and 25 degrees C. Four methods were used to monitor the reaction of albumin with soman: progressive inhibition of the aryl acylamidase activity of albumin, the release of fluoride ion from soman, 31P NMR, and mass spectrometry. Inhibition (phosphonylation) was slow with a bimolecular rate constant of 15 +/- 3 M(-1) min (-1). MALDI-TOF and tandem mass spectrometry of the soman-albumin adduct showed that albumin was phosphonylated on tyrosine 411. No secondary dealkylation of the adduct (aging) occurred. Covalent docking simulations and 31P NMR experiments showed that albumin has no enantiomeric preference for the four stereoisomers of soman. Spontaneous reactivation at pH 8.0 and 25 degrees C, measured as regaining of aryl acylamidase activity and decrease of covalent adduct (pinacolyl methylphosphonylated albumin) by NMR, occurred at a rate of 0.0044 h (-1), indicating that the adduct is quite stable ( t1/2 = 6.5 days). At pH 7.4 and 22 degrees C, the covalent soman-albumin adduct, measured by MALDI-TOF mass spectrometry, was more stable ( t1/2 = 20 days). Though the concentration of albumin in plasma is very high (about 0.6 mM), its reactivity with soman (phosphonylation and phosphotriesterase activity) is too slow to play a major role in detoxification of the highly toxic organophosphorus compound soman. Increasing the bimolecular rate constant of albumin for organophosphates is a protein engineering challenge that could lead to a new class of bioscavengers to be used against poisoning by nerve agents. Soman-albumin adducts detected by mass spectrometry could be useful for the diagnosis of soman exposure.
TL;DR: It is speculated that the formation of an M2HsTf complex of high affinity may predict a lobe-closed conformation that leads to a favorable interaction with TfR1, and has implications for the metabolism of Ti(IV) in human serum.
Abstract: The trafficking of titanium(IV) by human serum transferrin (HsTf) has been implicated in the physiology of this hydrolysis-prone metal. The current work broadens to include the further interactions of Ti(IV) in serum that bear on this model. Ti2HsTf (2 equiv) binds the transferrin receptor TfR1 with Kd1 = 6.3 ± 0.4 nM and Kd2 = 410 ± 150 nM, values that are the tightest yet measured for a metal other than iron but weaker than the corresponding ones for Fe2HsTf due to both slightly slower on rates and slightly faster off rates. Comparing the affinities of metals for HsTf with the affinities of the resulting M2HsTf species for TfR1, we speculate that the formation of an M2HsTf complex of high affinity may predict a lobe-closed conformation that leads to a favorable interaction with TfR1. Human serum albumin (HSA), an important serum competitor for metal binding, can bind up to 20 equiv of Ti(IV) supplied in several forms. With some ligands, Ti(IV) may bind to the N-terminal metal binding site of albumin, fo...
TL;DR: Comparison of the physical characteristics and HSA interaction parameters for the POMs of the present work and those studied previously showed that the overall charge of the clusters is not the single parameter governing the binding process and its consequences.
TL;DR: The present spectroscopic investigation supports the notion that HSA could be considered as the prototype of monomeric allosteric proteins.
Abstract: Human serum albumin (HSA), the most prominent protein in blood plasma, is able to bind a wide range of endogenous and exogenous compounds. Among the endogenous ligands, HSA is a significant transporter of heme, the heme−HSA complex being present in blood plasma. Drug binding to heme−HSA affects allosterically the heme affinity for HSA and vice versa. Heme−HSA, heme, and their complexes with ibuprofen have been characterized by electronic absorption, resonance Raman, and electron paramagnetic resonance (EPR) spectroscopy. Comparison of the results for the heme and heme−HSA systems has provided insight into the structural consequences on the heme pocket of ibuprofen binding. The pentacoordinate tyrosine-bound heme coordination of heme−HSA, observed in the absence of ibuprofen, becomes hexacoordinate low spin upon ibuprofen binding, and heme dissociates at increasing drug levels. The electronic absorption spectrum and ν(Fe−CO)/ν(CO) vibrational frequencies of the CO−heme−HSA−ibuprofen complex, together with ...
TL;DR: Using the best working conditions, the development of a RNA-aptamer-based optical biosensor (aptasensor) for C-reactive protein (CRP) achieves a detection limit of 0.005 ppm, with good selectivity towards human serum albumin.
Abstract: The development of a RNA-aptamer-based optical biosensor (aptasensor) for C-reactive protein (CRP) is reported CRP is an important clinical biomarker; it was the first acute-phase protein to be discovered (1930) and is a sensitive systemic marker of inflammation and tissue damage It has also a prognostic value for patients with acute coronary syndrome The average concentration of CRP in serum is 08 ppm and it increases in response to a variety of inflammatory stimuli, such as trauma, tissue necrosis, infection and myocardial infarction The interaction between the 44-base RNA aptamer and the target analyte CRP is studied In particular, the influence of the aptamer immobilization procedure (chemistry, length, concentration), as well as the binding conditions, ie, the influence on the binding of different buffers, the presence of Ca2+ ion and the specificity (against human serum albumin) have been evaluated Using the best working conditions, we achieved a detection limit of 0005 ppm, with good selectivity towards human serum albumin Some preliminary experiments in serum are reported
TL;DR: The main determinants of the cobalt-HSA binding assay mechanism of action include but are not limited to: the proportion of intact N-terminus of HSA, HSA concentration, plasma cysteine/cystine ratio, plasma pH, and the state of oxidation of cys34 of H SA.
TL;DR: The results indicate that previously determined in vitro Km values for CYP2C9 substrates are almost certainly overestimates, and accurate in vitro-in vivo extrapolation of kinetic data for CYC2C8 substrates is achievable.
Abstract: This study characterized the mechanism by which bovine serum albumin (BSA) reduces the K(m) for phenytoin (PHY) hydroxylation and the implications of the "albumin effect" for in vitro-in vivo extrapolation of kinetic data for CYP2C9 substrates. BSA and essentially fatty acid-free human serum albumin (HSA-FAF) reduced the K(m) values for PHY hydroxylation (based on unbound substrate concentration) by human liver microsomes (HLMs) and recombinant CYP2C9 by approximately 75%, with only a minor effect on V(max). In contrast, crude human serum albumin increased the K(m) with both enzyme sources. Mass spectrometric analysis of incubations containing HLMs was consistent with the hypothesis that BSA sequesters long-chain unsaturated acids (arachidonic, linoleic, oleic) released from membranes. A mixture of arachidonic, linoleic and oleic acids, at a concentration corresponding to 1/20 of the content of HLMs, doubled the K(m) for PHY hydroxylation by CYP2C9, without affecting V(max). This effect was reversed by addition of BSA to incubations. K(i) values for arachidonic acid inhibition of human liver microsomal- and CYP2C9-catalyzed PHY hydroxylation were 3.8 and 1.6 microM, respectively. Similar effects were observed with heptadecanoic acid, the most abundant long-chain unsaturated acid present in Escherichia coli membranes. Extrapolation of intrinsic clearance (CL(int)) values for each enzyme source determined in the presence of BSA and HSA-FAF accurately predicted the known CL(int) for PHY hydroxylation in vivo. The results indicate that previously determined in vitro K(m) values for CYP2C9 substrates are almost certainly overestimates, and accurate in vitro-in vivo extrapolation of kinetic data for CYP2C9 substrates is achievable.