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Sample records for serum protein binding

  1. Erythropoietin binding protein from mammalian serum

    DOEpatents

    Clemons, G.K.

    1997-04-29

    Purified mammalian erythropoietin binding-protein is disclosed, and its isolation, identification, characterization, purification, and immunoassay are described. The erythropoietin binding protein can be used for regulation of erythropoiesis by regulating levels and half-life of erythropoietin. A diagnostic kit for determination of level of erythropoietin binding protein is also described. 11 figs.

  2. Erythropoietin binding protein from mammalian serum

    DOEpatents

    Clemons, Gisela K.

    1997-01-01

    Purified mammalian erythropoietin binding-protein is disclosed, and its isolation, identification, characterization, purification, and immunoassay are described. The erythropoietin binding protein can be used for regulation of erythropoiesis by regulating levels and half-life of erythropoietin. A diagnostic kit for determination of level of erythropoietin binding protein is also described.

  3. Comparative serum protein binding of anthracycline derivatives.

    PubMed

    Chassany, O; Urien, S; Claudepierre, P; Bastian, G; Tillement, J P

    1996-01-01

    The binding of doxorubicin, iododoxorubicin, daunorubicin, epirubicin, pirarubicin, zorubicin, aclarubicin, and mitoxantrone to 600 microM human serum albumin and 50 microM alpha 1-acid glycoprotein was studied by ultrafiltration at 37 degrees C and pH 7.4. Anthracycline concentrations (total and free) were determined by high-performance liquid chromatography (HPLC) with fluorometric detection. Binding to albumin (600 microM) varied from 61% (daunorubicin) to 94% (iododoxorubicin). The binding to alpha 1-acid glycoprotein (50 microM) was more variable, ranging from 31% (epirubicin) to 64% (zorubicin), and was essentially related to the hydrophobicity of the derivatives. Simulations showed that the total serum binding varied over a broad range from 71% (doxorubicin) to 96% (iododoxorubicin). We recently reported that the binding to lipoproteins of a series of eight anthracycline analogues could be ascribed to chemicophysical determinants of lipophilicity [2]. The present study was conducted to evaluate in vitro the contribution of albumin and alpha 1-acid glycoprotein to the total serum binding of these drugs.

  4. A new aspect of serum protein binding of tolbutamide.

    PubMed

    Ayanoğlu, G; Uihlein, M; Grigoleit, H G

    1986-02-01

    Tolbutamide is known to bind highly to serum proteins. Quite different values have, however, been reported for binding, ranging from 80 to 99 percent. In this study, in vivo and in vitro binding of increasing concentrations of tolbutamide to human serum proteins were evaluated. In vitro studies were done serum from three healthy males and for in vivo studies serum samples from eight healthy males who had received 1,000 mg tolbutamide were used. Protein binding was determined by equilibrium dialysis, using DIANORM system. Tolbutamide concentrations were determined by HPLC method of Uihlein and Hack. The results suggest that there is an increase in percent tolbutamide bound with increasing concentrations of tolbutamide. Generally, an inverse relationship between the total concentration of a drug in serum and its bound fraction is observed. Our findings seem to be contrary to this, at least within the concentration range studied. There exist at least two binding sites on albumin with different affinities for tolbutamide and most probably, at low concentrations, the drug binds mainly to the high affinity sites, whereas at higher concentrations additional drug will bind to the lower affinity sites leading to the observed increase in fraction bound with concentration. In conclusion it may be said that serum protein binding is a much more complicated phenomenon than generally stated and that the normal observations are only true for some ideal compounds where only one site of adsorption has to be taken into account.

  5. Grizzly bear corticosteroid binding globulin: Cloning and serum protein expression.

    PubMed

    Chow, Brian A; Hamilton, Jason; Alsop, Derek; Cattet, Marc R L; Stenhouse, Gordon; Vijayan, Mathilakath M

    2010-06-01

    Serum corticosteroid levels are routinely measured as markers of stress in wild animals. However, corticosteroid levels rise rapidly in response to the acute stress of capture and restraint for sampling, limiting its use as an indicator of chronic stress. We hypothesized that serum corticosteroid binding globulin (CBG), the primary transport protein for corticosteroids in circulation, may be a better marker of the stress status prior to capture in grizzly bears (Ursus arctos). To test this, a full-length CBG cDNA was cloned and sequenced from grizzly bear testis and polyclonal antibodies were generated for detection of this protein in bear sera. The deduced nucleotide and protein sequences were 1218 bp and 405 amino acids, respectively. Multiple sequence alignments showed that grizzly bear CBG (gbCBG) was 90% and 83% identical to the dog CBG nucleotide and amino acid sequences, respectively. The affinity purified rabbit gbCBG antiserum detected grizzly bear but not human CBG. There were no sex differences in serum total cortisol concentration, while CBG expression was significantly higher in adult females compared to males. Serum cortisol levels were significantly higher in bears captured by leg-hold snare compared to those captured by remote drug delivery from helicopter. However, serum CBG expression between these two groups did not differ significantly. Overall, serum CBG levels may be a better marker of chronic stress, especially because this protein is not modulated by the stress of capture and restraint in grizzly bears.

  6. Biologically active protein fragments containing specific binding regions of serum albumin or related proteins

    NASA Technical Reports Server (NTRS)

    Carter, Daniel C. (Inventor)

    1998-01-01

    In accordance with the present invention, biologically active protein fragments can be constructed which contain only those specific portions of the serum albumin family of proteins such as regions known as subdomains IIA and IIIA which are primarily responsible for the binding properties of the serum albumins. The artificial serums that can be prepared from these biologically active protein fragments are advantageous in that they can be produced much more easily than serums containing the whole albumin, yet still retain all or most of the original binding potential of the full albumin proteins. In addition, since the protein fragment serums of the present invention can be made from non-natural sources using conventional recombinant DNA techniques, they are far safer than serums containing natural albumin because they do not carry the potentially harmful viruses and other contaminants that will be found in the natural substances.

  7. Camptothecin-binding site in human serum albumin and protein transformations induced by drug binding.

    PubMed

    Fleury, F; Ianoul, A; Berjot, M; Feofanov, A; Alix, A J; Nabiev, I

    1997-07-14

    Circular dichroism (CD) and Raman spectroscopy were employed in order to locate a camptothecin (CPT)-binding site within human serum albumin (HSA) and to identify protein structural transformations induced by CPT binding. A competitive binding of CPT and 3'-azido-3'-deoxythymidine (a ligand occupying IIIA structural sub-domain of the protein) to HSA does not show any competition and demonstrates that the ligands are located in the different binding sites, whereas a HSA-bound CPT may be replaced by warfarin, occupying IIA structural sub-domain of the protein. Raman and CD spectra of HSA and HSA/CPT complexes show that the CPT-binding does not induce changes of the global protein secondary structure. On the other hand, Raman spectra reveal pronounced CPT-induced local structural modifications of the HSA molecule, involving changes in configuration of the two disulfide bonds and transfer of a single Trp-residue to hydrophilic environment. These data suggest that CPT is bound in the region of interdomain connections within the IIA structural domain of HSA and it induces relative movement of the protein structural domains.

  8. Absence of serum growth hormone binding protein in patients with growth hormone receptor deficiency (Laron dwarfism)

    SciTech Connect

    Daughaday, W.H.; Trivedi, B.

    1987-07-01

    It has recently been recognized that human serum contains a protein that specifically binds human growth hormone (hGH). This protein has the same restricted specificity for hGH as the membrane-bound GH receptor. To determine whether the GH-binding protein is a derivative of, or otherwise related to, the GH receptor, the authors have examined the serum of three patients with Laron-type dwarfism, a condition in which GH refractoriness has been attributed to a defect in the GH receptor. The binding of /sup 125/I-labeled hGH incubated with serum has been measured after gel filtration of the serum through an Ultrogel AcA 44 minicolumn. Results are expressed as percent of specifically bound /sup 125/I-hGH and as specific binding relative to that of a reference serum after correction is made for endogenous GH. The mean +/- SEM of specific binding of sera from eight normal adults (26-46 years of age) was 21.6 +/- 0.45%, and the relative specific binding was 101.1 +/- 8.6%. Sera from 11 normal children had lower specific binding of 12.5 +/- 1.95% and relative specific binding of 56.6 +/- 9.1%. Sera from three children with Laron-type dwarfism lacked any demonstrable GH binding, whereas sera from 10 other children with other types of nonpituitary short stature had normal relative specific binding. They suggest that the serum GH-binding protein is a soluble derivative of the GH receptor. Measurement of the serum GH-binding protein may permit recognition of other abnormalities of the GH receptor.

  9. Characterization and properties of steroid binding protein in Bufo arenarum serum.

    PubMed

    Fernández, S N; Mansilla-Whitacre, Z C; Miceli, D C

    1994-08-01

    Serum steroid binding properties of mature Bufo arenarum females were studied. Binding data obtained using charcoal adsorption assay and equilibrium dialysis methods indicates a single protein, named Bufo arenarum sex binding protein (Ba SBP), which binds 5 alpha-dihydrotestosterone (DHT), testosterone (T), and estradiol-17 beta (E2) with high affinity (10(-7) M-1 - 10(8) M-1) and fair capacity (10(-6) M). Scatchard plot analysis demonstrated the coexistence of two binding sites. Ba SBP has a sedimentation coefficient of 5.2 S in sucrose gradient centrifugation in low salt and under steady-state conditions. The specificity of this protein, determined by competitive binding experiments, is comparable to human SBP. DHT and T bind with higher affinity than E2. Estriol and estrone competed poorly, while diethylstilbestrol and C21 steroids did not compete. The binding capacity of this protein is under estrogenic control.

  10. THE INFLUENCE OF SERUM BINDING PROTEINS AND CLEARANCE ON THE COMPARATIVE RECEPTOR BINDING POTENCY OF ENDOCRINE ACTIVE COMPOUNDS

    EPA Science Inventory

    THE INFLUENCE OF SERUM BINDING PROTEINS AND CLEARANCE ON THE COMPARATIVE RECEPTOR BINDING POTENCY OF ENDOCRINE ACTIVE COMPOUNDS. JG Teeguarden1 and HA Barton2. 1ENVIRON International, Ruston LA; 2US EPA, ORD, NHEERL, ETD, Pharmacokinetics Branch, RTP, NC.

    One measure of th...

  11. Immunonephelometry and radial immunodiffusion compared for measuring serum retinol-binding protein.

    PubMed

    Malvy, D J; Povéda, J D; Debruyne, M; Burtschy, B; Dostalova, L; Amédée-Manesme, O

    1993-01-01

    We compared a nephelometric method and a radial immunodiffusion (RID) assay for the measurement of retinol-binding protein in samples of serum from children with malignancies. The mean (+/- standard deviation) retinol-binding protein concentration as measured by the Behring Nephelometer was 31.0 +/- 15.6 mg/l; the mean by RID was 31.2 +/- 15.7 mg/l. This difference was not statistically significant by Student's t test (P = 0.6), and the correlation coefficient (r) was 0.87. Thus, the Behring Nephelometer method measures retinol-binding protein rapidly and as accurately as radial immunodiffusion.

  12. Fatty acid-binding site environments of serum vitamin D-binding protein and albumin are different

    PubMed Central

    Swamy, Narasimha; Ray, Rahul

    2008-01-01

    Vitamin D-binding protein (DBP) and albumin (ALB) are abundant serum proteins and both possess high-affinity binding for saturated and unsaturated fatty acids. However, certain differences exist. We surmised that in cases where serum albumin level is low, DBP presumably can act as a transporter of fatty acids. To explore this possibility we synthesized several alkylating derivatives of 14C-palmitic acid to probe the fatty acid binding pockets of DBP and ALB. We observed that N-ethyl-5-phenylisooxazolium-3′-sulfonate-ester (WRK ester) of 14C-palmitic acid specifically labeled DBP; but p-nitrophenyl- and N-hydroxysuccinimidyl-esters failed to do so. However, p-nitrophenyl ester of 14C-palmitic acid specifically labeled bovine ALB, indicating that the micro-environment of the fatty acid-binding domains of DBP and ALB may be different; and DBP may not replace ALB as a transporter of fatty acids. PMID:18374965

  13. Detergents as probes of hydrophobic binding cavities in serum albumin and other water-soluble proteins.

    PubMed Central

    Kragh-Hansen, U; Hellec, F; de Foresta, B; le Maire, M; Møller, J V

    2001-01-01

    As an extension of our studies on the interaction of detergents with membranes and membrane proteins, we have investigated their binding to water-soluble proteins. Anionic aliphatic compounds (dodecanoate and dodecylsulfate) were bound to serum albumin with high affinity at nine sites; related nonionic detergents (C12E8 and dodecylmaltoside) were bound at seven to eight sites, many in common with those of dodecanoate. The compounds were also bound in the hydrophobic cavity of beta-lactoglobulin, but not to ovalbumin. In addition to the generally recognized role of the Sudlow binding region II of serum albumin (localized at the IIIA subdomain) in fatty acid binding, quenching of the fluorescence intensity of tryptophan-214 by 7,8-dibromododecylmaltoside and 12-bromododecanoate also implicate the Sudlow binding region I (subdomain IIA) as a locus for binding of aliphatic compounds. Our data document the usefulness of dodecyl amphipathic compounds as probes of hydrophobic cavities in water-soluble proteins. In conjunction with recent x-ray diffraction analyses of fatty acid binding as the starting point we propose a new symmetrical binding model for the location of nine high-affinity sites on serum albumin for aliphatic compounds. PMID:11371462

  14. Binding of colchicine and thiocolchicoside to human serum proteins and blood cells.

    PubMed

    Sabouraud, A; Chappey, O; Dupin, T; Scherrmann, J M

    1994-08-01

    The binding of 3H-colchicine and its derivative 3H-thiocolchicoside to human serum, purified human proteins and blood cells was studied by equilibrium dialysis and centrifugation. Binding of colchicine and thiocolchicoside to human serum was 38.9 C +/- 4.7 and 12.8 C +/- 5.3%, respectively, essentially to albumin. Protein binding was not dependent on the concentration of either drug between 10(-10) and 10(-5)M. The binding of colchicine and thiocolchicoside to isolated erythrocytes (55 C +/- 5.6 and 16.5 C +/- 2.1%, respectively) decreased markedly in the presence of human serum proteins, i.e. in whole blood (38.7 C +/- 3.1 and 3.4 C +/- 0.8%). Binding of colchicine and thiocolchicoside to other blood cells was very low C < 3%). These binding properties in the blood compartment do not predispose colchicine and thiocolchicoside to be pharmacokinetically sensitive to binding displacement by drug interactions.

  15. Binding of labeled thyroxin analog to serum proteins evaluated after radioimmunoassay of free thyroxin

    SciTech Connect

    Arevalo, G.

    1989-03-01

    In ambulatory patients, assay of free thyroxin (FT4) in serum correlates well with thyroid status and with results obtained by equilibrium dialysis. The validity of FT4 results has been questioned mainly in euthyroid patients with altered concentrations of thyroid hormone-binding proteins, as in nonthyroidal illness, hereditary analbuminemia, familial dysalbuminemic hyperthyroxinemia (FDH), and the presence of iodothyronine-binding antibodies. I present here a study of the binding of (/sup 125/I)T4-derivative to serum proteins in the supernate, which is ordinarily discarded after determination of FT4 by one-step radioimmunoassay with dextran-coated charcoal used to separate the free and bound fractions. The results are expressed as a ratio, with results for a normal serum pool as reference. The average ratio was high in hyperthyroid subjects, 1.26 (SD 0.12, n = 25), and in hypoalbuminemia, 1.20 (SD 0.10, n = 15), and low in FDH, 0.62 (SD 0.11, n = 9), and hypothyroid subjects, 0.90 (SD 0.06, n = 20). In normal individuals it was 0.98 (SD 0.05, n = 30). Determination of the analog-binding rate complements the FT4 result and allows for the recognition of cases with abnormal binding by serum proteins, without recourse to other tests recommended for thyroid-function studies.

  16. Cellular Binding of Anionic Nanoparticles is Inhibited by Serum Proteins Independent of Nanoparticle Composition.

    PubMed

    Fleischer, Candace C; Kumar, Umesh; Payne, Christine K

    2013-09-01

    Nanoparticles used in biological applications encounter a complex mixture of extracellular proteins. Adsorption of these proteins on the nanoparticle surface results in the formation of a "protein corona," which can dominate the interaction of the nanoparticle with the cellular environment. The goal of this research was to determine how nanoparticle composition and surface modification affect the cellular binding of protein-nanoparticle complexes. We examined the cellular binding of a collection of commonly used anionic nanoparticles: quantum dots, colloidal gold nanoparticles, and low-density lipoprotein particles, in the presence and absence of extracellular proteins. These experiments have the advantage of comparing different nanoparticles under identical conditions. Using a combination of fluorescence and dark field microscopy, flow cytometry, and spectroscopy, we find that cellular binding of these anionic nanoparticles is inhibited by serum proteins independent of nanoparticle composition or surface modification. We expect these results will aid in the design of nanoparticles for in vivo applications.

  17. Identification of (L)-fucose-binding proteins from the Nile tilapia (Oreochromis niloticus L.) serum.

    PubMed

    Argayosa, Anacleto M; Lee, Yuan C

    2009-09-01

    Lectins are carbohydrate-binding proteins with many biological functions including cellular recognition and innate immunity. In this study, a major l-fucose-binding lectin from the serum of Nile tilapia (Oreochromis niloticus L.), designated as TFBP, was isolated by l-fucose-BSA Sepharose CL6B affinity chromatography. The SDS-PAGE (10%) analysis of TFBP revealed a major band of approximately 23 kDa with an N-terminal amino acid sequence of DQTETAGQQSXPQDIHAVLREL which did not give significant similarities to the protein databases using BLASTp searches. Ruthenium red staining indicate positive calcium-binding property of TFBP. The purified TFBP agglutinated human type O erythrocytes but not the type A and B fresh erythrocytes. Live Aeromonas hydrophila and Enterococcus faecalis cells were also agglutinated by the lectin. The fucose-binding proteins were detected in the soluble protein extracts from the gills, gut, head kidneys, liver, serum and spleen using a fucose-binding protein probe (l-fucose-BSA-horseradish peroxidase). The binding of TFBP with the l-fucose-BSA probe was inhibited by l-fucose but not by alpha-methyl-d-mannose.

  18. Binding of alkyl- and alkoxy-substituted simple phenolic compounds to human serum proteins.

    PubMed

    Ogata, N; Shibata, T

    2000-01-01

    Wood creosote, primarily a mixture of simple alkyl- and/or alkoxy-substituted phenolic compounds with closely related structures, has long been used as an oral antidiarrheal agent. The use of wood creosote as a parenteral antidiarrheal agent was investigated, and for basic pharmacokinetic data we measured the extent of equilibrium binding of its six major constituent phenolic compounds to human serum proteins using an ultrafiltration method. The percent binding of these major constituent phenolic compounds, namely phenol, guaiacol, p-cresol, o-cresol, creosol and 4-ethylguaiacol, bound to 40-mg/ml human serum albumin was 15.5+/-0.9, 28.0+/-1.5, 37.2+/-0.7, 52.3+/-5.3, 36.8+/-2.0 and 56.7+/-2.4%, respectively, while percent binding to human serum (68 mg protein/ml) was 41.3+/-0.7, 42.6+/-0.5, 64.8+/-0.4, 70.1+/-1.6, 65.7+/-0.2 and 83.1+/-0.1% (mean +/- standard deviation, n = 4), respectively, when tested individually at a concentration of 500 micromol/l. Saturation of binding was not observed for the phenolic compounds up to a concentration of 50 mmol/l. Phenolic compounds with a lipophilic substituent showed higher percent binding to proteins than those without it. We conclude that simple phenolic compounds having alkyl- and/or alkoxy-substituents bind to serum proteins to a considerable extent and that the binding is hydrophobic and nonspecific.

  19. Isomer-Specific Binding Affinity of Perfluorooctanesulfonate (PFOS) and Perfluorooctanoate (PFOA) to Serum Proteins.

    PubMed

    Beesoon, Sanjay; Martin, Jonathan W

    2015-05-05

    Perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) are among the most prominent contaminants in human serum, and these were historically manufactured as technical mixtures of linear and branched isomers. The isomers display unique pharmacokinetics in humans and in animal models, but molecular mechanisms underlying isomer-specific PFOS and PFOA disposition have not previously been studied. Here, ultrafiltration devices were used to examine (i) the dissociation constants (Kd) of individual PFOS and PFOA isomers with human serum albumin (HSA) and (ii) relative binding affinity of isomers in technical mixtures spiked to whole calf serum and human serum. Measurement of HSA Kd's demonstrated that linear PFOS (Kd=8(±4)×10(-8) M) was much more tightly bound than branched PFOS isomers (Kd range from 8(±1)×10(-5) M to 4(±2)×10(-4) M). Similarly, linear PFOA (Kd=1(±0.9)×10(-4) M) was more strongly bound to HSA compared to branched PFOA isomers (Kd range from 4(±2)×10(-4) M to 3(±2)×10(-4) M). The higher binding affinities of linear PFOS and PFOA to total serum protein were confirmed when both calf serum and human serum were spiked with technical mixtures. Overall, these data provide a mechanistic explanation for the longer biological half-life of PFOS in humans, compared to PFOA, and for the higher transplacental transfer efficiencies and renal clearance of branched PFOS and PFOA isomers, compared to the respective linear isomer.

  20. Pharmacokinetics of warfarin in rats: role of serum protein binding and tissue distribution

    SciTech Connect

    Cheung, W.K.

    1985-01-01

    The purpose of this study was to explore the role of serum protein binding and tissue distribution in the non-linear pharmacokinetics of warfarin in rats. The first phase of the research was an attempt to elucidate the causes of intersubject differences in serum protein binding of warfarin in rats. It was found that the distribution of S-warfarin between blood and liver, kidneys, muscle, or fatty tissue was non-linear. Based on the tissue distribution data obtained, a physiologically-based pharmacokinetic model was developed to describe the time course of S-warfarin concentrations in the serum and tissues of rats. The proposed model was able to display the dose-dependent pharmacokinetics of warfarin in rats. Namely a lower clearance and a smaller apparent volume of distribution with increasing dose, which appear to be due to the presence of capacity-limited, high-affinity binding sites for warfarin in various tissues. To determine if the binding of warfarin to the high-affinity binding sites in the liver of rats is reversible, concentrations of S-warfarin in the liver and serum of rats were monitored for a very long time after an intravenous injection of a 1 mg/kg dose. In another study in rats, non-radioactive warfarin was found to be able to displace tissue-bound C/sup 14/-warfarin which was administered about 200 hours before the i.v. injection of the non-radioactive warfarin, showing that the binding of warfarin to the high-affinity binding sites in the body is persistent and reversible.

  1. Association of androgen with gender difference in serum adipocyte fatty acid binding protein levels

    PubMed Central

    Hu, Xiang; Ma, Xiaojing; Pan, Xiaoping; Luo, Yuqi; Xu, Yiting; Xiong, Qin; Bao, Yuqian; Jia, Weiping

    2016-01-01

    Clinical investigations have indicated women have higher levels of adipocyte fatty acid binding protein (A-FABP) than men. The present study aimed to identify factors related to gender difference in serum A-FABP levels. A total of 507 participants (194 men, 132 premenopausal women, and 181 postmenopausal women) were enrolled in the present study. Serum A-FABP levels increased in the order from men to premenopausal women to postmenopausal women in both body mass index categories (<25.0 and ≥25.0 kg/m2; all P < 0.05). Multiple stepwise regression analyses showed that after adjustment for factors related to serum A-FABP levels, the trunk fat mass was an independent and positive factor of serum A-FABP levels. For men, total testosterone was associated independently and inversely with serum A-FABP levels. For pre- and postmenopausal women, bioavailable testosterone and total testosterone were independent and positive factors associated with serum A-FABP levels, respectively. The present study demonstrated that the androgen was correlated with the serum A-FABP levels negatively in men, but positively in women. With these effects on the fat content, especially trunk fat, androgen might contribute to the gender difference in serum A-FABP levels. PMID:27270834

  2. Determination of retinol-binding protein in serum by kinetic immunonephelometry with polyethylene glycol pretreatment.

    PubMed

    Hallworth, M J; Calvin, J; Price, C P

    1984-11-01

    This work describes the use of polyethylene glycol as a pretreatment reagent to remove endogenous light scattering material from serum samples prior to automated immunonephelometric analysis on a centrifugal analyser. An assay system for retinol-binding protein is described, which allows rapid (10 minutes) quantitation of retinol-binding protein in serum samples with a detection limit of 5 mg/L and between-assay coefficients of variation ranging from 2.9% to 4.0%. The assay range is 5-80 mg/L and accuracy comparisons with a Mancini single radial immunodiffusion method yield a regression line y = 0.89 x + 0.52 (r = 0.98, n = 22). The problem of analyte precipitation associated with use of pretreatment regimes is discussed.

  3. Nontypeable Haemophilus influenzae protein E binds vitronectin and is important for serum resistance.

    PubMed

    Hallström, Teresia; Blom, Anna M; Zipfel, Peter F; Riesbeck, Kristian

    2009-08-15

    Nontypeable Haemophilus influenzae (NTHi) commonly causes local disease in the upper and lower respiratory tract and has recently been shown to interfere with both the classical and alternative pathways of complement activation. The terminal pathway of the complement system is regulated by vitronectin that is a component of both plasma and the extracellular matrix. In this study, we identify protein E (PE; 16 kDa), which is a recently characterized ubiquitous outer membrane protein, as a vitronectin-binding protein of NTHi. A PE-deficient NTHi mutant had a markedly reduced survival in serum compared with the PE-expressing isogenic NTHi wild type. Moreover, the PE-deficient mutant showed a significantly decreased binding to both soluble and immobilized vitronectin. In parallel, PE-expressing Escherichia coli bound soluble vitronectin and adhered to immobilized vitronectin compared with controls. Surface plasmon resonance technology revealed a K(D) of 0.4 microM for the interaction between recombinant PE and immobilized vitronectin. Moreover, the PE-dependent vitronectin-binding site was located at the heparin-binding domains of vitronectin and the major vitronectin-binding domain was found in the central core of PE (aa 84-108). Importantly, vitronectin bound to the surface of NTHi 3655 reduced membrane attack complex-induced hemolysis. In contrast to incubation with normal human serum, NTHi 3655 showed a reduced survival in vitronectin-depleted human serum, thus demonstrating that vitronectin mediates a protective role at the bacterial surface. Our findings show that PE, by binding vitronectin, may play an important role in NTHi pathogenesis.

  4. Serum amyloid A is a retinol binding protein that transports retinol during bacterial infection

    PubMed Central

    Derebe, Mehabaw G; Zlatkov, Clare M; Gattu, Sureka; Ruhn, Kelly A; Vaishnava, Shipra; Diehl, Gretchen E; MacMillan, John B; Williams, Noelle S; Hooper, Lora V

    2014-01-01

    Retinol plays a vital role in the immune response to infection, yet proteins that mediate retinol transport during infection have not been identified. Serum amyloid A (SAA) proteins are strongly induced in the liver by systemic infection and in the intestine by bacterial colonization, but their exact functions remain unclear. Here we show that mouse and human SAAs are retinol binding proteins. Mouse and human SAAs bound retinol with nanomolar affinity, were associated with retinol in vivo, and limited the bacterial burden in tissues after acute infection. We determined the crystal structure of mouse SAA3 at a resolution of 2 Å, finding that it forms a tetramer with a hydrophobic binding pocket that can accommodate retinol. Our results thus identify SAAs as a family of microbe-inducible retinol binding proteins, reveal a unique protein architecture involved in retinol binding, and suggest how retinol is circulated during infection. DOI: http://dx.doi.org/10.7554/eLife.03206.001 PMID:25073702

  5. Monte carlo method-based QSAR modeling of penicillins binding to human serum proteins.

    PubMed

    Veselinović, Jovana B; Toropov, Andrey A; Toropova, Alla P; Nikolić, Goran M; Veselinović, Aleksandar M

    2015-01-01

    The binding of penicillins to human serum proteins was modeled with optimal descriptors based on the Simplified Molecular Input-Line Entry System (SMILES). The concentrations of protein-bound drug for 87 penicillins expressed as percentage of the total plasma concentration were used as experimental data. The Monte Carlo method was used as a computational tool to build up the quantitative structure-activity relationship (QSAR) model for penicillins binding to plasma proteins. One random data split into training, test and validation set was examined. The calculated QSAR model had the following statistical parameters: r(2)  = 0.8760, q(2)  = 0.8665, s = 8.94 for the training set and r(2)  = 0.9812, q(2)  = 0.9753, s = 7.31 for the test set. For the validation set, the statistical parameters were r(2)  = 0.727 and s = 12.52, but after removing the three worst outliers, the statistical parameters improved to r(2)  = 0.921 and s = 7.18. SMILES-based molecular fragments (structural indicators) responsible for the increase and decrease of penicillins binding to plasma proteins were identified. The possibility of using these results for the computer-aided design of new penicillins with desired binding properties is presented.

  6. Marsupial and monotreme serum immunoglobulin binding by proteins A, G and L and anti-kangaroo antibody.

    PubMed

    Vaz, Paola K; Hartley, Carol A; Browning, Glenn F; Devlin, Joanne M

    2015-12-01

    Serological studies are often conducted to examine exposure to infectious agents in wildlife populations. However, specific immunological reagents for wildlife species are seldom available and can limit the study of infectious diseases in these animals. This study examined the ability of four commercially available immunoglobulin-binding reagents to bind serum immunoglobulins from 17 species within the Marsupialia and Monotremata. Serum samples were assessed for binding, using immunoblots and ELISAs (Enzyme-linked immunosorbent assays), to three microbially-derived proteins - staphylococcal protein A, streptococcal protein G and peptostreptococcal protein L. Additionally, an anti-kangaroo antibody was included for comparison. The inter- and intra-familial binding patterns of the reagents to serum immunoglobulins varied and evolutionary distance between animal species was not an accurate predictor of the ability of reagents to bind immunoglobulins. Results from this study can be used to inform the selection of appropriate immunological reagents in future serological studies in these clades.

  7. Structure and evolutionary origin of the gene encoding a human serum mannose-binding protein.

    PubMed Central

    Taylor, M E; Brickell, P M; Craig, R K; Summerfield, J A

    1989-01-01

    The N-terminal sequence of the major human serum mannose-binding protein (MBP1) was shown to be identical at all positions determined with the amino acid sequence predicted from a cDNA clone of a human liver MBP mRNA. An oligonucleotide corresponding to part of the sequence of this cDNA clone was used to isolate a cosmid genomic clone containing a homologous gene. The intron/exon structure of this gene was found to closely resemble that of the gene encoding a rat liver MBP (MBP A). The nucleotide sequence of the exons differed in several places from that of the human cDNA clone published by Ezekowitz, Day & Herman [(1988) J. Exp. Med. 167, 1034-1046]. The MBP molecule comprises a signal peptide, a cysteine-rich domain, a collagen-like domain, a 'neck' region and a carbohydrate-binding domain. Each domain is encoded by a separate exon. This genomic organization lends support to the hypothesis that the gene arose during evolution by a process of exon shuffling. Several consensus sequences that may be involved in controlling the expression of human serum MBP have been identified in the promoter region of the gene. The consensus sequences are consistent with the suggestion that this mammalian serum lectin is regulated as an acute-phase protein synthesized by the liver. PMID:2590164

  8. Regulation of inflammation-primed activation of macrophages by two serum factors, vitamin D3-binding protein and albumin.

    PubMed Central

    Yamamoto, N; Kumashiro, R; Yamamoto, M; Willett, N P; Lindsay, D D

    1993-01-01

    A very small amount (0.0005 to 0.001%) of an ammonium sulfate [50% saturated (NH4)2SO4]-precipitable protein fraction of alpha 2-globulin efficiently supported inflammation-primed activation of macrophages. This fraction contains vitamin D3-binding protein essential for macrophage activation. Comparative macrophage activation studies with fetal calf serum, alpha 2-globulin fraction, 50% (NH4)2SO4 precipitate, and purified bovine vitamin D3-binding protein revealed that fetal calf serum and alpha 2-globulin fraction appear to contain an inhibitor for macrophage activation while ammonium sulfate precipitate contains no inhibitor. This inhibitor was found to be serum albumin. When bovine serum albumin (25 micrograms/ml) was added to a medium supplemented with 0.0005 to 0.05% (NH4)2SO4 precipitate or 1 to 10 ng of vitamin D3-binding protein per ml, activation of macrophages was inhibited. PMID:8225612

  9. An integrated bioanalytical platform for supporting high-throughput serum protein binding screening.

    PubMed

    Zhang, Jun; Shou, Wilson Z; Vath, Marianne; Kieltyka, Kasia; Maloney, Jennifer; Elvebak, Larry; Stewart, Jeremy; Herbst, John; Weller, Harold N

    2010-12-30

    Quantification of small molecules using liquid chromatography/tandem mass spectrometry (LC/MS/MS) on a triple quadrupole mass spectrometer has become a common practice in bioanalytical support of in vitro adsorption, distribution, metabolism and excretion (ADME) screening. The bioanalysis process involves primarily three indispensable steps: MS/MS optimization for a large number of new chemical compounds undergoing various screening assays in early drug discovery, high-throughput sample analysis with LC/MS/MS for those chemically diverse compounds using the optimized MS/MS conditions, and post-acquisition data review and reporting. To improve overall efficiency of ADME bioanalysis, an integrated system was proposed featuring an automated and unattended MS/MS optimization, a staggered parallel LC/MS/MS for high-throughput sample analysis, and a sophisticated software tool for LC/MS/MS raw data review as well as biological data calculation and reporting. The integrated platform has been used in bioanalytical support of a serum protein binding screening assay with high speed, high capacity, and good robustness. In this new platform, a unique sample dilution scheme was also introduced. With this dilution design, the total number of analytical samples was reduced; therefore, the total operation time was reduced and the overall throughput was further improved. The performance of the protein binding screening assay was monitored with two controls representing high and low binding properties and an acceptable inter-assay consistency was achieved. This platform has been successfully used for the determination of serum protein binding in multiple species for more than 4000 compounds.

  10. Structural modification of serum vitamin D3-binding protein and immunosuppression in AIDS patients.

    PubMed

    Yamamoto, N; Naraparaju, V R; Srinivasula, S M

    1995-11-01

    A serum glycoprotein, vitamin D3-binding protein (Gc protein), can be converted by beta-galactosidase of stimulated B lymphocytes and sialidase of T lymphocytes to a potent macrophage-activating factor (MAF), a protein with N-acetylgalactosamine as the remaining sugar moiety. Thus, Gc protein is a precursor for MAF. Treatment of purified Gc protein with immobilized beta-galactosidase and sialidase generates an extremely high-titered MAF (GcMAF). When peripheral blood monocytes/macrophages of 46 HIV-infected patients were treated with GcMAF (100 pg/ml), the monocytes/macrophages of all patients were efficiently activated. However, the MAF precursor activity of plasma Gc protein was low in 16 (35%) of of these patients. Loss of the MAF precursor activity appeared to be due to deglycosylation of plasma Gc protein by alpha-N-acetylgalactosaminidase found in the patient blood stream. Levels of plasma alpha-N-acetylgalactosaminidase activity in individual patients had an inverse correlation with the MAF precursor activity of their plasma Gc protein. Thus, precursor activity of Gc protein and alpha-N-acetylgalactosaminidase activity in patient blood can serve as diagnostic and prognostic indices.

  11. QSAR modeling of β-lactam binding to human serum proteins

    NASA Astrophysics Data System (ADS)

    Hall, L. Mark; Hall, Lowell H.; Kier, Lemont B.

    2003-02-01

    The binding of beta-lactams to human serum proteins was modeled with topological descriptors of molecular structure. Experimental data was the concentration of protein-bound drug expressed as a percent of the total plasma concentration (percent fraction bound, PFB) for 87 penicillins and for 115 β-lactams. The electrotopological state indices (E-State) and the molecular connectivity chi indices were found to be the basis of two satisfactory models. A data set of 74 penicillins from a drug design series was successfully modeled with statistics: r2=0.80, s = 12.1, q2=0.76, spress=13.4. This model was then used to predict protein binding (PFB) for 13 commercial penicillins, resulting in a very good mean absolute error, MAE = 12.7 and correlation coefficient, q2=0.84. A group of 28 cephalosporins were combined with the penicillin data to create a dataset of 115 beta-lactams that was successfully modeled: r2=0.82, s = 12.7, q2=0.78, spress=13.7. A ten-fold 10% leave-group-out (LGO) cross-validation procedure was implemented, leading to very good statistics: MAE = 10.9, spress=14.0, q2 (or r2 press)=0.78. The models indicate a combination of general and specific structure features that are important for estimating protein binding in this class of antibiotics. For the β-lactams, significant factors that increase binding are presence and electron accessibility of aromatic rings, halogens, methylene groups, and =N- atoms. Significant negative influence on binding comes from amine groups and carbonyl oxygen atoms.

  12. Serum fatty acid binding protein 4, free fatty acids and metabolic risk markers

    PubMed Central

    Karakas, Sidika E.; Almario, Rogelio U.; Kim, Kyoungmi

    2009-01-01

    Fatty acid binding protein (FABP) 4 chaperones free fatty acids (FFA) in the adipocytes during lipolysis. Serum FFA relates to Metabolic Syndrome (METS) and serum FABP4 is emerging as a novel risk marker. In 36 overweight/obese women, serum FABP4 and FFA were measured hourly during 5-hour oral glucose tolerance test (OGTT). Insulin resistance was determined using frequently sampled intravenous GTT (FS-IVGTT). Serum lipids and inflammation markers were measured at fasting. During OGTT, serum FABP4 decreased by 40%, reaching its nadir at 3h (from 45.3±3.1 to 31.9±1.6 ng/mL) and stayed below the baseline at 5 h (35.9±2.2 ng/mL) (p < 0.0001 for both, compared to the baseline). Serum FFA decreased by 10 fold, reaching a nadir at 2h (from 0.611±0.033 to 0.067±0.004 mmol/L), then rebounded to 0.816±0.035 mmol/ L at 5h (p < 0.001 for both, compared to baseline). Both fasting-FABP4 and nadir-FABP4 correlated with obesity. Nadir-FABP4 correlated also with insulin resistance parameters from FS-IVGTT and with inflammation. Nadir-FFA, but not fasting-FFA, correlated with the METS-parameters. In conclusion, fasting-FABP4 related to metabolic risk markers more strongly than fasting-FFA. Nadir-FABP4 and nadir-FFA measured after glucose loading may provide better risk assessment than the fasting values. PMID:19394980

  13. Deglycosylation of serum vitamin D3-binding protein leads to immunosuppression in cancer patients.

    PubMed

    Yamamoto, N; Naraparaju, V R; Asbell, S O

    1996-06-15

    Serum vitamin D3-binding protein (Gc protein) can be converted by beta-galactosidase of B cells and sialidase of T cells to a potent macrophage activating factor, a protein with N-acetylgalactosamine as the remaining sugar moiety. Thus, Gc protein is the precursor of the macrophage activating factor (MAF). Treatment of Gc protein with immobilized beta-galactosidase and sialidase generates an extremely high titered MAF, Gc-MAF. When peripheral blood monocytes/macrophages of 52 patients bearing various types of cancer were incubated with 100 pg/ml of GcMAF, the monocytes/macrophages of all patients were efficiently activated. However, the MAF precursor activity of patient plasma Gc protein was found to be severely reduced in about 25% of this patient population. About 45% of the patients had moderately reduced MAF precursor activities. Loss of the precursor activity was found to be due to deglycosylation of plasma Gc protein by alpha-N-acetylgalactosaminidase detected in the patient's bloodstream. The source of the enzyme appeared to be cancerous cells. Radiation therapy decreased plasma alpha-N-acetylgalactosaminidase activity with concomitant increase of precursor activity. This implies that radiation therapy decreases the number of cancerous cells capable of secreting alpha-N-acetylgalactosaminidase. Both alpha-N-acetylgalactosaminidase activity and MAF precursor activity of Gc protein in patient bloodstream can serve as diagnostic and prognostic indices.

  14. Liver Retinol Transporter and Receptor for Serum Retinol-binding Protein (RBP4)*

    PubMed Central

    Alapatt, Philomena; Guo, Fangjian; Komanetsky, Susan M.; Wang, Shuping; Cai, Jinjin; Sargsyan, Ashot; Rodríguez Díaz, Eduardo; Bacon, Brandon T.; Aryal, Pratik; Graham, Timothy E.

    2013-01-01

    Vitamin A (retinol) is absorbed in the small intestine, stored in liver, and secreted into circulation bound to serum retinol-binding protein (RBP4). Circulating retinol may be taken up by extrahepatic tissues or recycled back to liver multiple times before it is finally metabolized or degraded. Liver exhibits high affinity binding sites for RBP4, but specific receptors have not been identified. The only known high affinity receptor for RBP4, Stra6, is not expressed in the liver. Here we report discovery of RBP4 receptor-2 (RBPR2), a novel retinol transporter expressed primarily in liver and intestine and induced in adipose tissue of obese mice. RBPR2 is structurally related to Stra6 and highly conserved in vertebrates, including humans. Expression of RBPR2 in cultured cells confers high affinity RBP4 binding and retinol transport, and RBPR2 knockdown reduces RBP4 binding/retinol transport. RBPR2 expression is suppressed by retinol and retinoic acid and correlates inversely with liver retinol stores in vivo. We conclude that RBPR2 is a novel retinol transporter that potentially regulates retinol homeostasis in liver and other tissues. In addition, expression of RBPR2 in liver and fat suggests a possible role in mediating established metabolic actions of RBP4 in those tissues. PMID:23105095

  15. Serum vitamin D, vitamin D binding protein, and lung cancer survival

    PubMed Central

    Anic, Gabriella M.; Weinstein, Stephanie J.; Mondul, Alison M.; Männistö, Satu; Albanes, Demetrius

    2014-01-01

    Objectives Vitamin D may prolong cancer survival by inhibiting tumor progression and metastasis, however, there are limited epidemiologic studies regarding the association between circulating 25-hydroxyvitamin D (25(OH)D) and lung cancer survival. The aim of this study was to examine the relationship between serum 25(OH)D and lung cancer specific survival and to evaluate whether vitamin D binding protein (DBP) concentration modified this association. Materials and Methods 25(OH)D and DBP were measured in fasting serum samples from 500 male lung cancer cases in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study. Cox proportional hazards regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CI) for lung cancer related death according to quartiles of season-specific 25(OH)D, DBP, and the molar ratio of 25(OH)D:DBP, a proxy for free circulating 25(OH)D. Results Comparing highest to lowest quartiles, serum 25(OH)D (HR=1.18; 95% CI: 0.89–1.56) and DBP (HR=0.95; 95% CI: 0.71–1.26) were not associated with lung cancer survival and DBP concentration did not modify the association with 25(OH)D (p for interaction=0.56). There was suggestion of an association between higher serum 25(OH)D and better survival from adenocarcinoma (HR=0.64; 95% CI: 0.17–2.45) and small cell carcinoma (HR=0.55; 95% CI: 0.21–1.45), but these estimates were based on a relatively small number of cases. Conclusion Serum 25(OH)D was not associated with overall lung cancer survival regardless of DBP concentration, however, these findings should be examined in other studies that include women and subjects with higher 25(OH)D levels. PMID:25456734

  16. Serum Galectin-9 and Galectin-3-Binding Protein in Acute Dengue Virus Infection.

    PubMed

    Liu, Kuan-Ting; Liu, Yao-Hua; Chen, Yen-Hsu; Lin, Chun-Yu; Huang, Chung-Hao; Yen, Meng-Chi; Kuo, Po-Lin

    2016-05-27

    Dengue fever is a serious threat for public health and induces various inflammatory cytokines and mediators, including galectins and glycoproteins. Diverse immune responses and immunological pathways are induced in different phases of dengue fever progression. However, the status of serum galectins and glycoproteins is not fully determined. The aim of this study was to investigate the serum concentration and potential interaction of soluble galectin-1, galectin-3, galectin-9, galectin-3 binding protein (galectin-3BP), glycoprotein 130 (gp130), and E-, L-, and P-selectin in patients with dengue fever in acute febrile phase. In this study, 317 febrile patients (187 dengue patients, 150 non-dengue patients that included 48 patients with bacterial infection and 102 patients with other febrile illness) who presented to the emergency department and 20 healthy controls were enrolled. Our results showed the levels of galectin-9 and galectin-3BP were significantly higher in dengue patients than those in healthy controls. Lower serum levels of galectin-1, galectin-3, and E-, L-, and P-selectin in dengue patients were detected compared to bacteria-infected patients, but not to healthy controls. In addition, strong correlation between galectin-9 and galectin-3BP was observed in dengue patients. In summary, our study suggested galectin-9 and galectin-3BP might be critical inflammatory mediators in acute dengue virus infection.

  17. First evidence of protein G-binding protein in the most primitive vertebrate: serum lectin from lamprey (Lampetra japonica).

    PubMed

    Xue, Zhuang; Pang, Yue; Liu, Xin; Zheng, Zhen; Xiao, Rong; Jin, Minli; Han, Yinglun; Su, Peng; Lv, Li; Wang, Jihong; Li, QingWei

    2013-12-01

    The intelectins, a recently identified subgroup of extracellular animal lectins, are glycan-binding receptors that recognize glycan epitopes on foreign pathogens in host systems. Here, we have described NPGBP (novel protein G-binding protein), a novel serum lectin found in the lamprey, Lampetra japonica. RT-PCR yielded a 1005 bp cDNA sequence from the lamprey liver encoding a 334 amino acid secretory protein with homology to mammalian and aquatic organism intelectins. Gene expression analyses showed that the NPGBP gene was expressed in the blood, intestines, kidney, heart, gill, liver, adipose tissue and gonads. NPGBP was isolated by protein G-conjugated agarose immunoprecipitation, and SDS-PAGE analyses showed that NPGBP migrated as a specific band (∼35 and ∼124 kDa under reducing and non-reducing conditions, respectively). These results suggested that NPGBP forms monomers and tetramers. NPGBP gene expression was induced by in vivo bacterial stimulation, and NPGBP showed different agglutination activities against pathogenic Gram-positive bacteria, Gram-negative bacteria and fungi. The induction of NPGBP suggested that it plays an important role in defense against microorganisms in the internal circulation system of the lamprey. When incubated with an unrelated antibody, the specific binding between NPGBP and protein G was competitively inhibited, indicating that NPGBP and the Fc region of Ig bind to the same site on protein G. We thus assume that the tertiary structure of NPGBP is similar to that of the Fc region of Ig. Additionally, NPGBP can effectively promote endothelial cell mitosis. These findings suggest that NPGBP plays a role in the immune defense against microorganisms, and this study represents one of the few examples of the characterization and functional analysis of an aquatic organism intelectin.

  18. Intestinal Dysbiosis and Lowered Serum Lipopolysaccharide-Binding Protein in Parkinson’s Disease

    PubMed Central

    Hasegawa, Satoru; Goto, Sae; Tsuji, Hirokazu; Okuno, Tatsuya; Asahara, Takashi; Nomoto, Koji; Shibata, Akihide; Fujisawa, Yoshiro; Minato, Tomomi; Okamoto, Akira; Ohno, Kinji; Hirayama, Masaaki

    2015-01-01

    Background The intestine is one of the first affected organs in Parkinson’s disease (PD). PD subjects show abnormal staining for Escherichia coli and α-synuclein in the colon. Methods We recruited 52 PD patients and 36 healthy cohabitants. We measured serum markers and quantified the numbers of 19 fecal bacterial groups/genera/species by quantitative RT-PCR of 16S or 23S rRNA. Although the six most predominant bacterial groups/genera/species covered on average 71.3% of total intestinal bacteria, our analysis was not comprehensive compared to metagenome analysis or 16S rRNA amplicon sequencing. Results In PD, the number of Lactobacillus was higher, while the sum of analyzed bacteria, Clostridium coccoides group, and Bacteroides fragilis group were lower than controls. Additionally, the sum of putative hydrogen-producing bacteria was lower in PD. A linear regression model to predict disease durations demonstrated that C. coccoides group and Lactobacillus gasseri subgroup had the largest negative and positive coefficients, respectively. As a linear regression model to predict stool frequencies showed that these bacteria were not associated with constipation, changes in these bacteria were unlikely to represent worsening of constipation in the course of progression of PD. In PD, the serum lipopolysaccharide (LPS)-binding protein levels were lower than controls, while the levels of serum diamine oxidase, a marker for intestinal mucosal integrity, remained unchanged in PD. Conclusions The permeability to LPS is likely to be increased without compromising the integrity of intestinal mucosa in PD. The increased intestinal permeability in PD may make the patients susceptible to intestinal dysbiosis. Conversely, intestinal dysbiosis may lead to the increased intestinal permeability. One or both of the two mechanisms may be operational in development and progression of PD. PMID:26539989

  19. Albumin-coated SPIONs: an experimental and theoretical evaluation of protein conformation, binding affinity and competition with serum proteins

    NASA Astrophysics Data System (ADS)

    Yu, Siming; Perálvarez-Marín, Alex; Minelli, Caterina; Faraudo, Jordi; Roig, Anna; Laromaine, Anna

    2016-07-01

    The variety of nanoparticles (NPs) used in biological applications is increasing and the study of their interaction with biological media is becoming more important. Proteins are commonly the first biomolecules that NPs encounter when they interact with biological systems either in vitro or in vivo. Among NPs, super-paramagnetic iron oxide nanoparticles (SPIONs) show great promise for medicine. In this work, we study in detail the formation, composition, and structure of a monolayer of bovine serum albumin (BSA) on SPIONs. We determine, both by molecular simulations and experimentally, that ten molecules of BSA form a monolayer around the outside of the SPIONs and their binding strength to the SPIONs is about 3.5 × 10-4 M, ten times higher than the adsorption of fetal bovine serum (FBS) on the same SPIONs. We elucidate a strong electrostatic interaction between BSA and the SPIONs, although the secondary structure of the protein is not affected. We present data that supports the strong binding of the BSA monolayer on SPIONs and the properties of the BSA layer as a protein-resistant coating. We believe that a complete understanding of the behavior and morphology of BSA-SPIONs and how the protein interacts with SPIONs is crucial for improving NP surface design and expanding the potential applications of SPIONs in nanomedicine.The variety of nanoparticles (NPs) used in biological applications is increasing and the study of their interaction with biological media is becoming more important. Proteins are commonly the first biomolecules that NPs encounter when they interact with biological systems either in vitro or in vivo. Among NPs, super-paramagnetic iron oxide nanoparticles (SPIONs) show great promise for medicine. In this work, we study in detail the formation, composition, and structure of a monolayer of bovine serum albumin (BSA) on SPIONs. We determine, both by molecular simulations and experimentally, that ten molecules of BSA form a monolayer around the

  20. Integration of binding peptide selection and multifunctional particles as tool-box for capture of soluble proteins in serum

    PubMed Central

    Cusano, Angela Maria; Causa, Filippo; Moglie, Raffaella Della; Falco, Nunzia; Scognamiglio, Pasqualina Liana; Aliberti, Anna; Vecchione, Raffaele; Battista, Edmondo; Marasco, Daniela; Savarese, Marika; Raucci, Umberto; Rega, Nadia; Netti, Paolo Antonio

    2014-01-01

    In this paper, we report on a general approach for the detection of a specific tumoural biomarker directly in serum. Such detection is made possible using a protein-binding peptide selected through an improved phage display technique and then conjugated to engineered microparticles (MPs). Protein biomarkers represent an unlimited source of information for non-invasive diagnostic and prognostic tests; MP-based assays are becoming largely used in manipulation of soluble biomarkers, but their direct use in serum is hampered by the complex biomolecular environment. Our technique overcomes the current limitations as it produces a selective MP—engineered with an antifouling layer—that ‘captures’ the relevant protein staying impervious to the background. Our system succeeds in fishing-out the human tumour necrosis factor alpha directly in serum with a high selectivity degree. Our method could have great impact in soluble protein manipulation and detection for a wide variety of diagnostic applications. PMID:25100324

  1. Integration of binding peptide selection and multifunctional particles as tool-box for capture of soluble proteins in serum.

    PubMed

    Cusano, Angela Maria; Causa, Filippo; Moglie, Raffaella Della; Falco, Nunzia; Scognamiglio, Pasqualina Liana; Aliberti, Anna; Vecchione, Raffaele; Battista, Edmondo; Marasco, Daniela; Savarese, Marika; Raucci, Umberto; Rega, Nadia; Netti, Paolo Antonio

    2014-10-06

    In this paper, we report on a general approach for the detection of a specific tumoural biomarker directly in serum. Such detection is made possible using a protein-binding peptide selected through an improved phage display technique and then conjugated to engineered microparticles (MPs). Protein biomarkers represent an unlimited source of information for non-invasive diagnostic and prognostic tests; MP-based assays are becoming largely used in manipulation of soluble biomarkers, but their direct use in serum is hampered by the complex biomolecular environment. Our technique overcomes the current limitations as it produces a selective MP--engineered with an antifouling layer--that 'captures' the relevant protein staying impervious to the background. Our system succeeds in fishing-out the human tumour necrosis factor alpha directly in serum with a high selectivity degree. Our method could have great impact in soluble protein manipulation and detection for a wide variety of diagnostic applications.

  2. New approach to measure protein binding based on a parallel artificial membrane assay and human serum albumin.

    PubMed

    Lázaro, Elisabet; Lowe, Philip J; Briand, Xavier; Faller, Bernard

    2008-04-10

    We report here a new, label-free approach to measure serum protein binding constants. The assay is able to measure HSA K d values in the milli-molar to micromolar range. The protein is not immobilized on any surface and the assay self-corrects for nonspecific adsorption. No mass balance is required to get accurate binding constants and it is not necessary to wait for equilibrium to extract the binding constant. The assay runs in a 96-well format using commercially available parts and is, therefore, relatively easy to implement and automate. As the chemical membranes used are not water permeable, there is no volume change due to the osmotic pressure and pretreatment (soaking) is not necessary. The concept can potentially be extended to other proteins and could thus serve as a label-free technique for general binding constant measurements.

  3. A novel V(IV)O-pyrimidinone complex: synthesis, solution speciation and human serum protein binding.

    PubMed

    Gonçalves, Gisela; Tomaz, Isabel; Correia, Isabel; Veiros, Luís F; Castro, M Margarida C A; Avecilla, Fernando; Palacio, Lorena; Maestro, Miguel; Kiss, Tamás; Jakusch, Tamás; Garcia, M Helena V; Pessoa, João Costa

    2013-09-07

    The pyrimidinones mhcpe, 2-methyl-3H-5-hydroxy-6-carboxy-4-pyrimidinone ethyl ester (mhcpe, 1), 2,3-dimethyl-5-benzyloxy-6-carboxy-4-pyrimidinone ethyl ester (dbcpe, 2) and N-methyl-2,3-dimethyl-5-hydroxy-6-carboxyamido-4-pyrimidinone (N-MeHOPY, 3), are synthesized and their structures determined by single crystal X-ray diffraction. The acid-base properties of 1 are studied by potentiometric and spectrophotometric methods, the pK(a) values being 1.14 and 6.35. DFT calculations were carried out to determine the most stable structure for each of the H2L(+), HL and L(-) forms (HL = mhcpe) and assign the groups involved in the protonation-deprotonation processes. The mhcpe(-) ligand forms stable complexes with V(IV)O(2+) in the pH range 2 to 10, and potentiometry, EPR and UV-Vis techniques are used to identify and characterize the V(IV)O-mhcpe species formed. The results are consistent with the formation of V(IV)O, (V(IV)O)L, (V(IV)O)L2, (V(IV)O)2L2H(-2), (V(IV)O)L2H(-1), (V(IV)O)2L2H(-3), (V(IV)O)LH(-2) species and V(IV)O-hydrolysis products. Calculations indicate that the global binding ability of mhcpe towards V(IV)O(2+) is similar to that of maltol (Hmaltol = 3-hydroxy-2-methyl-4H-pyran-4-one) and lower than that of 1,2-dimethyl-3-hydroxy-4-pyridinone (Hdhp). The interaction of V(IV)O-complexes with human plasma proteins (transferrin and albumin) is studied by circular dichroism (CD), EPR and (51)V NMR spectroscopy. V(IV)O-mhcpe-protein ternary complexes are formed in both cases. The binding of V(IV)O(2+) to transferrin (hTF) in the presence of mhcpe involves mainly (V(IV)O)1(hTF)(mhcpe)1, (V(IV)O)2(hTF)(mhcpe)1 and (V(IV)O)2(hTF)(mhcpe)2 species, bound at the Fe(III) binding sites, and the corresponding conditional formation constants are determined. Under the conditions expected to prevail in human blood serum, CD data indicate that the V(IV)O-mhcpe complexes mainly bind to hTF; the formation of V(IV)O-hTF-mhcpe complexes occurs in the presence of Fe(III) as well

  4. Serum concentrations of retinol-binding protein 4 in women with and without gestational diabetes

    PubMed Central

    Zemany, L.; Krugluger, W.; Schernthaner, G. H.; Mittermayer, F.; Schnack, C.; Rahman, R.; Brix, J.; Kahn, B. B.; Schernthaner, G.

    2009-01-01

    Aims/hypothesis Pregnancy is characterised by temporarily increased insulin resistance. Gestational diabetes occurs when pancreatic beta cell function is unable to compensate for this insulin resistance. Retinol-binding protein 4 (RBP4) could be related to insulin resistance. We hypothesised that RBP4 is elevated in gestational diabetes. Methods Serum RBP4, transthyretin and retinol were cross-sectionally measured in 42 women with gestational diabetes and 45 pregnant controls. Of these, 20 women with and 22 without gestational diabetes were included in an additional longitudinal study. RBP4 was determined by enzyme immunometric assay (EIA) and western blot. Results Women with gestational diabetes had lower RBP4 EIA and western blot levels than controls (median 6.8 [interquartile range, 3.9–14.3] vs 11.3 [7.8–19.9] μg/ml, p<0.001 and 25.1 [21.7–29.6] vs 26.6 [23.5–32.2] μg/ml, p=0.026). Transthyretin and the RBP4:transthyretin molar ratio were comparable between the groups. Serum retinol was lower (p<0.001) and the RBP4 Western blot level: retinol molar ratio was higher in women with gestational diabetes (p=0.044). RBP4 was not associated with the glucose or homeostasis model assessment of insulin resistance (HOMA-IR), but in gestational diabetes the RBP4:retinol molar ratio correlated with blood glucose and negatively with 2 h post-load insulin. The RBP4:transthyretin ratio correlated with HOMA-IR and fasting insulin in controls. In women with gestational diabetes RBP4 EIA and western blot levels increased after delivery. Retinol increased in both groups, while transthyretin and the RBP4:transthyretin ratio were not altered after parturition. Conclusions/interpretation RBP4 measured by two different techniques is not elevated, but the RBP4:retinol molar ratio is higher and correlates with fasting blood glucose in women with gestational diabetes. Thus, the RBP4:retinol ratio and the RBP4:transthyretin ratio are more informative than RBP4 levels alone when

  5. Computational modeling of serum-binding proteins and clearance in extrapolations across life stages and species for endocrine active compounds.

    PubMed

    Teeguarden, Justin G; Barton, Hugh A

    2004-06-01

    One measure of the potency of compounds that lead to the effects through ligand-dependent gene transcription is the relative affinity for the critical receptor. Endocrine active compounds that are presumed to act principally through binding to the estrogen receptor (e.g., estradiol, genistein, bisphenol A, and octylphenol) comprise one class of such compounds. For making simple comparisons, receptor-binding affinity has been equated to in vivo potency, which consequently defines the dose-response characteristics for the compound. Direct extrapolation of in vitro estimated affinities to the corresponding in vivo system and to specific species or life stages (e.g., neonatal, pregnancy) can be misleading. Accurate comparison of the potency of endocrine active compounds requires characterization of biochemical and pharmacokinetic factors that affect their free concentration. Quantitative in vitro and in vivo models were developed for integrating pharmacokinetics factors (e.g., serum protein and receptor-binding affinities, clearance) that affect potency. Data for parameterizing these models for several estrogenic compounds were evaluated and the models exercised. While simulations of adult human or rat sera were generally successful, difficulties in describing early life stages were identified. Exogenous compounds were predicted to be largely ineffective at competing estradiol off serum-binding proteins, suggesting this was unlikely to be physiologically significant. Discrepancies were identified between relative potencies based upon modeling in vitro receptor-binding activity versus in vivo activity in the presence of clearance and serum-binding proteins. The examples illustrate the utility of this approach for integrating available experimental data from in vitro and in vivo studies to estimate the relative potency of these compounds.

  6. Serum Vitamin D, Vitamin D Binding Protein, and Risk of Colorectal Cancer

    PubMed Central

    Anic, Gabriella M.; Weinstein, Stephanie J.; Mondul, Alison M.; Männistö, Satu; Albanes, Demetrius

    2014-01-01

    Background We previously reported a positive association between serum 25-hydroxyvitamin D (25(OH)D) and colorectal cancer risk. To further elucidate this association, we examined the molar ratio of 25(OH)D to vitamin D binding protein (DBP), the primary 25(OH)D transport protein, and whether DBP modified the association between 25(OH)D and colorectal cancer risk. Methods In a nested case-control study within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study, controls were 1∶1 matched to 416 colorectal cancer cases based on age and date of blood collection. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CI) for quartiles of 25(OH)D, DBP, and the molar ratio of 25(OH)D:DBP, a proxy for free, unbound circulating 25(OH)D. Results Comparing highest to lowest quartiles, DBP was not associated with colorectal cancer risk (OR = 0.91; 95% CI: 0.58, 1.42, p for trend  = 0.58); however, a positive risk association was observed for the molar ratio of 25(OH)D:DBP (OR = 1.44; 95% CI: 0.92, 2.26, p for trend  = 0.04). In stratified analyses, the positive association between 25(OH)D and colorectal cancer was stronger among men with DBP levels above the median (OR = 1.89; 95% CI: 1.07, 3.36, p for trend  = 0.01) than below the median (OR = 1.20; 95% CI: 0.68, 2.12, p for trend  = 0.87), although the interaction was not statistically significant (p for interaction  = 0.24). Conclusion Circulating DBP may influence the association between 25(OH)D and colorectal cancer in male smokers, with the suggestion of a stronger positive association in men with higher DBP concentrations. This finding should be examined in other populations, especially those that include women and non-smokers. PMID:25036524

  7. Separation of Fc-binding serum proteins by preparative flat-bed isotachophoresis.

    PubMed

    Nicolaisen, E M; Brogren, C H

    1982-10-29

    Preparative flat-bed isotachophoresis with discrete spacers was applied as a single-step procedure to separate 2 Fc-dependent activities of normal chicken serum, i.e., (1) the ability to raise the titre of haemagglutinating allo-antisera which is due to a high molecular weight beta-globulin (HEF), (2) the ability to activate guinea pig complement components in mixed complement reaction. The results demonstrate that the 2 activities can be clearly separated, and HEF must therefore be different from the first complement factor in the chicken. Under the chosen conditions the molecule active in the mixed complement reaction is not stacked in contrast to other serum protein including HEF. The same technique with human serum shows that human Clq behaves in the same was as the chicken complement factor. This means that by selective unstacking, flat-bed isotachophoresis can be used as an efficient single-step purification method for human and chicken Clq.

  8. Concentration of free growth hormone-binding protein in the serum of mice is not regulated by growth hormone.

    PubMed

    Sotelo, A I; Dominici, F P; Bartke, A; Turyn, D

    1997-05-01

    Ames dwarf mice that do not express growth hormone (GH) or prolactin (PRL) genes were used to study the effects of GH deficiency on the presence and the characteristics of GH-binding protein (GHBP) in serum. Chromatographic techniques were used to allow characterization of biological rather than immunological activity of GHBP. Two GH-binding fractions were found in dwarf mice serum, one with low affinity and high capacity (GHBPI) and one with high affinity, low capacity and lower molecular mass (GHBPII). Serum concentration of the high-affinity GHBP was 0.73 +/- 0.03 nM with a Kd of 6.3 +/- 1.7 nM. Since Ames dwarf mice have no GH in the circulation, all the GHBP is free. Interestingly, the concentration of GHBP in dwarf mice was similar to the levels of free GHBP measured in normal mice from the same line. Moreover, this value (0.7 nM) closely resembles the concentration of free GHBP in the serum of transgenic mice overexpressing GH, in which peripheral GH levels are grossly elevated. These observations can be interpreted as evidence that the levels of free GHBP in mouse serum are independent of GH concentration, and that GH influences only the levels of bound GHBP in peripheral circulation.

  9. Interaction study on bovine serum albumin physically binding to silver nanoparticles: Evolution from discrete conjugates to protein coronas

    NASA Astrophysics Data System (ADS)

    Guo, Jun; Zhong, Ruibo; Li, Wanrong; Liu, Yushuang; Bai, Zhijun; Yin, Jun; Liu, Jingran; Gong, Pei; Zhao, Xinmin; Zhang, Feng

    2015-12-01

    The nanostructures formed by inorganic nanoparticles together with organic molecules especially biomolecules have attracted increasing attention from both industries and researching fields due to their unique hybrid properties. In this paper, we systemically studied the interactions between amphiphilic polymer coated silver nanoparticles and bovine serum albumins by employing the fluorescence quenching approach in combination with the Stern-Volmer and Hill equations. The binding affinity was determined to 1.30 × 107 M-1 and the interaction was spontaneously driven by mainly the van der Waals force and hydrogen-bond mediated interactions, and negatively cooperative from the point of view of thermodynamics. With the non-uniform coating of amphiphilic polymer, the silver nanoparticles can form protein coronas which can become discrete protein-nanoparticle conjugates when controlling their molar ratios of mixing. The protein's conformational changes upon binding nanoparticles was also studied by using the three-dimensional fluorescence spectroscopy.

  10. Low Serum Levels of Prealbumin, Retinol Binding Protein, and Retinol Are Frequent in Adult Type 1 Diabetic Patients

    PubMed Central

    Bolado, Federico; Goñi, María José; Tamayo, Ibai; Ibáñez, Berta; Prieto, Carlos

    2016-01-01

    Aim. To determine the serum prealbumin (PA), retinol binding protein (RBP), and retinol levels in adult patients with type 1 diabetes (T1D) and to analyze some factors related to those levels. Methods. A total of 93 patients (47 women) were studied. Age, gender, BMI, duration of diabetes, chronic complications, HbA1c, lipid profile, creatinine, albumin, PA, RBP, and retinol were recorded. High and low parameter groups were compared by Mann–Whitney U and χ2 tests. Correlation between parameters was analyzed by Spearman's test. Odds of low levels were analyzed by univariate logistic regression and included in the multivariate analysis when significant. Results. 49.5%, 48.4%, and 30.1% of patients displayed serum PA, RBP, and retinol levels below normal values, respectively. A high correlation (Rho > 0.8) between PA, RBP, and retinol serum levels was found. Patients presenting low levels of any of them were predominantly women, normal-weighted, and with lower levels of triglycerides and serum creatinine. No differences in age, macrovascular complications, duration of diabetes, or HbA1c values were observed when comparing low and normal parameter groups. Conclusion. Low serum levels of PA, RBP, and retinol are frequent in T1D adult patients. This alteration is influenced by female sex and serum creatinine and triglyceride levels. PMID:28018921

  11. [Serum protein binding of fentanyl. The effect of postoperative acute phase reaction with elevated alpha 1-acid glycoprotein and methodologic problems in determination by equilibrium dialysis].

    PubMed

    Wiesner, G; Taeger, K; Peter, K

    1996-04-01

    Numerous basic drugs are extensively bound to alpha 1-acid glycoprotein. Fentanyl, with a pKa value of 8.43, is also a basic drug. Protein binding studies have yielded contradictory results concerning binding of fentanyl to alpha 1-acid glycoprotein. In this study we investigated time courses of serum protein concentrations and serum protein binding of fentanyl during postoperative acute phase reaction, assuming that an increase of alpha 1-acid glycoprotein is accompanied by an increase of serum protein binding, if fentanyl is extensively bound to alpha 1-acid glycoprotein. Fentanyl protein binding measurements using equilibrium dialysis can be affected by volume shifts and pH changes. Therefore, volume shifts from buffer to serum and the influence of various phosphate buffers on increasing pH due to loss of CO2 were also evaluated. METHODS. Thirteen patients with no history of renal or hepatic disease undergoing an operation with a significant acute phase reaction were studied. Preoperatively and on the first 3 postoperative days serum concentrations of alpha 1-acid glycoprotein, albumin, total protein and apolipoprotein A and B were determined by rocket immunoeolectrophoresis, biuret method and laser nephelometry, respectively. Corresponding serum protein binding of fentanyl was measured by adding 40 ng of fentanyl to 1 ml serum followed by equilibrium dialysis at 37 degrees C for 4 h. A 0.167 M phosphate buffer (pH 7.27), which gave a final pH of 7.40, was used. Volume shifts from buffer to serum were measured. Fentanyl concentration in serum before dialysis (FS) was determined by gas chromatography, and fentanyl concentration in buffer after dialysis (FB) was determined by radioimmunoassay. Serum protein binding (SPB) was calculated by the formula: SPB = (FS - FB - FB*c)/(FS - FB) where c is a correction factor. Ten randomly selected patient sera were dialyzed against four phosphate buffers of different pH values and molarities, and the serum pH at the end of

  12. Elevated Serum Levels of Retinol-Binding Protein 4 Are Associated with Breast Cancer Risk: A Case-Control Study

    PubMed Central

    Ma, Aiguo; Li, Na; Si, Hongzong

    2016-01-01

    Background Retinol binding protein 4 (RBP4) is a recently identified adipokine that is elevated in patients with obesity or type 2 diabetes. A growing body of research has shown that RBP4 is associated with several types of cancer. However, no studies have investigated the relationship between serum RBP4 levels and breast cancer risk. We performed a case-control study to evaluate the association between serum RBP4 levels and the risk of breast cancer. Methods From August 2012 to December 2013, four-hundred subjects including 200 patients diagnosed with primary breast cancer and 200 matched healthy women were consecutively enrolled from Affiliated Hospital of Qingdao University Medical College. Blood samples were collected from healthy controls and breast cancer patients before commencement of treatment. Enzyme-linked immunosorbent assay was used to evaluate the serum RBP4 levels in separated serum samples. Meanwhile, the characteristics of breast cancer cases and controls were collected from medical records and pathological data. Results The serum levels of RBP4 were significantly higher in patients with breast cancer than that in the healthy control group (33.77±9.92 vs. 28.77±6.47μg/ml, P < 0.05). Compared to the subjects in the lowest quartile of serum RBP4 level, the adjusted ORs (95% CIs) is 2.16(1.01–4.61) and 2.07 (1.07–4.00) for women in the second and highest RBP4 tertile, respectively. For breast cancer patients, patients with PR or ER negative displayed significantly higher serum RBP4 levels than those with PR or ER positive. Conclusion Our results for the first time suggested serum RBP4 levels could be associated with the risk of breast cancer. However, further prospective studies are essential to confirm these observed results. PMID:28002423

  13. Photoactivable analogs for labeling 25-hydroxyvitamin D3 serum binding protein and for 1,25-dihydroxyvitamin D3 intestinal receptor protein

    NASA Technical Reports Server (NTRS)

    Kutner, A.; Link, R. P.; Schnoes, H. K.; DeLuca, H. F.

    1986-01-01

    3-Azidobenzoates and 3-azidonitrobenzoates of 25-hydroxyvitamin D3 as well as 3-deoxy-3-azido-25-hydroxyvitamin D3 and 3-deoxy-3-azido-1,25-dihydroxyvitamin D3 were prepared as photoaffinity labels for vitamin D serum binding protein and 1,25-dihydroxyvitamin D3 intestinal receptor protein. The compounds prepared were easily activated by short- or long-wavelength uv light, as monitored by uv and ir spectrometry. The efficacy of the compounds to compete with 25-hydroxyvitamin D3 or 1,25-dihydroxyvitamin D3 for the binding site of serum binding protein and receptor, respectively, was studied to evaluate the vitamin D label with the highest affinity for the protein. The presence of an azidobenzoate or azidonitrobenzoate substituent at the C-3 position of 25-OH-D3 significantly decreased (10(4)- to 10(6)-fold) the binding activity. However, the labels containing the azido substituent attached directly to the vitamin D skeleton at the C-3 position showed a high affinity, only 20- to 150-fold lower than that of the parent compounds with their respective proteins. Therefore, 3-deoxy-3-azidovitamins present potential ligands for photolabeling of vitamin D proteins and for studying the structures of the protein active sites.

  14. Human serum albumin binding to silica nanoparticles--effect of protein fatty acid ligand.

    PubMed

    Ang, Joo Chuan; Henderson, Mark J; Campbell, Richard A; Lin, Jhih-Min; Yaron, Peter N; Nelson, Andrew; Faunce, Thomas; White, John W

    2014-06-07

    Neutron reflectivity shows that fatted (F-HSA) and defatted (DF-HSA) versions of human serum albumin behave differently in their interaction with silica nanoparticles premixed in buffer solutions although these proteins have close to the same surface excess when the silica is absent. In both cases a silica containing film is quickly established at the air-water interface. This film is stable for F-HSA at all relative protein-silica concentrations measured. This behaviour has been verified for two small silica nanoparticle radii (42 Å and 48 Å). Contrast variation and co-refinement have been used to find the film composition for the F-HSA-silica system. The film structure changes with protein concentration only for the DF-HSA-silica system. The different behaviour of the two proteins is interpreted as a combination of three factors: increased structural stability of F-HSA induced by the fatty acid ligand, differences in the electrostatic interactions, and the higher propensity of defatted albumin to self-aggregate. The interfacial structures of the proteins alone in buffer are also reported and discussed.

  15. Localization of the domains of the Haemophilus ducreyi trimeric autotransporter DsrA involved in serum resistance and binding to the extracellular matrix proteins fibronectin and vitronectin.

    PubMed

    Leduc, Isabelle; Olsen, Bonnie; Elkins, Christopher

    2009-02-01

    Resisting the bactericidal activity of naturally occurring antibodies and complement of normal human serum is an important element in the evasion of innate immunity by bacteria. In the gram-negative mucosal pathogen Haemophilus ducreyi, serum resistance is mediated primarily by the trimeric autotransporter DsrA. DsrA also functions as an adhesin for the extracellular matrix proteins fibronectin and vitronectin and mediates attachment of H. ducreyi to keratinocytes. We sought to determine the domain(s) of the 236-residue DsrA protein required for serum resistance and extracellular matrix protein binding. A 140-amino-acid truncated protein containing only the C-terminal portion of the passenger domain and the entire translocator domain of DsrA exhibited binding to fibronectin and vitronectin and conferred serum resistance to an H. ducreyi serum-sensitive strain. A shorter DsrA construct consisting of only 128 amino acids was unable to bind to extracellular matrix proteins but was serum resistant. We concluded that neither fibronectin binding nor vitronectin binding is required for high-level serum resistance in H. ducreyi.

  16. Localization of the Domains of the Haemophilus ducreyi Trimeric Autotransporter DsrA Involved in Serum Resistance and Binding to the Extracellular Matrix Proteins Fibronectin and Vitronectin▿

    PubMed Central

    Leduc, Isabelle; Olsen, Bonnie; Elkins, Christopher

    2009-01-01

    Resisting the bactericidal activity of naturally occurring antibodies and complement of normal human serum is an important element in the evasion of innate immunity by bacteria. In the gram-negative mucosal pathogen Haemophilus ducreyi, serum resistance is mediated primarily by the trimeric autotransporter DsrA. DsrA also functions as an adhesin for the extracellular matrix proteins fibronectin and vitronectin and mediates attachment of H. ducreyi to keratinocytes. We sought to determine the domain(s) of the 236-residue DsrA protein required for serum resistance and extracellular matrix protein binding. A 140-amino-acid truncated protein containing only the C-terminal portion of the passenger domain and the entire translocator domain of DsrA exhibited binding to fibronectin and vitronectin and conferred serum resistance to an H. ducreyi serum-sensitive strain. A shorter DsrA construct consisting of only 128 amino acids was unable to bind to extracellular matrix proteins but was serum resistant. We concluded that neither fibronectin binding nor vitronectin binding is required for high-level serum resistance in H. ducreyi. PMID:19015257

  17. Serum retinol-binding protein-induced endothelial inflammation is mediated through the activation of toll-like receptor 4

    PubMed Central

    Du, Mei; Martin, Ashley; Hays, Franklin; Johnson, Jennifer; Farjo, Rafal A.

    2017-01-01

    Purpose Elevation of serum retinol-binding protein 4 (RBP4) induces inflammation in primary human retinal microvascular endothelial cells (HRECs) via a retinol-independent mechanism; thus, it may play a causative role in the development and progression of vascular lesions in diabetic retinopathy (DR). Since HRECs do not express the classical RBP4 receptor, stimulated by retinoic acid gene 6 (STRA6), this study focuses on identifying the endothelial cell receptor and signaling that mediate RBP4-induced inflammation. Methods HRECs were treated with a toll-like receptor 4 (TLR4) small molecule inhibitor (Cli95, also known as TAK-242), TLR4 neutralizing antibody, or mitogen-activated protein kinase (MAPK) inhibitors before treatment with purified recombinant RBP4. The HREC inflammatory response was quantified by in vitro leukostasis assays, western blotting, and enzyme-linked immunosorbent assay (ELISA). To understand how the serum binding partner for RBP4, transthyretin (TTR), may affect RBP4 activity, we also measured RBP4 and TTR levels in serum and retinal lysates from RBP4-Tg and wild-type mice. Results TLR4 inhibition significantly reduced RBP4-induced expression of pro-inflammatory proteins and in vitro leukostasis. RBP4 treatment significantly increased phosphoactivation of p38 and c-Jun N-terminal protein kinase (JNK). The p38 inhibitor (SB203580) attenuated RBP4-stimulated vascular cell adhesion molecule 1 (VCAM-1), intracellular adhesion molecule 1 (ICAM-1), monocyte chemoattractant protein (MCP-1), and interleukin 6 (IL-6) production, while the JNK inhibitor (SP600125) reduced RBP4-stimulated sICAM-1, endothelial cell selectin (E-selectin), and MCP-1 production. The MAPK inhibitors only showed partial (50–70%) suppression of the RBP4-stimulated proinflammatory response. Moreover, TLR4 inhibition did not decrease RBP4-induced MAPK phosphoactivation, suggesting that RBP4-mediated MAPK activation is TLR4 independent and occurs through a secondary unknown

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

    PubMed

    Ali, Manjoor; Kumar, Amit; Kumar, Mukesh; Pandey, Badri N

    2016-04-01

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

  19. Electrokinetic chromatographic estimation of the enantioselective binding of nomifensine to human serum albumin and total plasma proteins.

    PubMed

    Asensi-Bernardi, Lucía; Martín-Biosca, Yolanda; Sagrado, Salvador; Medina-Hernández, María J

    2012-11-01

    This report is the first evidence of enantioselective binding of nomifensine to human serum albumin (HSA) and plasma proteins. The overall process with HSA included: (i) consistent experimental design along two independent sessions; (ii) incubation of nomifensine-HSA designed mixtures; (iii) ultrafiltration for separating the unbound enantiomers fraction; (iv) electrokinetic chromatography (EKC) using heptakis-2,3,6-tri-O-methyl-β-cyclodextrin as chiral selector to provide experimental data for enantiomers (first, E1, and second, E2, eluted ones); and (v) a recent direct equation allowing univariate tests and robust statistics to provide consistent parameters and uncertainty. A significant enantioselectivity to HSA (2.7 ± 0.1) was encountered, related to a 1:1 stoichiometry and log affinity constants of 3.24 ± 0.10 and 3.67 ± 0.08 for E1 and E2, respectively. The protein binding (PB) estimated at physiological concentration levels was 40 ± 5 and 63 ± 4% for E1 and E2, respectively. The use of synthetic human sera allowed in vitro estimation of the total plasma PB for the racemate (61 ± 5%; coincident with in vivo values), and its enantiomers (58 ± 7 and 64 ± 4% for E1 and E2, respectively). Comparison allowed the relative importance of HSA respect to other plasma proteins for binding nomifensine to be established.

  20. Analysis of S100 calcium binding protein B serum levels in different types of traumatic intracranial lesions.

    PubMed

    Wolf, Harald; Frantal, Sophie; Pajenda, Gholam; Leitgeb, Johannes; Sarahrudi, Kambiz; Hajdu, Stefan

    2015-01-01

    The objective of this study was to determine whether the type of intracranial traumatic lesions, the number of simultaneous traumatic lesions, and the occurrence of skull and facial bone fractures have an influence on S100 calcium binding protein B (S100B) serum levels. Patients with blunt traumatic brain injury were prospectively enrolled into this cohort study over a period of 13 months. Venous blood samples were obtained prior to emergency cranial CT scan in all patients within 3 h after injury. The patients were then assigned into six groups: 1) concussion, 2) epidural hematoma, 3) subdural hematoma, 4) subarachnoid hemorrhage, 5) brain contusions, and 6) brain edema. The study included 1696 head trauma patients with a mean age of 57.7 ± 25.3 years, and 126 patients (8%) had 182 traumatic lesions on CT. Significant differences in S100B serum levels were found between cerebral edema and the other four bleeding groups: epidural p = 0.0002, subdural p < 0.0001, subarachnoid p = 0.0001, brain contusions p = 0.0003, and concussion p < 0.0001. Significant differences in S100B values between patients with one or two intracranial lesions (p = 0.014) or with three (p < 0.0001) simultaneous intracranial lesions were found. In patients with intracranial traumatic lesions, skull fractures, as well as skull and facial bone fractures occurring together, were identified as significant additional factors for the increase in serum S100B levels (p < 0.0001). Older age was also associated with elevated S100B serum levels (p < 0.0001). Our data show that peak S100B serum levels were found in patients with cerebral edema and brain contusions.

  1. Serum Lipopolysaccharide Binding Protein Levels Predict Severity of Lung Injury and Mortality in Patients with Severe Sepsis

    PubMed Central

    Villar, Jesús; Pérez-Méndez, Lina; Espinosa, Elena; Flores, Carlos; Blanco, Jesús; Muriel, Arturo; Basaldúa, Santiago; Muros, Mercedes; Blanch, Lluis; Artigas, Antonio; Kacmarek, Robert M.

    2009-01-01

    Background There is a need for biomarkers insuring identification of septic patients at high-risk for death. We performed a prospective, multicenter, observational study to investigate the time-course of lipopolysaccharide binding protein (LBP) serum levels in patients with severe sepsis and examined whether serial serum levels of LBP could be used as a marker of outcome. Methodology/Principal Findings LBP serum levels at study entry, at 48 hours and at day-7 were measured in 180 patients with severe sepsis. Data regarding the nature of infections, disease severity, development of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), and intensive care unit (ICU) outcome were recorded. LBP serum levels were similar in survivors and non-survivors at study entry (117.4±75.7 µg/mL vs. 129.8±71.3 µg/mL, P = 0.249) but there were significant differences at 48 hours (77.2±57.0 vs. 121.2±73.4 µg/mL, P<0.0001) and at day-7 (64.7±45.8 vs. 89.7±61.1 µg/ml, p = 0.017). At 48 hours, LBP levels were significantly higher in ARDS patients than in ALI patients (112.5±71.8 µg/ml vs. 76.6±55.9 µg/ml, P = 0.0001). An increase of LBP levels at 48 hours was associated with higher mortality (odds ratio 3.97; 95%CI: 1.84–8.56; P<0.001). Conclusions/Significance Serial LBP serum measurements may offer a clinically useful biomarker for identification of patients with severe sepsis having the worst outcomes and the highest probability of developing sepsis-induced ARDS. PMID:19718443

  2. [Changes in serum levels of IGF-I and its binding proteins and their relation to microcirculation in obese patients].

    PubMed

    Krsek, M; Prázný, M; Sucharda, P; Marek, J; Justová, V; Lacinová, Z

    2001-12-01

    The IGF-I system and its binding proteins participate in the pathogenesis of vascular affections under various pathological conditions. The mechanism and mode of its action were however not elucidated in details so far and views on its role are controversial. The objective of the study was to assess the relationship of this system and the blood flow in the microcirculation in obese patients. The authors examined 21 obese patients (BMI 39.7 +/- 7.3 kg/m2) and a group of healthy volunteers. They examined: serum concentrations of total IGF-I, free IGF-I, IGFBP-1,-2,-3, and -6, total cholesterol, HDL-cholesterol, LDL-cholesterol and triglycerides as well as the intimomedial thickness of the common carotid arteries and parameters of blood flow in the microcirculation, evaluated by a laser-Doppler examination. In obese patients there were significantly lower serum concentrations of IGF-I and free-IGF I (p < 0.05) as compared with the control group. Comparison of the function of the microcirculation revealed in obese patients, as compared with the control group, a lower percentage increase of perfusion after occlusion (PORH%, p < 0.05) and after heating (TH%, p < 0.05) and a slower onset of thermal hyperaemia (THmax/t, p < 0.05). In the control group serum concentrations of free-IGF-I correlated inversely with the maximum perfusion after heat induced hyperaemia (THmax (r = -0.54, p < 0.02) and the rate of onset of hyperaemia after heating (THmax/t) (r = 0.51, p < 0.02). In the group of obese patients serum concentrations of free-IGF-I correlated inversely with the maximum perfusion after heat induced hyperaemia (THmax) (r = -0.55, p < 0.02), and IGFBP-3 concentrations correlated inversely with maximum hyperaemia after occlusion (PORGmax) (r = -0.57, p < 0.01). The results suggest that the function of the microcirculation in obese subjects is affected. The activity of the IGF-I system and its binding proteins is related to the affected function of the microcirculation and

  3. High Serum Adipocyte Fatty Acid Binding Protein Is Associated with Metabolic Syndrome in Patients with Type 2 Diabetes

    PubMed Central

    Li, Jer-Chuan; Wu, Du-An; Hou, Jia-Sian; Subeq, Yi-Maun; Chen, Hsin-Dean

    2016-01-01

    Adipocyte fatty acid binding protein (A-FABP) is a key mediator of obesity-related metabolic syndrome (MetS). The aim of this study was to evaluate the relationship between A-FABP concentration and MetS in type 2 diabetes mellitus (DM) patients. Fasting blood samples were obtained from 165 type 2 DM volunteers. MetS and its components were defined using diagnostic criteria from the International Diabetes Federation. Among 165 DM patients, 113 patients (68.5%) had MetS. Diabetic persons who had MetS had significantly higher A-FABP levels (P < 0.001) than those without MetS. Female DM persons had higher A-FABP level than man (P < 0.001). No statistically significant differences in A-FABP levels were found in use of statin, fibrate, or antidiabetic drugs. Multivariate forward stepwise linear regression analysis revealed that body fat mass (P < 0.001), logarithmically transformed creatinine (log-creatinine; P < 0.001), female DM patients (P < 0.001), and logarithmically transformed high sensitive C-reactive protein (log-hs-CRP; P = 0.013) were positively correlated, while albumin (P = 0.004) and glomerular filtration rate (GFR; P = 0.043) were negatively correlated with serum A-FABP levels in type 2 DM patients. In this study, higher serum A-FABP level was positively associated with MetS in type 2 DM patients. PMID:28042581

  4. Photoaffinity labeling of serum vitamin D binding protein by 3-deoxy-3-azido-25-hydroxyvitamin D3

    SciTech Connect

    Link, R.P.; Kutner, A.; Schnoes, H.K.; DeLuca, H.F.

    1987-06-30

    3-Deoxy-3-azido-25-hydroxyvitamin D3 was covalently incorporated in the 25-hydroxyvitamin D3 binding site of purified human plasma vitamin D binding protein. Competition experiments showed that 3-deoxy-3-azido-25-hydroxyvitamin D3 and 25-hydroxyvitamin D3 bind at the same site on the protein. Tritiated 3-deoxy-3-azido-25-hydroxyvitamin D3 was synthesized from tritiated 25-hydroxyvitamin D3, retaining the high specific activity of the parent compound. The tritiated azido label bound reversibly to human vitamin D binding protein in the dark and covalently to human vitamin D binding protein after exposure to ultraviolet light. Reversible binding of tritiated 3-deoxy-3-azido-25-hydroxyvitamin D3 was compared to tritiated 25-hydroxyvitamin D3 binding to human vitamin D binding protein. Scatchard analysis of the data indicated equivalent maximum density binding sites with a KD,app of 0.21 nM for 25-hydroxyvitamin D3 and a KD,app of 1.3 nM for the azido derivative. Covalent binding was observed only after exposure to ultraviolet irradiation, with an average of 3% of the reversibly bound label becoming covalently bound to vitamin D binding protein. The covalent binding was reduced 70-80% when 25-hydroxyvitamin D3 was present, indicating strong covalent binding at the vitamin D binding site of the protein. When tritiated 3-deoxy-3-azido-25-hydroxyvitamin D3 was incubated with human plasma in the absence and presence of 25-hydroxyvitamin D3, 12% of the azido derivative was reversibly bound to vitamin D binding protein. After ultraviolet irradiation, four plasma proteins covalently bound the azido label, but vitamin D binding protein was the only protein of the four that was unlabeled in the presence of 25-hydroxyvitamin D3.

  5. Differential expression of serum glycodelin and insulin-like growth factor binding protein 1 in early pregnancy.

    PubMed

    Douglas, Nataki C; Thornton, Melvin H; Nurudeen, Sahadat K; Bucur, Maria; Lobo, Rogerio A; Sauer, Mark V

    2013-11-01

    This prospective study evaluated whether serum glycodelin and insulin-like growth factor binding protein 1 (IGFBP-1) predict the likelihood of embryo implantation in recipients undergoing donor egg in vitro fertilization. We measured glycodelin and IGFBP-1 at 6 points from lining check to lutenizing hormone (LH) + 31. β-Human chorionic gonadotropin levels were first measured at LH + 17. The recipients were divided into those without embryo implantation (group 1, n = 6) and those with successful implantation (group 2, n = 30). Although this is a negative study in that neither glycodelin nor IGFBP-1 alone reflected endometrial (EM) receptivity, the glycodelin/IGFBP-1 ratio on the day of blastocyst transfer was higher in recipients who achieved pregnancy (P = .05). At LH + 17, glycodelin was higher (P = .04), and IGFBP-1 was lower (P = .004) in recipients who achieved pregnancy when compared to those who did not. These observations are likely due to EM changes induced by successful embryo implantation.

  6. Serum adipocyte-fatty acid binding protein (FABP4) levels in women from Mexico exposed to polycyclic aromatic hydrocarbons (PAHs).

    PubMed

    Ochoa-Martínez, Ángeles C; Ruíz-Vera, Tania; Pruneda-Álvarez, Lucia G; González-Palomo, Ana K; Almendarez-Reyna, Claudia I; Pérez-Vázquez, Francisco J; Pérez-Maldonado, Iván N

    2017-01-01

    Recent studies indicate that exposure to polycyclic aromatic hydrocarbons (PAHs) is a very important risk factor for the development of cardiovascular diseases (CVDs). Correspondingly, adipocyte-fatty acid binding protein (FABP4, also known as aP2 and AFABP) has been proposed as a new, meaningful and useful biomarker to predict metabolic and cardiovascular diseases. Therefore, the aim of this study was to evaluate serum FABP4 levels in Mexican women exposed to PAHs. Urinary 1-hydroxypyrene ((1-OHP), exposure biomarker for PAHs) levels were quantified using a high-performance liquid chromatography (HPLC) technique, and serum FABP4 concentrations were analyzed using a commercially available ELISA kit. The mean urinary 1-OHP level found in women participating in this study was 1.30 ± 1.10 μmol/mol creatinine (2.45 ± 2.10 μg/g creatinine). Regarding serum FABP4 concentrations, the levels ranged from 3.80 to 62.5 ng/mL in the assessed population. Moreover, a significant association (p < 0.001) was found between urinary 1-OHP levels and serum FABP4 concentrations in women after adjusting for potential confounding variables. The presented data in this study can be considered only as a starting point for further studies. Then, in order to elucidate whether FABP4 represents a risk factor for CVD disease in humans exposed to air contaminants (such as PAHs), large epidemiological studies are necessary.

  7. High Serum Lipopolysaccharide-Binding Protein Level in Chronic Hepatitis C Viral Infection Is Reduced by Anti-Viral Treatments

    PubMed Central

    Nien, Hsiao-Ching; Hsu, Shih-Jer; Su, Tung-Hung; Yang, Po-Jen; Sheu, Jin-Chuan; Wang, Jin-Town; Chow, Lu-Ping; Chen, Chi-Ling

    2017-01-01

    Background Lipopolysaccharide-binding protein (LBP) has been reported to associate with metabolic diseases, such as obesity, diabetes, and non-alcoholic fatty liver disease. Since chronic hepatitis C virus (HCV) infection is associated with metabolic derangements, the relationship between LBP and HCV deserves additional studies. This study aimed to determine the serum LBP level in subjects with or without HCV infection and investigate the change of its level after anti-viral treatments with or without interferon. Methods and Findings We recruited 120 non-HCV subjects, 42 and 17 HCV-infected subjects respectively treated with peginterferon α-2a/ribavirin and direct-acting antiviral drugs. Basic information, clinical data, serum LBP level and abdominal ultrasonography were collected. All the subjects provided written informed consent before being enrolled approved by the Research Ethics Committee of the National Taiwan University Hospital. Serum LBP level was significantly higher in HCV-infected subjects than non-HCV subjects (31.0 ± 8.8 versus 20.0 ± 6.4 μg/mL; p-value < 0.001). After multivariate analyses, LBP at baseline was independently associated with body mass index, hemoglobin A1c, alanine aminotransferase (ALT) and HCV infection. Moreover, the baseline LBP was only significantly positively associated with ALT and inversely with fatty liver in HCV-infected subjects. The LBP level significantly decreased at sustained virologic response (27.4 ± 6.6 versus 34.6 ± 7.3 μg/mL, p-value < 0.001; 15.9 ± 4.4 versus 22.2 ± 5.7 μg/mL, p-value = 0.001), regardless of interferon-based or -free therapy. Conclusions LBP, an endotoxemia associated protein might be used as an inflammatory biomarker of both infectious and non-infectious origins in HCV-infected subjects. PMID:28107471

  8. Effects of Aerobic Exercise on Serum Retinol Binding Protein4, Insulin Resistance and Blood Lipids in Obese Women

    PubMed Central

    TAGHIAN, Farzaneh; ZOLFAGHARI, Maryam; HEDAYATI, Mehdi

    2014-01-01

    Abstract Background Retinol binding protein4 (RBP4) is a type of adipokine which transports vitamin A to serum. RBP4 could be a bridge between obesity and insulin resistance. This study aimed to investigate the effects of aerobic exercises on RBP4 serum’s concentration and metabolic syndrome risk factors in obese women. Methods Twenty obese women with body max index 35.81±3.67Kg/m2, fat percentage 43.98±4.02, and waist to hip ratio 1.03±0.05 were included and were randomly assigned to experimental and control groups. The experimental group received aerobic exercises for a period of 12 weeks each three sessions on treadmill workout. The treadmill speed were based on a 60-65 and 80-85 maximal heart rate percentage and duration of 15-20 and 45-50 minutes, at the beginning and the end of exercise, respectively. Body composition, serum glucose, insulin, TG, LDL-C, HDL-C, total cholesterol, and RBP4, were measured in both groups before and after the treatment by ELISA method. Insulin resistance was measured by HOMA-IR. To compare within group differences and between group comparisons t-correlated and t-independent tests were used, respectively. Results After 12 week aerobic exercises; weight, fat percentage, WHR, and BMI in the experimental group was significantly decreased (P<0.05). RBP4, insulin, insulin resistance, TG and HDL-C had significant differences between two groups. The cholesterol level, LDL-C and glucose did not have any significant changes. Conclusion The aerobic exercises can decrease body composition, insulin resistance, TG, and RBP4, so it can be beneficial for obese women’s health, because it. PMID:26060767

  9. A validated LC-MS/MS method of total and unbound lenvatinib quantification in human serum for protein binding studies by equilibrium dialysis.

    PubMed

    Mano, Yuji; Kusano, Kazutomi

    2015-10-10

    A sensitive method for the determination of total and unbound lenvatinib (Lenvima™), a novel tyrosine kinase inhibitor, in human serum was developed for protein binding studies using an equilibrium dialysis and liquid chromatography with tandem mass spectrometry. Serum samples (0.8 mL) were dialyzed against phosphate buffered saline (PBS) in dialyzer for 18 h at 37 °C to obtain dialysate and serum for unbound and total lenvatinib, respectively. After extraction by organic solvent, separation was achieved on a Symmetry Shield RP8 column with isocratic elution of 2 mM ammonium acetate (pH 4.0)-acetonitrile (3:2, v/v) at the flow rate of 0.2 mL/min. Detection was performed using API4000 with multiple reaction monitoring mode using positive electrospray ionization. The standard curve ranged from 0.0400 to 16.0 ng/mL and 0.0800 to 400 ng/mL as lenvatinib free base in PBS and serum, respectively. Accuracy and precision in the intra- and inter-batch reproducibility study were within the acceptance criteria. Various stability assessments including bench-top, freeze/thaw, processed samples, and frozen stability confirmed that lenvatinib was stable in serum and PBS. Application to in vivo protein binding studies in clinical studies was successfully performed and results showed that lenvatinib was highly protein bound in serum.

  10. Structural analogs of human insulin-like growth factor I with reduced affinity for serum binding proteins and the type 2 insulin-like growth factor receptor

    SciTech Connect

    Bayne, M.L.; Applebaum, J.; Chicchi, G.G.; Hayes, N.S.; Green, B.G.; Cascieri, M.A.

    1988-05-05

    Four structural analogs of human insulin-like growth factor I (hIGF-I) have been prepared by site-directed mutagenesis of a synthetic IGF-I gene and subsequent expression and purification of the mutant protein from the conditioned media of transformed yeast. (Phe/sup -1/, Val/sup 1/, Asn/sup 2/, Gln/sup 3/, His/sup 4/, Ser/sup 8/, His/sup 9/, Glu/sup 12/, Tyr/sup 15/, Leu/sup 16/)IGF-I (B-chain mutant), in which the first 16 amino acids of hIGF-I were replaced with the first 17 amino acids of the B-chain of insulin, has >1000-, 100-, and 2-fold reduced potency for human serum binding proteins, the rat liver type 2 IGF receptor, and the human placental type 1 IGF receptor, respectively. The B-chain mutant also has 4-fold increased affinity for the human placental insulin receptor. (Gln/sup 3/, Ala/sup 4/) IGF-I has 4-fold reduced affinity for human serum binding proteins, but is equipotent to hIGF-I at the types 1 and 2 IGF and insulin receptors. (Tyr/sup 15/, Leu/sup 16/) IGH-I has 4-fold reduced affinity for human serum binding proteins and 10-fold increased affinity for the insulin receptor. The peptide in which these four-point mutations are combined, (Gln/sup 3/, Ala/sup 4/, Tyr/sup 15/,Leu/sup 16/)IGF-I, has 600-fold reduced affinity for the serum binding proteins. All four of these mutants stimulate DNA synthesis in the rat vascular smooth muscle cell line A10 with potencies reflecting their potency at the type 1 IGF receptor. These studies identify some of the domains of hIGF-I which are responsible for maintaining high affinity binding with the serum binding protein and the type 2 IGF receptor. In addition, These peptides will be useful in defining the role of the type 2 IGF receptor and serum binding proteins in the physiological actions of hIGF-I.

  11. Differential Expression of Serum Glycodelin and Insulin-Like Growth Factor Binding Protein 1 in Early Pregnancy

    PubMed Central

    Thornton, Melvin H.; Nurudeen, Sahadat K.; Bucur, Maria; Lobo, Rogerio A.; Sauer, Mark V.

    2013-01-01

    This prospective study evaluated whether serum glycodelin and insulin-like growth factor binding protein 1 (IGFBP-1) predict the likelihood of embryo implantation in recipients undergoing donor egg in vitro fertilization. We measured glycodelin and IGFBP-1 at 6 points from lining check to lutenizing hormone (LH) + 31. β-Human chorionic gonadotropin levels were first measured at LH + 17. The recipients were divided into those without embryo implantation (group 1, n = 6) and those with successful implantation (group 2, n = 30). Although this is a negative study in that neither glycodelin nor IGFBP-1 alone reflected endometrial (EM) receptivity, the glycodelin/IGFBP-1 ratio on the day of blastocyst transfer was higher in recipients who achieved pregnancy (P = .05). At LH + 17, glycodelin was higher (P = .04), and IGFBP-1 was lower (P = .004) in recipients who achieved pregnancy when compared to those who did not. These observations are likely due to EM changes induced by successful embryo implantation. PMID:23585335

  12. Thiazolidinedione addition reduces the serum retinol-binding protein 4 in type 2 diabetic patients treated with metformin and sulfonylurea.

    PubMed

    Lin, Kun-Der; Chang, Yu-Hung; Wang, Chiao-Ling; Yang, Yi-Hsin; Hsiao, Pi-Jung; Li, Tzu-Hui; Shin, Shyi-Jang

    2008-06-01

    Retinol-binding protein 4 (RBP4) has been found to induce insulin resistance and to be increased in type 2 diabetes. Thiazolidinediones (TZDs) can improve insulin sensitivity through the activation of peroxisome proliferators-activated receptor-gamma (PPAR-gamma) and have been suggested as an adjunct to metformin (MF) and sulfonylurea (SU) in type 2 diabetes in a consensus statement from the ADA and EASD. Therefore, we investigated whether TZD could affect serum RBP4 level in type 2 diabetes already treated with MF and/or SU. Eighty-one type 2 diabetic patients were divided into 2 groups: (1) TZD group (n = 55): Pioglitazone 30 mg/day was given as an add-on medication; (2) SU group (n = 26): Gliclazide MR 30-120 mg or glimepiride 2-8 mg/day was prescribed. The average period of study was 97.1 days. Serum RBP4 and adiponectin were measured by enzyme-linked immunosorbent assay and radioimmunoassay, respectively. The addition of pioglitazone (TZD group) markedly decreased homeostasis model assessment of insulin resistance (HOMA-IR) (P = 0.021) compared with the SU group (P = 0.688). The change of RBP4 in the TZD group (-3.87 +/- 11.27 microg/mL) significantly differed from that in the SU group (2.52 +/- 8.24 microg/mL, P < 0.012). The increase of adiponectin in the TZD group (11.49 +/- 7.85 microg/mL) was apparently higher than that in the SU group (1.54 +/- 5.62 microg/mL, P < 0.001). Despite the change of glycosylated hemoglobin (HbA1c) did not differ (-0.77 +/- 1.3 vs -0.50 +/- 1.7, P = 0.446), the addition of pioglitazone could significantly lower serum RBP4 and HOMA-IR values, whereas an increased dosage of sulfonylurea agents did not alter HOMA-IR, RBP4, or adiponectin in type 2 diabetic patients who had been treated with metformin and/or sulfonylurea.

  13. Resveratrol binding to human serum albumin.

    PubMed

    N' soukpoe-Kossi, C N; St-Louis, C; Beauregard, M; Subirade, M; Carpentier, R; Hotchandani, S; Tajmir-Riahi, H A

    2006-12-01

    Resveratrol (Res), a polyphenolic compound found largely in the skin of red grape and wine, exhibits a wide range of pharmaceutical properties and plays a role in prevention of human cardiovascular diseases [Pendurthi et al., Arterioscler. Thromb. Vasc. Biol. 19, 419-426 (1999)]. It shows a strong affinity towards protein binding and used as inhibitor for cyclooxygenase and ribonuclease reductase. The aim of this study was to examine the interaction of resveratrol with human serum albumin (HSA) in aqueous solution at physiological conditions, using a constant protein concentration (0.3 mM) and various pigment contents (microM to mM). FTIR, UV-Visible, CD, and fluorescence spectroscopic methods were used to determine the resveratrol binding mode, the binding constant and the effects of pigment complexation on protein secondary structure. Structural analysis showed that resveratrol bind non-specifically (H-bonding) via polypeptide polar groups with overall binding constant of K(Res) = 2.56 x 10(5) M(-1). The protein secondary structure, analysed by CD spectroscopy, showed no major alterations at low resveratrol concentrations (0.125 mM), whereas at high pigment content (1 mM), major increase of alpha-helix from 57% (free HSA) to 62% and a decrease of beta-sheet from 10% (free HSA) to 7% occurred in the resveratrol-HSA complexes. The results indicate a partial stabilization of protein secondary structure at high resveratrol content.

  14. Serum Wisteria floribunda agglutinin-positive Mac-2 binding protein in non-alcoholic fatty liver disease

    PubMed Central

    Lai, Lee-Lee; Sthaneshwar, Pavai; Nik Mustapha, Nik Raihan; Goh, Khean-Lee; Mahadeva, Sanjiv

    2017-01-01

    Wisteria floribunda agglutinin-positive Mac-2 binding protein (WFA+-M2BP) has been suggested to be useful for the assessment of disease severity in non-alcoholic fatty liver disease (NAFLD). Consecutive adult NAFLD patients who had a liver biopsy were included. Serum WFA+-M2BP level was measured using a lectin-antibody sandwich immunoassay using a chemiluminescence enzyme immunoassay machine (HISCL-5000, Sysmex, Kobe, Japan). The measured levels were indexed using the following equation: Cut-off index (COI) = ([WFA+-M2BP]sample−[WFA+-M2BP]NC) / ([WFA+-M2BP]PC−[WFA+-M2BP]NC), where PC = positive control and NC = negative control. Histopathological examination of liver biopsy specimen was reported according to Non-Alcoholic Steatohepatitis (NASH) Clinical Research Network Scoring System. Data for 220 cases were analyzed. The AUROC of the COI for the diagnosis of NASH was 0.65. The AUROC of the COI for the diagnosis of steatosis grade ≥2 and 3 was 0.64 and 0.53, respectively. The AUROC of the COI for the diagnosis of lobular inflammation grade ≥1, ≥2 and 3 was 0.57, 0.68 and 0.59, respectively. The AUROC of the COI for the diagnosis of hepatocyte ballooning grade ≥1 and 2 was 0.64 and 0.65, respectively. The AUROC of the COI for the diagnosis of fibrosis stage ≥1, ≥2, ≥3 and 4 was 0.61, 0.71, 0.74 and 0.84, respectively. Out of the 220 cases, 152 cases were the same 76 patients who had a repeat liver biopsy after 48 weeks of intervention. The AUROC of the change in the COI to detect improvement in steatosis, lobular inflammation, hepatocyte ballooning and fibrosis was 0.57, 0.54, 0.59 and 0.52, respectively. In conclusion, serum WFA+-M2BP was most useful for the diagnosis of significant fibrosis, advanced fibrosis and cirrhosis in NAFLD patients. However, it was less useful for differentiating NASH from non-NASH, and for diagnosis and follow-up of the individual histopathological components of NASH. PMID:28369100

  15. Antioxidant flavonoids bind human serum albumin

    NASA Astrophysics Data System (ADS)

    Kanakis, C. D.; Tarantilis, P. A.; Polissiou, M. G.; Diamantoglou, S.; Tajmir-Riahi, H. A.

    2006-10-01

    Human serum albumin (HSA) is a principal extracellular protein with a high concentration in blood plasma and carrier for many drugs to different molecular targets. Flavonoids are powerful antioxidants and prevent DNA damage. The antioxidative protections are related to their binding modes to DNA duplex and complexation with free radicals in vivo. However, flavonoids are known to inhibit the activities of several enzymes such as calcium phospholipid-dependent protein kinase, tyrosine protein kinase from rat lung, phosphorylase kinase, phosphatidylinositol 3-kinase and DNA topoisomerases that exhibit the importance of flavonoid-protein interaction. This study was designed to examine the interaction of human serum albumin (HSA) with quercetin (que), kaempferol (kae) and delphinidin (del) in aqueous solution at physiological conditions, using constant protein concentration of 0.25 mM (final) and various drug contents of 1 μM-1 mM. FTIR and UV-vis spectroscopic methods were used to determine the polyphenolic binding mode, the binding constant and the effects of flavonoid complexation on protein secondary structure. The spectroscopic results showed that flavonoids are located along the polypeptide chains through H-bonding interactions with overall affinity constant of Kque = 1.4 × 10 4 M -1, Kkae = 2.6 × 10 5 M -1 and Kdel = 4.71 × 10 5 M -1. The protein secondary structure showed no alterations at low pigment concentration (1 μM), whereas at high flavonoid content (1 mM), major reduction of α-helix from 55% (free HSA) to 42-46% and increase of β-sheet from 15% (free HSA) to 17-19% and β-anti from 7% (free HSA) to 10-20% occurred in the flavonoid-HSA adducts. The major reduction of HSA α-helix is indicative of a partial protein unfolding upon flavonoid interaction.

  16. [Method of determining serum iron and iron-binding capacity without protein precipitation in very young children].

    PubMed

    Chenusha, V P; Voronka, G Sh

    1978-01-01

    A modification of bathophenanthroline method is described. The method was used for diagnostics of anemia and in order to control the treatment of anemia in children of early ages. The method was checked by estimation of known concentrations of iron in solutions as well as by addition of known amounts of iron to blood serum. Standard deviations ranged from +/- 1.04 to +/- 6.5 and variation coefficient--from 0.5% to 10%. Normal values of iron content and of iron-binding capacity of blood serum, estimated by means of the modified method in 30 healthy children of early ages, did not differ from the corresponding data published in the literature.

  17. Evaluation of an Albumin-Binding Domain Protein Fused to Recombinant Human IL-2 and Its Effects on the Bioactivity and Serum Half-Life of the Cytokine

    PubMed Central

    Adabi, Elham; Saebi, Fateme; Hasan-Abad, Amin Moradi; Teimoori-Toolabi, Ladan; Kardar, Gholam Ali

    2017-01-01

    Background: Cancer immunotherapy is a promising strategy for cancer treatment. In this strategy, the immune system is triggered to destroy cancer cells. IL-2 is an important factor in passive cancer immunotherapy that helps modulating some important immune functions. One of the IL-2 limitations is low serum half-life; therefore, repetitive high doses of the injections are required to maintain effective concentrations. High-dose IL-2 therapy results in severe side effects; thus, improvement of its serum half-life would provide therapeutic benefits. Methods: We have investigated a strategy that is able to utilize an albumin-binding domain (ABD) from streptococcal protein G. In this strategy, the fusion protein ABD-rIL-2 binds to serum albumin, which results in improvement of the IL-2 serum half-life. PET26b+ plasmid was used as an expression vector, which encoded rIL-2 and ABD-rIL-2, both fused to pelB secretion signal under the control of the strong bacteriophage T7 promoter. The constructs were expressed in E. coli Rosetta (DE3), and the recombinant proteins were purified from periplasmic fractions. Results: The analysis of in vitro bioactivity proved that the fusion of ABD to rIL-2 does not interfere with its bioactivity. ABD-rIL-2 fusion protein indicated higher serum half-life compared to rIL-2, when it was tested in the BALB/c mice. Conclusion: The current study provides an alternative strategy to extend the half-life and improve pharmacokinetic properties of rIL-2 without reducing its bioactivity in vitro. PMID:27805072

  18. Long-term effects of insulin-like growth factor (IGF)-I on serum IGF-I, IGF-binding protein-3 and acid labile subunit in Laron syndrome patients with normal growth hormone binding protein.

    PubMed

    Kanety, H; Silbergeld, A; Klinger, B; Karasik, A; Baxter, R C; Laron, Z

    1997-12-01

    A minority of patients with Laron syndrome have normal serum GH binding protein (GHBP), indicating that the defect is elsewhere than in the extracellular domain of the GH receptor. We have evaluated the effect of long-term IGF-I treatment on serum IGF-binding protein (IGFBP)-3 and the acid-labile subunit (ALS) in three sibling with Laron syndrome caused by a GH post-receptor defect and with normal GHBP. The children (a boy aged 3 years, a girl aged 4 years and a boy aged 10 years) were treated by daily s.c. injection of IGF-I in a dose of 150 micrograms/kg. IGFBP-3 was measured by RIA and Western ligand blotting, ALS by RIA. Based values of IGFBP-3 and ALS were low. During IGF-I treatment, the IGFBP-3 concentrations in the girl gradually increased, whereas in the boys there was a 60% decrease during the first week, followed by gradual increase towards baseline. The ALS concentrations followed a similar pattern. We conclude that IGF-I treatment induces and initial suppression and then an increase in the IGFBP-3 and ALS concentrations, confirming data from animal experiments that IGFBP-3 synthesis is not solely under GH control. The differences in responsiveness between the female and male siblings may reflect genetic differences, or lower circulating concentrations of IGF-I in the boys compared with the girl.

  19. Serum amyloid A, protein Z, and C4b-binding protein β chain as new potential biomarkers for pulmonary tuberculosis

    PubMed Central

    Jiang, Ting-Ting; Shi, Li-Ying; Wei, Li-Liang; Li, Xiang; Yang, Su; Wang, Chong; Liu, Chang-Ming; Chen, Zhong-Liang; Tu, Hui-Hui; Li, Zhong-Jie; Li, Ji-Cheng

    2017-01-01

    The aim of this study was to discover novel biomarkers for pulmonary tuberculosis (TB). Differentially expressed proteins in the serum of patients with TB were screened and identified by iTRAQ-two dimensional liquid chromatography tandem mass spectrometry analysis. A total of 79 abnormal proteins were discovered in patients with TB compared with healthy controls. Of these, significant differences were observed in 47 abnormally expressed proteins between patients with TB or pneumonia and chronic obstructive pulmonary disease (COPD). Patients with TB (n = 136) exhibited significantly higher levels of serum amyloid A (SAA), vitamin K-dependent protein Z (PROZ), and C4b-binding protein β chain (C4BPB) than those in healthy controls (n = 66) (P<0.0001 for each) albeit significantly lower levels compared with those in patients with pneumonia (n = 72) (P<0.0001 for each) or COPD (n = 72) (P<0.0001, P<0.0001, P = 0.0016, respectively). After 6 months of treatment, the levels of SAA and PROZ were significantly increased (P = 0.022, P<0.0001, respectively), whereas the level of C4BPB was significantly decreased (P = 0.0038) in treated TB cases (n = 72). Clinical analysis showed that there were significant differences in blood clotting and lipid indices in patients with TB compared with healthy controls, patients with pneumonia or COPD, and treated TB cases (P<0.05). Correlation analysis revealed significant correlations between PROZ and INR (rs = 0.414, P = 0.044), and between C4BPB and FIB (rs = 0.617, P = 0.0002) in patients with TB. Receiver operating characteristic curve analysis revealed that the area under the curve value of the diagnostic model combining SAA, PROZ, and C4BPB to discriminate the TB group from the healthy control, pneumonia, COPD, and cured TB groups was 0.972, 0.928, 0.957, and 0.969, respectively. Together, these results suggested that SAA, PROZ, and C4BPB may serve as new potential biomarkers for TB. Our study may thus provide experimental data for

  20. Purification of IgD from human serum--a novel application of recombinant M. catarrhalis IgD-binding protein (MID).

    PubMed

    Samuelsson, Martin; Forsgren, Arne; Riesbeck, Kristian

    2006-12-20

    Moraxella catarrhalis IgD-binding protein (MID) is a multimeric outer membrane protein belonging to the family of autotransporters. The IgD-binding domain of MID is located between amino acids MID 962-1200 and binds to amino acids 198-224 of the IgD C(H)1 region. In the present study, we describe a method to purify IgD from serum with high levels of IgD using a two-step affinity chromatography process. The first step involves depletion of MID-specific antibodies of all classes from serum using the non-IgD-binding fragment MID(1000-1200). This step is followed by selective capture of IgD with MID(962-1200). Furthermore, we demonstrate that the eluted IgD is pure, intact and functional for use in downstream applications. Our approach reduces the non-specificity commonly associated with lectin-based IgD purification regimes that rely on glycosylation of the IgD molecule.

  1. Water participation in molecular recognition and protein-ligand association: Probing the drug binding site "Sudlow I" in human serum albumin

    NASA Astrophysics Data System (ADS)

    Al-Lawatia, Najla; Steinbrecher, Thomas; Abou-Zied, Osama K.

    2012-03-01

    Human serum albumin (HSA) plays an important role in the transport and disposition of endogenous and exogenous ligands present in blood. Its capacity to reversibly bind a large variety of drugs results in its prevailing role in drug pharmacokinetics and pharmacodynamics. In this work, we used 7-hydroxyquinoline (7HQ) as a probe to study the binding nature of one of the major drug binding sites of HSA (Sudlow I) and to reveal the local environment around the probe in the binding site. The interaction between 7HQ and HSA at a physiological pH of 7.2 was investigated using steady-state and lifetime spectroscopic measurements, molecular docking and molecular dynamics (MD) simulations methods. The fluorescence results indicate a selective interaction between 7HQ and the Trp214 residue. The reduction in both the intensity and lifetime of the Trp214 fluorescence upon probe binding indicates the dominant role of static quenching. Molecular docking and MD simulations show that 7HQ binds in Sudlow site I close to Trp214, confirming the experimental results, and pinpoint the dominant role of hydrophobic interaction in the binding site. Electrostatic interactions were also found to be important in which two water molecules form strong hydrogen bonds with the polar groups of 7HQ. Detection of water in the binding site agrees with the absorption and fluorescence results that show the formation of a zwitterion tautomer of 7HQ. The unique spectral signatures of 7HQ in water make this molecule a potential probe for detecting the presence of water in nanocavities of proteins. Interaction of 7HQ with water in the binding site shows that water molecules can be crucial for molecular recognition and association in protein binding sites.

  2. The associations of diet with serum insulin-like growth factor I and its main binding proteins in 292 women meat-eaters, vegetarians, and vegans.

    PubMed

    Allen, Naomi E; Appleby, Paul N; Davey, Gwyneth K; Kaaks, Rudolf; Rinaldi, Sabina; Key, Timothy J

    2002-11-01

    The lower rates of some cancers in Asian countries than in Western countries may be partly because of diet, although the mechanisms are unknown. The aim of this cross-sectional study was to determine whether a plant-based (vegan) diet is associated with a lower circulating level of insulin-like growth factor I (IGF-I) compared with a meat-eating or lacto-ovo-vegetarian diet among 292 British women, ages 20-70 years. The mean serum IGF-I concentration was 13% lower in 92 vegan women compared with 99 meat-eaters and 101 vegetarians (P = 0.0006). The mean concentrations of both serum IGF-binding protein (IGFBP)-1 and IGFBP-2 were 20-40% higher in vegan women compared with meat-eaters and vegetarians (P = 0.005 and P = 0.0008 for IGFBP-1 and IGFBP-2, respectively). There were no significant differences in IGFBP-3, C-peptide, or sex hormone-binding globulin concentrations between the diet groups. Intake of protein rich in essential amino acids was positively associated with serum IGF-I (Pearson partial correlation coefficient; r = 0.27; P < 0.0001) and explained most of the differences in IGF-I concentration between the diet groups. These data suggest that a plant-based diet is associated with lower circulating levels of total IGF-I and higher levels of IGFBP-1 and IGFBP-2.

  3. The influence of manganese deficiency on serum IGF-1 and IGF binding proteins in the male rat.

    PubMed

    Clegg, M S; Donovan, S M; Monaco, M H; Baly, D L; Ensunsa, J L; Keen, C L

    1998-10-01

    Young male rats subjected to a dietary manganese (Mn) deficiency respond to the deficiency by reducing their growth rate. The growth hormone (GH)/insulin-like growth factor (IGF) axis is critical for linear growth; this system is exquisitely sensitive to the nutritional state of the animal. In this study, we examined circulating GH, IGF-1, and insulin levels in Mn-deficient (-Mn; fed a 0.5 microg Mn/g diet) and sufficient (+Mn; fed a 45 microg Mn/g diet) male Sprague-Dawley rats. Additionally, we examined the distribution of circulating IGF binding proteins (IGFBPs) in animals of both dietary groups as these proteins modulate IGF-1 action in vivo and in vitro, and have been demonstrated to be altered in a number of nutritional and physiological states. Body weight was significantly reduced in -Mn relative to +Mn rats. Consistent with other studies, daily food intake was not altered. However, cumulative food intake (over 3 months) was marginally lower in -Mn versus +Mn animals. -Mn animals displayed lower circulating concentrations of IGF-1 (66% of control levels) and insulin (60% of control levels) despite having significant elevations in circulating GH levels relative to +Mn animals (140% of control levels). The IGFBP profile of -Mn animals reflected their elevated GH status, as we observed increased binding of tracer (125I-IGF-1) to the circulating IGFBP-3 complex (120% of control binding) using native chromatography techniques. Interestingly, the lower circulating insulin concentrations of -Mn animals did not result in dramatic elevations in lower-molecular-weight binding proteins. In summary, we demonstrate that in young male rats, Mn deficiency is associated with alterations in IGF metabolism. These alterations may contribute to the growth and bone abnormalities observed in -Mn animals.

  4. Identification of drug-binding sites on human serum albumin using affinity capillary electrophoresis and chemically modified proteins as buffer additives.

    PubMed

    Kim, Hee Seung; Austin, John; Hage, David S

    2002-03-01

    A technique based on affinity capillary electrophoresis (ACE) and chemically modified proteins was used to screen the binding sites of various drugs on human serum albumin (HSA). This involved using HSA as a buffer additive, following the site-selective modification of this protein at two residues (tryptophan 214 or tyrosine 411) located in its major binding regions. The migration times of four compounds (warfarin, ibuprofen, suprofen and flurbiprofen) were measured in the presence of normal or modified HSA. These times were then compared and the mobility shifts observed with the modified proteins were used to identify the binding regions of each injected solute on HSA. Items considered in optimizing this assay included the concentration of protein placed into the running buffer, the reagents used to modify HSA, and the use of dextran as a secondary additive to adjust protein mobility. The results of this method showed good agreement with those of previous reports. The advantages and disadvantages of this approach are examined, as well as its possible extension to other solutes.

  5. Studies of the Interaction between Isoimperatorin and Human Serum Albumin by Multispectroscopic Method: Identification of Possible Binding Site of the Compound Using Esterase Activity of the Protein

    PubMed Central

    Ranjbar, Samira; Shokoohinia, Yalda; Ghobadi, Sirous; Gholamzadeh, Saeed; Moradi, Nastaran; Ashrafi-Kooshk, Mohammad Reza; Aghaei, Abbas

    2013-01-01

    Isoimperatorin is one of the main components of Prangos ferulacea as a linear furanocoumarin and used as anti-inflammatory, analgesic, antispasmodic, and anticancer drug. Human serum albumin (HSA) is a principal extracellular protein with a high concentration in blood plasma and carrier for many drugs to different molecular targets. Since the carrying of drug by HSA may affect on its structure and action, we decided to investigate the interaction between HSA and isoimperatorin using fluorescence and UV spectroscopy. Fluorescence data indicated that isoimperatorin quenches the intrinsic fluorescence of the HSA via a static mechanism and hydrophobic interaction play the major role in the drug binding. The binding average distance between isoimperatorin and Trp 214 of HSA was estimated on the basis of the theory of Förster energy transfer. Decrease of protein surface hydrophobicity (PSH) was also documented upon isoimperatorin binding. Furthermore, the synchronous fluorescence spectra show that the microenvironment of the tryptophan residues does not have obvious changes. Site marker compettive and fluorescence experiments revealed that the binding of isoimperatorin to HSA occurred at or near site I. Finally, the binding details between isoimperatorin and HSA were further confirmed by molecular docking and esterase activity inhibition studies which revealed that drug was bound at subdomain IIA. PMID:24319355

  6. Polyamine analogues bind human serum albumin.

    PubMed

    Beauchemin, R; N'soukpoé-Kossi, C N; Thomas, T J; Thomas, T; Carpentier, R; Tajmir-Riahi, H A

    2007-10-01

    Polyamine analogues show antitumor activity in experimental models, and their ability to alter activity of cytotoxic chemotherapeutic agents in breast cancer is well documented. Association of polyamines with nucleic acids and protein is included in their mechanism of action. The aim of this study was to examine the interaction of human serum albumin (HSA) with several polyamine analogues, such as 1,11-diamino-4,8-diazaundecane (333), 3,7,11,15-tetrazaheptadecane.4HCl (BE-333), and 3,7,11,15,19-pentazahenicosane.5HCl (BE-3333), in aqueous solution at physiological conditions using a constant protein concentration and various polyamine contents (microM to mM). FTIR, UV-visible, and CD spectroscopic methods were used to determine the polyamine binding mode and the effects of polyamine complexation on protein stability and secondary structure. Structural analysis showed that polyamines bind nonspecifically (H-bonding) via polypeptide polar groups with binding constants of K333 = 9.30 x 10(3) M(-1), KBE-333 = 5.63 x 10(2) M(-1), and KBE-3333 = 3.66 x 10(2) M(-1). The protein secondary structure showed major alterations with a reduction of alpha-helix from 55% (free protein) to 43-50% and an increase of beta-sheet from 17% (free protein) to 29-36% in the 333, BE-333, and BE-3333 complexes, indicating partial protein unfolding upon polyamine interaction. HSA structure was less perturbed by polyamine analogues compared to those of the biogenic polyamines.

  7. Human Serum Albumin and HER2-Binding Affibody Fusion Proteins for Targeted Delivery of Fatty Acid-Modified Molecules and Therapy.

    PubMed

    Dong, Daoyuan; Xia, Guanjun; Li, Zhijun; Li, Zhiyu

    2016-10-03

    Human epidermal growth factor receptor 2 (HER2) is a well-studied therapeutic target as well as a biomarker of breast cancer. HER2-targeting affibody (ZHER2:342) is a novel small scaffold protein with an extreme high affinity against HER2 screened by phage display. However, the small molecular weight of ZHER2:342 has limited its pharmaceutical application. Human serum albumin (HSA) and ZHER2:342 fusion protein may not only extend the serum half-life of ZHER2:342 but also preserve the biological function of HSA to bind and transport fatty acids, which can be used to deliver fatty acid-modified therapeutics to HER2-positive cancer cells. Two HSA and ZHER2:342 fusion proteins, one with a single ZHER2:342 domain fused to the C terminus of HSA (rHSA-ZHER2) and another with two tandem copies of ZHER2:342 fused to the C terminus of HSA (rHSA-(ZHER2)2), have been constructed, expressed, and purified. Both fusion proteins possessed the HER2 and fatty acid (FA) binding abilities demonstrated by in vitro assays. Interestingly, rHSA-(ZHER2)2, not rHSA-ZHER2, was able to inhibit the proliferation of SK-BR-3 cells at a relatively low concentration, and the increase of HER2 and ERK1/2 phosphorylation followed by rHSA-(ZHER2)2 treatment has been observed. HSA fusion proteins are easy and economical to express, purify, and formulate. As expected, HSA fusion proteins and fusion protein-bound fatty acid-modified FITC could be efficiently taken up by cells. These results proved the feasibility of using HSA fusion proteins as therapeutic agents as well as carriers for targeted drug delivery.

  8. Comparative binding of antitumor indazolium [trans-tetrachlorobis(1H-indazole)ruthenate(III)] to serum transport proteins assayed by capillary zone electrophoresis.

    PubMed

    Timerbaev, Andrei R; Rudnev, Alexander V; Semenova, Olga; Hartinger, Christian G; Keppler, Bernhard K

    2005-06-15

    The indazolium [trans-tetrachlorobis(1H-indazole)ruthenate(III)] coordination compound shows notable antiproliferative activity in different tumor models and has recently ended phase I clinical trials as a lead anticancer metallodrug candidate. Its approval could be greatly facilitated if more precise information was available on the rate and degree of the drug's transformation occurring upon interaction with serum transport proteins and on the stability of the adducts formed. With this objective, a new method has been developed for the determination of the protein-binding rate and association constants under simulated physiological conditions by capillary zone electrophoresis (CZE). These binding parameters were assessed by monitoring the time- and concentration-dependent changes in peak area responses of reaction components, constructing the corresponding binding curves, and conducting a mathematical analysis. Comparison of the apparent rate constants determined by CZE revealed that indazolium [trans-tetrachlorobis(1H-indazole)ruthenate(III)] binds to transferrin much faster than to albumin: k=39.5 x 10(-4) and 3.3 x 10(-4)s(-1), respectively. The corresponding association constants are indicative of moderate metal-protein coordination, with a somewhat higher affinity of the Ru complex toward albumin (9910 and 6460 M(-1), respectively). The results of our study confirm in a quantitative manner that, in real bloodstream circumstances, plasma albumin may serve as a reservoir and a natural carrier of the administered ruthenium drug and hence mediate its accumulation in tumors.

  9. Vitamin D-binding protein, vitamin D status and serum bioavailable 25(OH)D of young Asian Indian males working in outdoor and indoor environments.

    PubMed

    Goswami, Ravinder; Saha, Soma; Sreenivas, Vishnubhatla; Singh, Namrata; Lakshmy, Ramakrishnan

    2017-03-01

    Urban Asian Indians generally have low serum 25(OH)D. Information on serum bioavailable 25(OH)D and the effect of prolonged sun-exposure in them is not known. We assessed serum 25(OH)D and bioavailable 25(OH)D in males with varying durations of sun-exposure in Delhi during August-September. Serum 25(OH)D, vitamin D-binding protein (DBP), bioavailable 25(OH)D, free 25(OH)D index, iPTH, ionized calcium and sun-index were assessed in outdoor, mixed outdoor-indoor and indoor workers (n = 88, 32 and 74, respectively). The mean sun-index (12.0 ± 6.25, 4.3 ± 2.20 and 0.7 ± 0.62, respectively; P < 0.001) was highest outdoors and lowest indoors. Serum 25(OH)D (29.0 ± 8.61, 19.1 ± 5.73 and 10.9 ± 4.19 ng/ml, respectively; P < 0.001), bioavailable 25(OH)D and free 25(OH)D index were maximum in outdoor workers followed by mixed-exposure and indoor workers. Their mean serum DBP levels (241.2 ± 88.77, 239.3 ± 83.40 and 216.6 ± 63.93 µg/ml, respectively; P = 0.12) were comparable. Mean serum iPTH was significantly lower in outdoor than indoor workers and showed inverse correlations with serum 25(OH)D, bioavailable 25(OH)D and free 25(OH)D index (r = -0.401, -0.269 and -0.236, respectively; P < 0.001 in all). Daily dietary-calorie intake was higher and calcium lower in outdoor than indoor workers. On regression analysis, sun-exposure was the only significant variable, increasing serum 25(OH)D by 2.03 ng/ml per hour of sun-exposure (95 % confidence interval 1.77-2.28; P < 0.001). Outdoor workers with prolonged sun-exposure were vitamin D-sufficient, with higher serum bioavailable 25(OH)D than the indoor workers during summer. Use of serum DBP levels did not affect the interpretation of their vitamin D status.

  10. Hepatic uptake of (TH)retinol bound to the serum retinol binding protein involves both parenchymal and perisinusoidal stellate cells

    SciTech Connect

    Blomhoff, R.; Norum, K.R.; Berg, T.

    1985-11-05

    We have studied the hepatic uptake of retinol bound to the circulating retinol binding protein-transthyretin complex. Labeled complex was obtained from the plasma of donor rats that were fed radioactive retinol. When labeled retinol-retinol binding protein-transthyretin complex was injected intravenously into control rats, about 45% of the administered dose was recovered in liver after 56 h. Parenchymal liver cells were responsible for an initial rapid uptake. Perisinusoidal stellate cells initially accumulated radioactivity more slowly than did the parenchymal cells, but after 16 h, these cells contained more radioactivity than the parenchymal cells. After 56 h, about 70% of the radioactivity recovered in liver was present in stellate cells. For the first 2 h after injection, most of the radioactivity in parenchymal cells was recovered as unesterified retinol. The radioactivity in the retinyl ester fraction increased after a lag period of about 2 h, and after 5 h more than 60% of the radioactivity was recovered as retinyl esters. In stellate cells, radioactivity was mostly present as retinyl esters at all time points examined. Uptake of retinol in both parenchymal cells and stellate cells was reduced considerably in vitamin A-deficient rats. Less than 5% of the injected dose of radioactivity was found in liver after 5-6 h (as compared to 25% in control rats), and the radioactivity recovered in liver from these animals was mostly in the unesterified retinol fraction. Studies with separated cells in vitro suggested that both parenchymal and stellate cells isolated from control rats were able to take up retinol from the retinol-retinol binding protein-transthyretin complex. This uptake was temperature dependent.

  11. Exploring the affinity binding of alkylmaltoside surfactants to bovine serum albumin and their effect on the protein stability: A spectroscopic approach.

    PubMed

    Hierrezuelo, J M; Carnero Ruiz, C

    2015-08-01

    Steady-state and time-resolved fluorescence together with circular dichroism (CD) spectroscopic studies was performed to examine the interactions between bovine serum albumin (BSA) and two alkylmaltoside surfactants, i.e. n-decyl-β-D-maltoside (β-C10G2) and n-dodecyl-β-D-maltoside (β-C12G2), having identical structures but different tail lengths. Changes in the intrinsic fluorescence of BSA from static as well as dynamic measurements revealed a weak protein-surfactant interaction and gave the corresponding binding curves, suggesting that the binding mechanism of surfactants to protein is essentially cooperative in nature. The behavior of both surfactants is similar, so that the differences detected were attributed to the more hydrophobic nature of β-C12G2, which favors the adsorption of micelle-like aggregates onto the protein surface. These observations were substantially demonstrated by data derived from synchronous, three-dimensional and anisotropy fluorescence experiments. Changes in the secondary structure of the protein induced by the interaction with surfactants were analyzed by CD to determine the contents of α-helix and β-strand. It was noted that whereas the addition of β-C10G2 appears to stabilize the secondary structure of the protein, β-C12G2 causes a marginal denaturation of BSA for a protein:surfactant molar ratio as high as 1 to 100.

  12. Deglycosylation of serum vitamin D3-binding protein by alpha-N-acetylgalactosaminidase detected in the plasma of patients with systemic lupus erythematosus.

    PubMed

    Yamamoto, N; Naraparaju, V R; Moore, M; Brent, L H

    1997-03-01

    A serum glycoprotein, Gc protein (vitamin D3-binding protein), can be converted by beta-galactosidase of B cells and sialidase of T cells to a potent macrophage-activating factor (MAF), a protein with N-acetylgalactosamine as the remaining sugar moiety. Thus, Gc protein is the precursor for MAF. Treatment of Gc protein with immobilized beta-galactosidase and sialidase generates a remarkably high titered macrophage-activating factor (GcMAF). When peripheral blood monocytes/ macrophages (designated macrophages) of 33 systemic lupus erythematosus patients were incubated with GcMAF (100 pg/ml), the macrophages of all patients were activated as determined by superoxide generation. However, the precursor activity of patient plasma Gc protein was lost or reduced in these patients. Loss of the precursor activity was the result of deglycosylation of plasma Gc protein by alpha-N-acetylgalactosaminidase activity found in the patient plasma. Levels of plasma alpha-N-acetylgalactosaminidase activity in individual patients had an inverse correlation with the MAF precursor activity of their plasma Gc protein. Deglycosylated Gc protein cannot be converted to macro-phage-activating factor. The resulting defect in macro-phage activation may lead to an inability to clear pathogenic immune complexes. Thus, elevated plasma alpha-N-acetylgalactosaminidase activity resulting in the loss of MAF precursor activity and reduced macro-phage activity may play a role in the pathogenesis of systemic lupus erythematosus.

  13. Characteristics of aldosterone binding in rat and human serum.

    PubMed

    Coirini, H; White, A; Marusic, E T; De Nicola, A F

    1982-01-01

    Binding of cortisol and corticosterone by serum proteins is well established, but discrepancies exist regarding aldosterone. We have observed that approximately 1% of 3H-aldosterone incubated with rat serum was bound in a time-dependent process, although it was not competed by a large excess of non-radioactive aldosterone, assessed by Florisil separation or gel filtration on Sephadex G-50 columns. After electrophoresis on cellulose acetate of rat serum incubated with 3H-aldosterone, specific or non-specific binding to protein fractions was not obtained. Further, a 10 000-fold molar excess of aldosterone (10 microM) displaced only 34% of the bound 3H-aldosterone to rat serum, preventing the calculation of the IC50 value. Increasing concentrations of aldosterone (3-83 nM) did not displace 3H-corticosterone bound in rat serum to presumably corticosterone binding globulin (CBG). In contrast, inhibition of this binding by 3-83 nM corticosterone was concentration dependent, showing an IC50 value of 10(-8) M. In normal human serum, binding of 3H-aldosterone demonstrated competition by a 100 and 1 000-fold excess of aldosterone. Displacement curves of 3H corticosterone bound to human serum by 1.7-75 nM corticosterone or 0.05-8.8 microM aldosterone yielded IC50 values in the range of 10(-8) M for corticosterone and 10(-6) M for aldosterone. With horse serum, aldosterone's binding affinity was three orders of magnitude lower than that of corticosterone. These studies suggest that in the rat aldosterone was loosely and weakly bound to a high capacity binder, possibly albumin. In agreement with the work of others, in humans aldosterone may be bound to both CBG and albumin. The current data do not substantiate for the presence of specific aldosterone binding proteins in serum.

  14. Does Fluoride Affect Serum Testosterone and Androgen Binding Protein with Age-Specificity? A Population-Based Cross-Sectional Study in Chinese Male Farmers.

    PubMed

    Duan, Leizhen; Zhu, Jingyuan; Wang, Keyan; Zhou, Guoyu; Yang, Yuejin; Cui, Liuxin; Huang, Hui; Cheng, Xuemin; Ba, Yue

    2016-12-01

    Many studies have demonstrated that exposure to excess fluoride was associated with a variety of diseases. Little is known about the variation of testosterone (T) levels caused by fluoride exposure. The aim of this study is to explore the association of fluoride exposure and age with serum T and androgen-binding protein (ABP) levels in male farmers. A cross-sectional study was conducted in a county of Henan Province, China, including high fluoride exposure from drinking water villages and control villages. Male farmers aged 18-55 years old who lived in these villages were recruited by cluster sampling and divided into a higher fluoride exposure group (HFG) and a lower fluoride exposure group (LFG) according to the level of urinary fluoride. Levels of T and ABP in serum were measured using chemiluminescence immunoassay (CLIA) and enzyme-linked immunosorbent assay (ELISA) respectively. Markedly lower T levels were observed in male farmers from the HFG than in those from the LFG (t = 2.496, P < 0.05). Furthermore, younger farmers, 18-29 and 30-39 years old, may be the most likely to have lower T levels when exposed to fluoride (P < 0.05). No significant differences were observed in serum ABP levels in all male farmers between the two groups with different fluoride exposure. These results supported that excess fluoride exposure decreased serum T levels of male farmers with age-specificity.

  15. Serum liver-type fatty acid-binding protein predicts recovery of graft function after kidney transplantation from donors after cardiac death.

    PubMed

    Kawai, Akihiro; Kusaka, Mamoru; Kitagawa, Fumihiko; Ishii, Junichi; Fukami, Naohiko; Maruyama, Takahiro; Sasaki, Hitomi; Shiroki, Ryoichi; Kurahashi, Hiroki; Hoshinaga, Kiyotaka

    2014-06-01

    Kidneys procured by donation after cardiac death (DCD) may increase the donor pool but are associated with high incidence of delayed graft function (DGF). Urinary liver-type fatty acid-binding protein (L-FABP) level is an early biomarker of renal injury after kidney transplantation (KTx); however, its utility is limited in DGF cases owing to urine sample unavailability. We examined whether serum L-FABP level predicts functional recovery of transplanted DCD kidneys. Consecutive patients undergoing KTx from living related donors (LD), brain-dead donors (BD), or DCD were retrospectively enrolled. Serum L-FABP levels were measured from samples collected before and after KTx. Serum L-FABP decreased rapidly in patients with immediate function, slowly in DGF patients, and somewhat increased in DGF patients requiring hemodialysis (HD) for >1 wk. Receiver-operating characteristic curve analysis demonstrated that DGF was predicted with 84% sensitivity (SE) and 86% specificity (SP) at cutoff of 9.0 ng/mL on post-operative day (POD) 1 and 68% SE and 90% SP at 6.0 on POD 2. DGF >7 d was predicted with 83% SE and 78% SP at 11.0 on POD 1 and 67% SE and 78% SP at 6.5 on POD 2. Serum L-FABP levels may predict graft recovery and need for HD after DCD KTx.

  16. Analysis of Multi-Site Drug-Protein Interactions by High-Performance Affinity Chromatography: Binding by Glimepiride to Normal or Glycated Human Serum Albumin

    PubMed Central

    Matsuda, Ryan; Li, Zhao; Zheng, Xiwei; Hage, David S.

    2015-01-01

    High-performance affinity chromatography (HPAC) was used in a variety of formats to examine multi-site interactions between glimepiride, a third-generation sulfonylurea drug, and normal or in vitro glycated forms of the transport protein human serum albumin (HSA). Frontal analysis revealed that glimepiride interacts with normal HSA and glycated HSA at a group of high affinity sites (association equilibrium constant, or Ka, 9.2–11.8 × 105 M−1 at pH 7.4 and 37°C) and a group of lower affinity regions (Ka, 5.9–16.2 × 103 M−1). Zonal elution competition studies were designed and carried out in both normal- and reversed-role formats to investigate the binding by this drug at specific sites. These experiments indicated that glimepiride was interacting at both Sudlow sites I and II. Allosteric effects were also noted with R-warfarin at Sudlow site I and with tamoxifen at the tamoxifen site on HSA. The binding at Sudlow site I had a 2.1- to 2.3-fold increase in affinity in going from normal HSA to the glycated samples of HSA. There was no significant change in the affinity for glimepiride at Sudlow site II in going from normal HSA to a moderately glycated sample of HSA, but a slight decrease in affinity was seen in going to a more highly glycated HSA sample. These results demonstrated how various HPAC-based methods can be used to profile and characterize multi-site binding by a drug such as glimepiride to a protein and its modified forms. The information obtained from this study should be useful in providing a better understanding of how drug-protein binding may be affected by glycation and of how separation and analysis methods based on HPAC can be employed to study systems with complex interactions or that involve modified proteins. PMID:26189669

  17. (PCG) Protein Crystal Growth Human Serum Albumin

    NASA Technical Reports Server (NTRS)

    1989-01-01

    (PCG) Protein Crystal Growth Human Serum Albumin. Contributes to many transport and regulatory processes and has multifunctional binding properties which range from various metals, to fatty acids, hormones, and a wide spectrum of therapeutic drugs. The most abundant protein of the circulatory system. It binds and transports an incredible variety of biological and pharmaceutical ligands throughout the blood stream. Principal Investigator on STS-26 was Larry DeLucas.

  18. α-Retinol is distributed through serum retinol-binding protein-independent mechanisms in the lactating sow-nursing piglet dyad.

    PubMed

    Dever, Joseph T; Surles, Rebecca L; Davis, Christopher R; Tanumihardjo, Sherry A

    2011-01-01

    α-Retinol (αR) is a structural isomer of retinol [vitamin A (VA)] that does not bind to serum retinol-binding protein (RBP). In this study, α-retinyl acetate (αRA) was synthesized and given orally (35 μmol) to VA-deficient lactating sows (n = 11) to assess its potential to trace RBP-independent retinol transport and tissue uptake. The αRA dose primarily appeared in sow serum as 4 α-retinyl esters (αRE) with peak serum total αR concentrations (the sum of the alcohol and ester forms) detected at 2 h (70 ± 23 nmol/L, mean ± SEM) postdose. From 0 to 40 h postdose, the percentage of serum total αR in the alcohol form did not increase. Rapid αR uptake into sow milk was observed with peak concentrations (371 ± 83 nmol/L) at 7.5 h postdose, consistent with the uptake of αRE from chylomicra. A high percentage of the αRA dose (62 ± 15%, mean ± SD) was present in the livers of sows (n = 6) killed 22-28 d postdose. Approximately 15-26% of the sow αRA dose was transferred to the livers of the nursing piglets (n = 17) after 3 d. In piglets and sows, a similar percentage of hepatic total αR was detected in the ester form as that of hepatic total retinol. Taken together, these data suggest that an oral dose of αRA effectively traces the uptake, esterification, chylomicron transport, and hepatic storage of retinol and may be useful for deciphering the role of RBP-independent delivery of retinol to other tissues.

  19. Protein Crystal Serum Albumin

    NASA Technical Reports Server (NTRS)

    1998-01-01

    As the most abundant protein in the circulatory system albumin contributes 80% to colloid osmotic blood pressure. Albumin is also chiefly responsible for the maintenance of blood pH. It is located in every tissue and bodily secretion, with extracellular protein comprising 60% of total albumin. Perhaps the most outstanding property of albumin is its ability to bind reversibly to an incredible variety of ligands. It is widely accepted in the pharmaceutical industry that the overall distribution, metabolism, and efficiency of many drugs are rendered ineffective because of their unusually high affinity for this abundant protein. An understanding of the chemistry of the various classes of pharmaceutical interactions with albumin can suggest new approaches to drug therapy and design. Principal Investigator: Dan Carter/New Century Pharmaceuticals

  20. Protein electrophoresis - serum

    MedlinePlus

    ... Hemolysis Hyperimmunization Immunoelectrophoresis - blood Immunofixation blood test Liver disease Malignancy Malnutrition Nephrotic syndrome Rheumatoid arthritis Serum globulin electrophoresis Serum iron test Systemic lupus erythematosus ...

  1. Prediction of Hepatocellular Carcinoma Development after Hepatitis C Virus Eradication Using Serum Wisteria floribunda Agglutinin-Positive Mac-2-Binding Protein

    PubMed Central

    Sato, Shunsuke; Genda, Takuya; Ichida, Takafumi; Amano, Nozomi; Sato, Sho; Murata, Ayato; Tsuzura, Hironori; Narita, Yutaka; Kanemitsu, Yoshio; Hirano, Katsuharu; Shimada, Yuji; Iijima, Katsuyori; Wada, Ryo; Nagahara, Akihito; Watanabe, Sumio

    2016-01-01

    We aimed to clarify the association between a novel serum fibrosis marker, Wisteria floribunda agglutinin-positive Mac-2-binding protein (WFA+-M2BP), and hepatocellular carcinoma (HCC) development in 355 patients with chronic hepatitis C who achieved sustained virologic response (SVR) through interferon-based antiviral therapy. Pretreatment serum WFA+-M2BP levels were quantified and the hazard ratios (HRs) for HCC development were retrospectively analyzed by Cox proportional hazard analysis. During the median follow-up time of 2.9 years, 12 patients developed HCC. Multivariate analysis demonstrated that high serum WFA+-M2BP (≥2.80 cut off index (COI), HR = 15.20, p = 0.013) and high fibrosis-4 (FIB-4) index (≥3.7, HR = 5.62, p = 0.034) were independent risk factors for HCC development. The three- and five-year cumulative incidence of HCC in patients with low WFA+-M2BP were 0.4% and 0.4%, respectively, whereas those of patients with high WFA+-M2BP were 7.7% and 17.6%, respectively (p < 0.001). In addition, combination of serum WFA+-M2BP and FIB-4 indices successfully stratified the risk of HCC: the five-year cumulative incidences of HCC were 26.9%, 6.8%, and 0.0% in patients with both, either, and none of these risk factors, respectively (p < 0.001). In conclusion, pretreatment serum WFA+-M2BP level is a useful predictor for HCC development after achieving SVR. PMID:27999409

  2. Effects of an endurance cycling competition on resting serum insulin-like growth factor I (IGF-I) and its binding proteins IGFBP-1 and IGFBP-3

    PubMed Central

    Chicharro, J; Lopez-Calderon, A; Hoyos, J; Martin-Velasco, A; Villa, G; Villanua, M; Lucia, A

    2001-01-01

    Objectives—To determine whether consecutive bouts of intense endurance exercise over a three week period alters serum concentrations of insulin-like growth factor I (IGF-I) and/or its binding proteins. Methods—Seventeen professional cyclists (mean (SEM) VO2MAX, 74.7 (2.1) ml/kg/min; age, 27 (1) years) competing in a three week tour race were selected as subjects. Blood samples were collected at each of the following time points: t0 (control, before the start of competition), t1 (end of first week), and t3 (end of third week). Serum levels of both total and free IGF-I and IGF binding proteins 1 and 3 (IGFBP-1 and IGFBP-3) were measured in each of the samples. Cortisol levels were measured in nine subjects. Results—A significant (p<0.01) increase was found in total IGF-I and IGFBP-1 at both t1 and t3 compared with to (IGF-I: 110.9 (17.7), 186.8 (12.0), 196.9 (14.7) ng/ml at t0, t1, and t3 respectively; IGFBP-1: 54.6 (6.6), 80.6 (8.0), and 89.2 (7.9) ng/ml at t0, t1, and t3 respectively). A significant (p<0.01) decrease was noted in free IGF-I at t3 compared with both to and t1 (t0: 0.9 (0.1) ng/ml; t1: 0.9 (0.1) ng/ml; t3: 0.7 (0.1) ng/ml); in contrast, IGFBP-3 levels remained stable throughout the race. Conclusions—It would appear that the increase in circulating levels of both IGF-I and its binding protein IGFBP-1 is a short term (one week) endocrine adaptation to endurance exercise. After three weeks of training, total IGF-I and IGFBP-1 remained stable, whereas free IGF-I fell below starting levels. Key Words: cycling; insulin-like growth factor; exercise; endurance; binding proteins PMID:11579061

  3. Comparative spectroscopic studies on drug binding characteristics and protein surface hydrophobicity of native and modified forms of bovine serum albumin: Possible relevance to change in protein structure/function upon non-enzymatic glycation

    NASA Astrophysics Data System (ADS)

    Khodarahmi, Reza; Karimi, Seyyed Arash; Ashrafi Kooshk, Mohammad Reza; Ghadami, Seyyed Abolghasem; Ghobadi, Sirous; Amani, Mojtaba

    2012-04-01

    The interaction between serum albumin (SA) and drugs has provided an interesting ground for understanding of drug effects, especially in drug distribution and drug-drug interaction on SA, in the case of multi-drug therapy. Determination of the impact of various factors on drug-protein interaction is especially important upon significant binding of drug to albumin. In the present study, the interaction of two drugs (furosemide and indomethacin) with native and modified albumins were investigated by using various spectroscopic methods. Fluorescence data indicated that 1:1 binding of drugs to bovine serum albumin (BSA) is associated with quenching of albumin intrinsic fluorescence. The Job's plot also confirmed that drug binds to BSA via mentioned stoichiometry. Analysis of the quenching and thermodynamic parameters indicated that intermolecular interactions between drug and albumin may change upon protein modification. The theoretical analyses also suggested some conformational changes of interacting side chains in subdomain IIA binding site (at the vicinity of W237), which were in good agreement with experimental data. Decrease of protein surface hydrophobicity (PSH) was also observed upon both albumin modification and drug binding.

  4. Comparative spectroscopic studies on drug binding characteristics and protein surface hydrophobicity of native and modified forms of bovine serum albumin: possible relevance to change in protein structure/function upon non-enzymatic glycation.

    PubMed

    Khodarahmi, Reza; Karimi, Seyyed Arash; Ashrafi Kooshk, Mohammad Reza; Ghadami, Seyyed Abolghasem; Ghobadi, Sirous; Amani, Mojtaba

    2012-04-01

    The interaction between serum albumin (SA) and drugs has provided an interesting ground for understanding of drug effects, especially in drug distribution and drug-drug interaction on SA, in the case of multi-drug therapy. Determination of the impact of various factors on drug-protein interaction is especially important upon significant binding of drug to albumin. In the present study, the interaction of two drugs (furosemide and indomethacin) with native and modified albumins were investigated by using various spectroscopic methods. Fluorescence data indicated that 1:1 binding of drugs to bovine serum albumin (BSA) is associated with quenching of albumin intrinsic fluorescence. The Job's plot also confirmed that drug binds to BSA via mentioned stoichiometry. Analysis of the quenching and thermodynamic parameters indicated that intermolecular interactions between drug and albumin may change upon protein modification. The theoretical analyses also suggested some conformational changes of interacting side chains in subdomain IIA binding site (at the vicinity of W237), which were in good agreement with experimental data. Decrease of protein surface hydrophobicity (PSH) was also observed upon both albumin modification and drug binding.

  5. Hevea latex lectin binding protein in C-serum as an anti-latex coagulating factor and its role in a proposed new model for latex coagulation.

    PubMed

    Wititsuwannakul, Rapepun; Pasitkul, Piyaporn; Jewtragoon, Pattavuth; Wititsuwannakul, Dhirayos

    2008-02-01

    A distinct protein specifically recognized by its strong interaction with Hevea latex lectin (HLL) was detected in the aqueous C-serum fraction of centrifuged fresh latex. This C-serum lectin binding protein (CS-HLLBP) exhibited strong inhibition of HLL-induced hemagglutination. The CS-HLLBP was purified to homogeneity by a protocol that included ammonium sulfate fractionation, size exclusion and ion exchange chromatography. The purified CS-HLLBP had a specific HI titer of 0.23microg ml(-1). Its M(r)s analyzed by SDS-PAGE was ca. 40kDa and that by gel filtration was ca. 204kDa. It has a pI value of 4.7, an optimum activity between pH 6 and10 and was heat stable up to 50 degrees C. The HI activity of CS-HLLBP was abolished upon treatment with chitinase. The CS-HLLBP inhibited HLL-induced rubber particle aggregation in a dose dependent manner. A highly positive correlation between CS-HLLBP activity and rubber yield per tapping was found. The correlations for fresh latex (r=0.98, P<0.01) and dry rubber (r=0.95, P<0.01) were both highly significant. This indicated that the CS-HLLBP might be used as a reliable marker for the mass screening of young seedlings to identify and select clones with potential to be superior producers of rubber. A latex anti-coagulating role of the CS-HLLBP is proposed. The findings described in this 3 paper series have been used to propose a new model of rubber latex coagulation that logically describes roles for the newly characterized latex lectin and the two lectin binding proteins.

  6. Retinol binding protein and vitamin D associations with serum antibody isotypes, serum influenza virus-specific neutralizing activities and airway cytokine profiles.

    PubMed

    Jones, B G; Oshansky, C M; Bajracharya, R; Tang, L; Sun, Y; Wong, S S; Webby, R; Thomas, P G; Hurwitz, J L

    2016-02-01

    Vitamin A supports the induction of immunoglobulin (Ig)A responses at mucosal surfaces in mice, but much less is known about the influence of vitamins on antibody isotype expression in humans. To address this knowledge gap, we examined 46 residual blood samples from adults and children, some of whom were experiencing influenza virus infections of the respiratory tract. Assays were performed for retinol binding protein (RBP, a surrogate for vitamin A), vitamin D (a related vitamin) and antibody isotypes. Results showed that all but two tested samples exhibited RBP and/or vitamin D insufficiencies or deficiencies. Vitamin D correlated with blood IgM and IgG3, while RBP correlated with IgG4 and IgA. RBP also correlated positively with age and with influenza virus-specific antibody neutralization titres. Individuals with low blood RBP levels exhibited the highest frequencies of over-expressed cytokines and growth factors in nasal wash samples, an indication of inflamed mucosal tissues. While cause-effect relationships were not discerned, results support a hypothesis that vitamins directly influence B cell isotype expression in humans, and by so doing may help protect mucosal surfaces from respiratory viral disease.

  7. Lecithin:retinol acyltransferase is critical for cellular uptake of vitamin A from serum retinol-binding protein.

    PubMed

    Amengual, Jaume; Golczak, Marcin; Palczewski, Krzysztof; von Lintig, Johannes

    2012-07-13

    Vitamin A (all-trans-retinol) must be adequately distributed within the mammalian body to produce visual chromophore in the eyes and all-trans-retinoic acid in other tissues. Vitamin A is transported in the blood bound to retinol-binding protein (holo-RBP), and its target cells express an RBP receptor encoded by the Stra6 (stimulated by retinoic acid 6) gene. Here we show in mice that cellular uptake of vitamin A from holo-RBP depends on functional coupling of STRA6 with intracellular lecithin:retinol acyltransferase (LRAT). Thus, vitamin A uptake from recombinant holo-RBP exhibited by wild type mice was impaired in Lrat(-/-) mice. We further provide evidence that vitamin A uptake is regulated by all-trans-retinoic acid in non-ocular tissues of mice. When in excess, vitamin A was rapidly taken up and converted to its inert ester form in peripheral tissues, such as lung, whereas in vitamin A deficiency, ocular retinoid uptake was favored. Finally, we show that the drug fenretinide, used clinically to presumably lower blood RBP levels and thus decrease circulating retinol, targets the functional coupling of STRA6 and LRAT to increase cellular vitamin A uptake in peripheral tissues. These studies provide mechanistic insights into how vitamin A is distributed to peripheral tissues in a regulated manner and identify LRAT as a critical component of this process.

  8. Factor H-binding protein is important for meningococcal survival in human whole blood and serum and in the presence of the antimicrobial peptide LL-37.

    PubMed

    Seib, K L; Serruto, D; Oriente, F; Delany, I; Adu-Bobie, J; Veggi, D; Aricò, B; Rappuoli, R; Pizza, M

    2009-01-01

    Factor H-binding protein (fHBP; GNA1870) is one of the antigens of the recombinant vaccine against serogroup B Neisseria meningitidis, which has been developed using reverse vaccinology and is the basis of a meningococcal B vaccine entering phase III clinical trials. Binding of factor H (fH), an inhibitor of the complement alternative pathway, to fHBP enables N. meningitidis to evade killing by the innate immune system. All fHBP null mutant strains analyzed were sensitive to killing in ex vivo human whole blood and serum models of meningococcal bacteremia with respect to the isogenic wild-type strains. The fHBP mutant strains of MC58 and BZ83 (high fHBP expressors) survived in human blood and serum for less than 60 min (decrease of >2 log(10) CFU), while NZ98/254 (intermediate fHBP expressor) and 67/00 (low fHBP expressor) showed decreases of >1 log(10) CFU after 60 to 120 min of incubation. In addition, fHBP is important for survival in the presence of the antimicrobial peptide LL-37 (decrease of >3 log(10) CFU after 2 h of incubation), most likely due to electrostatic interactions between fHBP and the cationic LL-37 molecule. Hence, the expression of fHBP by N. meningitidis strains is important for survival in human blood and human serum and in the presence of LL-37, even at low levels. The functional significance of fHBP in mediating resistance to the human immune response, in addition to its widespread distribution and its ability to induce bactericidal antibodies, indicates that it is an important component of the serogroup B meningococcal vaccine.

  9. Serum retinol binding protein 4 is negatively related to beta cell function in Chinese women with non-alcoholic fatty liver disease: a cross-sectional study

    PubMed Central

    2013-01-01

    Background To observe the relationship between serum retinol binding protein 4(RBP4) and β cell function in Chinese subjects with non-alcoholic fatty liver disease (NAFLD) and without known diabetes. Methods 106 patients diagnosed as fatty liver by ultrasonography (M/F: 61/45; aged 47.44 ± 14.16 years) were enrolled in our current cross-sectional study. Subjects with known diabetes, chronic virus hepatitis and excessive alcohol consumption were excluded. Serum RBP4 was detected by ELISA and validated by quantitative Western blotting. β cell function were assessed by HOMA in all subjects and by hyperglycemic clamp in 17 normal glucose tolerance subjects (M = 6, F = 11). Results The levels of serum RBP4 in men were higher than that in women (55.96 ± 11.14 vs 45.87 ± 10.31 μg/ml, p < 0.001). Pearson’s correlation analysis demonstrated that in women, serum RBP4 levels were significantly associated with fasting blood glucose (FBG), HOMA-β, and increment of first phase insulin secretion (1PH), but not associated with age, BMI, waist circumference, WHR, systolic (SBP) and diastolic blood pressure (DBP), TC, TG, HDL-c, LDL-c, 2 h blood glucose, HOMA-IR, ALT, AST, γ-GT, hepatic fat content (HFC), and insulin sensitivity index (ISI). However, in men, serum RBP4 levels were significantly associated with HDL-c, ALT, AST, but not associated with any other parameters as mentioned above. A stepwise multiple linear regression analysis demonstrated that in women, HOMA-IR and RBP4 were significantly associated with HOMA-β, while in men, HOMA-IR and BMI were significantly variables associated with HOMA-β. Conclusions Serum RBP4, secreted mainly by liver and adipose tissue, may involve in the pathogenesis of β cell dysfunction in Chinese women patients with NAFLD. PMID:24160775

  10. Serum insulin-like growth factors I and II, insulin-like growth factor binding protein-3 and risk of breast cancer in the Japan Collaborative Cohort study.

    PubMed

    Sakauchi, Fumio; Nojima, Masanori; Mori, Mitsuru; Wakai, Kenji; Suzuki, Sadao; Tamakoshi, Akiko; Ito, Yoshinori; Watanabe, Yoshiyuki; Inaba, Yutaka; Tajima, Kazuo; Nakachi, Kei

    2009-12-01

    The Japan Collaborative Cohort Study for Evaluation of Cancer Risk (JACC Study) was planned in the late 1980s as a large-scale cohort study of persons in various areas of Japan. In the present study, we conducted a nested case-control study and examined associations of breast cancer risk with serum levels of insulin-like growth factors I and II (IGF-I, IGF-II), as well as insulin-like growth factor binding protein-3 (IGFBP-3), among women who participated in the JACC Study and donated blood at the baseline. Sixty-three women who died or suffered from breast cancer were examined. Two or three controls were selected to match each case for age at recruitment and the study area. Controls were alive and not diagnosed as having breast cancer at the diagnosis date of the cases. Associations between the serum IGF-I, IGF-II, IGFBP-3 and breast cancer risk were evaluated using a conditional logistic regression model. In premenopausal Japanese women, IGF-I showed a marginal negative dose-dependent association with the breast cancer risk (trend P= 0.08), but any link disappeared on taking into account IGFBP-3 (trend P= 0.47), which was likely to be inversely associated with the risk. In postmenopausal women, IGFBP-3 showed a marginal dose-dependent association with the risk (trend P= 0.06). Further studies are needed to confirm these findings.

  11. Protein binding and in vitro serum thromboxane B2 inhibition by flunixin meglumine and meclofenamic acid in dog, goat and horse blood.

    PubMed

    Galbraith, E A; McKellar, Q A

    1996-07-01

    Flunixin was highly protein bound in the serum of dogs (92.2 per cent), goats (84.8 per cent) and horses (86.9 per cent). Meclofenamic acid was also highly protein bound, although there were larger differences between the extent of the binding in dogs (90.3 per cent), goats (84.7 per cent) and horses (99.8 per cent). Both flunixin and meclofenamic acid were potent inhibitors of the in vitro generation of thromboxane (Tx) B2 in blood. Flunixin inhibited the generation of TxB2 by 50 per cent of the maximum response (IC50) in dog, goat and horse blood at concentrations of 0.10, 0.02 and 0.04 microM respectively and by 100 per cent (Imax) at 2.07, 0.14 and 2.07 microM respectively. The IC50 values of meclofenamic acid in dogs, goats and horses were 0.77, 0.80 and 0.30 microM respectively and the Imax values were 3.93, 3.63 and 3.56 microM respectively. When the concentrations of flunixin were corrected for protein binding, it was estimated that the IC50 of the unbound fractions in dogs, goats and horses were 0.008, 0.003 and 0.005 microM, respectively. Similarly corrected values for meclofenamic acid were 0.075, 0.122 and 0.001 microM respectively.

  12. Serum 25-hydroxyvitamin D, vitamin D binding protein, and risk of colorectal cancer in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial

    PubMed Central

    Weinstein, Stephanie J.; Purdue, Mark P.; Smith-Warner, Stephanie A.; Mondul, Alison M.; Black, Amanda; Ahn, Jiyoung; Huang, Wen-Yi; Horst, Ronald L.; Kopp, William; Rager, Helen; Ziegler, Regina G.; Albanes, Demetrius

    2014-01-01

    The potential role of vitamin D in cancer prevention has generated substantial interest, and laboratory experiments indicate several anti-cancer properties for vitamin D compounds. Prospective studies of circulating 25-hydroxyvitamin D [25(OH)D], the accepted biomarker of vitamin D status, suggest an inverse association with colorectal cancer risk, but with some inconsistencies. Furthermore, the direct or indirect impact of the key transport protein, vitamin D binding protein (DBP), has not been examined. We conducted a prospective study of serum 25(OH)D and DBP concentrations and colorectal cancer risk in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, based on 476 colorectal cancer cases and 476 controls, matched on age, sex, race, and date of serum collection. All subjects underwent sigmoidoscopic screening at baseline and once during follow-up. Conditional logistic regression estimated odds ratios (ORs) and 95% confidence intervals (CIs). Circulating 25(OH)D was inversely associated with colorectal cancer (OR=0.60, 95% CI 0.38-0.94 for highest versus lowest quintile, p-trend 0.01). Adjusting for recognized colorectal cancer risk factors and accounting for seasonal vitamin D variation did not alter the findings. Neither circulating DBP nor the 25(OH)D:DBP molar ratio, a proxy for free circulating 25(OH)D, was associated with risk (OR=0.82, 95% CI 0.54-1.26, and OR=0.79, 95% CI 0.52-1.21, respectively), and DBP did not modify the 25(OH)D association. The current study eliminated confounding by colorectal cancer screening behavior, and supports an association between higher vitamin D status and substantially lower colorectal cancer risk, but does not indicate a direct or modifying role for DBP. PMID:25156182

  13. Cellulose binding domain proteins

    SciTech Connect

    Shoseyov, Oded; Shpiegl, Itai; Goldstein, Marc; Doi, Roy

    1998-01-01

    A cellulose binding domain (CBD) having a high affinity for crystalline cellulose and chitin is disclosed, along with methods for the molecular cloning and recombinant production thereof. Fusion products comprising the CBD and a second protein are likewise described. A wide range of applications are contemplated for both the CBD and the fusion products, including drug delivery, affinity separations, and diagnostic techniques.

  14. Cellulose binding domain proteins

    DOEpatents

    Shoseyov, O.; Shpiegl, I.; Goldstein, M.; Doi, R.

    1998-11-17

    A cellulose binding domain (CBD) having a high affinity for crystalline cellulose and chitin is disclosed, along with methods for the molecular cloning and recombinant production. Fusion products comprising the CBD and a second protein are likewise described. A wide range of applications are contemplated for both the CBD and the fusion products, including drug delivery, affinity separations, and diagnostic techniques. 16 figs.

  15. Associations of serum insulin-like growth factor-I and insulin-like growth factor-binding protein 3 levels with biomarker-calibrated protein, dairy product and milk intake in the Women's Health Initiative.

    PubMed

    Beasley, Jeannette M; Gunter, Marc J; LaCroix, Andrea Z; Prentice, Ross L; Neuhouser, Marian L; Tinker, Lesley F; Vitolins, Mara Z; Strickler, Howard D

    2014-03-14

    It is well established that protein-energy malnutrition decreases serum insulin-like growth factor (IGF)-I levels, and supplementation of 30 g of whey protein daily has been shown to increase serum IGF-I levels by 8 % after 2 years in a clinical trial. Cohort studies provide the opportunity to assess associations between dietary protein intake and IGF axis protein levels under more typical eating conditions. In the present study, we assessed the associations of circulating IGF axis protein levels (ELISA, Diagnostic Systems Laboratories) with total biomarker-calibrated protein intake, as well as with dairy product and milk intake, among postmenopausal women enrolled in the Women's Health Initiative (n 747). Analyses were carried out using multivariate linear regression models that adjusted for age, BMI, race/ethnicity, education, biomarker-calibrated energy intake, alcohol intake, smoking, physical activity and hormone therapy use. There was a positive association between milk intake and free IGF-I levels. A three-serving increase in milk intake per d (approximately 30 g of protein) was associated with an estimated average 18·6 % higher increase in free IGF-I levels (95 % CI 0·9, 39·3 %). However, total IGF-I and insulin-like growth factor-binding protein 3 (IGFBP-3) levels were not associated with milk consumption and nor were there associations between biomarker-calibrated protein intake, biomarker-calibrated energy intake, and free IGF-I, total IGF-I or IGFBP-3 levels. The findings of the present study carried out in postmenopausal women are consistent with clinical trial data suggesting a specific relationship between milk consumption and serum IGF-I levels, although in the present study this association was only statistically significant for free, but not total, IGF-I or IGFBP-3 levels.

  16. Association of serum retinol and carotenoids with insulin-like growth factors and insulin-like growth factor binding protein-3 among control subjects of a nested case-control study in the Japan Collaborative Cohort Study.

    PubMed

    Suzuki, Koji; Ito, Yoshinori; Hashimoto, Shuji; Kawado, Miyuki; Inoue, Takashi; Ando, Masahiko; Watanabe, Yoshiyuki; Inaba, Yutaka; Tajima, Kazuo; Nakachi, Kei; Tamakoshi, Akiko

    2009-12-01

    Insulin-like growth factor (IGF)-I and its main binding protein, IGFBP-3, modulate cell growth and survival, and thus are thought to be important for tumor development. Carotenoids and retinol have been linked to the prevention of several cancers. We here evaluated associations of serum levels of carotenoids and retinol with IGF-I, IGF-II, and IGFBP-3 within the context of the JACC Study. The study subjects were 924 controls (578 men and 346 women) of a nested case-control study of lung and colorectal cancer risk. Using frozen-stored sera, serum levels of a-carotene, b-carotene, lycopene, b-cryptoxanthin, zeaxanthin/lutein, and retinol were separately determined using high-performance liquid chromatography. Serum levels of IGF-I, IGF-II, and IGFBP-3 were measured by immuno-radiometric assay. Confounding factors-adjusted least squares mean levels of serum IGF-I, IGF-II, and IGFBP-3 for each quartile of serum levels of carotenoids and retinol were estimated. Serum IGF-I, IGF-II, and IGFBP-3 levels increased with increasing serum retinol levels. Moreover, serum IGF-I levels were significantly higher in highest quartile of serum provitamin A, such as a-carotene, b-carotene, and b-cryptoxanthin, among women. Serum IGFBP-3 levels decreased with increasing serum lycopene levels in women and with increasing serum zeaxanthin/lutein levels in men. The current study indicates that positive associations exist for serum retinol levels with serum levels of IGF-I, IGF-II, and IGFBP-3 independent of age, BMI, smoking habits, drinking habits, and intake of energy and protein among Japanese healthy men and women.

  17. Human Serum Amyloid A3 (SAA3) Protein, Expressed as a Fusion Protein with SAA2, Binds the Oxidized Low Density Lipoprotein Receptor

    PubMed Central

    Tomita, Takeshi; Ieguchi, Katsuaki; Sawamura, Tatsuya; Maru, Yoshiro

    2015-01-01

    Serum amyloid A3 (SAA3) possesses characteristics distinct from the other serum amyloid A isoforms, SAA1, SAA2, and SAA4. High density lipoprotein contains the latter three isoforms, but not SAA3. The expression of mouse SAA3 (mSAA3) is known to be up-regulated extrahepatically in inflammatory responses, and acts as an endogenous ligand for the toll-like receptor 4/MD-2 complex. We previously reported that mSAA3 plays an important role in facilitating tumor metastasis by attracting circulating tumor cells and enhancing hyperpermeability in the lungs. On the other hand, human SAA3 (hSAA3) has long been regarded as a pseudogene, which is in contrast to the abundant expression levels of the other isoforms. Although the nucleotide sequence of hSAA3 is very similar to that of the other SAAs, a single oligonucleotide insertion in exon 2 causes a frame-shift to generate a unique amino acid sequence. In the present study, we identified that hSAA3 was transcribed in the hSAA2-SAA3 fusion transcripts of several human cell lines. In the fusion transcript, hSAA2 exon 3 was connected to hSAA3 exon 1 or hSAA3 exon 2, located approximately 130kb downstream from hSAA2 exon 3 in the genome, which suggested that it is produced by alternative splicing. Furthermore, we succeeded in detecting and isolating hSAA3 protein for the first time by an immunoprecipitation-enzyme linked immune assay system using monoclonal and polyclonal antibodies that recognize the hSAA3 unique amino acid sequence. We also demonstrated that hSAA3 bound oxidized low density lipoprotein receptor (oxLDL receptor, LOX-1) and elevated the phosphorylation of ERK, the intracellular MAP-kinase signaling protein. PMID:25738827

  18. Binding sites of retinol and retinoic acid with serum albumins.

    PubMed

    Belatik, A; Hotchandani, S; Bariyanga, J; Tajmir-Riahi, H A

    2012-02-01

    Retinoids are effectively transported in the bloodstream via serum albumins. We report the complexation of bovine serum albumin (BSA) with retinol and retinoic acid at physiological conditions, using constant protein concentration and various retinoid contents. FTIR, CD and fluorescence spectroscopic methods and molecular modeling were used to analyze retinoid binding site, the binding constant and the effects of complexation on BSA stability and secondary structure. Structural analysis showed that retinoids bind BSA via hydrophilic and hydrophobic interactions with overall binding constants of K(Ret)(-BSA) = 5.3 (±0.8) × 10(6) M(-1) and K(Retac-BSA) = 2.3 (±0.4) × 10(6) M(-1). The number of bound retinoid molecules (n) was 1.20 (±0.2) for retinol and 1.8 (±0.3) for retinoic acid. Molecular modeling showed the participation of several amino acids in retinoid-BSA complexes stabilized by H-bonding network. The retinoid binding altered BSA conformation with a major reduction of α-helix from 61% (free BSA) to 36% (retinol-BSA) and 26% (retinoic acid-BSA) with an increase in turn and random coil structures indicating a partial protein unfolding. The results indicate that serum albumins are capable of transporting retinoids in vitro and in vivo.

  19. Ghrelin binding to serum albumin and its biological impact.

    PubMed

    Lufrano, Daniela; Trejo, Sebastián A; Llovera, Ramiro E; Salgueiro, Mariano; Fernandez, Gimena; Martínez Damonte, Valentina; González Flecha, F Luis; Raingo, Jesica; Ermácora, Mario R; Perelló, Mario

    2016-11-15

    Ghrelin is an octanoylated peptide hormone that plays a key role in the regulation of the body weight and glucose homeostasis. In plasma, ghrelin circulates bound to larger proteins whose identities are partially established. Here, we used size exclusion chromatography, mass spectrometry and isothermal titration microcalorimetry to show that ghrelin interacts with serum albumin. Furthermore, we found that such interaction displays an estimated dissociation constant (KD) in the micromolar range and involves albumin fatty-acid binding sites as well as the octanoyl moiety of ghrelin. Notably, albumin-ghrelin interaction reduces the spontaneous deacylation of the hormone. Both in vitro experiments-assessing ghrelin ability to inhibit calcium channels-and in vivo studies-evaluating ghrelin orexigenic effects-indicate that the binding to albumin affects the bioactivity of the hormone. In conclusion, our results suggest that ghrelin binds to serum albumin and that this interaction impacts on the biological activity of the hormone.

  20. Interactive association of drugs binding to human serum albumin.

    PubMed

    Yang, Feng; Zhang, Yao; Liang, Hong

    2014-02-27

    Human serum albumin (HSA) is an abundant plasma protein, which attracts great interest in the pharmaceutical industry since it can bind a remarkable variety of drugs impacting their delivery and efficacy and ultimately altering the drug's pharmacokinetic and pharmacodynamic properties. Additionally, HSA is widely used in clinical settings as a drug delivery system due to its potential for improving targeting while decreasing the side effects of drugs. It is thus of great importance from the viewpoint of pharmaceutical sciences to clarify the structure, function, and properties of HSA-drug complexes. This review will succinctly outline the properties of binding site of drugs in IIA subdomain within the structure of HSA. We will also give an overview on the binding characterization of interactive association of drugs to human serum albumin that may potentially lead to significant clinical applications.

  1. Spectroscopic study on binding of rutin to human serum albumin

    NASA Astrophysics Data System (ADS)

    Pastukhov, Alexander V.; Levchenko, Lidiya A.; Sadkov, Anatoli P.

    2007-10-01

    Steady-state and time-resolved fluorescence spectroscopy techniques were used to study the interaction of the flavonoid rutin with human serum albumin (HSA) as well as spectral properties of the protein-bound flavonoid. Both quenching of the intrinsic fluorescence of the protein (Trp214) and the ligand fluorescence, appearing upon complexation with HSA, were used to determine binding parameters. The binding constant determined from the quenching of the Trp214 fluorescence by rutin is equal to 6.87 ± 0.22 × 10 4 M -1 and that obtained from the fluorescence of HSA-bound rutin is 3.8 ± 0.4 × 10 4 M -1. Based on the Job plot analysis, the 1:1 binding stoichiometry for the HSA-rutin complex was determined. The efficient quenching of the Trp214 fluorescence by rutin, fluorescence resonance energy transfer from excited Trp214 to rutin, and competitive binding of warfarin indicate that the binding site for the flavonoid is situated within subdomain IIA of HSA. The presence of the sugar moiety in the flavonoid molecule reduces affinity of rutin for binding to HSA but does not affect the binding stoichiometry and location of the binding site compared with aglycone analogues.

  2. Elevated serum levels of Wisteria floribunda agglutinin-positive human Mac-2 binding protein predict the development of hepatocellular carcinoma in hepatitis C patients

    PubMed Central

    Yamasaki, Kazumi; Tateyama, Masakuni; Abiru, Seigo; Komori, Atsumasa; Nagaoka, Shinya; Saeki, Akira; Hashimoto, Satoru; Sasaki, Ryu; Bekki, Shigemune; Kugiyama, Yuki; Miyazoe, Yuri; Kuno, Atsushi; Korenaga, Masaaki; Togayachi, Akira; Ocho, Makoto; Mizokami, Masashi; Narimatsu, Hisashi; Yatsuhashi, Hiroshi

    2014-01-01

    The Wisteria floribunda agglutinin-positive human Mac-2-binding protein (WFA+-M2BP) was recently shown to be a liver fibrosis glycobiomarker with a unique fibrosis-related glycoalteration. We evaluated the ability of WFA+-M2BP to predict the development of hepatocellular carcinoma (HCC) in patients who were infected with the hepatitis C virus (HCV). A total of 707 patients who had been admitted to our hospital with chronic HCV infection without other potential risk factors were evaluated to determine the ability of WFA+-M2BP to predict the development of HCC; factors evaluated included age, sex, viral load, genotypes, fibrosis stage, aspartate and alanine aminotransferase levels, bilirubin, albumin, platelet count, alpha-fetoprotein (AFP), WFA+-M2BP, and the response to interferon (IFN) therapy. Serum WFA+-M2BP levels were significantly increased according to the progression of liver fibrosis stage (P < 0.001). In each distinctive stage of fibrosis (F0-F1, F2, F3, and F4), the risk of development of HCC was increased according to the elevation of WFA+-M2BP. Multivariate analysis identified age >57 years, F4, AFP >20 ng/mL, WFA+-M2BP ≥4, and WFA+-M2BP 1-4 as well as the response to IFN (no therapy vs. sustained virological response) as independent risk factors for the development of HCC. The time-dependent areas under the receiver operating characteristic curve demonstrated that the WFA+-M2BP assay predicted the development of HCC with higher diagnostic accuracy than AFP. Conclusion: WFA+-M2BP can be applied as a useful surrogate marker for the risk of HCC development, in addition to liver biopsy. (Hepatology 2014;60:1563–1570) PMID:25042054

  3. Platinum group metallodrug-protein binding studies by capillary electrophoresis - inductively coupled plasma-mass spectrometry: a further insight into the reactivity of a novel antitumor ruthenium(III) complex toward human serum proteins.

    PubMed

    Polec-Pawlak, Kasia; Abramski, Jan K; Semenova, Olga; Hartinger, Christian G; Timerbaev, Andrei R; Keppler, Bernhard K; Jarosz, Maciej

    2006-03-01

    Biochemical speciation analysis has become a hot area of CE research due largely to growing emergence of inductively coupled plasma (ICP)-MS as a proper detection technique. A benefit of CE-ICP-MS coupling in species-selective analysis of anticancer metal-based drugs is the possibility of distinguishing the signals of the intact drug and its metabolites and hence of quantifying them independently. This advantage (over CE with UV-vis detection) was exploited here in order to gain better knowledge about the rate and degree of the transformation of indazolium [trans-tetrachlorobis(1H-indazole)ruthenate(III)] (KP1019), a promising tumor-inhibiting agent that successfully finished phase I clinical studies, upon its binding toward individual serum transport proteins. At increasing the KP1019/protein molar ratio, the reaction rate expressed by an evolving peak of the protein adduct became faster, with the equilibrium state being reached after about 40 and 60 min of incubation at 37 degrees C for transferrin and albumin, respectively. The binding reaction was shown to obey the first-order character that enabled for reliable calculation of the corresponding rate constants as (28.7 +/- 1.5) x 10(-4) and (10.6 +/- 0.7) x 10(-4)/s, respectively. When incubated with a ten-fold excess of KP1019, albumin and transferrin bound, respectively, up to 8 and 10 equiv. of ruthenium (Ru). Relative affinity of KP1019 toward different proteins under simulated physiological conditions was also characterized in terms of the overall binding constants (5600 and 10 600/M, respectively). To emphasize the difference in the protein-binding behavior, a competitive interaction of KP1019 was followed by CE-ICP-MS at the actual molar ratio of proteins in blood, i.e. a ten-fold excess of albumin over transferrin. The fact that KP1019 binds to albumin stronger than to transferrin was manifested by finding almost all ruthenium (98-99%) in the albumin fraction.

  4. Biogenic and synthetic polyamines bind bovine serum albumin.

    PubMed

    Dubeau, S; Bourassa, P; Thomas, T J; Tajmir-Riahi, H A

    2010-06-14

    Biogenic polyamines are found to modulate protein synthesis at different levels, while polyamine analogues have shown major antitumor activity in multiple experimental models, including breast cancer. The aim of this study was to examine the interaction of bovine serum albumin (BSA) with biogenic polyamines, spermine and spermidine, and polyamine analogues 3,7,11,15-tetrazaheptadecane x 4 HCl (BE-333) and 3,7,11,15,19-pentazahenicosane x 5 HCl (BE-3333) in aqueous solution at physiological conditions. FTIR, UV-visible, CD, and fluorescence spectroscopic methods were used to determine the polyamine binding mode and the effects of polyamine complexation on protein stability and secondary structure. Structural analysis showed that polyamines bind BSA via both hydrophilic and hydrophobic interactions. Stronger polyamine-protein complexes formed with biogenic than synthetic polyamines with overall binding constants of K(spm) = 3.56 (+/-0.5) x 10(5) M(-1), K(spmd) = 1.77 (+/-0.4) x 10(5) M(-1), K(BE-333) = 1.11 (+/-0.3) x 10(4) M(-1) and K(BE-3333) = 3.90 (+/-0.7) x 10(4) M(-1) that correlate with their positively charged amino group contents. Major alterations of protein conformation were observed with reduction of alpha-helix from 63% (free protein) to 55-33% and increase of turn 12% (free protein) to 28-16% and random coil from 6% (free protein) to 24-17% in the polyamine-BSA complexes, indicating a partial protein unfolding. These data suggest that serum albumins might act as polyamine carrier proteins in delivering polyamine analogues to target tissues.

  5. Pharmacokinetics of gestodene and ethinylestradiol in 14 women during three months of treatment with a new tri-step combination oral contraceptive: serum protein binding of gestodene and influence of treatment on free and total testosterone levels in the serum.

    PubMed

    Kuhnz, W; Baumann, A; Staks, T; Dibbelt, L; Knuppen, R; Jütting, G

    1993-10-01

    The pharmacokinetics of gestodene (GEST) and ethinylestradiol (EE2) were determined in 14 healthy women (age 18 to 32 years) during a treatment period of three months with a new tri-step combination oral contraceptive (Milvane). Prior to this treatment period, the same women received a single administration of a coated tablet containing 0.1 mg GEST together with 0.03 mg EE2. There was a wash-out phase of one week between both treatments. Following single dose administration, a mean terminal half-life of 18 h was observed for GEST. The total clearance was 0.9 ml x min-1 x kg-1 and the volume of distribution was 84 l. During a treatment cycle, GEST levels in the serum accumulated by a factor of 8 as compared to single dose administration. Steady-state drug levels were reached during the second half of each cycle. As compared to single dose administration, the following changes were observed for GEST at the end of treatment cycles one and three: prolonged terminal half-life (20 to 22 h), reduced total (0.16 ml x min-1 x kg-1) and free clearance (ca. 27 ml x min-1 x kg-1), reduced volume of distribution (ca. 18 l). A concomitant EE2-induced increase in the SHBG concentrations by a factor of three as compared to pretreatment values was observed during a treatment cycle and appeared to be mainly responsible for the changes in the pharmacokinetics of GEST. Marked changes were also seen for the serum protein binding of GEST. After single dose administration, the free fraction of GEST was 1.3% and the fractions bound to SHBG and albumin were 69.4% and 29.3%, respectively. At the end of cycle one, the free fraction was only 0.6% and the fractions bound to SHBG and albumin were 81.4% and 18.0%, respectively. There was no difference in corresponding pharmacokinetic parameters and in the serum protein binding of GEST at the end of cycles one and three. On the last day of treatment cycles one and three, the AUC(0-4h) values of EE2 were 299.2 and 278.1 pg x ml-1 x h, respectively

  6. 21 CFR 866.5765 - Retinol-binding protein immunological test system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Retinol-binding protein immunological test system....5765 Retinol-binding protein immunological test system. (a) Identification. A retinol-binding protein... the retinol-binding protein that binds and transports vitamin A in serum and urine. Measurement...

  7. 21 CFR 866.5765 - Retinol-binding protein immunological test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Retinol-binding protein immunological test system....5765 Retinol-binding protein immunological test system. (a) Identification. A retinol-binding protein... the retinol-binding protein that binds and transports vitamin A in serum and urine. Measurement...

  8. 21 CFR 866.5765 - Retinol-binding protein immunological test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Retinol-binding protein immunological test system....5765 Retinol-binding protein immunological test system. (a) Identification. A retinol-binding protein... the retinol-binding protein that binds and transports vitamin A in serum and urine. Measurement...

  9. 21 CFR 866.5765 - Retinol-binding protein immunological test system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Retinol-binding protein immunological test system....5765 Retinol-binding protein immunological test system. (a) Identification. A retinol-binding protein... the retinol-binding protein that binds and transports vitamin A in serum and urine. Measurement...

  10. 21 CFR 866.5765 - Retinol-binding protein immunological test system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Retinol-binding protein immunological test system....5765 Retinol-binding protein immunological test system. (a) Identification. A retinol-binding protein... the retinol-binding protein that binds and transports vitamin A in serum and urine. Measurement...

  11. Relations between high-affinity binding sites of markers for binding regions on human serum albumin.

    PubMed Central

    Kragh-Hansen, U

    1985-01-01

    Binding of warfarin, digitoxin, diazepam, salicylate and Phenol Red, individually or in different pair combinations, to defatted human serum albumin at ligand/protein molar ratios less than 1:1 was studied at pH 7.0. The binding was determined by ultrafiltration. Some of the experiments were repeated with the use of equilibrium dialysis in order to strengthen the results. Irrespective of the method used, all ligands bind to one high-affinity binding site with an association constant in the range 10(4)-10(6) M-1. High-affinity binding of the following pair of ligands took place independently: warfarin-Phenol Red, warfarin-diazepam, warfarin-digitoxin and digitoxin-diazepam. Simultaneous binding of warfarin and salicylate led to a mutual decrease in binding of one another, as did simultaneous binding of digitoxin and Phenol Red. Both effects could be accounted for by a coupling constant. The coupling constant is the factor by which the primary association constants are affected; in these examples of anti-co-operativity the factor has a value between 0 and 1. In the first example it was calculated to be 0.8 and in the latter 0.5. Finally, digitoxin and salicylate were found to compete for a common high-affinity binding site. The present findings support the proposal of four separate primary binding sites for warfarin, digitoxin (and salicylate), diazepam and Phenol Red. An attempt to correlate this partial binding model for serum albumin with other models in the literature is made. PMID:3977850

  12. Transporting testosterone and its dimers by serum proteins.

    PubMed

    Chanphai, P; Vesper, A R; Bekale, L; Bérubé, G; Tajmir-Riahi, H A

    2015-12-01

    A substantial part of steroids is bound to serum proteins in vivo. We report the association of testosterone and it aliphatic dimer (alip) and aromatic dimer (arom) with human serum albumin (HSA) and bovine serum albumin (BSA) in aqueous solution at physiological pH. Multiple spectroscopic methods, transmission electron microscopy (TEM) and molecular modeling were used to characterize steroid-protein binding and protein aggregation process. Spectroscopic analysis showed that steroids bind protein via hydrophobic, hydrophilic and H-bonding interactions. HSA forms more stable complexes than BSA. The binding affinity of steroid-protein adducts is testosterone>dimer-aromatic>dimer-aliphatic. Transmission electron microscopy showed major changes in protein morphology as steroid-protein complexation occurred with increase in the diameter of the protein aggregate indicating encapsulation of steroids by serum proteins. Modeling showed the presence of H-bonding stabilized testosterone-protein complexes with the free binding energy of -12.95 for HSA and -11.55 kcal/mol for BSA, indicating that the interaction process is spontaneous at room temperature. Steroid complexation induced more perturbations of BSA conformation than HSA.

  13. Piezoelectric microcantilever serum protein detector

    NASA Astrophysics Data System (ADS)

    Capobianco, Joseph A.

    The development of a serum protein detector will provide opportunities for better screening of at-risk cancer patients, tighter surveillance of disease recurrence and better monitoring of treatment. An integrated system that can process clinical samples for a number of different types of biomarkers would be a useful tool in the early detection of cancer. Also, screening biomarkers such as antibodies in serum would provide clinicians with information regarding the patient's response to treatment. Therefore, the goal of this study is to develop a sensor which can be used for rapid, all-electrical, real-time, label-fee, in-situ, specific quantification of cancer markers, e.g., human epidermal receptor 2 (Her2) or antibodies, in serum. To achieve this end, piezoelectric microcantilever sensors (PEMS) were constructed using an 8 mum thick lead magnesium niobate-lead titanate (PMN-PT) freestanding film as the piezoelectric layer. The desired limit of detection is on the order of pg/mL. In order to achieve this goal the higher frequency lateral extension modes were used. Also, as the driving and sensing of the PEMS is electrical, the PEMS must be insulated in a manner that allows it to function in aqueous solutions. The insulation layer must also be compatible with standardized bioconjugation techniques. Finally, detection of both cancer antigens and antibodies in serum was carried out, and the results were compared to a standard commercialized protocol. PEMS have demonstrated the capability of detecting Her2 at a concentration of 5 pg/mL in diluted human serum (1:40) in less than 1 hour. The approach can be easily translated into the clinical setting because the sensitivity is more than sufficient for monitoring prognosis of breast cancer patients. In addition to Her2 detection, antibodies in serum were assayed in order to demonstrate the feasibility of monitoring the immune response for antibody-dependent cellular cytotoxicity (ADCC) in patients on antibody therapies

  14. Effects of glycation on meloxicam binding to human serum albumin

    NASA Astrophysics Data System (ADS)

    Trynda-Lemiesz, Lilianna; Wiglusz, Katarzyna

    2011-05-01

    The current study reports a binding of meloxicam a pharmacologically important new generation, non-steroidal anti-inflammatory drug to glycated form of the human serum albumin (HSA). The interaction of the meloxicam with nonglycated and glycated albumin has been studied at pH 7.4 in 0.05 M sodium phosphate buffer with 0.1 M NaCl, using fluorescence quenching technique and circular dichroism spectroscopy. Results of the present study have shown that the meloxicam could bind both forms of albumin glycated and nonglycated at a site, which was close to the tryptophan residues. Similarly, how for native albumin glycated form has had one high affinity site for the drug with association constants of the order of 10 5 M -1. The glycation process of the HSA significantly has affected the impact of the meloxicam on the binding of other ligands such as warfarin and bilirubin. The affinity of the glycated albumin for bilirubin as for native albumin has been reduced by meloxicam but observed effect was weaker by half (about 20%) compared with nonglycated albumin. In contrast to the native albumin meloxicam binding to glycated form of the protein only slightly affected the binding of warfarin. It seemed possible that the effects on warfarin binding might be entirely attributable to the Lys 199 modification which was in site I.

  15. Synthetic human serum albumin Sudlow I binding site mimics.

    PubMed

    Karlsson, Björn C G; Rosengren, Annika M; Näslund, Inga; Andersson, Per Ola; Nicholls, Ian A

    2010-11-25

    Here, we report the design, synthesis, and characterization of molecularly imprinted polymer (MIP) derived mimics of the human serum albumin (HSA) Sudlow I site-the binding site for the anticoagulant warfarin. MIP design was based upon a combination of experimental ((1)H NMR) and computational (molecular dynamics) methods. Two MIPs and corresponding nonimprinted reference polymers were synthesized and characterized (scanning electron microscopy; nitrogen sorption; and Fourier transform infrared spectroscopy). MIP-ligand recognition was examined using radioligand binding studies, where the largest number of selective sites was found in a warfarin-imprinted methacrylic acid-ethylene dimethacrylate copolymer (MAA-MIP). The warfarin selectivity of this MIP was confirmed using radioligand displacement and zonal chromatographic studies. A direct comparison of MIP-warfarin binding characteristics with those of the HSA Sudlow I binding site was made, and similarities in site population (per gram polymer or protein) and affinities were observed. The warfarin selectivity of the MIP suggests its potential for use as a recognition element in a MIP-based warfarin sensor and even as a model to aid in understanding and steering blood-plasma protein-regulated transport processes or even for the development of warfarin sensors.

  16. Optical spectroscopic exploration of binding of Cochineal Red A with two homologous serum albumins.

    PubMed

    Bolel, Priyanka; Mahapatra, Niharendu; Halder, Mintu

    2012-04-11

    Cochineal Red A is a negatively charged synthetic azo food colorant and a potential carcinogen. We present here the study of binding of Cochineal Red A with two homologous serum albumins, human (HSA) and bovine (BSA), in aqueous pH 7.4 buffer by optical spectroscopic techniques. Protein intrinsic fluorescence quenching by Cochineal Red A occurs through ground-state static interaction and its binding with BSA is stronger than with HSA. The magnitudes of thermodynamic parameters suggest that dye binding occurs principally via electrostatic complexation. Site-marker competitive binding shows that Cochineal Red A binds primarily to site I of serum albumins. Circular dichroic spectra indicate that dye binding results in some conformational modification of serum albumins. Increased ionic strength of the medium results in lowering of binding. This study provides an important insight into possible means of removal of dye toxicity.

  17. Characterization of the Effect of Drug-Drug Interaction on Protein Binding in Concurrent Administration of Sulfamethoxazol and Diclofenac Sodium Using Bovine Serum Albumin

    PubMed Central

    Hossain, Md Kamal; Khatun, Amina; Rahman, Mahmudur; Akter, Md Nahid; Chowdhury, Sadia Afreen; Alam, SM Mahbubul

    2016-01-01

    Purpose: This project was aimed to determine the effect of concurrent administration of sulfamethoxazole and diclofenac sodium. Methods: Equilibrium dialysis method was adopted to study different protein binding aspects of sulfamethoxazole and diclofenac sodium. Results: Sulfamethoxazole showed two types of association constants; high affinity constant 29.0±0.20×106 M-1 with lower number of binding sites of 0.7±1 and low affinity constant 1.13±0.20×106 M-1 with higher number of binding sites of 3.45±1 at pH 7.4 and 40 °C temperature. Diclofenac sodium showed high affinity constant 33.66±0.20×106 M-1 with lower number of binding sites of 1.01±1 and low affinity constant 1.72±0.20×106 M-1 with higher number of binding sites of 6.40±1 at the same condition. Site specific probe displacement data implied that site-I, warfarin sodium site, was the high affinity site, while site-II, diazepam site, was the low affinity site for these drugs. During concurrent administration, sulfamethoxazole increased the free concentration of diclofenac sodium from 17.5±0.14% to 70.0±0.014% in absence and from 22.5±0.07% to 83.0±0.014% in presence of site-I specific probe. Diclofenac sodium also increased the free concentration of sulfamethoxazole from 2.8±0.07% to 52.0±0.14% and from 8.5±0.014% to 64.4±0.07% in absence and presence of site-I specific probe respectively. Conclusion: The study revealed that the concurrent administration of sulfamethoxazole and diclofenac sodium may result drug concentration alteration in blood. PMID:28101466

  18. Physicochemical aspects of the energetics of binding of sulphanilic acid with bovine serum albumin

    NASA Astrophysics Data System (ADS)

    Banipal, Tarlok S.; Kaur, Amandeep; Banipal, Parampaul K.

    2017-01-01

    The thermodynamic study of the binding of sulphanilic acid with model transport protein bovine serum albumin is a promising approach in the area of synthesizing new sulfa drugs with improved therapeutic effect. Thus, such binding studies play an important role in the rational drug design process. The binding between sulphanilic acid and bovine serum albumin has been studied using calorimetry, light scattering in combination with spectroscopic and microscopic techniques. The calorimetric data reveals the presence of two sequential nature of binding sites where the first binding site has stronger affinity ( 104 M- 1) and second binding site has weaker affinity ( 103 M- 1). However, the spectroscopic (absorption and fluorescence) results suggest the presence of single low affinity binding site ( 103 M- 1) on protein. The contribution of polar and non-polar interactions to the binding process has been explored in the presence of various additives. It is found that sulphanilic acid binds with high affinity at Sudlow site II and with low affinity at Sudlow site I of protein. Light scattering and circular dichroism measurements have been used to study the effect on the molecular topology and conformation of protein, respectively. Thus these studies provide important insights into the binding of sulphanilic acid with bovine serum albumin both quantitatively and qualitatively.

  19. Exploring the binding mechanism of ondansetron hydrochloride to serum albumins: spectroscopic approach.

    PubMed

    B, Sandhya; Hegde, Ashwini H; K C, Ramesh; J, Seetharamappa

    2012-02-01

    The mechanism of interaction of ondansetron hydrochloride (OND) to serum albumins [bovine serum albumin (BSA) and human serum albumin (HSA)] was studied for the first time employing fluorimetric, circular dichroism, FTIR and UV-vis absorption techniques under the simulated physiological conditions. Fluorimetric results were utilized to investigate the binding and conformational characteristics of protein upon interaction with varying concentrations of the drug. Higher binding constant values revealed the strong interaction between the drug and protein while the number of binding sites close to unity indicated single class of binding site for OND in protein. Thermodynamic results revealed that both hydrogen bond and hydrophobic interactions played a major role in stabilizing drug-protein complex. Site marker competitive experiments indicated that the OND bound to albumins at subdomin II A (Sudlow's site I). Further, the binding distance between OND and serum albumin was calculated based on the Förster's theory of non-radioactive energy transfer and found to be 2.30 and 3.41 nm, respectively for OND-BSA and OND-HSA. The circular dichroism data revealed that the presence of OND decreased the α-helix content of serum albumins. 3D-fluorescence results also indicated the conformational changes in protein upon interaction with OND. Further, the effects of some cations have been investigated in the interaction of drug to protein.

  20. Exploring the binding mechanism of ondansetron hydrochloride to serum albumins: Spectroscopic approach

    NASA Astrophysics Data System (ADS)

    Sandhya, B.; Hegde, Ashwini H.; K. C., Ramesh; Seetharamappa, J.

    2012-02-01

    The mechanism of interaction of ondansetron hydrochloride (OND) to serum albumins [bovine serum albumin (BSA) and human serum albumin (HSA)] was studied for the first time employing fluorimetric, circular dichroism, FTIR and UV-vis absorption techniques under the simulated physiological conditions. Fluorimetric results were utilized to investigate the binding and conformational characteristics of protein upon interaction with varying concentrations of the drug. Higher binding constant values revealed the strong interaction between the drug and protein while the number of binding sites close to unity indicated single class of binding site for OND in protein. Thermodynamic results revealed that both hydrogen bond and hydrophobic interactions played a major role in stabilizing drug-protein complex. Site marker competitive experiments indicated that the OND bound to albumins at subdomin II A (Sudlow's site I). Further, the binding distance between OND and serum albumin was calculated based on the Förster's theory of non-radioactive energy transfer and found to be 2.30 and 3.41 nm, respectively for OND-BSA and OND-HSA. The circular dichroism data revealed that the presence of OND decreased the α-helix content of serum albumins. 3D-fluorescence results also indicated the conformational changes in protein upon interaction with OND. Further, the effects of some cations have been investigated in the interaction of drug to protein.

  1. The prion protein binds thiamine.

    PubMed

    Perez-Pineiro, Rolando; Bjorndahl, Trent C; Berjanskii, Mark V; Hau, David; Li, Li; Huang, Alan; Lee, Rose; Gibbs, Ebrima; Ladner, Carol; Dong, Ying Wei; Abera, Ashenafi; Cashman, Neil R; Wishart, David S

    2011-11-01

    Although highly conserved throughout evolution, the exact biological function of the prion protein is still unclear. In an effort to identify the potential biological functions of the prion protein we conducted a small-molecule screening assay using the Syrian hamster prion protein [shPrP(90-232)]. The screen was performed using a library of 149 water-soluble metabolites that are known to pass through the blood-brain barrier. Using a combination of 1D NMR, fluorescence quenching and surface plasmon resonance we identified thiamine (vitamin B1) as a specific prion ligand with a binding constant of ~60 μM. Subsequent studies showed that this interaction is evolutionarily conserved, with similar binding constants being seen for mouse, hamster and human prions. Various protein construct lengths, both with and without the unstructured N-terminal region in the presence and absence of copper, were examined. This indicates that the N-terminus has no influence on the protein's ability to interact with thiamine. In addition to thiamine, the more biologically abundant forms of vitamin B1 (thiamine monophosphate and thiamine diphosphate) were also found to bind the prion protein with similar affinity. Heteronuclear NMR experiments were used to determine thiamine's interaction site, which is located between helix 1 and the preceding loop. These data, in conjunction with computer-aided docking and molecular dynamics, were used to model the thiamine-binding pharmacophore and a comparison with other thiamine binding proteins was performed to reveal the common features of interaction.

  2. Asymmetric dimethylarginine (ADMA) in human blood: effects of extended haemodialysis in the critically ill patient with acute kidney injury, protein binding to human serum albumin and proteolysis by thermolysin.

    PubMed

    Sitar, Mustafa Erinc; Kayacelebi, Arslan Arinc; Beckmann, Bibiana; Kielstein, Jan T; Tsikas, Dimitrios

    2015-09-01

    Free, non-protein bound asymmetrically guanidine-dimethylated arginine (ADMA) is an endogenous inhibitor of nitric oxide (NO) synthesis. Human erythrocytic membrane comprises considerable amounts of large (>50 kDa) ADMA-containing proteins. Location in the erythrocyte membrane and identity and physiological functions of ADMA-containing proteins are unrevealed. In healthy subjects, the concentration of free ADMA in heparinised plasma is almost identical to that of serum. We hypothesised that the robustness of free ADMA concentration in human blood is due to a remarkable resistance of erythrocytic ADMA-containing proteins against proteases. In vivo, we investigated the course of the concentration of ADMA in serum and EDTA plasma of a critically ill patient with acute kidney injury during extended haemodialysis. In vitro, we studied the effects of thermolysin, a useful experimental proteolytic enzyme of erythrocyte membrane proteins, on erythrocytic ADMA. The protein binding (PB) of ADMA to human serum albumin (HSA) was also determined. In these studies, ADMA was measured by a previously reported, fully validated GC-MS/MS method. We measured almost identical ADMA concentrations in plasma and serum samples of the patient. During dialysis, the circulating ADMA concentration decreased slowly and moderately indicating removal of this substance, which was however much less than expected from its low molecular weight (202 Da) and high water solubility. After dialysis, circulating ADMA concentration increased again, a phenomenon called rebound, and ADMA reached higher levels compared to the baseline. The PB value of ADMA to HSA was about 30 %. This surprisingly high PB value of ADMA to HSA may be an explanation for the rather poor dialysance of ADMA. Washed human erythrocytes suspended in phosphate-buffered physiological saline were found not to release appreciable amounts of free and ADMA-containing proteins. The lack of effect of coagulation or anticoagulation on the

  3. A high-quality secretome of A549 cells aided the discovery of C4b-binding protein as a novel serum biomarker for non-small cell lung cancer.

    PubMed

    Luo, Xiaoyang; Liu, Yansheng; Wang, Rui; Hu, Haichuan; Zeng, Rong; Chen, Haiquan

    2011-04-01

    Cancer secretomes are a promising source for biomarker discovery. The analysis of cancer secretomes still faces some difficulties mainly related to the intracellular contamination, which hinders the qualification and follow-up validations. This study aimed to establish a high-quality secretome of A549 cells by using the cellular proteome as a reference and to test the merits of this refined secretome for biomarker discovery for non-small cell lung cancer (NSCLC). Using one-dimensional gel electrophoresis followed by liquid-chromatography tandem mass spectrometry, we comprehensively investigated the secretome and the concurrent cellular proteome of A549 cells. A high-quality secretome consisting of 382 proteins was refined from 889 initial secretory proteins. More than 85.3% of proteins were annotated as secreted and 76.8% as extracellular or membrane-bound. The discriminative power of the lung-cancer associated secretome was confirmed by gene expression and serum proteomic data. The elevated level of C4b-binding Protein (C4BP) in NSCLC blood was verified by enzyme-linked immunosorbent assays (ELISA, p = 6.07e-6). Moreover, the serum C4BP level in 89 patients showed a strong association with the clinical staging of NSCLC. Our reference-experiment-driven strategy is simple and widely applicable, and may facilitate the identification of novel promising biomarkers of lung cancer.

  4. Interaction of triprolidine hydrochloride with serum albumins: thermodynamic and binding characteristics, and influence of site probes.

    PubMed

    Sandhya, B; Hegde, Ashwini H; Kalanur, Shankara S; Katrahalli, Umesha; Seetharamappa, J

    2011-04-05

    The interaction between triprolidine hydrochloride (TRP) to serum albumins viz. bovine serum albumin (BSA) and human serum albumin (HSA) has been studied by spectroscopic methods. The experimental results revealed the static quenching mechanism in the interaction of TRP with protein. The number of binding sites close to unity for both TRP-BSA and TRP-HSA indicated the presence of single class of binding site for the drug in protein. The binding constant values of TRP-BSA and TRP-HSA were observed to be 4.75 ± 0.018 × 10(3) and 2.42 ± 0.024 × 10(4)M(-1) at 294 K, respectively. Thermodynamic parameters indicated that the hydrogen bond and van der Waals forces played the major role in the binding of TRP to proteins. The distance of separation between the serum albumin and TRP was obtained from the Förster's theory of non-radioactive energy transfer. The metal ions viz., K(+), Ca(2+), Co(2+), Cu(2+), Ni(2+), Mn(2+) and Zn(2+) were found to influence the binding of the drug to protein. Displacement experiments indicated the binding of TRP to Sudlow's site I on both BSA and HSA. The CD, 3D fluorescence spectra and FT-IR spectral results revealed the changes in the secondary structure of protein upon interaction with TRP.

  5. Increased serum cortisol binding in chronic active hepatitis

    SciTech Connect

    Orbach, O.; Schussler, G.C.

    1989-01-01

    A high serum cortisol concentration, apparently due to increased cortisol-binding globulin (CBG), was found in a patient (index case) with chronic active hepatitis (CAH). We therefore performed further studies to determine whether increased cortisol binding is generally associated with CAH. Serum samples were obtained from 15 hospitalized patients with long-term liver function test elevations but no evidence of cirrhosis, 15 normal subjects without a history of hepatitis, four healthy pregnant women, and 10 alcoholic patients with stigmata of cirrhosis. Serum cortisol binding was measured by an adaptation of a previously described charcoal uptake method. Thyroxine-binding globulin (TBG) and sex hormone-binding globulin were determined by radioimmunoassays. Charcoal uptake of 125I cortisol from sera of normal subjects and additional patients with CAH revealed that increased serum cortisol binding by a saturable site, presumably CBG, was associated with CAH. Cortisol binding was significantly correlated with immunoassayable TBG, suggesting that in CAH, similar mechanisms may be responsible for increasing the serum concentrations of CBG and TBG.

  6. Intronic mutation in the growth hormone (GH) receptor gene from a girl with Laron syndrome and extremely high serum GH binding protein: extended phenotypic study in a very large pedigree.

    PubMed

    Silbergeld, A; Dastot, F; Klinger, B; Kanety, H; Eshet, R; Amselem, S; Laron, Z

    1997-01-01

    Laron syndrome (LS) is a hereditary form of GH resistance due to molecular defects in the GH receptor (GHR). Most of the identified mutations are located in the extracellular domain of the receptor, resulting in a lack of serum GHBP in the majority of LS patients. We present an LS patient with supranormal levels of serum GHBP, in addition to 35 of her relatives. The proband is a 3.5 year-old Druse girl with severe short stature (height SDS -5.1), high GH (250 micrograms/l), low IGF-I (2.7 nmol/l) and IGFBP-3 (410 micrograms/l), both unresponsive to exogenous GH. The binding capacity of the serum GHBP was 22 nM (adult reference serum, 0.7 nM), with an affinity constant Ka = 1.9 x 10(9) M-1 comparable to that of normal sera (Ka = 1.7-2.1 x 10(9) M-1). The apparent MW of the GHBP was approximately 60-80 kDa, similar to that of control sera. In the proband's sister, parents, grandparents and uncles, extremely high GHBP values were observed (43.0 +/- 4.8 RSB, n = 10) compared with normal adults (0.81 +/- 0.06 RSB) (p < 0.001). The remaining subjects had normal or moderately elevated GHBP levels. Serum GH in adults with high GHBP was significantly elevated above control values (6.0 +/- 0.9 micrograms/l vs 0.76 +/- 0.13 microgram/l, p < 0.001). Serum IGF-I and IGFBP-3 levels were normal in all the subjects, with the exception of an aunt (IGF-I 3.9 nmol/l) and the proband's sister (IGFBP-3 460 micrograms/l). All the subjects' heights were within the normal range. Analysis of the GHR gene performed in the proband revealed an as yet undescribed homozygous intronic point mutation. It consists of a G-->T substitution at nucleotide 785-1 preceding exon 8, a sequence that encodes the transmembrane domain. This mutation, which destroys the invariant dinucleotide of the splice acceptor site, is expected to alter GHR mRNA splicing and to be responsible for skipping exon 8. The resulting truncated protein that retains GH binding activity is probably no longer anchored in the cell

  7. Serum Protein Profile Alterations in Hemodialysis Patients

    SciTech Connect

    Murphy, G A; Davies, R W; Choi, M W; Perkins, J; Turteltaub, K W; McCutchen-Maloney, S L; Langlois, R G; Curzi, M P; Trebes, J E; Fitch, J P; Dalmasso, E A; Colston, B W; Ying, Y; Chromy, B A

    2003-11-18

    Background: Serum protein profiling patterns can reflect the pathological state of a patient and therefore may be useful for clinical diagnostics. Here, we present results from a pilot study of proteomic expression patterns in hemodialysis patients designed to evaluate the range of serum proteomic alterations in this population. Methods: Surface-Enhanced Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (SELDI-TOFMS) was used to analyze serum obtained from patients on periodic hemodialysis treatment and healthy controls. Serum samples from patients and controls were first fractionated into six eluants on a strong anion exchange column, followed by application to four array chemistries representing cation exchange, anion exchange, metal affinity and hydrophobic surfaces. A total of 144 SELDI-TOF-MS spectra were obtained from each serum sample. Results: The overall profiles of the patient and control samples were consistent and reproducible. However, 30 well-defined protein differences were observed; 15 proteins were elevated and 15 were decreased in patients compared to controls. Serum from one patient exhibited novel protein peaks suggesting possible additional changes due to a secondary disease process. Conclusion: SELDI-TOF-MS demonstrated dramatic serum protein profile differences between patients and controls. Similarity in protein profiles among dialysis patients suggests that patient physiological responses to end-stage renal disease and/or dialysis therapy have a major effect on serum protein profiles.

  8. [Is cobalt-binding capacity of serum a new perspective diagnostic marker?].

    PubMed

    Litus, E A; Zaĭtsev, V G; Verovskiĭ, V E; Goncharova, L V; Dudchenko, G P; Ostrovskiĭ, O V

    2014-01-01

    The aim of this study was to determine the reference interval of serum cobalt-binding capacity (CoBC) and to estimate the effect of factors unrelated to oxidative modification of serum albumin on this diagnostic marker. A group of healthy volunteers (n=194), a group of patients with autoimmune diseases (n=44) and a group of patients with diabetes type 2 (n=50) participated in this study. The regional reference interval was found to be 0,462-0,744 mmol Co 2+ /l of serum. The study of serum CoBC in two groups of patients showed that the CoBC level strongly depends on the serum protein profile. Therefore, this diagnostic test may be used for diagnosing ischemia, but other pathologies associated with changes in a ratio of blood protein fractions can also influence the serum CoBC level.

  9. Cellulose binding domain fusion proteins

    SciTech Connect

    Shoseyov, Oded; Shpiegl, Itai; Goldstein, Marc A.; Doi, Roy H.

    1998-01-01

    A cellulose binding domain (CBD) having a high affinity for crystalline cellulose and chitin is disclosed, along with methods for the molecular cloning and recombinant production thereof. Fusion products comprising the CBD and a second protein are likewise described. A wide range of applications are contemplated for both the CBD and the fusion products, including drug delivery, affinity separations, and diagnostic techniques.

  10. Cellulose binding domain fusion proteins

    DOEpatents

    Shoseyov, O.; Yosef, K.; Shpiegl, I.; Goldstein, M.A.; Doi, R.H.

    1998-02-17

    A cellulose binding domain (CBD) having a high affinity for crystalline cellulose and chitin is disclosed, along with methods for the molecular cloning and recombinant production. Fusion products comprising the CBD and a second protein are likewise described. A wide range of applications are contemplated for both the CBD and the fusion products, including drug delivery, affinity separations, and diagnostic techniques. 16 figs.

  11. Binding and modification of proteins by methylglyoxal under physiological conditions. A kinetic and mechanistic study with N alpha-acetylarginine, N alpha-acetylcysteine, and N alpha-acetyllysine, and bovine serum albumin.

    PubMed

    Lo, T W; Westwood, M E; McLellan, A C; Selwood, T; Thornalley, P J

    1994-12-23

    The physiological alpha-oxoaldehyde methylglyoxal binds and modifies arginine, lysine, and cysteine residues in proteins. The kinetics and mechanism of these reactions were investigated with N alpha-acetylamino acids and bovine serum albumin at pH 7.4 and 37 degrees C. The reaction of methylglyoxal with N alpha-acetylarginine involved the initial reversible formation of glycosylamine and 4,5-dihydroxy-5-methylimidazolidine derivatives, with further slow irreversible conversion to an imidazolone, N alpha-acetyl-N delta- (5-methyl-4-imidazolon-2-yl)ornithine. The imidazolone was fluorescent with an excitation lambda max value of 320 nm and an emission lambda max value of 398 nm. Methylglyoxal reacted reversibly with N alpha-acetyllysine to form glycosylamine and bisglycosylamine derivatives. Further reaction of these glycosylamines occurred to form brown, fluorescent oligomers that were not characterized. Methylglyoxal reacted rapidly and reversibly with N alpha-acetylcysteine to form the hemithioacetal adduct. The reaction of methylglyoxal with bovine serum albumin (BSA) at pH 7.4 and 37 degrees C involved the reversible and irreversible formation of methylglyoxal-BSA adducts. Irreversible modification of BSA occurred mainly on arginine residues to form imidazolone. The formation of methylglyoxal-modified proteins involves glycoxidation leading to advanced glycation end product-like fluorescence. It is expected to be increased in diabetes mellitus and may be linked to the development of diabetic complications.

  12. Binding of plant alkaloids berberine and palmatine to serum albumins: a thermodynamic investigation.

    PubMed

    Khan, Asma Yasmeen; Hossain, Maidul; Kumar, Gopinatha Suresh

    2013-01-01

    The thermodynamics of the interaction of two pharmaceutically important isoquinoline alkaloids berberine and palmatine with bovine and human serum albumin was investigated using calorimetric techniques, and the data was supplemented with fluorescence and circular dichroism studies. Thermodynamic results revealed that there was only one class of binding sites for both alkaloids on BSA and HSA. The equilibrium constant was of the order of 10(4) M(-1) for both the alkaloids to serum albumins but the magnitude was slightly higher with HSA. Berberine showed higher affinity over palmatine to both proteins. The binding was enthalpy dominated and entropy favoured for both the alkaloids to BSA and HSA. Salt dependent studies suggested that electrostatic interaction had a significant role in the binding process, the binding affinity reduced as the salt concentration increased. Temperature dependent calorimetric data yielded heat capacity values that suggested the involvement of different molecular forces in the complexation of the two alkaloids with BSA and HSA. 3D fluorescence, synchronous fluorescence and circular dichroism data suggested that the binding of the alkaloids changed the conformation of proteins by reducing their helicity. Destabilization of the protein conformation was also revealed from differential scanning calorimetry studies. Overall, the alkaloids bound strongly to serum albumins, but berberine was a better binder to both serum proteins compared to palmatine.

  13. The complexity of condensed tannin binding to bovine serum albumin--An isothermal titration calorimetry study.

    PubMed

    Kilmister, Rachel L; Faulkner, Peta; Downey, Mark O; Darby, Samuel J; Falconer, Robert J

    2016-01-01

    Isothermal titration calorimetry was applied to study the binding of purified proanthocyanidin oligomers to bovine serum albumin (BSA). The molecular weight of the proanthocyanidin oligomer had a major impact on its binding to BSA. The calculated change in enthalpy (ΔH) and association constant (Ka) became greater as the oligomer size increased then plateaued at the heptameric oligomer. These results support a model for precipitation of proteins by proanthocyanidin where increased oligomer size enhanced the opportunity for cross linkages between proteins ultimately forming sediment-able complexes. The authors suggest tannin binding to proteins is opportunistic and involves multiple sites, each with a different Ka and ΔH of binding. The ΔH of binding comprises both an endothermic hydrophobic interaction and exothermic hydrogen bond component. This suggests the calculated entropy value (ΔS) for tannin-protein interactions is subject to a systematic error and should be interpreted with caution.

  14. Binding of endotoxin to macrophages: distinct effects of serum constituents.

    PubMed

    Tahri-Jouti, M A; Chaby, R

    1991-07-01

    The respective roles of serum lipoproteins, and of the complement component C3, in the binding of endotoxin (LPS) to macrophages were analyzed by an in vitro assay using [3H]LPS. The addition of an anti-C3 serum in the medium induced an apparent abolishment of the specific binding of LPS to mouse macrophages, but this effect appeared to be due to an actual increase of nonspecific binding. Isolated complexes of LPS with lipoproteins of high density (HDL3) and of very high density (VHDL) did not bind to macrophages. Furthermore, addition of HDL3 and VHDL in the incubation medium inhibited the specific binding of LPS to macrophages. These results suggest that C3 reduces nonspecific interactions between LPS and macrophages whereas associations between LPS and HDL3 or VHDL inhibit specific LPS-macrophage interactions.

  15. Binding of anthracycline derivatives to human serum lipoproteins.

    PubMed

    Chassany, O; Urien, S; Claudepierre, P; Bastian, G; Tillement, J P

    1994-01-01

    The binding of eight anthracycline analogues (including mitoxantrone) to isolated serum lipoproteins (high, low and very low density lipoproteins) was studied in order to elucidate some determinants of their interaction with lipidic structures. Serum lipoproteins were isolated by ultracentrifugation. Drug binding experiments were run by ultrafiltration at 37 degrees C and pH 7.4. Anthracycline concentrations (total and free) were determined by HPLC with fluorometric detection. All the ligands were significantly bound to the three lipoprotein classes, and for each ligand the binding increased as the lipidic fraction of lipoprotein increased. From doxorubicin to iododoxorubicin, there was a tenfold increase in lipoprotein binding (doxorubicin < mitoxantrone < epirubicin < daunorubicin < pirarubicin < aclarubicin < zorubicin < iododoxorubicin). For all the ligands studied, the extent of lipoprotein binding appears to be related to chemical determinants of lipophilicity.

  16. Binding of globular proteins to DNA from surface tension measurement.

    PubMed

    Mitra, A; Chattoraj, D K; Chakraborty, P

    2001-10-01

    Extent of binding (gammap) of globular proteins to calf-thymus DNA have been measured in mole per mole of nucleotide as function of equilibrium protein concentration. We have exploited measurement of the surface tension of the protein solution in the presence and absence of DNA to calculate the binding ration (gammap). Interaction of bovine serum albumin with DNA has been studied at different pH. Interaction of bovine serum albumin with DNA has been studied at different pH, ionic strength and in presence of Ca2+. Interaction of BSA with denatured DNA has also been investigated. Binding isotherms for other globular proteins like beta-lactoglobulin, alpha-lactalbumin and lysozyme have been compared under identical physicochemical condition. It has been noted with considerable interest that globular form of protein is important to some extent in protein-DNA interaction. An attempt has been made to explain the significance of difference in binding ratios of these two biopolymers in aqueous medium for different systems in the light of electrostatic and hydrophobic effects. Values of maximum binding ration (gammap(m)) at saturated level for different systems have been also presented. The Gibb's free energy decrease (-deltaG0) of the binding of proteins to DNA has been compared more precisely for the saturation of binding sites in the DNA with the change of activity of protein in solution from zero to unity in the rational mole fraction scale.

  17. Locating the binding sites of Pb(II) ion with human and bovine serum albumins.

    PubMed

    Belatik, Ahmed; Hotchandani, Surat; Carpentier, Robert; Tajmir-Riahi, Heidar-Ali

    2012-01-01

    Lead is a potent environmental toxin that has accumulated above its natural level as a result of human activity. Pb cation shows major affinity towards protein complexation and it has been used as modulator of protein-membrane interactions. We located the binding sites of Pb(II) with human serum (HSA) and bovine serum albumins (BSA) at physiological conditions, using constant protein concentration and various Pb contents. FTIR, UV-visible, CD, fluorescence and X-ray photoelectron spectroscopic (XPS) methods were used to analyse Pb binding sites, the binding constant and the effect of metal ion complexation on HSA and BSA stability and conformations. Structural analysis showed that Pb binds strongly to HSA and BSA via hydrophilic contacts with overall binding constants of K(Pb-HSA) = 8.2 (±0.8)×10(4) M(-1) and K(Pb-BSA) = 7.5 (±0.7)×10(4) M(-1). The number of bound Pb cation per protein is 0.7 per HSA and BSA complexes. XPS located the binding sites of Pb cation with protein N and O atoms. Pb complexation alters protein conformation by a major reduction of α-helix from 57% (free HSA) to 48% (metal-complex) and 63% (free BSA) to 52% (metal-complex) inducing a partial protein destabilization.

  18. Clinical relevance of drug binding to plasma proteins

    NASA Astrophysics Data System (ADS)

    Ascenzi, Paolo; Fanali, Gabriella; Fasano, Mauro; Pallottini, Valentina; Trezza, Viviana

    2014-12-01

    Binding to plasma proteins highly influences drug efficacy, distribution, and disposition. Serum albumin, the most abundant protein in plasma, is a monomeric multi-domain macromolecule that displays an extraordinary ligand binding capacity, providing a depot and carrier for many endogenous and exogenous compounds, such as fatty acids and most acidic drugs. α-1-Acid glycoprotein, the second main plasma protein, is a glycoprotein physiologically involved in the acute phase reaction and is the main carrier for basic and neutral drugs. High- and low-density lipoproteins play a limited role in drug binding and are natural drug delivery system only for few lipophilic drugs or lipid-based formulations. Several factors influence drug binding to plasma proteins, such as pathological conditions, concurrent administration of drugs, sex, and age. Any of these factors, in turn, influences drug efficacy and toxicity. Here, biochemical, biomedical, and biotechnological aspects of drug binding to plasma proteins are reviewed.

  19. Multiplexed microfluidic quantification of proteins in serum

    NASA Astrophysics Data System (ADS)

    Rajan, Nitin; Rajauria, Sukumar; Cleland, Andrew

    2015-03-01

    Rapid and low cost immunoassays targeting proteins in blood or other bodily fluids are highly sought after for point-of-care devices and early screening of patients. Immunoturbidimetric assays utilize latex particles functionalized with antibodies, with particle aggregation in the presence of the analyte detected by a change in absorbance. Using a high throughput micro-fluidic particle analyzer based solely on electrical signals (resistive pulse sensing), we are able to accurately quantify the degree of aggregation by analyzing the changes in the particle size distribution. Thus we study the aggregation of streptavidin (SAv) coated beads in the presence of biotinylated bovine serum albumin as a proof-of-principle assay and extract the binding capacity of the SAv beads from the dose-response curve. We also use our aggregation measurement platform to characterize a commercial C-reactive protein (CRP) immunoturbidimetric assay (hsCRP, Diazyme Inc.). We obtain a linear calibration curve as well as a better limit of detection of CRP than that obtained by absorbance measurements. By using different bead sizes functionalized with different antibodies, multiplexed analyte detection is also possible. We demonstrate this by combining the commercial anti-CRP functionalized beads (0.4 microns) with biotin coated beads (1.0 microns), and carry out the simultaneous detection of SAv and CRP in a single sample.

  20. On the interaction of luminol with human serum albumin: Nature and thermodynamics of ligand binding

    NASA Astrophysics Data System (ADS)

    Moyon, N. Shaemningwar; Mitra, Sivaprasad

    2010-09-01

    The mechanism and thermodynamic parameters for the binding of luminol (LH 2) with human serum albumin was explored by steady state and picosecond time-resolved fluorescence spectroscopy. It was shown that out of two possible LH 2 conformers present is solution, only one is accessible for binding with HSA. The thermodynamic parameters like enthalpy (Δ H) and entropy (Δ S) change corresponding to the ligand binding process were also estimated by performing the experiment at different temperatures. The ligand replacement experiment with bilirubin confirms that LH 2 binds into the sub-domain IIA of the protein.

  1. Protein binding assay for hyaluronate

    SciTech Connect

    Lacy, B.E.; Underhill, C.B.

    1986-11-01

    A relatively quick and simple assay for hyaluronate was developed using the specific binding protein, hyaluronectin. The hyaluronectin was obtained by homogenizing the brains of Sprague-Dawley rats, and then centrifuging the homogenate. The resulting supernatant was used as a source of crude hyaluronectin. In the binding assay, the hyaluronectin was mixed with (/sup 3/H)hyaluronate, followed by an equal volume of saturated (NH/sub 4/)/sub 2/SO/sub 4/, which precipitated the hyaluronectin and any (/sup 3/H)hyaluronate associated with it, but left free (/sup 3/H)hyaluronate in solution. The mixture was then centrifuged, and the amount of bound (/sup 3/H)hyaluronate in the precipitate was determined. Using this assay, the authors found that hyaluronectin specifically bound hyaluronate, since other glycosaminoglycans failed to compete for the binding protein. In addition, the interaction between hyaluronectin and hyaluronate was of relatively high affinity, and the size of the hyaluronate did not appear to substantially alter the amount of binding. To determine the amount of hyaluronate in an unknown sample, they used a competition assay in which the binding of a set amount of (/sup 3/H)hyaluronate was blocked by the addition of unlabeled hyaluronate. By comparing the degree of competition of the unknown samples with that of known amounts of hyaluronate, it was possible to determine the amount of hyaluronate in the unknowns. They have found that this method is sensitive to 1 ..mu..g or less of hyaluronate, and is unaffected by the presence of proteins.

  2. (PCG) Protein Crystal Growth Horse Serum Albumin

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Horse Serum Albumin crystals grown during the USML-1 (STS-50) mission's Protein Crystal Growth Glovebox Experiment. These crystals were grown using a vapor diffusion technique at 22 degrees C. The crystals were allowed to grow for nine days while in orbit. Crystals of 1.0 mm in length were produced. The most abundant blood serum protein, regulates blood pressure and transports ions, metabolites, and therapeutic drugs. Principal Investigator was Edward Meehan.

  3. Purification of LPS Binding Substances in Inflammatory Serum

    DTIC Science & Technology

    1990-07-31

    I believe we have made considerable progress. NA. Purification of LPS binding substances in inflammatory serum ’ We radiolabeled E . Coli 018, E . Coli ...0113, E . Coli 0111:B4 and, S. typhimurium by growing the organisms in tritated broth and extracting the 3H-LPS by the hot phenol method as described...HPLC system which will speed up the work. B. Binding of 3H-LPS to substances in polyclonal serum to E . Coli J5 Although not written into the initial

  4. Calorimetric investigation of diclofenac drug binding to a panel of moderately glycated serum albumins.

    PubMed

    Indurthi, Venkata S K; Leclerc, Estelle; Vetter, Stefan W

    2014-08-01

    Glycation alters the drug binding properties of serum proteins and could affect free drug concentrations in diabetic patients with elevated glycation levels. We investigated the effect of bovine serum albumin glycation by eight physiologically relevant glycation reagents (glucose, ribose, carboxymethyllysine, acetoin, methylglyoxal, glyceraldehyde, diacetyl and glycolaldehyde) on diclofenac drug binding. We used this non-steroidal anti-inflammatory drug diclofenac as a paradigm for acidic drugs with high serum binding and because of its potential cardiovascular risks in diabetic patients. Isothermal titration calorimetry showed that glycation reduced the binding affinity Ka of serum albumin and diclofenac 2 to 6-fold by reducing structural rigidity of albumin. Glycation affected the number of drug binding sites in a glycation reagent dependent manner and lead to a 25% decrease for most reagent, expect for ribose, with decreased by 60% and for the CML-modification, increased the number of binding sites by 60%. Using isothermal titration calorimetry and differential scanning calorimetry we derived the complete thermodynamic characterization of diclofenac binding to all glycated BSA samples. Our results suggest that glycation in diabetic patients could significantly alter the pharmacokinetics of the widely used over-the-counter NSDAI drug diclofenac and with possibly negative implications for patients.

  5. Data of protein-RNA binding sites.

    PubMed

    Lee, Wook; Park, Byungkyu; Choi, Daesik; Han, Kyungsook

    2017-02-01

    Despite the increasing number of protein-RNA complexes in structure databases, few data resources have been made available which can be readily used in developing or testing a method for predicting either protein-binding sites in RNA sequences or RNA-binding sites in protein sequences. The problem of predicting protein-binding sites in RNA has received much less attention than the problem of predicting RNA-binding sites in protein. The data presented in this paper are related to the article entitled "PRIdictor: Protein-RNA Interaction predictor" (Tuvshinjargal et al. 2016) [1]. PRIdictor can predict protein-binding sites in RNA as well as RNA-binding sites in protein at the nucleotide- and residue-levels. This paper presents four datasets that were used to test four prediction models of PRIdictor: (1) model RP for predicting protein-binding sites in RNA from protein and RNA sequences, (2) model RaP for predicting protein-binding sites in RNA from RNA sequence alone, (3) model PR for predicting RNA-binding sites in protein from protein and RNA sequences, and (4) model PaR for predicting RNA-binding sites in protein from protein sequence alone. The datasets supplied in this article can be used as a valuable resource to evaluate and compare different methods for predicting protein-RNA binding sites.

  6. Binding of several benzodiazepines to bovine serum albumin: Fluorescence study

    NASA Astrophysics Data System (ADS)

    Machicote, Roberta G.; Pacheco, María E.; Bruzzone, Liliana

    2010-10-01

    The interactions of lorazepam, oxazepam and bromazepam with bovine serum albumin (BSA) were studied by fluorescence spectrometry. The Stern-Volmer quenching constants and corresponding thermodynamic parameters Δ H, Δ G and Δ S were calculated. The binding constants and the number of binding sites were also investigated. The distances between the donor (BSA) and the acceptors (benzodiazepines) were obtained according to fluorescence resonance energy transfer and conformational changes of BSA were observed from synchronous fluorescence spectra.

  7. Binding of a chromen-4-one Schiff's base with bovine serum albumin: capping with β-cyclodextrin influences the binding.

    PubMed

    Chandrasekaran, Sowrirajan; Sudha, Natesan; Premnath, D; Enoch, Israel V M V

    2015-09-01

    This work deals with the synthesis of 6-methyl-3-[(4'-methylphenyl)imino]methyl-4H-chromen-4-one (MMPIMC), its binding to β-cyclodextrin, and the influence of the cyclodextrin complexation on the compound's binding to bovine serum albumin (BSA). The 1:2 stoichiometry for the complexation of MMPIMC with β-cyclodextrin is determined with the binding constant of 1.90 × 10(4) M(-2). The structure of host-guest complex plays a role in protein binding of MMPIMC. One- and two-dimensional NMR spectra are used to determine the mode of binding of the guest to β-cyclodextrin cavity and the structure of the inclusion complex is proposed. The binding of MMPIMC with BSA in the absence and the presence of β-cyclodextrin is studied. The binding strengths of MMPIMC-BSA (1.73 × 10(5) M(-1)) and β-cyclodextrin-complexed MMPIMC-BSA (9.0 × 10(4) M(-1)) show difference in magnitude. The Förster Resonance Energy Transfer efficiency and the proximity of the donor and acceptor molecules, are modulated by β-cyclodextrin. Molecular modeling is used to optimize the sites and mode of binding of MMPIMC with bovine serum albumin.

  8. Stereoselective binding of chiral drugs to plasma proteins.

    PubMed

    Shen, Qi; Wang, Lu; Zhou, Hui; Jiang, Hui-di; Yu, Lu-shan; Zeng, Su

    2013-08-01

    Chiral drugs show distinct biochemical and pharmacological behaviors in the human body. The binding of chiral drugs to plasma proteins usually exhibits stereoselectivity, which has a far-reaching influence on their pharmacological activities and pharmacokinetic profiles. In this review, the stereoselective binding of chiral drugs to human serum albumin (HSA), α1-acid glycoprotein (AGP) and lipoprotein, three most important proteins in human plasma, are detailed. Furthermore, the application of AGP variants and recombinant fragments of HSA for studying enantiomer binding properties is also discussed. Apart from the stereoselectivity of enantiomer-protein binding, enantiomer-enantiomer interactions that may induce allosteric effects are also described. Additionally, the techniques and methods used to determine drug-protein binding parameters are briefly reviewed.

  9. Stereoselective binding of chiral drugs to plasma proteins

    PubMed Central

    Shen, Qi; Wang, Lu; Zhou, Hui; Jiang, Hui-di; Yu, Lu-shan; Zeng, Su

    2013-01-01

    Chiral drugs show distinct biochemical and pharmacological behaviors in the human body. The binding of chiral drugs to plasma proteins usually exhibits stereoselectivity, which has a far-reaching influence on their pharmacological activities and pharmacokinetic profiles. In this review, the stereoselective binding of chiral drugs to human serum albumin (HSA), α1-acid glycoprotein (AGP) and lipoprotein, three most important proteins in human plasma, are detailed. Furthermore, the application of AGP variants and recombinant fragments of HSA for studying enantiomer binding properties is also discussed. Apart from the stereoselectivity of enantiomer-protein binding, enantiomer-enantiomer interactions that may induce allosteric effects are also described. Additionally, the techniques and methods used to determine drug-protein binding parameters are briefly reviewed. PMID:23852086

  10. Detergent activation of the binding protein in the folate radioassay

    SciTech Connect

    Hansen, S.I.; Holm, J.; Lyngbye, J.

    1982-01-01

    A minor cow's whey protein associated with ..beta..-lactoglobulin is used as binding protein in the competitive radioassay for serum and erythrocyte folate. Seeking to optimize the assay, we tested the performance of binder solutions of increasing purity. The folate binding protein was isolated from cow's whey by means of CM-Sepharose CL-6B cation-exchange chromatography, and further purified on a methotrexate-AH-Sepharose 4B affinity matrix. In contrast to ..beta..-lactoglobulin, the purified protein did not bind folate unless the detergents cetyltrimethylammonium (10 mmol/Ll) or Triton X-100 (1 g/L) were present. Such detergent activation was not needed in the presence of serum. There seems to be a striking analogy between these phenomena and the well-known reactivation of certain purified membrane-derived enzymes by surfactants (lipids/detergents).

  11. Spectroscopic and molecular modelling studies of binding mechanism of metformin with bovine serum albumin

    NASA Astrophysics Data System (ADS)

    Sharma, Deepti; Ojha, Himanshu; Pathak, Mallika; Singh, Bhawna; Sharma, Navneet; Singh, Anju; Kakkar, Rita; Sharma, Rakesh K.

    2016-08-01

    Metformin is a biguanide class of drug used for the treatment of diabetes mellitus. It is well known that serum protein-ligand binding interaction significantly influence the biodistribution of a drug. Current study was performed to characterize the binding mechanism of metformin with serum albumin. The binding interaction of the metformin with bovine serum albumin (BSA) was examined using UV-Vis absorption spectroscopy, fluorescence, circular dichroism, density functional theory and molecular docking studies. Absorption spectra and fluorescence emission spectra pointed out the weak binding of metformin with BSA as was apparent from the slight change in absorbance and fluorescence intensity of BSA in presence of metformin. Circular dichroism study implied the significant change in the conformation of BSA upon binding with metformin. Density functional theory calculations showed that metformin has non-planar geometry and has two energy states. The docking studies evidently signified that metformin could bind significantly to the three binding sites in BSA via hydrophobic, hydrogen bonding and electrostatic interactions. The data suggested the existence of non-covalent specific binding interaction in the complexation of metformin with BSA. The present study will certainly contribute to the development of metformin as a therapeutic molecule.

  12. A spectroscopic and molecular docking approach on the binding of tinzaparin sodium with human serum albumin

    NASA Astrophysics Data System (ADS)

    Abdullah, Saleh M. S.; Fatma, Sana; Rabbani, Gulam; Ashraf, Jalaluddin M.

    2017-01-01

    Protein bound toxins are poorly removed by conventional extracorporeal therapies. Venous thromboembolism (VTE) is a major cause of morbidity and mortality in patients with cancer. The interaction between tinzaparin, an inhibitor of angiotensin converting enzyme and human serum albumin, a principal plasma protein in the liver has been investigated in vitro under a simulated physiological condition by UV-vis spectrophotometry and fluorescence spectrometry. The intrinsic fluorescence intensity of human serum albumin was strongly quenched by tinzaparin (TP). The binding constants and binding stoichiometry can be calculated from the data obtained from fluorescence quenching experiments. The negative value of ΔG° reveals that the binding process is a spontaneous process. Thermodynamic analysis shows that the HSA-TP complex formation occurs via hydrogen bonds, hydrophobic interactions and undergoes slight structural changes as evident by far-UV CD. It indicated that the hydrophobic interactions play a main role in the binding of TP to human serum albumin. In addition, the distance between TP (acceptor) and tryptophan residues of human serum albumin (donor) was estimated to be 2.21 nm according to the Förster's resonance energy transfer theory. For the deeper understanding of the interaction, thermodynamic, and molecular docking studies were performed as well. Our docking results suggest that TP forms stable complex with HSA (Kb ∼ 104) and its primary binding site is located in subdomain IIA (Sudlow Site I). The results obtained herein will be of biological significance in pharmacology and clinical medicine.

  13. Differential binding of thyroxine and triiodothyronine to acidic isoforms of thyroid hormone binding globulin in human serum

    SciTech Connect

    Terasaki, T.; Pardridge, W.M.

    1988-05-17

    The differential availability of thyroxine (T/sub 4/) and 3,5,3'-triiodothyronine (T/sub 3/) to liver from the circulating thyroid hormone binding globulin (TBG)-bound pool suggests that the two thyroid hormones may bind to different TBG isoforms in human serum. In the present study, the binding of (/sup 125/I)T/sub 4/ and (/sup 125/I)T/sub 3/ to human serum proteins was investigated by using slab gel isoelectric focusing and chromatofocusing. In normal human male serum, (/sup 125/I)T/sub 4/ was localized to four isoforms of TBG called TBG-I, -II, -III, and -IV, with isoelectric points (pI's) of 4.30, 4.35, 4.45, and 4.55, respectively. (/sup 125/I)T/sub 3/ was localized to only two isoforms of TBG, TBG-III, and -IV, with pI's that were identical with those for (/sup 125/I)T/sub 4/. In normal female serum, (/sup 125/I)T/sub 4/ was localized to the same four isoforms of TBG as those of normal male serum, while (/sup 125/I)T/sub 3/ was localized to TBG-II, -III, -IV, and -V (pI = 4.65). In pregnant female serum, (/sup 125/I)T/sub 4/ was localized to five isoforms, whereas (/sup 125/I)T/sub 3/ was localized to four. IEF was also performed with male serum loaded with various concentrations of unlabeled T/sub 3/. The K/sub i/ values of T/sub 3/ binding to TBG-I, -II, -III, and -IV were 5.0, 2.4, 0.86, and 0.46 nM, respectively. The TBG isoforms in normal male serum were also separated by sequential concanavalin A-Sepharose affinity chromatography and the chromatofocusing (pH range of 3.5-5.0). T/sub 4/ preferentially bound to the most acidic isoforms of TBG in the pI range of 3.8-4.0, whereas the less acidic fractions (pH 4.0-4.2) bound both T/sub 4/ and T/sub 3/. In conclusion, this study shows that T/sub 4/ and T/sub 3/ do not bind to a single competitive binding site on TBG. Instead, T/sub 4/ is preferentially bound by the most acidic TBG isoforms owing to a 10-fold lower affinity of T/sub 3/ for these proteins.

  14. Serum corticosteroid binding globulin expression is modulated by fasting in polar bears (Ursus maritimus).

    PubMed

    Chow, Brian A; Hamilton, Jason; Cattet, Marc R L; Stenhouse, Gordon; Obbard, Martyn E; Vijayan, Mathilakath M

    2011-01-01

    Polar bears (Ursus maritimus) from several subpopulations undergo extended fasting during the ice-free season. However, the animals appear to conserve protein despite the prolonged fasting, though the mechanisms involved are poorly understood. We hypothesized that elevated concentrations of corticosteroid binding globulin (CBG), the primary cortisol binding protein in circulation, lead to cortisol resistance and provide a mechanism for protein conservation during extended fasting. The metabolic state (feeding vs. fasting) of 16 field sampled male polar bears was determined based on their serum urea to creatinine ratio (>25 for feeding vs. <5 for fasting). There were no significant differences in serum cortisol levels between all male and female polar bears sampled. Serum CBG expression was greater in lactating females relative to non-lactating females and males. CBG expression was significantly higher in fasting males when compared to non-fasting males. This leads us to suggest that CBG expression may serve as a mechanism to conserve protein during extended fasting in polar bears by reducing systemic free cortisol concentrations. This was further supported by a lower serum glucose concentration in the fasting bears. As well, a lack of an enhanced adrenocortical response to acute capture stress supports our hypothesis that chronic hunger is not a stressor in this species. Overall, our results suggest that elevated serum CBG expression may be an important adaptation to spare proteins by limiting cortisol bioavailability during extended fasting in polar bears.

  15. Proteomic evaluation of sheep serum proteins

    PubMed Central

    2012-01-01

    Background The applications of proteomic strategies to ovine medicine remain limited. The definition of serum proteome may be a good tool to identify useful protein biomarkers for recognising sub-clinical conditions and overt disease in sheep. Findings from bovine species are often directly translated for use in ovine medicine. In order to characterize normal protein patterns and improve knowledge of molecular species-specific characteristics, we generated a two-dimensional reference map of sheep serum. The possible application of this approach was tested by analysing serum protein patterns in ewes with mild broncho-pulmonary disease, which is very common in sheep and in the peripartum period which is a stressful time, with a high incidence of infectious and parasitic diseases. Results This study generated the first reference 2-DE maps of sheep serum. Overall, 250 protein spots were analyzed, and 138 identified. Compared with healthy sheep, serum protein profiles of animals with rhino-tracheo-bronchitis showed a significant decrease in protein spots identified as transthyretin, apolipoprotein A1 and a significant increase in spots identified as haptoglobin, endopin 1b and alpha1B glycoprotein. In the peripartum period, haptoglobin, alpha-1-acid glycoprotein, apolipoprotein A1 levels rose, while transthyretin content dropped. Conclusions This study describes applications of proteomics in putative biomarker discovery for early diagnosis as well as for monitoring the physiological and metabolic situations critical for ovine welfare. PMID:22630135

  16. The Binding Constant of Estradiol to Bovine Serum Albumin: An Upper-Level Experiment Utilizing Tritium-Labeled Estradiol and Liquid Scintillation Counting

    ERIC Educational Resources Information Center

    Peihong Liang; Adhyaru, Bhavin; Pearson, Wright L.; Williams, Kathryn R.

    2006-01-01

    The experiment used [to the third power]H-labeled estradiol to determine the binding constant of estradiol to bovine serum albumin. Estradiol must complex with serum proteins for the transport in the blood stream because of its low solubility in aqueous systems and estradiol-protein binding constant, where K[subscript B] is important to understand…

  17. Induced Long-Range Attractive Potentials of Human Serum Albumin by Ligand Binding

    SciTech Connect

    Sato, Takaaki; Komatsu, Teruyuki; Nakagawa, Akito; Tsuchida, Eishun

    2007-05-18

    Small-angle x-ray scattering and dielectric spectroscopy investigation on the solutions of recombinant human serum albumin and its heme hybrid revealed that heme incorporation induces a specific long-range attractive potential between protein molecules. This is evidenced by the enhanced forward intensity upon heme binding, despite no hindrance to rotatory Brownian motion, unbiased colloid osmotic pressure, and discontiguous nearest-neighbor distance, confirming monodispersity of the proteins. The heme-induced potential may play a trigger role in recognition of the ligand-filled human serum albumins in the circulatory system.

  18. Interactions of apomorphine with serum and tissue proteins

    SciTech Connect

    Smith, R.V.; Velagapudi, R.B.; McLean, A.M.; Wilcox, R.E.

    1985-05-01

    Physical and covalent interactions of apomorphine with serum and tissue proteins could influence the drug's disposition and pharmacological activities in mammals. Ultrafiltration, equilibrium dialysis, and ultraviolet spectrophotometric methods have been used to study the reversible binding of apomorphine to bovine, human, rat, and swine plasma proteins. The degree of binding was generally greater than 90%, but variations were noted in some instances on the basis of drug concentrations and pH over the range of 6.8-7.8. Incubation of (8,9-/sup 3/H2)apomorphine with bovine serum albumin led to retention of radioactivity and a stoichiometrically controlled released of tritium which arose from the reaction of an electrophilic drug oxidation product and protein, producing drug-protein conjugates. In vitro experiments with mouse striatal brain preparations indicated parallel covalent binding reactions. In vivo experiments in mice indicated accumulation of radioactivity in brain regions and other tissues following daily injections of (8,9-/sup 3/H2)apomorphine for 14 days. The physical and covalent interactions of apomorphine with mammalian tissue proteins could be the cause of longer disposition half-lives in mammals than those previously reported. The covalent interactions, in particular, may be important in elucidating the mechanism of apomorphine-induced behavioral effects in mice.

  19. Preferential binding of fisetin to the native state of bovine serum albumin: spectroscopic and docking studies.

    PubMed

    Singha Roy, Atanu; Pandey, Nitin Kumar; Dasgupta, Swagata

    2013-04-01

    We have investigated the binding of the biologically important flavonoid fisetin with the carrier protein bovine serum albumin using multi-spectroscopic and molecular docking methods. The binding constants were found to be in the order of 10(4) M(-1) and the number of binding sites was determined as one. MALDI-TOF analyses showed that one fisetin molecule binds to a single bovine serum albumin (BSA) molecule which is also supported by fluorescence quenching studies. The negative Gibbs free energy change (∆G°) values point to a spontaneous binding process which occurs through the presence of electrostatic forces with hydrophobic association that results in a positive entropy change (+51.69 ± 1.18 J mol(-1) K(-1)). The unfolding and refolding of BSA in urea have been studied in absence and presence of fisetin using steady-state fluorescence and lifetime measurements. Urea denaturation studies indicate that fisetin is gradually released from its binding site on the protein. In the absence of urea, an increase in temperature that causes denaturation of the protein results in the release of fisetin from its bound state indicating that fisetin binds only to the native state of the protein. The circular dichroism (CD) and Fourier transform infrared (FTIR) spectroscopic studies showed an increase in % α-helix content of BSA after binding with fisetin. Site marker displacement studies in accordance with the molecular docking results suggested that fisetin binds in close proximity of the hydrophobic cavity in site 1 (subdomain IIA) of the protein. The PEARLS (Program of Energetic Analysis of Receptor Ligand System) has been used to estimate the interaction energy of fisetin with BSA and the results are in good correlation with the experimental findings.

  20. Synthesis of imidazole derivatives and the spectral characterization of the binding properties towards human serum albumin

    NASA Astrophysics Data System (ADS)

    Yue, Yuanyuan; Dong, Qiao; Zhang, Yajie; Li, Xiaoge; Yan, Xuyang; Sun, Yahui; Liu, Jianming

    2016-01-01

    Small molecular drugs that can combine with target proteins specifically, and then block relative signal pathway, finally obtain the purpose of treatment. For this reason, the synthesis of novel imidazole derivatives was described and this study explored the details of imidazole derivatives binding to human serum albumin (HSA). The data of steady-state and time-resolved fluorescence showed that the conjugation of imidazole derivatives with HSA yielded quenching by a static mechanism. Meanwhile, the number of binding sites, the binding constants, and the thermodynamic parameters were also measured; the raw data indicated that imidazole derivatives could spontaneously bind with HSA through hydrophobic interactions and hydrogen bonds which agreed well with the results from the molecular modeling study. Competitive binding experiments confirmed the location of binding. Furthermore, alteration of the secondary structure of HSA in the presence of the imidazole derivatives was tested.

  1. Engineering RNA-binding proteins for biology.

    PubMed

    Chen, Yu; Varani, Gabriele

    2013-08-01

    RNA-binding proteins play essential roles in the regulation of gene expression. Many have modular structures and combine relatively few common domains in various arrangements to recognize RNA sequences and/or structures. Recent progress in engineering the specificity of the PUF class RNA-binding proteins has shown that RNA-binding domains may be combined with various effector or functional domains to regulate the metabolism of targeted RNAs. Designer RNA-binding proteins with tailored sequence specificity will provide valuable tools for biochemical research as well as potential therapeutic applications. In this review, we discuss the suitability of various RNA-binding domains for engineering RNA-binding specificity, based on the structural basis for their recognition. We also compare various protein engineering and design methods applied to RNA-binding proteins, and discuss future applications of these proteins.

  2. Serum protein mediators of dementia and aging proper

    PubMed Central

    Royall, Donald R.; Al-Rubaye, Safa; Bishnoi, Ram; Palmer, Raymond F.

    2016-01-01

    The latent variable “δ” (for “dementia”) appears to be uniquely responsible for the dementing aspects of cognitive impairment. Age, depressive symptoms, gender and the apolipoprotein E (APOE) ε4 allele are independently associated with δ. In this analysis, we explore serum proteins as potential mediators of age's specific association with δ in a large, ethnically diverse longitudinal cohort, the Texas Alzheimer's Research and Care Consortium (TARCC). 22 serum proteins were recognized as partial mediators of age's association with δ. These include Insulin-like Growth Factor-Binding Protein 2 (IGF-BP2), which we had previously associated with age-specific cognitive change, and both Pancreatic Polypeptide (PP) and von Willebrand Factor (vWF), previously associated with δ. Nine other δ-related proteins were not confirmed by this ethnicity adjusted analysis. Our findings suggest that age's association with the disabling fraction of cognitive performance is partially mediated by serum proteins, somatomedins and hormones. Those proteins may offer targets for the specific treatment of age-related effects on dementia severity and conversion risk. PMID:27922822

  3. Binding of trivalent chromium to serum transferrin is sufficiently rapid to be physiologically relevant.

    PubMed

    Deng, Ge; Wu, Kristi; Cruce, Alex A; Bowman, Michael K; Vincent, John B

    2015-02-01

    Transferrin, the major iron transport protein in the blood, also transports trivalent chromium in vivo. Recent in vitro studies have, however, suggested that the binding of chromic ions to apotransferrin is too slow to be biologically relevant. Nevertheless, the in vitro studies have generally failed to adequately take physiological bicarbonate concentrations into account. In aqueous buffer (with ambient (bi)carbonate concentrations), the binding of chromium to transferrin is too slow to be physiologically relevant, taking days to reach equilibrium with the protein's associated conformational changes. However, in the presence of 25mM (bi)carbonate, the concentration in human blood, chromic ions bind rapidly and tightly to transferrin. Details of the kinetics of chromium binding to human serum transferrin and conalbumin (egg white transferrin) in the presence of bicarbonate and other major potential chromium ligands are described and are consistent with transferrin being the major chromic ion transporter from the blood to tissues.

  4. Calcium-binding proteins and development

    NASA Technical Reports Server (NTRS)

    Beckingham, K.; Lu, A. Q.; Andruss, B. F.; McIntire, L. V. (Principal Investigator)

    1998-01-01

    The known roles for calcium-binding proteins in developmental signaling pathways are reviewed. Current information on the calcium-binding characteristics of three classes of cell-surface developmental signaling proteins (EGF-domain proteins, cadherins and integrins) is presented together with an overview of the intracellular pathways downstream of these surface receptors. The developmental roles delineated to date for the universal intracellular calcium sensor, calmodulin, and its targets, and for calcium-binding regulators of the cytoskeleton are also reviewed.

  5. CHARACTERIZATION OF DRUG INTERACTIONS WITH SERUM PROTEINS BY USING HIGH-PERFORMANCE AFFINITY CHROMATOGRAPHY

    PubMed Central

    Hage, David S.; Anguizola, Jeanethe; Barnaby, Omar; Jackson, Abby; Yoo, Michelle J.; Papastavros, Efthimia; Pfaunmiller, Erika; Sobansky, Matt; Tong, Zenghan

    2011-01-01

    The binding of drugs with serum proteins can affect the activity, distribution, rate of excretion, and toxicity of pharmaceutical agents in the body. One tool that can be used to quickly analyze and characterize these interactions is high-performance affinity chromatography (HPAC). This review shows how HPAC can be used to study drug-protein binding and describes the various applications of this approach when examining drug interactions with serum proteins. Methods for determining binding constants, characterizing binding sites, examining drug-drug interactions, and studying drug-protein dissociation rates will be discussed. Applications that illustrate the use of HPAC with serum binding agents such as human serum albumin, α1-acid glycoprotein, and lipoproteins will be presented. Recent developments will also be examined, such as new methods for immobilizing serum proteins in HPAC columns, the utilization of HPAC as a tool in personalized medicine, and HPAC methods for the high-throughput screening and characterization of drug-protein binding. PMID:21395530

  6. Mannose-Binding Lectin Serum Levels in Patients With Candiduria

    PubMed Central

    Moslem, Maryam; Zarei Mahmoudabadi, Ali; Fatahinia, Mahnaz; Kheradmand, Alireza

    2015-01-01

    Background: Candida species are normal mycoflora of human body which are capable to cause urinary tract infection (UTI). Mannose-binding lectin (MBL) is a kind of innate immune system and decreasing plasma levels of MBL may disrupt the natural immune response and increase susceptibility to infections. Objectives: The aim of the present study was to assess MBL in the serum of patients with candiduria and compare them with control. Patients and Methods: The blood and urine samples were collected from 335 patients (hospitalized in Golestan hospital, Ahvaz) using standard methods and the growing colonies on CHROMagar were identified using routine diagnostic tests. MBL activity in the serum of 45 patients with candiduria and 45 controls was measured using Eastbiopharm enzyme-linked immunosorbent assay (ELISA) kit. Results: In this study, 45 (13.4 %) urine samples were positive for Candida species (17 males and 28 females). The most common isolated yeast was Candida albicans (34%), followed by C. glabrata (32.1%), C. tropicalis (9.4%), other Candida species (22.6%), and Rhodotorula species (1.9%). The mean serum levels of MBL were 0.85 ± 0.01 ng/mL and 1.02 ± 0.03 ng/mL among candiduric patients and controls, respectively, and there was no significant difference between the two groups (P = 0.6). Conclusions: Our results showed that there was no significant relationship between MBL serum levels and candiduria. PMID:26870314

  7. Oxysterol sulfation by cytosolic sulfotransferase suppresses liver X receptor/sterol regulatory element binding protein-1c signaling pathway and reduces serum and hepatic lipids in mouse models of nonalcoholic fatty liver disease.

    PubMed

    Bai, Qianming; Zhang, Xin; Xu, Leyuan; Kakiyama, Genta; Heuman, Douglas; Sanyal, Arun; Pandak, William M; Yin, Lianhua; Xie, Wen; Ren, Shunlin

    2012-06-01

    Cytosolic sulfotransferase (SULT2B1b) catalyzes oxysterol sulfation. 5-Cholesten-3β-25-diol-3-sulfate (25HC3S), one product of this reaction, decreases intracellular lipids in vitro by suppressing liver X receptor/sterol regulatory element binding protein (SREBP)-1c signaling, with regulatory properties opposite to those of its precursor 25-hydroxycholesterol. Upregulation of SULT2B1b may be an effective strategy to treat hyperlipidemia and hepatic steatosis. The objective of the study was to explore the effect and mechanism of oxysterol sulfation by SULT2B1b on lipid metabolism in vivo. C57BL/6 and LDLR(-/-) mice were fed with high-cholesterol diet or high-fat diet for 10 weeks and infected with adenovirus encoding SULT2B1b. SULT2B1b expressions in different tissues were determined by immunohistochemistry and Western blot. Sulfated oxysterols in liver were analyzed by high-pressure liquid chromatography. Serum and hepatic lipid levels were determined by kit reagents and hematoxylin and eosin staining. Gene expressions were determined by real-time reverse transcriptase polymerase chain reaction and Western Blot. Following infection, SULT2B1b was successfully overexpressed in the liver, aorta, and lung tissues, but not in the heart or kidney. SULT2B1b overexpression, combined with administration of 25-hydroxycholesterol, significantly increased the formation of 25HC3S in liver tissue and significantly decreased serum and hepatic lipid levels, including triglycerides, total cholesterol, free cholesterol, and free fatty acids, as compared with controls in both C57BL/6 and LDLR(-/-) mice. Gene expression analysis showed that increases in SULT2B1b expression were accompanied by reduction in key regulators and enzymes involved in lipid metabolism, including liver X receptor α, SREBP-1, SREBP-2, acetyl-CoA carboxylase-1, and fatty acid synthase. These findings support the hypothesis that 25HC3S is an important endogenous regulator of lipid biosynthesis.

  8. Lipopolysaccharide binding protein in preterm infants

    PubMed Central

    Behrendt, D; Dembinski, J; Heep, A; Bartmann, P

    2004-01-01

    Objective: To assess serum concentrations of lipopolysaccharide binding protein (LBP) in preterm infants with neonatal bacterial infection (NBI). Methods: Blood samples were analysed of 57 preterm (28+1 to 36+6, median 33+2 weeks gestation) and 17 term infants admitted to the neonatal intensive care unit within the first 72 hours of life with suspicion of NBI. Samples were obtained at first suspicion of sepsis and after 12 and 24 hours. Diagnosis of NBI was confirmed by raised concentrations of C reactive protein and/or interleukin 6. The influence of gestational age and labour was analysed. Results: Maximum LBP concentrations in infants with NBI were greatly increased compared with infants without NBI (13.0–46.0 µg/ml (median 20.0 µg/ml) v 0.6–17.4 µg/ml (median 4.2 µg/ml)). LBP concentrations in infected infants were not yet significantly raised when NBI was first suspected. The LBP concentrations of preterm infants were comparable to those of term infants. Regression analysis revealed no significant effect of labour or gestational age on LBP. Conclusions: Raised LBP concentrations indicate NBI in preterm and term infants. Preterm infants of > 28 weeks gestation seem to be capable of producing LBP as efficiently as term infants. Neonatal LBP concentrations are not influenced by labour. LBP may be a useful diagnostic marker of NBI in preterm infants. PMID:15499153

  9. Ligand binding strategies of human serum albumin: how can the cargo be utilized?

    PubMed

    Varshney, Ankita; Sen, Priyankar; Ahmad, Ejaz; Rehan, Mohd; Subbarao, Naidu; Khan, Rizwan Hasan

    2010-01-01

    Human serum albumin (HSA), being the most abundant carrier protein in blood and a modern day clinical tool for drug delivery, attracts high attention among biologists. Hence, its unfolding/refolding strategies and exogenous/endogenous ligand binding preference are of immense use in therapeutics and clinical biochemistry. Among its fellow proteins albumin is known to carry almost every small molecule. Thus, it is a potential contender for being a molecular cargo/or nanovehicle for clinical, biophysical and industrial purposes. Nonetheless, its structure and function are largely regulated by various chemical and physical factors to accommodate HSA to its functional purpose. This multifunctional protein also possesses enzymatic properties which may be used to convert prodrugs to active therapeutics. This review aims to highlight current overview on the binding strategies of protein to various ligands that may be expected to lead to significant clinical applications.

  10. Monobodies and other synthetic binding proteins for expanding protein science.

    PubMed

    Sha, Fern; Salzman, Gabriel; Gupta, Ankit; Koide, Shohei

    2017-03-01

    Synthetic binding proteins are constructed using nonantibody molecular scaffolds. Over the last two decades, in-depth structural and functional analyses of synthetic binding proteins have improved combinatorial library designs and selection strategies, which have resulted in potent platforms that consistently generate binding proteins to diverse targets with affinity and specificity that rival those of antibodies. Favorable attributes of synthetic binding proteins, such as small size, freedom from disulfide bond formation and ease of making fusion proteins, have enabled their unique applications in protein science, cell biology and beyond. Here, we review recent studies that illustrate how synthetic binding proteins are powerful probes that can directly link structure and function, often leading to new mechanistic insights. We propose that synthetic proteins will become powerful standard tools in diverse areas of protein science, biotechnology and medicine.

  11. Structural basis of non-steroidal anti-inflammatory drug diclofenac binding to human serum albumin.

    PubMed

    Zhang, Yao; Lee, Philbert; Liang, Shichu; Zhou, Zuping; Wu, Xiaoyang; Yang, Feng; Liang, Hong

    2015-11-01

    Human serum albumin (HSA) is the most abundant protein in plasma, which plays a central role in drug pharmacokinetics because most compounds bound to HSA in blood circulation. To understand binding characterization of non-steroidal anti-inflammatory drugs to HSA, we resolved the structure of diclofenac and HSA complex by X-ray crystallography. HSA-palmitic acid-diclofenac structure reveals two distinct binding sites for three diclofenac in HSA. One diclofenac is located at the IB subdomain, and its carboxylate group projects toward polar environment, forming hydrogen bond with one water molecule. The other two diclofenac molecules cobind in big hydrophobic cavity of the IIA subdomain without interactive association. Among them, one binds in main chamber of big hydrophobic cavity, and its carboxylate group forms hydrogen bonds with Lys199 and Arg218, as well as one water molecule, whereas another diclofenac binds in side chamber, its carboxylate group projects out cavity, forming hydrogen bond with Ser480.

  12. New insight into the binding interaction of hydroxylated carbon nanotubes with bovine serum albumin.

    PubMed

    Guan, Yonghui; Zhang, Hongmei; Wang, Yanqing

    2014-04-24

    In order to understand the effects of carbon nanotubes on the structural stability of proteins, the ligand-binding ability, fibrillation, and chemical denaturation of bovine serum albumin in the presence of a multi-walled hydroxylated carbon nanotubes (HO-MWCNTs) was characterized by UV-vis, circular dichroism, fluorescence spectroscopy and molecule modeling methods at the molecular level. The experiment results indicated that the fluorescence intensity of BSA was decreased obviously in presence of HO-MWCNTs. The binding interaction of HO-MWCNTs with BSA led to the secondary structure changes of BSA. This interaction could not only affect the ligand-binding ability of BSA, but also change the rate of fibrillation and denaturation of BSA. This work gave us some important information about the structures and properties of protein induced by carbon nanotubes.

  13. Tamoxifen and curcumin binding to serum albumin. Spectroscopic study

    NASA Astrophysics Data System (ADS)

    Maciążek-Jurczyk, M.; Maliszewska, M.; Pożycka, J.; Równicka-Zubik, J.; Góra, A.; Sułkowska, A.

    2013-07-01

    Tamoxifen (TMX) is widely used for the breast cancer treatment and is known as chemopreventive agent. Curcumin (CUR) is natural phenolic compound with broad spectrum of biological activity e.g. anti-inflammatory, antimicrobial, antiviral, antifungal and chemopreventive. Combination of tamoxifen and curcumin could be more effective with lower toxicity than each agent alone in use for the treatment or chemoprevention of breast cancer. Binding of drugs to serum albumin is an important factor, which determines toxicity and therapeutic dosage of the drugs. When two drugs are administered together the competition between them for the binding site on albumin can result in a decrease in bound fraction and an increase in the concentration of free biologically active fraction of drug.

  14. Binding of volatile anesthetics to serum albumin: measurements of enthalpy and solvent contributions.

    PubMed

    Sawas, Abdul H; Pentyala, Srinivas N; Rebecchi, Mario J

    2004-10-05

    This study directly examines the enthalpic contributions to binding in aqueous solution of closely related anesthetic haloethers (desflurane, isoflurane, enflurane, and sevoflurane), a haloalkane (halothane), and an intravenous anesthetic (propofol) to bovine and human serum albumin (BSA and HSA) using isothermal titration calorimetry. Binding to serum albumin is exothermic, yielding enthalpies (DeltaH(obs)) of -3 to -6 kcal/mol for BSA with a rank order of apparent equilibrium association constants (K(a) values): desflurane > isoflurane approximately enflurane > halothane >or= sevoflurane, with the differences being largely ascribed to entropic contributions. Competition experiments indicate that volatile anesthetics, at low concentrations, share the same sites in albumin previously identified in crystallographic and photo-cross-linking studies. The magnitude of the observed DeltaH increased linearly with increased reaction temperature, reflecting negative changes in heat capacities (DeltaC(p)). These -DeltaC(p) values significantly exceed those calculated for burial of each anesthetic in a hydrophobic pocket. The enhanced stabilities of the albumin/anesthetic complexes and -DeltaC(p) are consistent with favorable solvent rearrangements that promote binding. This idea is supported by substitution of D(2)O for H(2)O that significantly reduces the favorable binding enthalpy observed for desflurane and isoflurane, with an opposing increase of DeltaS(obs). From these results, we infer that solvent restructuring, resulting from release of water weakly bound to anesthetic and anesthetic-binding sites, is a dominant and favorable contributor to the enthalpy and entropy of binding to proteins.

  15. Characterization of binding of N'-nitrosonornicotine to protein

    SciTech Connect

    Hughes, M.F.

    1986-01-01

    The NADPH-dependent activation of the carcinogenic nitrosamine, N'-nitrosonornicotine (NNN) to a reactive intermediate which binds covalently to protein was assessed using male Sprague-Dawley rat liver and lung microsomes. The NADPH-dependent covalent binding of (/sup 14/C)NNN to liver and lung microsomes was linear with time up to 90 and 45 min, respectively and was also linear with protein concentrations up to 3.0 and 2.0 mg/ml, respectively. The apparent K/sub m/ and V/sub max/ of the NADPH-dependent binding to liver microsomes were determined from the initial velocities. Addition of the thiols glutathione, cystein, N-acetylcysteine or 2-mercapthoethanol significantly decreased the non-NADPH-dependent binding to liver microsomal protein, but did not affect the NADPH-dependent binding. Glutathione was required in order to observe any NADPH-dependent binding to lung microsomal protein. In lung microsomes, SKF-525A significantly decreased the NADPH-dependent binding by 79%. Replacement of an air atmosphere with N/sub 2/ or CO:O/sub 2/ (8:2) significantly decreased the NADPH-dependent binding of (/sup 14/C)NNN to liver microsomal protein by 40% or 27% respectively. Extensive covalent binding of (/sup 14/C)NNN to liver and muscle microsomal protein occurred in the absence of an NADPH-generating system, in the presence of 50% methanol and also to bovine serum albumin, indicating a nonenzymatic reaction. These data indicate that cytochrome P-450 is at least in part responsible for the metabolic activation of the carcinogen NNN, but also suggest additional mechanisms of activation.

  16. Steady-State Fluorescence Anisotropy to Investigate Flavonoids Binding to Proteins

    ERIC Educational Resources Information Center

    Ingersoll, Christine M.; Strollo, Christen M.

    2007-01-01

    The steady-state fluorescence anisotropy is employed to study the binding of protein of a model protein, human serum albumin, to a commonly used flavonoid, quercetin. The experiment describes the thermodynamics, as well as the biochemical interactions of such binding effectively.

  17. Computational Prediction of RNA-Binding Proteins and Binding Sites

    PubMed Central

    Si, Jingna; Cui, Jing; Cheng, Jin; Wu, Rongling

    2015-01-01

    Proteins and RNA interaction have vital roles in many cellular processes such as protein synthesis, sequence encoding, RNA transfer, and gene regulation at the transcriptional and post-transcriptional levels. Approximately 6%–8% of all proteins are RNA-binding proteins (RBPs). Distinguishing these RBPs or their binding residues is a major aim of structural biology. Previously, a number of experimental methods were developed for the determination of protein–RNA interactions. However, these experimental methods are expensive, time-consuming, and labor-intensive. Alternatively, researchers have developed many computational approaches to predict RBPs and protein–RNA binding sites, by combining various machine learning methods and abundant sequence and/or structural features. There are three kinds of computational approaches, which are prediction from protein sequence, prediction from protein structure, and protein-RNA docking. In this paper, we review all existing studies of predictions of RNA-binding sites and RBPs and complexes, including data sets used in different approaches, sequence and structural features used in several predictors, prediction method classifications, performance comparisons, evaluation methods, and future directions. PMID:26540053

  18. Inactivation of anthracyclines by serum heme proteins.

    PubMed

    Wagner, Brett A; Teesch, Lynn M; Buettner, Garry R; Britigan, Bradley E; Burns, C Patrick; Reszka, Krzysztof J

    2007-06-01

    We have previously shown that the anticancer agent doxorubicin undergoes oxidation and inactivation when exposed to myeloperoxidase-containing human leukemia HL-60 cells, or to isolated myeloperoxidase, in the presence of hydrogen peroxide and nitrite. In the current study we report that commercial fetal bovine serum (FBS) alone oxidizes doxorubicin in the presence of hydrogen peroxide and that nitrite accelerates this oxidation. The efficacy of inactivation was dependent on the concentration of serum present; no reaction was observed when hydrogen peroxide or serum was omitted. Peroxidase activity assays, based on oxidation of 3,3',5,5'-tetramethylbenzidine, confirmed the presence of a peroxidase in the sera from several suppliers. The peroxidative activity was contained in the >10000 MW fraction. We also found that hemoglobin, a heme protein likely to be present in commercial FBS, is capable of oxidizing doxorubicin in the presence of hydrogen peroxide and that nitrite further stimulates the reaction. In contrast to intact doxorubicin, the serum + hydrogen peroxide + nitrite treated drug appeared to be nontoxic for PC3 human prostate cancer cells. Together, this study shows that (pseudo)peroxidases present in sera catalyze oxidation of doxorubicin by hydrogen peroxide and that this diminishes the tumoricidal activity of the anthracycline, at least in in vitro settings. Finally, this study also points out that addition of H2O2 to media containing FBS will stimulate peroxidase-type of reactions, which may affect cytotoxic properties of studied compounds.

  19. Spectroscopic and molecular docking studies on the charge transfer complex of bovine serum albumin with quinone in aqueous medium and its influence on the ligand binding property of the protein.

    PubMed

    Satheshkumar, Angupillai; Elango, Kuppanagounder P

    2014-09-15

    The spectral techniques such as UV-Vis, (1)H NMR and fluorescence and electrochemical experiments have been employed to investigate the interaction between 2-methoxy-3,5,6-trichloro-1,4-benzoquinone (MQ; a water soluble quinone) and bovine serum albumin (BSA) in aqueous medium. The fluorescence of BSA was quenched by MQ via formation of a 1:1 BSA-MQ charge transfer adduct with a formation constant of 3.3×10(8) L mol(-1). Based on the Forster's theory the binding distance between them is calculated as 2.65 nm indicating high probability of binding. For the first time, influence of quinone on the binding property of various types of ligands such as aspirin, ascorbic acid, nicotinimide and sodium stearate has also been investigated. The results indicated that the strong and spontaneous binding existing between BSA and MQ, decreased the intensity of binding of these ligands with BSA. Since Tryptophan (Trp) is the basic residue present in BSA, a comparison between binding property of Trp-MQ adduct with that of BSA-MQ with these ligands has also been attempted. 1H NMR titration study indicated that the Trp forms a charge transfer complex with MQ, which reduces the interaction of Trp with the ligands. Molecular docking study supported the fact that the quinone interacts with the Trp212 unit of the BSA and the free energy change of binding (ΔG) for the BSA-MQ complex was found to be -46 kJ mol(-1), which is comparable to our experimental free energy of binding (-49 kJ mol(-1)) obtained from fluorescence study.

  20. Spectroscopic and molecular docking studies on the charge transfer complex of bovine serum albumin with quinone in aqueous medium and its influence on the ligand binding property of the protein

    NASA Astrophysics Data System (ADS)

    Satheshkumar, Angupillai; Elango, Kuppanagounder P.

    2014-09-01

    The spectral techniques such as UV-Vis, 1H NMR and fluorescence and electrochemical experiments have been employed to investigate the interaction between 2-methoxy-3,5,6-trichloro-1,4-benzoquinone (MQ; a water soluble quinone) and bovine serum albumin (BSA) in aqueous medium. The fluorescence of BSA was quenched by MQ via formation of a 1:1 BSA-MQ charge transfer adduct with a formation constant of 3.3 × 108 L mol-1. Based on the Forster’s theory the binding distance between them is calculated as 2.65 nm indicating high probability of binding. For the first time, influence of quinone on the binding property of various types of ligands such as aspirin, ascorbic acid, nicotinimide and sodium stearate has also been investigated. The results indicated that the strong and spontaneous binding existing between BSA and MQ, decreased the intensity of binding of these ligands with BSA. Since Tryptophan (Trp) is the basic residue present in BSA, a comparison between binding property of Trp-MQ adduct with that of BSA-MQ with these ligands has also been attempted. 1H NMR titration study indicated that the Trp forms a charge transfer complex with MQ, which reduces the interaction of Trp with the ligands. Molecular docking study supported the fact that the quinone interacts with the Trp212 unit of the BSA and the free energy change of binding (ΔG) for the BSA-MQ complex was found to be -46 kJ mol-1, which is comparable to our experimental free energy of binding (-49 kJ mol-1) obtained from fluorescence study.

  1. Protein D of Haemophilus influenzae is not a universal immunoglobulin D-binding protein.

    PubMed Central

    Sasaki, K; Munson, R S

    1993-01-01

    Haemophilus influenzae type b and nontypeable H. influenzae have been reported to bind human immunoglobulin D (IgD). IgD myeloma sera from five patients were tested for the ability of IgD to bind to H. influenzae. Serotype b strains bound human IgD in four of the five sera tested. IgD in the fifth serum bound strongly to type b strain MinnA but poorly to other type b strains. Additionally, IgD binding was not observed when nontypeable strains were tested. The gene for protein D, the putative IgD-binding protein, was cloned from the IgD-binding H. influenzae type b strain MinnA and expressed in Escherichia coli. IgD binding to E. coli expressing protein D was not demonstrable. Recombinant protein D was purified, and antisera were generated in rabbits. Using these rabbit sera, we detected protein D in nontypeable as well as serotype b strains by Western blotting (immunoblotting). In contrast, IgD myeloma protein 4490, which was previously reported to bind to protein D by Ruan and coworkers (M. Ruan, M. Akkoyunlu, A. Grubb, and A. Forsgren, J. Immunol. 145:3379-3384), bound strongly to both type b and nontypeable H. influenzae as well as to E. coli expressing protein D. Thus, IgD binding is a general property of H. influenzae type b strains but not a general property of nontypeable strains, although both type b and nontypeable strains produce protein D. With the exception of IgD myeloma protein 4490 binding, we have no evidence for a role of protein D in IgD binding to H. influenzae. Images PMID:8514409

  2. Identification of low-abundance proteins in serum via the isolation of HSP72 complexes.

    PubMed

    Tanaka, Masako; Shiota, Masayuki; Nakao, Takafumi; Uemura, Ryo; Nishi, Satoshi; Ohkawa, Yasuyuki; Matsumoto, Masaki; Yamaguchi, Maki; Osada-Oka, Mayuko; Inagaki, Azusa; Takahashi, Katsuyuki; Nakayama, Keiichi I; Gi, Min; Izumi, Yasukatsu; Miura, Katsuyuki; Iwao, Hiroshi

    2016-03-16

    Heat shock protein 72 (HSP72) is an intracellular molecular chaperone that is overexpressed in tumor cells, and has also been detected in extracellular regions such as the blood. HSP72 forms complexes with peptides and proteins that are released from tumors. Accordingly, certain HSP72-binding proteins/peptides present in the blood of cancer patients may be derived from tumor cells. In this study, to effectively identify low-abundance proteins/peptides in the blood as tumor markers, we established a method for isolating HSP72-binding proteins/peptides from serum. Nine HSP72-specific monoclonal antibodies were conjugated to N-hydroxysulfosuccinimide-activated Sepharose beads (NHq) and used to isolate HSP72 complexes from serum samples. Precipitated proteins were then identified by LC-MS/MS analysis. Notably, this approach enabled the isolation of low-abundance proteins from serum without albumin removal. Moreover, by subjecting the serum samples of ten patients with multiple myeloma (MM) to NHq analysis, we identified 299 proteins present in MM HSP72 complexes, including 65 intracellular proteins. Among the intracellular proteins detected, 21 were present in all serum samples tested, while 11 were detected in both the conditioned media from cultured multiple myeloma cells and serum from MM patients. These results suggest that the NHq method can be applied to discover candidate tumor markers.

  3. Studies on binding interactions between clenbuterol hydrochloride and two serum albumins by multispectroscopic approaches in vitro.

    PubMed

    Wang, Qin; Zhang, Shengrui

    2014-08-01

    In this study, binding properties of clenbuterol hydrochloride (CL) with human serum albumin (HSA) and bovine serum albumin (BSA) were examined using constant protein concentrations and various CL contents under physiological conditions. The binding parameters were confirmed using fluorescence quenching spectroscopy at various temperatures. The experimental results confirmed that the quenching mechanisms of CL and HSA/BSA were both static quenching processes. The thermodynamic parameters, namely, enthalpy change (ΔH) and entropy change (ΔS), were calculated according to the van't Hoff equation, which suggested that the electrostatic interactions were the predominant intermolecular forces in stabilizing the CL-HSA complex, and hydrogen bonds and van der Waals force were the predominant intermolecular forces in stabilizing the CL-BSA complex. Furthermore, the conformational changes of HSA/BSA in the presence of CL were determined using the data obtained from three-dimensional fluorescence spectroscopy, ultraviolet-visible absorption spectroscopy and circular dichroism spectroscopy.

  4. Binding of human serum albumin to PEGylated liposomes: insights into binding numbers and dynamics by fluorescence correlation spectroscopy.

    PubMed

    Kristensen, Kasper; Urquhart, Andrew J; Thormann, Esben; Andresen, Thomas L

    2016-12-01

    Liposomes for medical applications are often administered by intravenous injection. Once in the bloodstream, the liposomes are covered with a "protein corona", which impacts the behavior and eventual fate of the liposomes. Currently, many aspects of the liposomal protein corona are not well understood. For example, there is generally a lack of knowledge about the liposome binding affinities and dynamics of common types of blood plasma proteins. Fluorescence correlation spectroscopy (FCS) is a powerful experimental technique that potentially can provide such knowledge. In this study, we have used FCS to investigate the binding of human serum albumin (HSA) to standard types of PEGylated fluid-phase liposomes (consisting of DOPC and DOPE-PEG2k) and PEGylated gel-phase liposomes (consisting of DSPC and DSPE-PEG2k) with various PEG chain surface densities. We detected no significant binding of HSA to the PEGylated fluid-phase liposomes. In contrast, we found that HSA bound tightly to the PEGylated gel-phase liposomes, although only a low number of HSA molecules could be accommodated per liposome. Overall, we believe that our data provides a useful benchmark for other researchers interested in studying the liposomal protein corona.

  5. Location and binding mechanism of an ESIPT probe 3-hydroxy-2-naphthoic acid in unsaturated fatty acid bound serum albumins.

    PubMed

    Ghorai, Shyamal Kr; Tripathy, Debi Ranjan; Dasgupta, Swagata; Ghosh, Sanjib

    2014-02-05

    The binding site and the binding mechanism of 3-hydroxy-2-naphthoic acid (3HNA) in oleic acid (OA) bound serum albumins (bovine serum albumin (BSA) and human serum albumin (HSA)) have been determined using steady state and time resolved emission of tryptophan residues (Trp) in proteins and the ESIPT emission of 3HNA. Time resolved anisotropy of the probe 3HNA and low temperature phosphorescence of Trp residues of BSA in OA bound BSA at 77K reveals a drastic change of the binding site of 3HNA in the ternary system compared to that in the free protein. 3HNA binds near Trp213 in the ternary system whereas 3HNA binds near Trp134 in the free protein. The structure of OA bound BSA generated using docking methodology exhibits U-bend configuration of all bound OA. The docked pose of 3HNA in the free protein and in OA bound albumins (ternary systems) and the concomitant perturbation of the structure of proteins around the binding region of 3HNA corroborate the enhanced ESIPT emission of 3HNA and the energy transfer efficiency from the donor Trp213 of BSA to 3HNA acceptor in 3HNA-OA-BSA system.

  6. Structure and Function of Lipopolysaccharide Binding Protein

    NASA Astrophysics Data System (ADS)

    Schumann, Ralf R.; Leong, Steven R.; Flaggs, Gail W.; Gray, Patrick W.; Wright, Samuel D.; Mathison, John C.; Tobias, Peter S.; Ulevitch, Richard J.

    1990-09-01

    The primary structure of lipopolysaccharide binding protein (LBP), a trace plasma protein that binds to the lipid A moiety of bacterial lipopolysaccharides (LPSs), was deduced by sequencing cloned complementary DNA. LBP shares sequence identity with another LPS binding protein found in granulocytes, bactericidal/permeability-increasing protein, and with cholesterol ester transport protein of the plasma. LBP may control the response to LPS under physiologic conditions by forming high-affinity complexes with LPS that bind to monocytes and macrophages, which then secrete tumor necrosis factor. The identification of this pathway for LPS-induced monocyte stimulation may aid in the development of treatments for diseases in which Gram-negative sepsis or endotoxemia are involved.

  7. SVOP Is a Nucleotide Binding Protein

    PubMed Central

    Yao, Jia; Bajjalieh, Sandra M.

    2009-01-01

    Background Synaptic Vesicle Protein 2 (SV2) and SV2-related protein (SVOP) are transporter-like proteins that localize to neurotransmitter-containing vesicles. Both proteins share structural similarity with the major facilitator (MF) family of small molecule transporters. We recently reported that SV2 binds nucleotides, a feature that has also been reported for another MF family member, the human glucose transporter 1 (Glut1). In the case of Glut1, nucleotide binding affects transport activity. In this study, we determined if SVOP also binds nucleotides and assessed its nucleotide binding properties. Methodology/Principal Findings We performed in vitro photoaffinity labeling experiments with the photoreactive ATP analogue, 8-azido-ATP[γ] biotin and purified recombinant SVOP-FLAG fusion protein. We found that SVOP is a nucleotide-binding protein, although both its substrate specificity and binding site differ from that of SV2. Within the nucleotides tested, ATP, GTP and NAD show same level of inhibition on SVOP-FLAG labeling. Dose dependent studies indicated that SVOP demonstrates the highest affinity for NAD, in contrast to SV2, which binds both NAD and ATP with equal affinity. Mapping of the binding site revealed a single region spanning transmembrane domains 9–12, which contrasts to the two binding sites in the large cytoplasmic domains in SV2A. Conclusions/Significance SVOP is the third MF family member to be found to bind nucleotides. Given that the binding sites are unique in SVOP, SV2 and Glut1, this feature appears to have arisen separately. PMID:19390693

  8. Drug binding to human serum albumin: abridged review of results obtained with high-performance liquid chromatography and circular dichroism.

    PubMed

    Ascoli, Giorgio A; Domenici, Enrico; Bertucci, Carlo

    2006-09-01

    The drug binding to plasma and tissue proteins are fundamental factors in determining the overall pharmacological activity of a drug. Human serum albumin (HSA), together with alpha1-acid glycoprotein (AGP), are the most important plasma proteins, which act as drug carriers, with drug pharmacokinetic implications, resulting in important clinical impacts for drugs that have a relatively narrow therapeutic index. 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. Furthermore, their applications to the study of changes in the binding properties of the protein arising by the reversible or covalent binding of drugs are discussed, and examples of physiological relevance reported. Perspectives of these studies reside in supporting the development of new drugs, which require miniaturization to facilitate the screening of classes of compounds for their binding to the target protein, and a deeper characterization of the mechanisms involved in the molecular recognition processes.

  9. Alteration of methotrexate binding to human serum albumin induced by oxidative stress. Spectroscopic comparative study

    NASA Astrophysics Data System (ADS)

    Maciążek-Jurczyk, M.; Sułkowska, A.; Równicka-Zubik, J.

    2016-01-01

    Changes of oxidative modified albumin conformation by comparison of non-modified (HSA) and modified (oHSA) human serum albumin absorption spectra, Red Edge Excitation Shift (REES) effect and fluorescence synchronous spectra were investigated. Studies of absorption spectra indicated that changes in the value of absorbance associated with spectral changes in the region from 200 to 250 nm involve structural alterations related to variations in peptide backbone conformation. Analysis of the REES effect allowed for the observation of changes caused by oxidation in the region of the hydrophobic pocket containing the tryptophanyl residue. Synchronous fluorescence spectroscopy confirmed changes of the position of the tryptophanyl and tyrosil residues fluorescent band. Effect of oxidative stress on binding of methotrexate (MTX) was investigated by spectrofluorescence, UV-VIS and 1HNMR spectroscopy. MTX caused the fluorescence quenching of non-modified (HSA) and modified (oHSA) human serum albumin molecule. The values of binding constants, Hill's coefficients and a number of binding sites in the protein molecule in the high affinity binding site were calculated for the binary MTX-HSA and MTX-oHSA systems. For these systems, qualitative analysis in the low affinity binding sites was performed with the use of the 1HNMR technique.

  10. Binding of chloroquine-conjugated gold nanoparticles with bovine serum albumin.

    PubMed

    Joshi, Prachi; Chakraborty, Soumyananda; Dey, Sucharita; Shanker, Virendra; Ansari, Z A; Singh, Surinder P; Chakrabarti, Pinak

    2011-03-15

    We have conjugated chloroquine, an anti-malarial, antiviral and anti-tumor drug, with thiol-functionalized gold nanoparticles and studied their binding interaction with bovine serum albumin (BSA) protein. Gold nanoparticles have been synthesized using sodium borohydride as reducing agent and 11-mercaptoundecanoic acid as thiol functionalizing ligand in aqueous medium. The formation of gold nanoparticles was confirmed from the characteristic surface plasmon absorption band at 522 nm and transmission electron microscopy revealed the average particle size to be ~7 nm. Chloroquine was conjugated to thiolated gold nanoparticles by using EDC/NHS chemistry and the binding was analyzed using optical density measurement and Fourier transform infrared spectroscopy. The chloroquine-conjugated gold nanoparticles (GNP-Chl) were found to interact efficiently with BSA. Thermodynamic parameters suggest that the binding is driven by both enthalpy and entropy, accompanied with only a minor alteration in protein's structure. Competitive drug binding assay revealed that the GNP-Chl bind at warfarin binding site I in subdomain IIA of BSA and was further supported by Trp212 fluorescence quenching measurements. Unraveling the nature of interactions of GNP-Chl with BSA would pave the way for the design of nanotherapeutic agents with improved functionality, enriching the field of nanomedicine.

  11. Photo selective protein immobilization using bovine serum albumin

    NASA Astrophysics Data System (ADS)

    Kim, Wan-Joong; Kim, Ansoon; Huh, Chul; Park, Chan Woo; Ah, Chil Seong; Kim, Bong Kyu; Yang, Jong-Heon; Chung, Kwang Hyo; Choi, Yo Han; Hong, Jongcheol; Sung, Gun Yong

    2012-11-01

    A simple and selective technique which immobilizes protein onto a solid substrate by using UV illumination has been developed. In protein immobilization, a Bovine serum albumin (BSA) performed bifunctional role as a cross-linker between substrate and proteins and as a blocker inhibiting a nonspecific protein adsorption. A new photo-induced protein immobilization process has been investigated at each step by fluorescence microscopy, ellipsometry, and Fourier transform infrared (FT-IR) spectroscopy. A UV photomask has been used to induce selective protein immobilization on target regions of the surface of the SiO2 substrates under UV illumination with negligible nonspecific binding. The UV illumination also showed improved photostability than the conventional methods which employed bifunctional photo-crosslinker molecules of photo-reactive diazirine. This new UV illumination-based photo-addressable protein immobilization provides a new approach for developing novel protein microarrays for multiplexed sensing as well as other types of bio-immobilization in biomedical devices and biotechnologies.

  12. Determinants of the plasma protein binding of theophylline in health.

    PubMed Central

    Buss, D; Leopold, D; Smith, A P; Routledge, P A

    1983-01-01

    1 The plasma protein binding of theophylline was determined after addition of [14C]-theophylline (15 micrograms/ml) to plasma from 24 healthy drug-free volunteers and equilibrium dialysis for 2 h at 37 degrees C. 2 The percentage of drug unbound was 60.0% +/- 2.2% (s.d.) with very little variation between individuals. The binding ratio of theophylline was not significantly related to the plasma albumin or alpha 1-acid glycoprotein (AAG) concentrations but was significantly, although weakly, negatively related to the logarithm of the non-esterified fatty acid concentration (NEFA) (r = 0.443, P less than 0.05). 3 Intravenous administration of heparin (1000 units) caused a significant rise in plasma NEFA concentration and in the percentage of drug unbound in plasma after equilibrium dialysis. 4 In human serum albumin solutions, the binding ratio of theophylline was significantly related to the albumin concentration and at the albumin concentration seen in the 24 normal subjects, the percentage of drug unbound was almost identical. Addition of AAG in physiological concentrations did not enhance theophylline binding but oleic acid, and to a lesser extent palmitic acid, reduced binding significantly. 5 The percentage of theophylline unbound in plasma varied markedly with pH so that at pH7 the percentage unbound was 52% greater than at pH 8. There was no evidence of concentration dependence of binding up to 140 micrograms/ml theophylline. 6 Theophylline appears to bind almost exclusively to albumin and its plasma protein binding varies little in healthy subjects, showing no concentration-dependence over the therapeutic range of concentrations. The binding is affected by pH and by NEFA concentration, however, and these factors may be of greater importance in disease states. Caution should be employed in the use of heparin in studies of plasma protein binding of theophylline. PMID:6849774

  13. Reversible binding of tolmetin, zomepirac, and their glucuronide conjugates to human serum albumin and plasma.

    PubMed

    Ojingwa, J C; Spahn-Langguth, H; Benet, L Z

    1994-02-01

    Acyl glucuronides of drugs and bilirubin have been shown in the past decade to be reactive metabolites undergoing acyl migration and irreversible binding. The latter reaction has been hypothesized to be facilitated by or to proceed through the formation of a reversible complex. Furthermore, it has been suggested that the decreased binding seen in patients with compromised excretory function may be due to competition by elevated plasma concentrations of the glucuronides. In these reversible binding studies, we characterized the extent and the "site" of binding of tolmetin, zomepirac, their glucuronides and isomeric conjugates. We also examined the displacement between the parent drugs and their glucuronide conjugates using a rapid ultrafiltration method. Tolmetin exhibited three classes of binding sites with a primary association constant of 1.7 x 10(6) M-1 (Kd1 = 0.60 microM). The primary association constant of zomepirac (1.16 x 10(6) M-1, Kd1 = 0.86 microM) is similar to that of tolmetin. The beta 1 and alpha/beta 3 glucuronides of both compounds bind to a lesser extent than their parent aglycones. The isomeric glucuronide conjugates of both compounds showed much stronger binding than the beta/1 conjugates. Of the four glucuronides investigated, tolmetin glucuronide-alpha/beta 3 isomer was bound by fatty acid free human serum albumin with the highest affinity (4.6 x 10(5) M-1, Kd = 2.22 microM). Protein binding of the parent drugs and conjugates were decreased significantly at pH 5.0. In displacement studies, except for salicylate and acetylsalicylate, drugs known to bind to Sites I and II as well as the digitoxin and tamoxifen binding sites had little inhibitory effect on the binding of tolmetin, zomepirac, and their glucuronide conjugates.

  14. Probing the binding of fluoxetine hydrochloride to human serum albumin by multispectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Katrahalli, Umesha; Jaldappagari, Seetharamappa; Kalanur, Shankara S.

    2010-01-01

    The interaction between human serum albumin (HSA) and fluoxetine hydrochloride (FLX) have been studied by using different spectroscopic techniques viz., fluorescence, UV-vis absorption, circular dichroism and FTIR under simulated physiological conditions. Fluorescence results revealed the presence of static type of quenching mechanism in the binding of FLX to HSA. The values of binding constant, K of FLX-HSA were evaluated at 289, 300 and 310 K and were found to be 1.90 × 10 3, 1.68 × 10 3 and 1.45 × 10 3 M -1, respectively. The number of binding sites, n was noticed to be almost equal to unity thereby indicating the presence of a single class of binding site for FLX on HSA. Based on the thermodynamic parameters, Δ H0 and Δ S0 nature of binding forces operating between HSA and FLX were proposed. Spectral results revealed the conformational changes in protein upon interaction. Displacement studies indicated the site I as the main binding site for FLX on HSA. The effect of common ions on the binding of FLX to HSA was also investigated.

  15. Methyl-triclosan binding to human serum albumin: multi-spectroscopic study and visualized molecular simulation.

    PubMed

    Lv, Wenjuan; Chen, Yonglei; Li, Dayong; Chen, Xingguo; Leszczynski, Jerzy

    2013-10-01

    Methyl-triclosan (MTCS), a transformation product and metabolite of triclosan, has been widely spread in environment through the daily use of triclosan which is a commonly used anti-bacterial and anti-fungal substance in consumer products. Once entering human body, MTCS could affect the conformation of human serum albumin (HSA) by forming MTCS-HSA complex and alter function of protein and endocrine in human body. To evaluate the potential toxicity of MTCS, the binding mechanism of HSA with MTCS was investigated by UV-vis absorption, circular dichroism and Fourier transform infrared spectroscopy. Binding constants, thermodynamic parameters, the binding forces and the specific binding site were studied in detail. Binding constant at room tempreture (T = 298K) is 6.32 × 10(3)L mol(-1); ΔH(0), ΔS(0) and ΔG(0) were 22.48 kJ mol(-1), 148.16 J mol(-1)K(-1) and -21.68 kJ mol(-1), respectively. The results showed that the interactions between MTCS and HSA are mainly hydrophobic forces. The effects of MTCS on HSA conformation were also discussed. The binding distance (r = 1.2 nm) for MTCS-HSA system was calculated by the efficiency of fluorescence resonance energy transfer. The visualized binding details were also exhibited by molecular modeling method and the results could agree well with that from the experimental study.

  16. Evaluation of the enantioselective binding of imazalil to human serum albumin by capillary electrophoresis.

    PubMed

    Asensi-Bernardi, Lucía; Martín-Biosca, Yolanda; Escuder-Gilabert, Laura; Sagrado, Salvador; Medina-Hernández, María José

    2015-11-01

    In this work, a methodology for the evaluation of enantioselective binding of imazalil (IMA) enantiomers to human serum albumin (HSA) that does not require the separation of free and bound to HSA fractions is developed. This methodology comprises the incubation of IMA-HSA designed mixtures for 30 min directly in the capillary electrophoresis system and the subsequent direct injection and chiral separation of IMA employing highly sulfated β-cyclodextrin as chiral selector and the complete filling technique. Two mathematical approaches were used to estimate apparent affinity constants (K1), protein binding and enantioselectivity (ES) for both enantiomers of IMA. Moderate enantioselective binding of IMA enantiomers to HSA (ES = 2.0) was shown by the 1:1 stoichiometry and log K1 values of 3.4 ± 0.4 and 3.1 ± 0.3 for the first and second eluted enantiomers, respectively.

  17. Behind the scenes of vitamin D binding protein: more than vitamin D binding.

    PubMed

    Delanghe, Joris R; Speeckaert, Reinhart; Speeckaert, Marijn M

    2015-10-01

    Although being discovered in 1959, the number of published papers in recent years reveals that vitamin D binding protein (DBP), a member of the albuminoid superfamily, is a hot research topic. Besides the three major phenotypes (DBP1F, DBP1S and DBP2), more than 120 unique variants have been described of this polymorphic protein. The presence of DBP has been demonstrated in different body fluids (serum, urine, breast milk, ascitic fluid, cerebrospinal fluid, saliva and seminal fluid) and organs (brain, heart, lungs, kidneys, placenta, spleen, testes and uterus). Although the major function is binding, solubilization and transport of vitamin D and its metabolites, the name of this glycoprotein hides numerous other important biological functions. In this review, we will focus on the analytical aspects of the determination of DBP and discuss in detail the multifunctional capacity [actin scavenging, binding of fatty acids, chemotaxis, binding of endotoxins, influence on T cell response and influence of vitamin D binding protein-macrophage activating factor (DBP-MAF) on bone metabolism and cancer] of this abundant plasma protein.

  18. Surface-Based Protein Binding Pocket Similarity

    PubMed Central

    Spitzer, Russell; Cleves, Ann E.; Jain, Ajay N.

    2011-01-01

    Protein similarity comparisons may be made on a local or global basis and may consider sequence information or differing levels of structural information. We present a local 3D method that compares protein binding site surfaces in full atomic detail. The approach is based on the morphological similarity method which has been widely applied for global comparison of small molecules. We apply the method to all-by-all comparisons two sets of human protein kinases, a very diverse set of ATP-bound proteins from multiple species, and three heterogeneous benchmark protein binding site data sets. Cases of disagreement between sequence-based similarity and binding site similarity yield informative examples. Where sequence similarity is very low, high pocket similarity can reliably identify important binding motifs. Where sequence similarity is very high, significant differences in pocket similarity are related to ligand binding specificity and similarity. Local protein binding pocket similarity provides qualitatively complementary information to other approaches, and it can yield quantitative information in support of functional annotation. PMID:21769944

  19. Tuning the serum persistence of human serum albumin domain III:diabody fusion proteins

    PubMed Central

    Kenanova, Vania E.; Olafsen, Tove; Salazar, Felix B.; Williams, Lawrence E.; Knowles, Scott; Wu, Anna M.

    2010-01-01

    The long circulation persistence of human serum albumin (HSA) is enabled by its domain III (DIII) interaction with the neonatal Fc receptor (FcRn). A protein scaffold based on HSA DIII was designed. To modify the serum half life of the scaffold, residues H535, H510, and H464 were individually mutated to alanine. HSA DIII wild type (WT) and variants were fused to the anti-carcinoembryonic antigen (CEA) T84.66 diabody (Db), radiolabeled with 124I and injected into xenografted athymic mice for serial PET/CT imaging. All proteins targeted the CEA-positive tumor. The mean residence times (MRT) of the proteins, calculated by quantifying blood activity from the PET images, were: Db-DIII WT (56.7 h), H535A (25 h), H510A (20 h), H464A (17 h), compared with Db (2.9 h). Biodistribution confirmed the order of blood clearance from slow to fast: Db-DIII WT > H535A > H510A > H464A > Db with 4.0, 2.0, 1.8, 1.6 and 0.08 %ID/g of remaining blood activity at 51 h, respectively. This study demonstrates that attenuating the DIII–FcRn interaction provides a way of controlling the pharmacokinetics of the entire Db-DIII fusion protein without compromising tumor targeting. H464 appears to be most crucial for FcRn binding (greatest reduction in MRT), followed by H510 and H535. By mutating the DIII scaffold, we can dial serum kinetics for imaging or therapy applications. PMID:20802234

  20. Cortisol levels, binding, and properties of corticosteroid-binding globulin in the serum of primates.

    PubMed

    Klosterman, L L; Murai, J T; Siiteri, P K

    1986-01-01

    New World primates have exceptionally high plasma levels of cortisol and other steroid hormones when compared with humans and other primates. It has been suggested that this difference can be explained by either low affinity or concentration of cellular steroid receptors. We have assessed cortisol availability in serum from several species of New and Old World primates under physiological conditions (whole serum at 37 degrees C). Measurements were made of total and free cortisol, corticosteroid-binding globulin (CBG) binding capacity and affinity for cortisol, distribution of cortisol in serum, and its binding to albumin. In agreement with earlier reports, plasma free cortisol levels in Old World primates, prosimians, and humans range from 10-300 nM. However, very high total plasma cortisol together with low CBG binding capacity and affinity result in free cortisol concentrations of 1-4 microM in some New World primates (squirrel monkey and marmosets) but not in others such as the titi and capuchin. In squirrel monkeys, free cortisol levels are far greater than might be predicted from the affinity of the glucocorticoid receptor estimated in cultured skin fibroblasts. In addition to low affinity, CBG from squirrel monkeys and other New World primates exhibits differences in electrophoretic mobility and sedimentation behavior in sucrose density ultracentrifugation, suggestive of a molecular weight that is approximately twice that of CBG from other species. Together with other data these results indicate that the apparent glucocorticoid resistance found in New World primates is a complex phenomenon that is not easily explained by present concepts of glucocorticoid action.

  1. Lipid binding proteins from parasitic platyhelminthes.

    PubMed

    Alvite, Gabriela; Esteves, Adriana

    2012-01-01

    TWO MAIN FAMILIES OF LIPID BINDING PROTEINS HAVE BEEN IDENTIFIED IN PARASITIC PLATYHELMINTHES: hydrophobic ligand binding proteins (HLBPs) and fatty acid binding proteins (FABPs). Members of the former family of proteins are specific to the Cestoda class, while FABPs are conserved across a wide range of animal species. Because Platyhelminthes are unable to synthesize their own lipids, these lipid-binding proteins are important molecules in these organisms. HLBPs are a high molecular mass complex of proteins and lipids. They are composed of subunits of low molecular mass proteins and a wide array of lipid molecules ranging from CoA esters to cholesterol. These proteins are excretory-secretory molecules and are key serological tools for diagnosis of diseases caused by cestodes. FABPs are mainly intracellular proteins of low molecular weight. They are also vaccine candidates. Despite that the knowledge of their function is scarce, the differences in their molecular organization, ligand preferences, intra/extracellular localization, evolution, and phylogenetic distribution, suggest that platyhelminths HLBPs and FABPs should play different functions. FABPs might be involved in the removal of fatty acids from the inner surface of the cell membrane and in their subsequent targeting to specific cellular destinations. In contrast, HLBPs might be involved in fatty acid uptake from the host environment.

  2. The binding domain structure of retinoblastoma-binding proteins.

    PubMed Central

    Figge, J.; Breese, K.; Vajda, S.; Zhu, Q. L.; Eisele, L.; Andersen, T. T.; MacColl, R.; Friedrich, T.; Smith, T. F.

    1993-01-01

    The retinoblastoma gene product (Rb), a cellular growth suppressor, complexes with viral and cellular proteins that contain a specific binding domain incorporating three invariant residues: Leu-X-Cys-X-Glu, where X denotes a nonconserved residue. Hydrophobic and electrostatic properties are strongly conserved in this segment even though the nonconserved amino acids vary considerably from one Rb-binding protein to another. In this report, we present a diagnostic computer pattern for a high-affinity Rb-binding domain featuring the three conserved residues as well as the conserved physico-chemical properties. Although the pattern encompasses only 10 residues (with only 4 of these explicitly defined), it exhibits 100% sensitivity and 99.95% specificity in database searches. This implies that a certain pattern of structural and physico-chemical properties encoded by this short sequence is sufficient to govern specific Rb binding. We also present evidence that the secondary structural conformation through this region is important for effective Rb binding. PMID:8382993

  3. Drug-drug plasma protein binding interactions of ivacaftor.

    PubMed

    Schneider, Elena K; Huang, Johnny X; Carbone, Vincenzo; Baker, Mark; Azad, Mohammad A K; Cooper, Matthew A; Li, Jian; Velkov, Tony

    2015-06-01

    Ivacaftor is a novel cystic fibrosis (CF) transmembrane conductance regulator (CFTR) potentiator that improves the pulmonary function for patients with CF bearing a G551D CFTR-protein mutation. Because ivacaftor is highly bound (>97%) to plasma proteins, there is the strong possibility that co-administered CF drugs may compete for the same plasma protein binding sites and impact the free drug concentration. This, in turn, could lead to drastic changes in the in vivo efficacy of ivacaftor and therapeutic outcomes. This biochemical study compares the binding affinity of ivacaftor and co-administered CF drugs for human serum albumin (HSA) and α1 -acid glycoprotein (AGP) using surface plasmon resonance and fluorimetric binding assays that measure the displacement of site-selective probes. Because of their ability to strongly compete for the ivacaftor binding sites on HSA and AGP, drug-drug interactions between ivacaftor are to be expected with ducosate, montelukast, ibuprofen, dicloxacillin, omeprazole, and loratadine. The significance of these plasma protein drug-drug interactions is also interpreted in terms of molecular docking simulations. This in vitro study provides valuable insights into the plasma protein drug-drug interactions of ivacaftor with co-administered CF drugs. The data may prove useful in future clinical trials for a staggered treatment that aims to maximize the effective free drug concentration and clinical efficacy of ivacaftor.

  4. [Microcalorimetric study of the parameters of dicloxacillin binding with human serum albumin at different temperatures].

    PubMed

    Markovich, M N; Isakovich, L G; Klinichev, V F

    1986-08-01

    The thermodynamic parameters of human serum albumin (HSA) binding with dicloxacillin, an antibiotic widely used in clinical practice, were determined with the method of differential flow microcalorimetry at 18, 25, 30, 37 and 45 degrees C. The experiments were performed at two ionic strengths: 0.02 and 0.15. Two hypothetic models of interaction in the HSA-drug system were considered in processing the data for the curves of calorimetric titration. The first model implies the presence of independent homogeneous active sites on the protein. In accordance with the second model there are one primary and secondary independent homogeneous active sites on the biopolymer molecule. It is shown that dicloxacillin association with HSA proceeds according to the mechanism suggesting the presence of one primary and one secondary active sites on the protein molecule. The binding process in the system studied is exothermic, the enthalpy increasing at the temperature change from 18 to 45 degrees C. At the same time the binding constant and enthropy of the system decrease. The influence of the solution ionic strength on the binding process was practically lacking. On the basis of the analysis of the thermodynamic data it is concluded that the character of the binding in the HSA-dicloxacillin system at 18-30 degrees C is hydrophobic. With an increase in the temperature the hydrophoby level decreases.

  5. Binding of ring-substituted indole-3-acetic acids to human serum albumin.

    PubMed

    Soskić, Milan; Magnus, Volker

    2007-07-01

    The plant hormone, indole-3-acetic acid (IAA), and its ring-substituted derivatives have recently attracted attention as promising pro-drugs in cancer therapy. Here we present relative binding constants to human serum albumin for IAA and 34 of its derivatives, as obtained using the immobilized protein bound to a support suitable for high-performance liquid chromatography. We also report their octanol-water partition coefficients (logK(ow)) computed from retention data on a C(18) coated silica gel column. A four-parameter QSPR (quantitative structure-property relationships) model, based on physico-chemical properties, is put forward, which accounts for more than 96% of the variations in the binding affinities of these compounds. The model confirms the importance of lipophilicity as a global parameter governing interaction with serum albumin, but also assigns significant roles to parameters specifically related to the molecular topology of ring-substituted IAAs. Bulky substituents at ring-position 6 increase affinity, those at position 2 obstruct binding, while no steric effects were noted at other ring-positions. Electron-withdrawing substituents at position 5 enhance binding, but have no obvious effect at other ring positions.

  6. Host humoral immune response to Leishmania lipid-binding protein.

    PubMed

    Maache, M; Azzouz, S; Diaz de la Guardia, R; Alvarez, P; Gil, R; de Pablos, L M; Osuna, A

    2005-06-01

    SUMMARY We report on the use of Leishmania donovani lipid-binding proteins (LBPs) as antigens capable of being recognized by serum from immunocompetent patients from southern Spain suffering from visceral leishmaniasis and from Peruvian patients with localized cutaneous leishmaniasis caused by Leishmania braziliensis. The absorbance found by immunoenzymatic techniques gave significantly different results for the serum samples from patients with and without leishmaniasis. Specificity by ELISA testing was 93.2% and sensibility 100%. Dot blots from human patient serum samples or naturally infected dogs from Spain gave similarly significant results. All the human serum samples from individuals with visceral leishmaniasis and the Leishmania-positive canine samples recognized two bands, with molecular weights of 8 and 57 kDa. The serum from individuals with cutaneous leishmaniasis caused by L. braziliensis recognized an additional band of 16 kDa. We discuss the role of Leishmania FABP and compare the immunological reactions found with serum samples from other protozoan infections such as toxoplasma and Chagas as well as bacterial infections such as tuberculosis and syphilis.

  7. Effects of gene carrier polyethyleneimines on the structure and binding capability of bovine serum albumin

    NASA Astrophysics Data System (ADS)

    Guo, Zhiyong; Kong, Zhijie; Wei, Yanshan; Li, Hua; Wang, Yajing; Huang, Aimin; Ma, Lin

    2017-02-01

    Polyethyleneimine (PEI), one of the most effective non-viral gene carriers, is also cytotoxic, however the molecular basis is poorly understood. Little is known about the effects of PEI on the structure and functions of the biomacromolecules. In this work, fluorescence, UV-vis absorption, circular dichroism (CD) spectroscopy and zeta-potential measurement were conducted to reveal the interaction between PEIs (average molecular weight 25, 10 and 1.8 kDa) and bovine serum albumin (BSA), and to evaluate the effects on the conformation of BSA as long as its binding capability to the model compounds, 8-anilino-1-naphthalenesulfonic acid (ANS) and quercetin. PEIs were found to complex with BSA and induced a conformational change of the protein by a major reduction of α-helix at PEI concentration < 0.2 mg·mL- 1 and an increase at higher PEI concentration. The binding efficacy of ANS and quercetin to BSA was greatly reduced by the competitive binding by PEI and influenced by the conformational change of BSA, which was found to display a similar trend to the change of the α-helix content of the protein. The polymer size played an important role in PEI-BSA interaction. PEI of higher molecular weight was more favorable to interact with BSA and more efficient to perturb the conformation and binding capability of the protein.

  8. Effects of gene carrier polyethyleneimines on the structure and binding capability of bovine serum albumin.

    PubMed

    Guo, Zhiyong; Kong, Zhijie; Wei, Yanshan; Li, Hua; Wang, Yajing; Huang, Aimin; Ma, Lin

    2017-02-15

    Polyethyleneimine (PEI), one of the most effective non-viral gene carriers, is also cytotoxic, however the molecular basis is poorly understood. Little is known about the effects of PEI on the structure and functions of the biomacromolecules. In this work, fluorescence, UV-vis absorption, circular dichroism (CD) spectroscopy and zeta-potential measurement were conducted to reveal the interaction between PEIs (average molecular weight 25, 10 and 1.8kDa) and bovine serum albumin (BSA), and to evaluate the effects on the conformation of BSA as long as its binding capability to the model compounds, 8-anilino-1-naphthalenesulfonic acid (ANS) and quercetin. PEIs were found to complex with BSA and induced a conformational change of the protein by a major reduction of α-helix at PEI concentration <0.2mg·mL(-1) and an increase at higher PEI concentration. The binding efficacy of ANS and quercetin to BSA was greatly reduced by the competitive binding by PEI and influenced by the conformational change of BSA, which was found to display a similar trend to the change of the α-helix content of the protein. The polymer size played an important role in PEI-BSA interaction. PEI of higher molecular weight was more favorable to interact with BSA and more efficient to perturb the conformation and binding capability of the protein.

  9. Folding funnels, binding funnels, and protein function.

    PubMed Central

    Tsai, C. J.; Kumar, S.; Ma, B.; Nussinov, R.

    1999-01-01

    Folding funnels have been the focus of considerable attention during the last few years. These have mostly been discussed in the general context of the theory of protein folding. Here we extend the utility of the concept of folding funnels, relating them to biological mechanisms and function. In particular, here we describe the shape of the funnels in light of protein synthesis and folding; flexibility, conformational diversity, and binding mechanisms; and the associated binding funnels, illustrating the multiple routes and the range of complexed conformers. Specifically, the walls of the folding funnels, their crevices, and bumps are related to the complexity of protein folding, and hence to sequential vs. nonsequential folding. Whereas the former is more frequently observed in eukaryotic proteins, where the rate of protein synthesis is slower, the latter is more frequent in prokaryotes, with faster translation rates. The bottoms of the funnels reflect the extent of the flexibility of the proteins. Rugged floors imply a range of conformational isomers, which may be close on the energy landscape. Rather than undergoing an induced fit binding mechanism, the conformational ensembles around the rugged bottoms argue that the conformers, which are most complementary to the ligand, will bind to it with the equilibrium shifting in their favor. Furthermore, depending on the extent of the ruggedness, or of the smoothness with only a few minima, we may infer nonspecific, broad range vs. specific binding. In particular, folding and binding are similar processes, with similar underlying principles. Hence, the shape of the folding funnel of the monomer enables making reasonable guesses regarding the shape of the corresponding binding funnel. Proteins having a broad range of binding, such as proteolytic enzymes or relatively nonspecific endonucleases, may be expected to have not only rugged floors in their folding funnels, but their binding funnels will also behave similarly

  10. Localization of Cellular Retinol-Binding Protein and Retinol-Binding Protein in Cells Comprising the Blood-Brain Barrier of Rat and Human

    NASA Astrophysics Data System (ADS)

    MacDonald, Paul N.; Bok, Dean; Ong, David E.

    1990-06-01

    Brain is not generally recognized as an organ that requiries vitamin A, perhaps because no obvious histologic lesions have been observed in severely vitamin A-deficient animals. However, brain tissue does contain cellular vitamin A-binding proteins and a nuclear receptor protein for retinoic acid. In the present study, immunohistochemical techniques were used to determine the cell-specific location of cellular retinol-binding protein in human and rat brain tissue. Cellular retinol-binding protein was localized specifically within the endothelial cells of the brain microvasculature and within the cuboidal epithelial cells of the choroid plexus, two primary sites of the mammalian blood-brain barrier. In addition, autoradiographic procedures demonstrated binding sites for serum retinol-binding protein in the choroidal epithelium. These observations suggest that a significant movement of retinol across the blood-brain barrier may occur.

  11. Elucidation of the binding sites of two novel Ru(II) complexes on bovine serum albumin.

    PubMed

    Nišavić, Marija; Masnikosa, Romana; Butorac, Ana; Perica, Kristina; Rilak, Ana; Korićanac, Lela; Hozić, Amela; Petković, Marijana; Cindrić, Mario

    2016-06-01

    Hyphenated mass spectrometry (MS) techniques have attained an important position in analysis of covalent and non-covalent interactions of metal complexes with peptides and proteins. The aim of the present study was to qualitatively and quantitatively determine ruthenium binding sites on a protein using tandem mass spectrometry and allied techniques, i.e. liquid chromatography (LC) and inductively coupled plasma optical emission spectrometry (ICP-OES). For that purpose, two newly synthesized Ru(II) complexes of a meridional geometry, namely mer-[Ru(4' Cl-tpy)(en)Cl](+) (1) and mer-[Ru(4' Cl-tpy)(dach)Cl](+) (2) (where 4' Cl-tpy=4'-chloro-2,2':6',2″-terpyridine, en=1,2-diaminoethane and dach=1,2-diaminocyclohexane), and bovine serum albumin were used. The binding of the complexes to the protein was investigated by means of size exclusion- and reversed phase-LC, ICP OES, matrix-assisted laser desorption ionization MS and MS/MS. Ruthenated peptide sequence and a binding target amino acid were revealed through accurate elucidation of MS/MS spectra. The results obtained in this study suggest a high binding capacity of the protein towards both complexes, with up to 5.77±0.14 and 6.95±0.43mol of 1 and 2 bound per mol of protein, respectively. The proposed binding mechanism for the selected complexes includes the release of Cl ligand, its replacement with water molecule and further coordination to electron donor histidine residue.

  12. Aspects of Protein, Chemistry, Part II: Oxygen-Binding Proteins

    ERIC Educational Resources Information Center

    Nixon, J. E.

    1977-01-01

    Compares differences in function and behavior of two oxygen-binding proteins, myoglobin found in muscle and hemoglobin found in blood. Describes the mechanism of oxygen-binding and allosteric effect in hemoglobin; also describes the effect of pH on the affinity of hemoglobin for oxygen. (CS)

  13. The binding of immunoglobulin Fc to cationic proteins.

    PubMed Central

    Pambakian, S; Poston, R N

    1987-01-01

    The interaction of cationic proteins with IgG, IgA and IgM were investigated by solid phase radioimmunoassay. All these immunoglobulins showed avid binding, IgM giving the strongest reaction, followed by IgA and then IgG. Fc fragments of IgG gave binding, but F(ab')2 fragments from the three main Ig classes did not, showing that the Fc region is the active part of the molecule. The effects of changes of ionic strength and pH are compatible with the interaction being ionic, and are similar to those seen between immunoglobulins and both Clq and cationic ion exchange gels. The addition of other serum proteins resulted in marked inhibition of the interaction. These phenomena are likely to have fundamental significance for the understanding of interactions of immunoglobulins in vivo and in vitro. Images Fig. 6 PMID:3652520

  14. Maltose-Binding Protein (MBP), a Secretion-Enhancing Tag for Mammalian Protein Expression Systems.

    PubMed

    Reuten, Raphael; Nikodemus, Denise; Oliveira, Maria B; Patel, Trushar R; Brachvogel, Bent; Breloy, Isabelle; Stetefeld, Jörg; Koch, Manuel

    2016-01-01

    Recombinant proteins are commonly expressed in eukaryotic expression systems to ensure the formation of disulfide bridges and proper glycosylation. Although many proteins can be expressed easily, some proteins, sub-domains, and mutant protein versions can cause problems. Here, we investigated expression levels of recombinant extracellular, intracellular as well as transmembrane proteins tethered to different polypeptides in mammalian cell lines. Strikingly, fusion of proteins to the prokaryotic maltose-binding protein (MBP) generally enhanced protein production. MBP fusion proteins consistently exhibited the most robust increase in protein production in comparison to commonly used tags, e.g., the Fc, Glutathione S-transferase (GST), SlyD, and serum albumin (ser alb) tag. Moreover, proteins tethered to MBP revealed reduced numbers of dying cells upon transient transfection. In contrast to the Fc tag, MBP is a stable monomer and does not promote protein aggregation. Therefore, the MBP tag does not induce artificial dimerization of tethered proteins and provides a beneficial fusion tag for binding as well as cell adhesion studies. Using MBP we were able to secret a disease causing laminin β2 mutant protein (congenital nephrotic syndrome), which is normally retained in the endoplasmic reticulum. In summary, this study establishes MBP as a versatile expression tag for protein production in eukaryotic expression systems.

  15. Potential toxicity of amphenicol antibiotic: binding of chloramphenicol to human serum albumin.

    PubMed

    Chen, Huilun; Rao, Honghao; He, Pengzhen; Qiao, Yongxiang; Wang, Fei; Liu, Haijun; Cai, Minmin; Yao, Jun

    2014-10-01

    Antibiotics are widely used in daily life but their abuse has posed a potential threat to human health. To evaluate the toxicity of chloramphenicol (CAP) at the protein level, the interaction between CAP and human serum albumin (HSA) was investigated by fluorescence, Ultraviolet-visible (UV-Vis) absorption, Fourier transform infrared (FT-IR) spectroscopy and molecular docking methods. Fluorescence data revealed that the fluorescence quenching of HSA by CAP was the result of the formation of CAP-HSA complex, and the binding constant was determined to be 3.196 × 10(4) L mol(-1) at 310 K. The thermodynamic determination indicated that the interaction was driven by enthalpy change and entropy change together, where the multiple hydrogen bonds (CAP and the residues Arg 222 and His 242 of HSA) and van der Waals forces were the dominant binding force. The site marker competition revealed that CAP bound into sub-domain IIA of HSA. The binding of CAP induced the drastic reduction in α-helix conformation and the significant enhancement in β-sheet conformation of HSA. Molecular docking study further confirmed the binding mode obtained by experimental study. This work provides a new quantitative evaluation method for antibiotics to cause the protein damage.

  16. Binding interactions of pefloxacin mesylate with bovine lactoferrin and human serum albumin*

    PubMed Central

    Fan, Ji-cai; Chen, Xiang; Wang, Yun; Fan, Cheng-ping; Shang, Zhi-cai

    2006-01-01

    The binding of pefloxacin mesylate (PFLX) to bovine lactoferrin (BLf) and human serum albumin (HSA) in dilute aqueous solution was studied using fluorescence spectra and absorbance spectra. The binding constant K and the binding sites n were obtained by fluorescence quenching method. The binding distance r and energy-transfer efficiency E between pefloxacin mesylate and bovine lactoferrin as well as human serum albumin were also obtained according to the mechanism of Förster-type dipole-dipole nonradiative energy-transfer. The effects of pefloxacin mesylate on the conformations of bovine lactoferrin and human serum albumin were also analyzed using synchronous fluorescence spectroscopy. PMID:16691639

  17. Binding of an Oligomeric Ellagitannin Series to Bovine Serum Albumin (BSA): Analysis by Isothermal Titration Calorimetry (ITC).

    PubMed

    Karonen, Maarit; Oraviita, Marianne; Mueller-Harvey, Irene; Salminen, Juha-Pekka; Green, Rebecca J

    2015-12-16

    A unique series of oligomeric ellagitannins was used to study their interactions with bovine serum albumin (BSA) by isothermal titration calorimetry. Oligomeric ellagitannins, ranging from monomer to heptamer and a mixture of octamer-undecamers, were isolated as individual pure compounds. This series allowed studying the effects of oligomer size and other structural features. The monomeric to trimeric ellagitannins deviated most from the overall trends. The interactions of ellagitannin oligomers from tetramers to octa-undecamers with BSA revealed strong similarities. In contrast to the equilibrium binding constant, enthalpy showed an increasing trend from the dimer to larger oligomers. It is likely that first the macrocyclic part of the ellagitannin binds to the defined binding sites on the protein surface and then the "flexible tail" of the ellagitannin coats the protein surface. The results highlight the importance of molecular flexibility to maximize binding between the ellagitannin and protein surfaces.

  18. Recombinant human serum amyloid A (apoSAAp) binds cholesterol and modulates cholesterol flux.

    PubMed

    Liang, J S; Sipe, J D

    1995-01-01

    During acute inflammation, the serum amyloid A (apoSAA) proteins apoSAA1 and apoSAA2 are transiently associated with high density lipoproteins (HDL) in concentrations of as much as 1000-fold more than their concentrations during homeostasis; however, their effect on HDL function is unclear. Recombinant apoSAAp, a hybrid of the closely related human apoSAA1 and apoSAA2 isoforms, was found to exhibit a high affinity for cholesterol. The adsorption of apoSAAp to polystyrene microtiter wells at physiological pH, temperature, and salt concentration was inhibited and reversed by cholesterol. ApoSAAp, to a greater extent than apoA-I, albumin, or fetal bovine serum, enhanced diffusion of cholesterol from HDL across a membrane that retained molecules > 3.5 kDa. Cholesterol from 25 nM to 125 microM inhibited binding of [3H]cholesterol to 167 nM apoSAAp. A cholesterol binding assay was developed to determine the dissociation constant for binding of [3H]cholesterol to apoSAAp; Kd = 1.7 +/- 0.3 x 10(-7) M and the maximum binding capacity (Bmax) is 1.1 +/- 0.1 mol/mol. After binding cholesterol, the apparent size of apoSAAp as determined by gel filtration on Sephacryl S-100 was increased from 12 to 23 kDa. ApoSAAp enhanced free [14C]cholesterol uptake from tissue culture medium by HepG2 cells, an effect that was dose dependent and blocked by polyclonal antibodies to human apoSAA1 and apoSAA2. ApoSAAp, unlike apoA-I, was taken up from serum-free medium by HepG2 cells and appeared to be degraded by cell-associated enzymes. Unlike peritoneal exudate cells, human HepG2 hepatoma cells do not secrete an enzyme that degrades apoSAAp. These results suggest that apoSAA can potentially serve as a transient cholesterol-binding protein.

  19. Carotenoid binding to proteins: Modeling pigment transport to lipid membranes.

    PubMed

    Reszczynska, Emilia; Welc, Renata; Grudzinski, Wojciech; Trebacz, Kazimierz; Gruszecki, Wieslaw I

    2015-10-15

    Carotenoid pigments play numerous important physiological functions in human organism. Very special is a role of lutein and zeaxanthin in the retina of an eye and in particular in its central part, the macula lutea. In the retina, carotenoids can be directly present in the lipid phase of the membranes or remain bound to the protein-pigment complexes. In this work we address a problem of binding of carotenoids to proteins and possible role of such structures in pigment transport to lipid membranes. Interaction of three carotenoids, beta-carotene, lutein and zeaxanthin with two proteins: bovine serum albumin and glutathione S-transferase (GST) was investigated with application of molecular spectroscopy techniques: UV-Vis absorption, circular dichroism and Fourier transform infrared spectroscopy (FTIR). Interaction of pigment-protein complexes with model lipid bilayers formed with egg yolk phosphatidylcholine was investigated with application of FTIR, Raman imaging of liposomes and electrophysiological technique, in the planar lipid bilayer models. The results show that in all the cases of protein and pigment studied, carotenoids bind to protein and that the complexes formed can interact with membranes. This means that protein-carotenoid complexes are capable of playing physiological role in pigment transport to biomembranes.

  20. The Bacillus thuringiensis insecticidal toxin binds biotin-containing proteins.

    PubMed Central

    Du, C; Nickerson, K W

    1996-01-01

    Brush border membrane vesicles from larvae of the tobacco hornworm, Manduca sexta, contain protein bands of 85 and 120 kDa which react directly with streptavidin conjugated to alkaline phosphatase. The binding could be prevented either by including 10 microM biotin in the reaction mixture or by prior incubation of the brush border membrane vesicles with an activated 60- to 65-kDa toxin from Bacillus thuringiensis HD-73. The ability of B. thuringiensis toxins to recognize biotin-containing proteins was confirmed by their binding to pyruvate carboxylase, a biotin-containing enzyme, as well as to biotinylated ovalbumin and biotinylated bovine serum albumin but not to their nonbiotinylated counterparts. Activated HD-73 toxin also inhibited the enzymatic activity of pyruvate carboxylase. The biotin binding site is likely contained in domain III of the toxin. Two highly conserved regions within domain III are similar in sequence to the biotin binding sites of avidin, streptavidin, and a biotin-specific monoclonal antibody. In particular, block 4 of the B. thuringiensis toxin contains the YAS biotin-specific motif. On the basis of its N-terminal amino acid sequence, the 120-kDa biotin-containing protein is totally distinct from the 120-kDa aminopeptidase N reported to be a receptor for Cry1Ac toxin. PMID:8702286

  1. Identification of lipopolysaccharide-binding proteins in porcine milk

    PubMed Central

    Shahriar, Farshid; Gordon, John R.; Simko, Elemir

    2006-01-01

    Septicemia and endotoxemia initiated by bacterial lipopolysaccharide (LPS) are relatively common in suckling and weaned piglets. Maternal milk is a source of both nutrition and immune protection for piglets. Passive transfer of colostral antibodies is necessary for protection of neonatal piglets against diseases, but the concentration of immunoglobulins in milk rapidly declines during the 1st wk of lactation in all mammals. We hypothesized, therefore, that nonimmunoglobulin substances in milk contribute to the innate protection of neonates against septicemia during the suckling period. Using LPS-affinity chromatography for isolation of LPS-binding proteins and liquid chromatography–mass spectrometry for their identification, we identified in porcine milk the following proteins with LPS-binding capacity: lactoferrin, soluble CD14, serum amyloid A, α-S1 casein, β-casein, and κ-casein. For lactoferrin, α-S1 casein, and κ-casein, in vitro pepsin digestion did not inhibit LPS-binding activity, whereas combined digestion with pepsin and pancreatin abolished it. The biologic functions of these LPS-binding proteins and peptides were not determined. PMID:17042375

  2. Probing the binding affinity of plasma proteins adsorbed on Au nanoparticles.

    PubMed

    Zhang, Xiaoning; Zhang, Junting; Zhang, Fan; Yu, Shaoning

    2017-04-06

    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.

  3. Computational analysis of maltose binding protein translocation

    NASA Astrophysics Data System (ADS)

    Chinappi, Mauro; Cecconi, Fabio; Massimo Casciola, Carlo

    2011-05-01

    We propose a computational model for the study of maltose binding protein translocation across α-hemolysin nanopores. The phenomenological approach simplifies both the pore and the polypeptide chain; however it retains the basic structural protein-like properties of the maltose binding protein by promoting the correct formation of its native key interactions. By considering different observables characterising the channel blockade and molecule transport, we verified that MD simulations reproduce qualitatively the behaviour observed in a recent experiment. Simulations reveal that blockade events consist of a capture stage, to some extent related to the unfolding kinetics, and a single file translocation process in the channel. A threshold mechanics underlies the process activation with a critical force depending on the protein denaturation state. Finally, our results support the simple interpretation of translocation via first-passage statistics of a driven diffusion process of a single reaction coordinate.

  4. Elucidation of the binding mechanism of coumarin derivatives with human serum albumin.

    PubMed

    Garg, Archit; Manidhar, Darla Mark; Gokara, Mahesh; Malleda, Chandramouli; Suresh Reddy, Cirandur; Subramanyam, Rajagopal

    2013-01-01

    Coumarin is a benzopyrone which is widely used as an anti-coagulant, anti-oxidant, anti-cancer and also to cure arthritis, herpes, asthma and inflammation. Here, we studied the binding of synthesized coumarin derivatives with human serum albumin (HSA) at physiological pH 7.2 by using fluorescence spectroscopy, circular dichroism spectroscopy, molecular docking and molecular dynamics simulation studies. By addition of coumarin derivatives to HSA the maximum fluorescence intensity was reduced due to quenching of intrinsic fluorescence upon binding of coumarin derivatives to HSA. The binding constant and free energy were found to be 1.957±0.01×10(5) M(-1), -7.175 Kcal M(-1) for coumarin derivative (CD) enamide; 0.837±0.01×10(5) M(-1), -6.685 Kcal M(-1) for coumarin derivative (CD) enoate, and 0.606±0.01×10(5) M(-1), -6.49 Kcal M(-1) for coumarin derivative methylprop (CDM) enamide. The CD spectroscopy showed that the protein secondary structure was partially unfolded upon binding of coumarin derivatives. Further, the molecular docking studies showed that coumarin derivatives were binding to HSA at sub-domain IB with the hydrophobic interactions and also with hydrogen bond interactions. Additionally, the molecular dynamics simulations studies contributed in understanding the stability of protein-drug complex system in the aqueous solution and the conformational changes in HSA upon binding of coumarin derivatives. This study will provide insights into designing of the new inspired coumarin derivatives as therapeutic agents against many life threatening diseases.

  5. Elucidation of the Binding Mechanism of Coumarin Derivatives with Human Serum Albumin

    PubMed Central

    Gokara, Mahesh; Malleda, Chandramouli; Suresh Reddy, Cirandur; Subramanyam, Rajagopal

    2013-01-01

    Coumarin is a benzopyrone which is widely used as an anti-coagulant, anti-oxidant, anti-cancer and also to cure arthritis, herpes, asthma and inflammation. Here, we studied the binding of synthesized coumarin derivatives with human serum albumin (HSA) at physiological pH 7.2 by using fluorescence spectroscopy, circular dichroism spectroscopy, molecular docking and molecular dynamics simulation studies. By addition of coumarin derivatives to HSA the maximum fluorescence intensity was reduced due to quenching of intrinsic fluorescence upon binding of coumarin derivatives to HSA. The binding constant and free energy were found to be 1.957±0.01×105 M−1, −7.175 Kcal M−1 for coumarin derivative (CD) enamide; 0.837±0.01×105 M−1, −6.685 Kcal M−1 for coumarin derivative (CD) enoate, and 0.606±0.01×105 M−1, −6.49 Kcal M−1 for coumarin derivative methylprop (CDM) enamide. The CD spectroscopy showed that the protein secondary structure was partially unfolded upon binding of coumarin derivatives. Further, the molecular docking studies showed that coumarin derivatives were binding to HSA at sub-domain IB with the hydrophobic interactions and also with hydrogen bond interactions. Additionally, the molecular dynamics simulations studies contributed in understanding the stability of protein-drug complex system in the aqueous solution and the conformational changes in HSA upon binding of coumarin derivatives. This study will provide insights into designing of the new inspired coumarin derivatives as therapeutic agents against many life threatening diseases. PMID:23724004

  6. Binding studies of L-3,4-dihydroxyphenylalanine with human serum albumin.

    PubMed

    Yeggoni, Daniel Pushparaju; Subramanyam, Rajagopal

    2014-12-01

    L-Dopa has been used to increase dopamine concentrations in the treatment of Parkinson's disease and dopamine-responsive dystonia. The binding interaction between L-dopa (phytochemical) and human serum albumin (HSA) under simulated physiological conditions was investigated by spectroscopic and molecular modeling methods. The results revealed that L-dopa caused fluorescence emission quenching of HSA through a static quenching procedure and the binding constant obtained was 2.3 ± 0.01 × 10(4) M(-1), which is corresponding to -5.9 kcal M(-1) of free energy at 25 °C. Interestingly, L-dopa is not binding to the α-1-acidglycoprotein, which is also a plasma protein and an acute phase protein. Furthermore, circular dichroism results confirm that in the presence of L-dopa the secondary structure of HSA is altered due to partial unfolding of the protein. Importantly, the displacement experiment with site specific probes, phenylbutazone (site I) and ibuprofen (site II), depicts that L-dopa binds particularly to site II of HSA. In addition, the molecular modeling results also confirmed that L-dopa is binding to the subdomain IIIA of HSA and is stabilized by hydrogen bonds and hydrophilic forces. Additionally, the molecular dynamic simulation studies showed that the HSA-L-dopa complex reaches an equilibration state at around 2 ns, which indicates that the HSA-L-dopa complex is very stable. These results provided valuable information of pharmacological mechanisms of L-dopa under in vivo conditions and play a pivotal role in the development of L-dopa-inspired drugs.

  7. Binding of an anticancer drug, axitinib to human serum albumin: Fluorescence quenching and molecular docking study.

    PubMed

    Tayyab, Saad; Izzudin, Mohamad Mirza; Kabir, Md Zahirul; Feroz, Shevin R; Tee, Wei-Ven; Mohamad, Saharuddin B; Alias, Zazali

    2016-09-01

    Binding characteristics of a promising anticancer drug, axitinib (AXT) to human serum albumin (HSA), the major transport protein in human blood circulation, were studied using fluorescence, UV-vis absorption and circular dichroism (CD) spectroscopy as well as molecular docking analysis. A gradual decrease in the Stern-Volmer quenching constant with increasing temperature revealed the static mode of the protein fluorescence quenching upon AXT addition, thus confirmed AXT-HSA complex formation. This was also confirmed from alteration in the UV-vis spectrum of HSA upon AXT addition. Fluorescence quenching titration results demonstrated moderately strong binding affinity between AXT and HSA based on the binding constant value (1.08±0.06×10(5)M(-1)), obtained in 10mM sodium phosphate buffer, pH7.4 at 25°C. The sign and magnitude of the enthalpy change (∆H=-8.38kJmol(-1)) as well as the entropy change (∆S=+68.21Jmol(-1)K(-1)) clearly suggested involvement of both hydrophobic interactions and hydrogen bonding in AXT-HSA complex formation. These results were well supported by molecular docking results. Three-dimensional fluorescence spectral results indicated significant microenvironmental changes around Trp and Tyr residues of HSA upon complexation with AXT. AXT binding to the protein produced significant alterations in both secondary and tertiary structures of HSA, as revealed from the far-UV and the near-UV CD spectral results. Competitive drug displacement results obtained with phenylbutazone (site I marker), ketoprofen (site II marker) and hemin (site III marker) along with molecular docking results suggested Sudlow's site I, located in subdomain IIA of HSA, as the preferred binding site of AXT.

  8. ABP: a novel AMPA receptor binding protein.

    PubMed

    Srivastava, S; Ziff, E B

    1999-04-30

    We review the cloning of a novel AMPA receptor binding protein (ABP) that interacts with GluR2/3 and is homologous to GRIP. ABP is enriched in the PSD with GluR2 and is localized to the PSD by EM. ABP binds GluR2 via the C-terminal VXI motif through a Class I PDZ interaction. ABP and GRIP can also homo- and heteromultimerize. Thus, ABP and GRIP may be involved in AMPA receptor regulation and localization, by linking it to other cytoskeletal or signaling molecules. We suggest that the ABP/GRIP and PSD-95 families form distinct scaffolds that anchor, respectively, AMPA and NMDA receptors. We are currently investigating proteins that bind ABP and that may regulate the AMPA receptor.

  9. Exploring the binding dynamics of BAR proteins.

    PubMed

    Kabaso, Doron; Gongadze, Ekaterina; Jorgačevski, Jernej; Kreft, Marko; Van Rienen, Ursula; Zorec, Robert; Iglič, Aleš

    2011-09-01

    We used a continuum model based on the Helfrich free energy to investigate the binding dynamics of a lipid bilayer to a BAR domain surface of a crescent-like shape of positive (e.g. I-BAR shape) or negative (e.g. F-BAR shape) intrinsic curvature. According to structural data, it has been suggested that negatively charged membrane lipids are bound to positively charged amino acids at the binding interface of BAR proteins, contributing a negative binding energy to the system free energy. In addition, the cone-like shape of negatively charged lipids on the inner side of a cell membrane might contribute a positive intrinsic curvature, facilitating the initial bending towards the crescent-like shape of the BAR domain. In the present study, we hypothesize that in the limit of a rigid BAR domain shape, the negative binding energy and the coupling between the intrinsic curvature of negatively charged lipids and the membrane curvature drive the bending of the membrane. To estimate the binding energy, the electric potential at the charged surface of a BAR domain was calculated using the Langevin-Bikerman equation. Results of numerical simulations reveal that the binding energy is important for the initial instability (i.e. bending of a membrane), while the coupling between the intrinsic shapes of lipids and membrane curvature could be crucial for the curvature-dependent aggregation of negatively charged lipids near the surface of the BAR domain. In the discussion, we suggest novel experiments using patch clamp techniques to analyze the binding dynamics of BAR proteins, as well as the possible role of BAR proteins in the fusion pore stability of exovesicles.

  10. Glycosylation status of vitamin D binding protein in cancer patients

    PubMed Central

    Rehder, Douglas S; Nelson, Randall W; Borges, Chad R

    2009-01-01

    On the basis of the results of activity studies, previous reports have suggested that vitamin D binding protein (DBP) is significantly or even completely deglycosylated in cancer patients, eliminating the molecular precursor of the immunologically important Gc macrophage activating factor (GcMAF), a glycosidase-derived product of DBP. The purpose of this investigation was to directly determine the relative degree of O-linked trisaccharide glycosylation of serum-derived DBP in human breast, colorectal, pancreatic, and prostate cancer patients. Results obtained by electrospray ionization-based mass spectrometric immunoassay showed that there was no significant depletion of DBP trisaccharide glycosylation in the 56 cancer patients examined relative to healthy controls. These results suggest that alternative hypotheses regarding the molecular and/or structural origins of GcMAF must be considered to explain the relative inability of cancer patient serum to activate macrophages. PMID:19642159

  11. Glycosylation status of vitamin D binding protein in cancer patients.

    PubMed

    Rehder, Douglas S; Nelson, Randall W; Borges, Chad R

    2009-10-01

    On the basis of the results of activity studies, previous reports have suggested that vitamin D binding protein (DBP) is significantly or even completely deglycosylated in cancer patients, eliminating the molecular precursor of the immunologically important Gc macrophage activating factor (GcMAF), a glycosidase-derived product of DBP. The purpose of this investigation was to directly determine the relative degree of O-linked trisaccharide glycosylation of serum-derived DBP in human breast, colorectal, pancreatic, and prostate cancer patients. Results obtained by electrospray ionization-based mass spectrometric immunoassay showed that there was no significant depletion of DBP trisaccharide glycosylation in the 56 cancer patients examined relative to healthy controls. These results suggest that alternative hypotheses regarding the molecular and/or structural origins of GcMAF must be considered to explain the relative inability of cancer patient serum to activate macrophages.

  12. Probing thyroglobulin in undiluted human serum based on pattern recognition and competitive adsorption of proteins

    NASA Astrophysics Data System (ADS)

    Wang, Ran; Huang, Shuai; Li, Jing; Chae, Junseok

    2014-10-01

    Thyroglobulin (Tg) is a sensitive indicator of persistent or recurrent differentiated thyroid cancer of follicular cell origin. Detection of Tg in human serum is challenging as bio-receptors, such as anti-Tg, used in immunoassay have relatively weak binding affinity. We engineer sensing surfaces using the competitive adsorption of proteins, termed the Vroman Effect. Coupled with Surface Plasmon Resonance, the "cross-responsive" interactions of Tg on the engineered surfaces produce uniquely distinguishable multiple signature patterns, which are discriminated using Linear Discriminant Analysis. Tg-spiked samples, down to 2 ng/ml Tg in undiluted human serum, are sensitively and selectively discriminated from the control (undiluted human serum).

  13. Standards for total serum protein assays--a collaborative study.

    PubMed

    Doumas, B T

    1975-07-01

    We have studied the standardization of total serum protein assay with the biuret reaction. Standard solutions were prepared from lyophilized preparations of human serum albumin and bovine serum albumin, with corrections made for volatile material and ash contents. These solutions and a solution of crystalline albumin standard were analyzed with a new stable biuret reagent, to establish absorptivity values (values for the absorbance of a 1 g/liter final reaction mixture). The mean values obtained were 0.302, 0.292, and 0.290 for human serum albumin, bovine serum albumin, and the crystalline albumin, respectively. We believe that the established absorptivity value will improve the accuracy of serum protein determinations. We studied the linearity of the relation between color produced and protein concentration, with use of the solutions described above and a serum pool. The color adheres to Beer's law up to the highest concentration tested: 3 g/liter for HSA and BSA, and 2.8 g/liter for serum in the final reaction mixture. The new biuret reagent has been stable for one year at room temperature. We recommend the use of bovine serum albumin as a primary standard for serum protein assays. It is inexpensive, easily available, and exhibits the best linearity in the biuret reaction.

  14. Differential modulation in binding of ketoprofen to bovine serum albumin in the presence and absence of surfactants: spectroscopic and calorimetric insights.

    PubMed

    Misra, Pinaki P; Kishore, Nand

    2013-07-01

    Surfactants have long been implicated in the unique static and dynamic effect on the structure and function of serum albumins. However, there is very little information on the mode of interactions of drugs to serum albumins in presence of surfactants. The importance of such studies lay in the fact that apart from binding to serum albumins, surfactants are known to radically influence the solvents' micro environment and protein structure. Thus, we have studied the binding of the racemic form of ketoprofen with bovine serum albumin at pH 7.4 in the presence and absence of hexadecyl trimethyl ammonium bromide, sodium dodecyl sulfate, Triton X-100, and NaCl. The structural studies of ketoprofen with bovine serum albumin as investigated by circular dichroism spectroscopy revealed a significant stabilization of bovine serum albumin. However, the combined presence of the surfactants, NaCl and ketoprofen, demonstrated an extremely erratic behavior in terms of stabilization. Further the values of Stern-Volmer and dynamic quenching constant suggested the binding site of ketoprofen to be scattered in the region of domain I B and II A, close to Trp 134. The results of differential scanning calorimetry revealed that the binding of ketoprofen to bovine serum albumin leads to its temperature-dependent separation into two units. The binding parameters of bovine serum albumin obtained from isothermal titration calorimetry in the combined presence of ketoprofen and surfactants/NaCl correlate well with the differential scanning calorimetry studies further confirming the localization of ketoprofen in domain I B and II A. In the combined presence of surfactants, NaCl and ketoprofen, the binding of ketoprofen to bovine serum albumin exhibited altered binding parameters far different from the binding of ketoprofen alone. Overall, the experimental findings strongly indicated positive as well as negative modulation in the binding of ketoprofen to bovine serum albumin in the presence of

  15. Enhanced protective antibody to a mutant meningococcal factor H-binding protein with low-factor H binding

    PubMed Central

    Granoff, Dan M.; Giuntini, Serena; Gowans, Flor A.; Lujan, Eduardo; Sharkey, Kelsey; Beernink, Peter T.

    2016-01-01

    Meningococcal factor H-binding protein (FHbp) is an antigen in 2 serogroup B meningococcal vaccines. FHbp specifically binds human and some nonhuman primate complement FH. To investigate the effect of binding of FH to FHbp on protective antibody responses, we immunized infant rhesus macaques with either a control recombinant FHbp antigen that bound macaque FH or a mutant antigen with 2 amino acid substitutions and >250-fold lower affinity for FH. The mutant antigen elicited 3-fold higher serum IgG anti-FHbp titers and up to 15-fold higher serum bactericidal titers than the control FHbp vaccine. When comparing sera with similar IgG anti-FHbp titers, the antibodies elicited by the mutant antigen gave greater deposition of complement component C4b on live meningococci (classical complement pathway) and inhibited binding of FH, while the anti-FHbp antibodies elicited by the control vaccine enhanced FH binding. Thus, the mutant FHbp vaccine elicited an anti-FHbp antibody repertoire directed at FHbp epitopes within the FH binding site, which resulted in greater protective activity than the antibodies elicited by the control vaccine, which targeted FHbp epitopes outside of the FH combining site. Binding of a host protein to a vaccine antigen impairs protective antibody responses, which can be overcome with low-binding mutant antigens. PMID:27668287

  16. Bovine Serum Albumin binding to CoCrMo nanoparticles and the influence on dissolution

    NASA Astrophysics Data System (ADS)

    Simoes, T. A.; Brown, A. P.; Milne, S. J.; Brydson, R. M. D.

    2015-10-01

    CoCrMo alloys exhibit good mechanical properties, excellent biocompatibility and are widely utilised in orthopaedic joint replacements. Metal-on-metal hip implant degradation leads to the release of metal ions and nanoparticles, which persist through the implant's life and could be a possible cause of health complications. This study correlates preferential binding between proteins and metal alloy nanoparticles to the alloy's corrosion behaviour and the release of metal ions. TEM images show the formation of a protein corona in all particles immersed in albumin containing solutions. Only molybdenum release was significant in these tests, suggesting high dissolution of this element when CoCrMo alloy nanoparticles are produced as wear debris in the presence of serum albumin. The same trend was observed during extended exposure of molybdenum reference nanoparticles to albumin.

  17. Quantifying drug-protein binding in vivo.

    SciTech Connect

    Buchholz, B; Bench, G; Keating III, G; Palmblad, M; Vogel, J; Grant, P G; Hillegonds, D

    2004-02-17

    Accelerator mass spectrometry (AMS) provides precise quantitation of isotope labeled compounds that are bound to biological macromolecules such as DNA or proteins. The sensitivity is high enough to allow for sub-pharmacological (''micro-'') dosing to determine macromolecular targets without inducing toxicities or altering the system under study, whether it is healthy or diseased. We demonstrated an application of AMS in quantifying the physiologic effects of one dosed chemical compound upon the binding level of another compound in vivo at sub-toxic doses [4].We are using tissues left from this study to develop protocols for quantifying specific binding to isolated and identified proteins. We also developed a new technique to quantify nanogram to milligram amounts of isolated protein at precisions that are comparable to those for quantifying the bound compound by AMS.

  18. Effects of serum, its protein and lipid extracts, and commercial serum proteins and lipid on the isolated frog heart.

    PubMed

    Singh, J; Hutton, T; Hussain, M; Waring, J J

    1991-01-01

    This study investigates the inotropic effects of serum, its protein and lipid extracts, and commercial serum proteins and lipid on the isolated, spontaneously-beating heart and superfused, hypodynamic ventricle of the frog. Serum taken from either man, horse, calf, frog, or rabbit evoked marked positive inotropic responses which were unaffected by cholinergic, serotonergic, and adrenergic receptor antagonists. Dialysed serum (dialisand) and void volume fractions from Sephadex G200-120 columns corresponding to large molecular weight constituents evoked marked positive inotropic responses. When serum was separated into fractions containing either proteins or lipids/lipoproteins by high-density ultracentrifugation or activated charcoal, both extracts evoked marked positive inotropic responses. Commercial serum globulins and serum containing a high proportion of immunoglobulins elicited large increases in contractile force, whereas serum albumin evoked a negative inotropic effect. Serum which was either boiled and/or treated with chymotrypsin to denature proteins also caused a marked increase in isometric twitch tension in the frog heart. Similar inotropic response was obtained with fractions of boiled serum eluted on columns of Sephadex G200-120. These fractions corresponded to molecular weight in the region of 60-70 kDa. However, the inotropic effect of boiled serum was abolished following pretreatment with lipase. Superfusion of frog hearts with commercial cardiolipin resulted in marked dose-dependent increases in contractile force. The results demonstrate the presence of at least two large molecular weight cardioactive principles in serum. These substances are comparable in size to constituents of serum proteins (e.g., globulins and immunoglobulins) and serum lipids/lipoproteins (e.g., cardiolipin) and may serve as physiological regulators of cardiac function.

  19. Characterization of the binding of nevadensin to bovine serum albumin by optical spectroscopic technique

    NASA Astrophysics Data System (ADS)

    Yu, Zhaolian; Li, Daojin; Ji, Baoming; Chen, Jianjun

    2008-10-01

    Binding of nevadensin to bovine serum albumin (BSA) has been studied in detail at 298 and 310 K using spectrophotometric technique. The intrinsic fluorescence of BSA was strongly quenched by the addition of nevadensin and spectroscopic observations are mainly rationalized in terms of a static quenching process at lower concentration of nevadensin ( Cdrug/ CBSA < 1) and a combined quenching process at higher concentration of nevadensin ( Cdrug/ CBSA > 1). The binding parameters for the reaction at a pH above (7.40) or below (3.40) the isoelectric point have been calculated according to the double logarithm regression curve. The thermodynamic parameters Δ H0, Δ G0, Δ S0 at different temperatures and binding mechanism of nevadensin to BSA at pH 7.40 and 3.40 were evaluated. The binding ability of nevadensin to BSA at pH 7.40 was stronger than that at pH 3.40. Steady fluorescence, synchronous fluorescence and circular dichroism (CD) were applied to investigate protein conformation. A value of 2.15 nm for the average distance r between nevadensin (acceptor) and tryptophan residues (Trp) of BSA (donor) was derived from the fluorescence resonance energy transfer. Moreover, influence of pH on the interaction nevadensin with BSA was investigated.

  20. A comparison study on the binding of hesperetin and luteolin to bovine serum albumin by spectroscopy

    NASA Astrophysics Data System (ADS)

    Tang, Lin; Jia, Wanteng

    2013-02-01

    Binding mechanism of luteolin (LUT) and hesperetin (HES) to bovine serum albumin (BSA) was investigated at 288,298,310 K and pH = 7.40 by UV absorption spectroscopy, fluorescence quenching and synchronous fluorescence spectroscopy. Under simulated physiological conditions, the fluorescence data indicated that hesperetin binding to BSA mainly occurs through a static mechanism. In contrast, binding of luteolin to BSA is a combined quenching process while static quenching is prevailing. Linear interval of the Stern-Volmer plot of LUT-BSA for the concentration ratio of LUT to BSA ranged from 0.5 to 1.25 was obtained. The thermodynamic parameters obtained from the Van't Hoff equation indicated that electrostatic force was the predominant force in the LUT-BSA and HES-BSA complex. The inner filter effect was eliminated to get accurate data. The conformational changes of BSA caused by LUT and HES were observed in the UV absorption. Results of fluorescence quenching and synchronous fluorescence showed that degree of luteolin-BSA quenching was higher than hesperetin-BSA quenching, which indicated that the 4'-hydroxide radical was more helpful to the ligand binding to proteins than 4'-methoxyl group for flavones.

  1. Controlling the taste receptor accessible structure of rebaudioside A via binding to bovine serum albumin.

    PubMed

    Mudgal, Samriddh; Keresztes, Ivan; Feigenson, Gerald W; Rizvi, S S H

    2016-04-15

    We illustrate a method that uses bovine serum albumin (BSA) to control the receptor-accessible part of rebaudioside A (Reb A). The critical micelle concentration (CMC) of Reb A was found to be 4.5 mM and 5 mM at pH 3 and 6.7 respectively. NMR studies show that below its CMC, Reb A binds weakly to BSA to generate a Reb A-protein complex ("RPC"), which is only modestly stable under varying conditions of pH (3.0-6.7) and temperature (4-40°C) with its binding affinities determined to be in the range of 5-280 mM. Furthermore, saturation transfer difference (STD) NMR experiments confirm that the RPC has fast exchange of the bitterness-instigating diterpene of Reb A into the binding sites of BSA. Our method can be used to alter the strength of Reb A-receptor interaction, as a result of binding of Reb A to BSA, which may ultimately lead to moderation of its taste.

  2. Serum ferritin and total iron-binding capacity to estimate iron storage in pigs.

    PubMed

    Smith, J E; Moore, K; Boyington, D; Pollmann, D S; Schoneweis, D

    1984-11-01

    The inability to accurately determine storage iron in baby pigs limits the development of new treatment programs. In pigs treated neonatally with iron dextran, serum ferritin had increased dramatically at ten days of age and then returned to near preinjection levels by 50 days of age. In contrast, serum ferritin in untreated pigs declined until they were offered creep feed at 21 days of age. When serum ferritin, serum iron, serum total iron-binding capacity, erythrocyte number, packed cell volume, and blood hemoglobin were measured in three-week-old pigs, serum ferritin combined with serum total iron-binding capacity correlated significantly with the total nonheme iron in the liver and spleen. The nonheme iron (in mg) could be predicted (r2 = 0.71) by the following expression: 8.7 + 0.6 (ferritin in ng/ml).

  3. Conjugation of a dipicolyl chelate to polypeptide conjugates increases binding affinities for human serum albumin and survival times in human serum.

    PubMed

    Balliu, Aleksandra; Baltzer, Lars

    2017-03-16

    The affinity for human serum albumin (HSA) of a series of 2-5 kDa peptides covalently linked to 3,5-bis[[bis(2-pyridylmethyl)amino]methyl]benzoic acid, a dipicolyl chelator with μM affinity for Zn2+, was found by surface plasmon resonance to increase in the presence of 1μM ZnCl2 at physiological pH. The dependence on polypeptide hydrophobicity was found to be minor, suggesting that the conjugates bound to the metal binding site and not to the fatty acid binding site. The affinity of the conjugates increased strongly with the positive charge of the polypeptides suggesting proximity to the negatively charged protein surface surrounding the metal binding site. The survival times of the peptides in human serum were extended as a consequence of stronger binding to HSA suggesting that Zn2+ ion chelating agents may provide a general route to increased survival times of peptides in serum in therapeutic and diagnostic applications without significantly increasing their molecular weights.

  4. Paracetamol and cytarabine binding competition in high affinity binding sites of transporting protein

    NASA Astrophysics Data System (ADS)

    Sułkowska, A.; Bojko, B.; Równicka, J.; Sułkowski, W. W.

    2006-07-01

    Paracetamol (acetaminophen, AA) the most popular analgesic drug is commonly used in the treatment of pain in patients suffering from cancer. In our studies, we evaluated the competition in binding with serum albumin between paracetamol (AA) and cytarabine, antyleukemic drug (araC). The presence of one drug can alter the binding affinity of albumin towards the second one. Such interaction can result in changing of the free fraction of the one of these drugs in blood. Two spectroscopic methods were used to determine high affinity binding sites and the competition of the drugs. Basing on the change of the serum albumin fluorescence in the presence of either of the drugs the quenching ( KQ) constants for the araC-BSA and AA-BSA systems were calculated. Analysis of UV difference spectra allowed us to describe the changes in drug-protein complexes (araC-albumin and AA-albumin) induced by the presence of the second drug (AA and araC, respectively). The mechanism of competition between araC and AA has been proposed.

  5. Probing the binding sites of antibiotic drugs doxorubicin and N-(trifluoroacetyl) doxorubicin with human and bovine serum albumins.

    PubMed

    Agudelo, Daniel; Bourassa, Philippe; Bruneau, Julie; Bérubé, Gervais; Asselin, Eric; Tajmir-Riahi, Heidar-Ali

    2012-01-01

    We located the binding sites of doxorubicin (DOX) and N-(trifluoroacetyl) doxorubicin (FDOX) with bovine serum albumin (BSA) and human serum albumins (HSA) at physiological conditions, using constant protein concentration and various drug contents. FTIR, CD and fluorescence spectroscopic methods as well as molecular modeling were used to analyse drug binding sites, the binding constant and the effect of drug complexation on BSA and HSA stability and conformations. Structural analysis showed that doxorubicin and N-(trifluoroacetyl) doxorubicin bind strongly to BSA and HSA via hydrophilic and hydrophobic contacts with overall binding constants of K(DOX-BSA) = 7.8 (± 0.7) × 10(3) M(-1), K(FDOX-BSA) = 4.8 (± 0.5)× 10(3) M(-1) and K(DOX-HSA) = 1.1 (± 0.3)× 10(4) M(-1), K(FDOX-HSA) = 8.3 (± 0.6)× 10(3) M(-1). The number of bound drug molecules per protein is 1.5 (DOX-BSA), 1.3 (FDOX-BSA) 1.5 (DOX-HSA), 0.9 (FDOX-HSA) in these drug-protein complexes. Docking studies showed the participation of several amino acids in drug-protein complexation, which stabilized by H-bonding systems. The order of drug-protein binding is DOX-HSA > FDOX-HSA > DOX-BSA > FDOX>BSA. Drug complexation alters protein conformation by a major reduction of α-helix from 63% (free BSA) to 47-44% (drug-complex) and 57% (free HSA) to 51-40% (drug-complex) inducing a partial protein destabilization. Doxorubicin and its derivative can be transported by BSA and HSA in vitro.

  6. Insulin-like growth factor binding proteins 4-6.

    PubMed

    Bach, Leon A

    2015-10-01

    Insulin-like growth factor binding proteins (IGFBPs) 4-6 have important roles as modulators of IGF actions. IGFBP-4 and IGFBP-6 predominantly inhibit IGF actions, whereas IGFBP-5 may enhance these actions under some circumstances. IGFBP-6 is unique among the IGFBPs for its marked IGF-II binding preference. IGFBPs 4-6 are found in the circulation as binary complexes with IGFs that can enter tissues. Additionally, about half of the circulating IGFBP-5 is found in ternary complexes with IGFs and an acid labile subunit; this high molecular complex cannot leave the circulation and acts as an IGF reservoir. IGFBPs 4-6 also have IGF-independent actions. These IGFBPs are regulated in a cell-specific manner and their dysregulation may play a role in a range of diseases including cancer. However, there is no clear clinical indication for measuring serum levels of these IGFBPs at present.

  7. Chloramphenicol binding to human serum albumin: Determination of binding constants and binding sites by steady-state fluorescence

    NASA Astrophysics Data System (ADS)

    Ding, Fei; Zhao, Guangyu; Chen, Shoucong; Liu, Feng; Sun, Ying; Zhang, Li

    2009-07-01

    The interaction between chloramphenicol and human serum albumin (HSA) was studied by fluorescence, UV/vis, circular dichroism (CD) and three-dimensional fluorescence spectroscopy. Fluorescence data revealed that the fluorescence quenching of HSA by chloramphenicol was the result of the formation of drug-HSA complex, and the effective quenching constants ( Ka) were 2.852 × 10 4, 2.765 × 10 4, 2.638 × 10 4 and 2.542 × 10 4 M -1 at 287, 295, 303 and 311 K, respectively. The thermodynamic parameters, enthalpy change (Δ H) and entropy change (Δ S) for the reaction were calculated to be -3.634 kJ mol -1 and 72.66 J mol -1 K -1 according to van't Hoff equation. The results indicated that the hydrophobic and electrostatic interactions played a major role in the binding of drug to HSA. The distance r between donor and acceptor was obtained to be 3.63 nm according to Förster's theory. Site marker competitive experiments indicated that the binding of drug to HSA primarily took place in subdomain IIA. The alterations of HSA secondary structure in the presence of chloramphenicol were confirmed by the evidences from synchronous fluorescence, CD and three-dimensional fluorescence spectra. In addition, the effect of common ions on the binding constants of drug-HSA complex was also discussed.

  8. Spectroscopic characterization of the binding mechanism of fluorescein and carboxyfluorescein in human serum albumin

    NASA Astrophysics Data System (ADS)

    Sulaiman, Saba A. J.; Kulathunga, H. Udani; Abou-Zied, Osama K.

    2015-03-01

    Fluorescein (FL) and some of its precursors have proven to be effective fluorescent tracers in pharmaceutical and medical applications owing to their high quantum yield of fluorescence in physiological conditions and their high membrane permeability. In order to protect FL from metabolic effects during the process of its delivery, human serum albumin (HSA) has been used as a carrier because of its compatibility with the human body. In the present work, we used spectroscopic methods to characterize the binding mechanisms of FL and one of its derivatives, 5(6)- carboxyfluorescein (CFL), in the HSA protein. The absorbance change of the two ligands (FL and CFL) was quantified as a function of the HSA concentration and the results indicate a moderate binding strength for the two ligands inside HSA (1.00 +/- 0.12 x 104 M-1). The quenching effect of FL(CFL) on the fluorescence intensity of W214 (the sole tryptophan in HSA) indicates that FL and CFL occupy Site I in the protein which is known to bind several hydrophobic drugs. By performing site-competitive experiments, the location of the ligands is determined to be similar to that of the anticoagulant drug warfarin. At higher ratios of [ligand]/[HSA], we observed an upward curvature in the Stern-Volmer plots which indicates that the ligands occupy more pockets in Site I, close to W214. Our results indicate that both ligands bind in HSA with a moderate strength that should not affect their release when used as fluorescent reporters. The chemical and physical identities of the two ligands are also preserved inside the HSA binding sites.

  9. Phylointeractomics reconstructs functional evolution of protein binding

    PubMed Central

    Kappei, Dennis; Scheibe, Marion; Paszkowski-Rogacz, Maciej; Bluhm, Alina; Gossmann, Toni Ingolf; Dietz, Sabrina; Dejung, Mario; Herlyn, Holger; Buchholz, Frank; Mann, Matthias; Butter, Falk

    2017-01-01

    Molecular phylogenomics investigates evolutionary relationships based on genomic data. However, despite genomic sequence conservation, changes in protein interactions can occur relatively rapidly and may cause strong functional diversification. To investigate such functional evolution, we here combine phylogenomics with interaction proteomics. We develop this concept by investigating the molecular evolution of the shelterin complex, which protects telomeres, across 16 vertebrate species from zebrafish to humans covering 450 million years of evolution. Our phylointeractomics screen discovers previously unknown telomere-associated proteins and reveals how homologous proteins undergo functional evolution. For instance, we show that TERF1 evolved as a telomere-binding protein in the common stem lineage of marsupial and placental mammals. Phylointeractomics is a versatile and scalable approach to investigate evolutionary changes in protein function and thus can provide experimental evidence for phylogenomic relationships. PMID:28176777

  10. The measurement of total serum proteins by the Biuret method.

    PubMed

    Lubran, M M

    1978-01-01

    The biuret reaction for proteins provides a simple and precise method for measuring serum proteins; Beer's law is obeyed to at least 10 g per dl. Several stable biuret reagents are available. Hemoglobin is the only important cause of interference which cannot be minimized by use of a sample blank. The mechanism of the biuret reaction is described and attention is drawn to the heterogeneity of the serum proteins and to the use of a certified albumin standard.

  11. Binding and conformational changes of human serum albumin upon interaction with 4-aminoantipyrine studied by spectroscopic methods and cyclic voltammetry.

    PubMed

    Gowda, Jayant I; Nandibewoor, Sharanappa T

    2014-04-24

    The interactions of 4-aminoantipyrine (AAP) with human serum albumin (HSA) have been studied by UV-visible spectroscopy, fluorescence spectroscopy and cyclic voltammetry. The binding of 4-aminoantipyrine quenches the HSA fluorescence, revealing a 1:1 interaction with a binding constant of about 10(5) M(-1). The experimental results showed that AAP effectively quenched the intrinsic fluorescence of HSA via dynamic type of quenching. In addition, according to the synchronous fluorescence spectra of HSA in presence of 4-aminoantipyrine, the tryptophan residue of the proteins are most perturbed by the binding process. The number of binding sites, the binding constant, site probe study, some common metal ions effect and the thermodynamic parameters were calculated.

  12. Kaempferol-human serum albumin interaction: Characterization of the induced chirality upon binding by experimental circular dichroism and TDDFT calculations

    NASA Astrophysics Data System (ADS)

    Matei, Iulia; Ionescu, Sorana; Hillebrand, Mihaela

    2012-10-01

    The experimental induced circular dichroism (ICD) and absorption spectra of the achiral flavonoid kaempferol upon binding to human serum albumin (HSA) were correlated to electronic CD and UV-vis spectra theoretically predicted by time-dependent density functional theory (TDDFT). The neutral and four anionic species of kaempferol in various conformations were considered in the calculations. The appearance of the experimental ICD signal was rationalized in terms of kaempferol binding to HSA in a distorted, chiral, rigid conformation. The comparison between the experimental and simulated spectra allowed for the identification of the kaempferol species that binds to HSA, namely the anion generated by deprotonation of the hydroxyl group in position 7. This approach constitutes a convenient method for evidencing the binding species and for determining its conformation in the binding pocket of the protein. Its main advantage over the UV-vis absorption method lays in the fact that only the bound ligand species gives an ICD signal.

  13. Spectral characterization of the binding and conformational changes of serum albumins upon interaction with an anticancer drug, anastrozole

    NASA Astrophysics Data System (ADS)

    Punith, Reeta; Seetharamappa, J.

    2012-06-01

    The present study employed different optical spectroscopic techniques viz., fluorescence, FTIR, circular dichroism (CD) and UV-vis absorption spectroscopy to investigate the mechanism of interaction of an anticancer drug, anastrozole (AZ) with transport proteins viz., bovine serum albumin (BSA) and human serum albumin (HSA). The drug, AZ quenched the intrinsic fluorescence of protein and the analysis of results revealed the presence of dynamic quenching mechanism. The binding characteristics of drug-protein were computed. The thermodynamic parameters, enthalpy change (ΔH°) and entropy change (ΔS°) were calculated to be +92.99 kJ/mol and +159.18 J/mol/K for AZ-BSA and, +99.43 kJ/mol and +159.19 J/mol/K for AZ-HSA, respectively. These results indicated that the hydrophobic forces stabilized the interaction between the drug and protein. CD, FTIR, absorption, synchronous and 3D fluorescence results indicated that the binding of AZ to protein induced structural perturbation in both serum albumins. The distance, r between the drug and protein was calculated based on the theory of Förster's resonance energy transfer and found to be 5.9 and 6.24 nm, respectively for AZ-BSA and AZ-HSA.

  14. Binding of coumarins to site I of human serum albumin. Effect of the fatty acids.

    PubMed

    Zatón, A M; Ferrer, J M; Ruiz de Gordoa, J C; Marquínez, M A

    1995-07-14

    It is known that binding site I on human serum albumin (HSA) consists of a zone of two overlapping regions: the specific binding region represented by warfarin binding and the specific binding region represented by azapropazone and phenylbutazone binding. In this paper binding parameters to defatted HSA and to HSA with fatty acids (molar ratio of fatty acid/HSA = 4) were compared. High-affinity binding sites for warfarin, 4-chromanol, 4-hydroxycoumarin, coumarin, 3-acetylcoumarin and phenylbutazone (759,549 M-1 > Ka > 67,024 M-1) constitute binding site I on HSA. In this binding area defatted HSA can bind two molecules of warfarin, but the presence of fatty acids diminish the binding capacity of warfarin to HSA (2 > n > 1).

  15. Evaluation of the binding interaction between bovine serum albumin and dimethyl fumarate, an anti-inflammatory drug by multispectroscopic methods

    NASA Astrophysics Data System (ADS)

    Jattinagoudar, Laxmi; Meti, Manjunath; Nandibewoor, Sharanappa; Chimatadar, Shivamurti

    2016-03-01

    The information of the quenching reaction of bovine serum albumin with dimethyl fumarate is obtained by multi-spectroscopic methods. The number of binding sites, n and binding constants, KA were determined at different temperatures. The effect of increasing temperature on Stern-Volmer quenching constants (KD) indicates that a dynamic quenching mechanism is involved in the interaction. The analysis of thermodynamic quantities namely, ∆H° and ∆S° suggested hydrophobic forces playing a major role in the interaction between dimethyl fumarate and bovine serum albumin. The binding site of dimethyl fumarate on bovine serum albumin was determined by displacement studies, using the site probes viz., warfarin, ibuprofen and digitoxin. The determination of magnitude of the distance of approach for molecular interactions between dimethyl fumarate and bovine serum albumin is calculated according to the theory of Förster energy transfer. The CD, 3D fluorescence spectra, synchronous fluorescence measurements and FT-IR spectral results were indicative of the change in secondary structure of the protein. The influence of some of the metal ions on the binding interaction was also studied.

  16. The role of serum proteins in Staphylococcus aureus adhesion to ethylene glycol coated surfaces.

    PubMed

    Schuster, Swen; Yu, Wenqi; Nega, Mulugeta; Chu, Ya-Yun; Zorn, Stefan; Zhang, Fajun; Götz, Friedrich; Schreiber, Frank

    2014-11-01

    Bacterial adhesion on implants is a first step in the development of chronic foreign body associated infections. Finding strategies to minimize bacterial adhesion may contribute to minimize such infections. It is known that surfaces with oligo-ethylene-glycol (EG3OMe) or poly-ethylene-glycol (PEG2k) terminations decrease unspecific protein adsorption and bacterial adhesion. However, little is known about the influence of serum and its components on bacterial adhesion. We therefore prepared two coatings on gold surface with HS-(CH2)11EG3OMe (EG3OMe) and PEG2k-thiol and studied the role of bovine serum albumin (BSA), γ-globulins, and serum on Staphylococcus aureus adhesion. While BSA and lysozyme showed no adherence even when applied at very high concentrations (100 mg/ml), γ-globulins adsorbed already from 10 mg/ml on. The adsorption of γ-globulins was, however, significantly decreased when it was mixed with BSA in a ratio of 3:1, as it is in the serum. Pretreatment of EG3OMe and PEG2k coatings with γ-globulins or serum strongly promoted adherence of S. aureus when resuspended in buffer, suggesting that γ-globulins play a pivotal role in promoting S. aureus adhesion by its IgG binding proteins; the finding that a spa-deletion mutant, lacking the IgG binding protein A, showed decreased adherence corroborated this. Similarly, when S. aureus was pretreated with serum or γ-globulins its adherence was also significantly decreased. Our findings show that particularly γ-globulins bind to the coated surfaces thus mediating adherence of S. aureus via its protein A. As pretreatment of S. aureus with serum or γ-globulins significantly decreased adherence, treatment of patients with γ-globulins before implant surgery might lower the risk of implant-associated infections.

  17. Extending serum half-life of albumin by engineering neonatal Fc receptor (FcRn) binding.

    PubMed

    Andersen, Jan Terje; Dalhus, Bjørn; Viuff, Dorthe; Ravn, Birgitte Thue; Gunnarsen, Kristin Støen; Plumridge, Andrew; Bunting, Karen; Antunes, Filipa; Williamson, Rebecca; Athwal, Steven; Allan, Elizabeth; Evans, Leslie; Bjørås, Magnar; Kjærulff, Søren; Sleep, Darrell; Sandlie, Inger; Cameron, Jason

    2014-05-09

    A major challenge for the therapeutic use of many peptides and proteins is their short circulatory half-life. Albumin has an extended serum half-life of 3 weeks because of its size and FcRn-mediated recycling that prevents intracellular degradation, properties shared with IgG antibodies. Engineering the strictly pH-dependent IgG-FcRn interaction is known to extend IgG half-life. However, this principle has not been extensively explored for albumin. We have engineered human albumin by introducing single point mutations in the C-terminal end that generated a panel of variants with greatly improved affinities for FcRn. One variant (K573P) with 12-fold improved affinity showed extended serum half-life in normal mice, mice transgenic for human FcRn, and cynomolgus monkeys. Importantly, favorable binding to FcRn was maintained when a single-chain fragment variable antibody was genetically fused to either the N- or the C-terminal end. The engineered albumin variants may be attractive for improving the serum half-life of biopharmaceuticals.

  18. In vitro study on the binding of anti-coagulant vitamin to bovine serum albumin and the influence of toxic ions and common ions on binding.

    PubMed

    Shaikh, S M T; Seetharamappa, J; Kandagal, P B; Manjunatha, D H

    2007-06-01

    The mechanism of binding of vitamin K(3) (VK(3)) with bovine serum albumin (BSA) was investigated by fluorescence, absorption and circular dichroism (CD) techniques under physiological conditions. The analysis of fluorescence data indicated the presence of static quenching mechanism in the binding. Various binding parameters have been evaluated. Thermodynamic parameters, the standard enthalpy change, DeltaH(0) and the standard entropy change, DeltaS(0) were observed to be -164.09 kJ mol(-1) and -465.08 J mol(-1)K, respectively. The quantitative analysis of CD spectra confirmed the change in secondary structure of the protein upon interaction with VK(3). The binding average distance, r between the donor (BSA) and acceptor (VK(3)) was determined based on the Förster's theory and it was found to be 3.3 nm. The effects of toxic ions and common ions on VK(3)-BSA system were also investigated.

  19. SDS-binding assay based on tyrosine fluorescence as a tool to determine binding properties of human serum albumin in blood plasma

    NASA Astrophysics Data System (ADS)

    Zhdanova, Nadezda; Shirshin, Evgeny; Fadeev, Victor; Priezzhev, Alexander

    2016-04-01

    Among all plasma proteins human serum albumin (HSA) is the most studied one as it is the main transport protein and can bind a wide variety of ligands especially fatty acids (FAs). The concentration of FAs bound to HSA in human blood plasma differs by three times under abnormal conditions (fasting, physical exercises or in case of social important diseases). In the present study a surfactant sodium dodecyl sulfate (SDS) was used to simulate FAs binding to HSA. It was shown that the increase of Tyr fluorescence of human blood plasma due to SDS addition can be completely explained by HSA-SDS complex formation. Binding parameters of SDS-HSA complex (average number of sites and apparent constant of complex formation) were determined from titration curves based on tyrosine (Tyr) fluorescence.

  20. KINETICS OF AMINO ACID INCORPORATION INTO SERUM PROTEINS

    PubMed Central

    Green, H.; Anker, H. S.

    1955-01-01

    1. The effect of varying body temperature on the rate of amino acid incorporation into serum protein does not give support to the idea that the rate of this process is adjusted in vivo to restore those protein molecules destroyed by thermal denaturation. The experimentally observed Q10 was about 3.9. 2. When amino acids are injected into the blood of animals in a steady state of serum protein turnover, a period of time elapses before these amino acids can be found in the serum proteins. This has been called transit time. At a given temperature (31°) it is the same in rabbits, turtles, and Limulus (1 hour). In rabbits and turtles it has a Q10 of 3.2. It appears to be specifically related to the process of synthesis (or release) of serum proteins. 3. It was not possible to affect the transit time or the incorporation rate by the administration of amino acid analogues. PMID:13221773

  1. Enrichment of low-abundance proteins from bovine and porcine serum samples for proteomic studies.

    PubMed

    Marco-Ramell, Anna; Bassols, Anna

    2010-12-01

    One of the main applications of serum proteomics is the identification of new biomarkers for animal disease or animal production. However, potential obstacles to these studies are the poor performance of affinity serum depletion methods based on human antigens when using animal samples, and loss of minor serum components bound to albumin and other proteins. In the present study, we have analyzed the efficiency and reproducibility of the ProteoMiner® beads with bovine and porcine serum samples, and compared to a traditional immunoaffinity-based albumin and IgG depletion system specific for human samples. The ProteoMiner kit is based on the use of a combinatorial peptide binding library and intends to enrich low-abundance proteins.

  2. Conjugation of biogenic and synthetic polyamines with serum proteins: A comprehensive review.

    PubMed

    Chanphai, P; Thomas, T J; Tajmir-Riahi, H A

    2016-11-01

    We have reviewed the conjugation of biogenic polyamines spermine (spm), spermidine (spmd) and synthetic polyamines 3,7,11,15-tetrazaheptadecane.4HCl (BE-333) and 3,7,11,15,19-pentazahenicosane.5HCl (BE-3333) with human serum albumin (HSA), bovine serum albumin (BSA) and milk beta-lactoglobulin (b-LG) in aqueous solution at physiological pH. The results of multiple spectroscopic methods and molecular modeling were analysed here and correlations between polyamine binding mode and protein structural changes were estabilished. Polyamine-protein bindings are mainly via hydrophilic and H-bonding contacts. BSA forms more stable conjugates than HSA and b-LG. Biogenic polyamines form more stable complexes than synthetic polyamines except in the case of b-LG, where the protein shows more hydrophobic character than HSA and BSA. The loading efficacies were 40-52%. Modeling showed the presence of several H-bonding systems, which stabilized polyamine-protein conjugates. Polyamine conjugation induced major alterations of serum protein conformations. The potential application of serum proteins in delivery of polyamines is evaluated here.

  3. Gene encoding herbicide safener binding protein

    SciTech Connect

    Walton, J.D.; Scott-Craig, J.S.

    1999-10-26

    The cDNA encoding safener binding protein (SafBP), also referred to as SBP1, is presented. The deduced amino acid sequence is provided. Methods of making and using SBP1 and SafBP to alter a plant's sensitivity to certain herbicides or a plant's responsiveness to certain safeners are also provided, as well as expression vectors, transgenic plants or other organisms transfected with vectors and seeds from the plants.

  4. Polynucleotides encoding TRF1 binding proteins

    DOEpatents

    Campisi, Judith; Kim, Sahn-Ho

    2002-01-01

    The present invention provides a novel telomere associated protein (Trf1-interacting nuclear protein 2 "Tin2") that hinders the binding of Trf1 to its specific telomere repeat sequence and mediates the formation of a Tin2-Trf1-telomeric DNA complex that limits telomerase access to the telomere. Also included are the corresponding nucleic acids that encode the Tin2 of the present invention, as well as mutants of Tin2. Methods of making, purifying and using Tin2 of the present invention are described. In addition, drug screening assays to identify drugs that mimic and/or complement the effect of Tin2 are presented.

  5. Novel retinoid-binding proteins from filarial parasites.

    PubMed Central

    Sani, B P; Vaid, A; Comley, J C; Montgomery, J A

    1985-01-01

    The present study deals with the discovery and partial characterization of specific binding proteins for retinol and retinoic acid from filarial parasites (worms of the superfamily Filarioidea), including those from two species of Onchocerca. These binding proteins, which are distinct in their physicochemical properties and in the mode of ligand interactions from the host-tissue retinoid-binding proteins, may be involved in the mediation of the putative biological roles of retinoids in the control of parasitic growth, differentiation and reproduction. Parasite retinol-binding protein and retinoic acid-binding protein exhibited specificity for binding retinol and retinoic acid respectively. Both the binding proteins showed an s20,w value of 2.0 S. On gel filtration, both proteins were retarded to a position corresponding to the same molecular size (19.0 kDa). On preparative columns, the parasite binding proteins exhibited isoelectric points at pH 5.7 and 5.75. Unlike the retinoid-binding proteins of mammalian and avian origin, the parasite retinoid-binding proteins showed a lack of mercurial sensitivity in ligand binding. The comparative amounts of retinoic acid-binding protein in five parasites, Onchocerca volvulus, Onchocerca gibsoni, Dipetalonema viteae, Brugia pahangi and Dirofilaria immitis, were between 2.7 and 3.1 pmol of retinoic acid bound/mg of extractable protein. However, the levels of parasite retinol-binding protein were between 4.8 and 5.8 pmol/mg, which is considerably higher than the corresponding levels of cellular retinol-binding protein of mammalian and avian origin. Both retinol- and retinoic acid-binding-protein levels in O. volvulus-infected human nodules and O. gibsoni-infected bovine nodules were similar to their levels in mammalian tissues. Also, these nodular binding proteins, like the host-binding proteins, exhibited mercurial sensitivity to ligand interactions. PMID:3004410

  6. Protein-protein binding before and after photo-modification of albumin

    NASA Astrophysics Data System (ADS)

    Rozinek, Sarah C.; Glickman, Randolph D.; Thomas, Robert J.; Brancaleon, Lorenzo

    2016-03-01

    Bioeffects of directed-optical-energy encompass a wide range of applications. One aspect of photochemical interactions involves irradiating a photosensitizer with visible light in order to induce protein unfolding and consequent changes in function. In the past, irradiation of several dye-protein combinations has revealed effects on protein structure. Beta lactoglobulin, human serum albumin (HSA) and tubulin have all been photo-modified with meso-tetrakis(4- sulfonatophenyl)porphyrin (TSPP) bound, but only in the case of tubulin has binding caused a verified loss of biological function (loss of ability to form microtubules) as a result of this light-induced structural change. The current work questions if the photo-induced structural changes that occur to HSA, are sufficient to disable its biological function of binding to osteonectin. The albumin-binding protein, osteonectin, is about half the molecular weight of HSA, so the two proteins and their bound product can be separated and quantified by size exclusion high performance liquid chromatography. TSPP was first bound to HSA and irradiated, photo-modifying the structure of HSA. Then native HSA or photo-modified HSA (both with TSPP bound) were compared, to assess loss in HSA's innate binding ability as a result of light-induced structure modification.

  7. Fluorescence analysis of competition of phenylbutazone and methotrexate in binding to serum albumin in combination treatment in rheumatology

    NASA Astrophysics Data System (ADS)

    Maciążek-Jurczyk, M.; Sułkowska, A.; Bojko, B.; Równicka, J.; Sułkowski, W. W.

    2009-04-01

    Combination of several drugs is often necessary especially during long-them therapy. The competition between drugs can cause a decrease of the amount of a drug bound to albumin. This results in an increase of the free, biological active fraction of the drug. The aim of the presented study was to describe the competition between phenylbutazone (Phe) and methotrexate (MTX), two drugs recommended for the treatment of rheumatology in binding to bovine (BSA) and human (HSA) serum albumin in the high affinity binding site. Fluorescence analysis was used to estimate the effect of drugs on the protein fluorescence and to define the binding and quenching properties of drugs-serum albumin complexes. The effect of the displacement of one drug from the complex of the other with serum albumin has been described on the basis of the comparison of the quenching curves and binding constants for the binary and ternary systems. The conclusion that both Phe and MTX form a binding site in the same subdomain (IIA) points to the necessity of using a monitoring therapy owning to the possible increase of the uncontrolled toxic effects.

  8. Binding site identification of metformin to human serum albumin and glycated human serum albumin by spectroscopic and molecular modeling techniques: a comparison study.

    PubMed

    Rahnama, Elaheh; Mahmoodian-Moghaddam, Maryam; Khorsand-Ahmadi, Sabra; Saberi, Mohammad Reza; Chamani, Jamshidkhan

    2015-01-01

    The interaction between metformin and human serum albumin (HSA), as well as its glycated form (gHSA) was investigated by multiple spectroscopic techniques, zeta potential, and molecular modeling under physiological conditions. The steady state and time-resolved fluorescence data displayed the quenching mechanism of HSA-metformin and gHSA-metformin was static. The binding information, including the binding constants, number of binding sites, effective quenching constant showed that the binding affinity of metformin to HSA was greater than to gHSA which also confirmed by anisotropy measurements. It was determined that metformin had two and one set of binding sites on HSA and gHSA, respectively. Far-UV CD spectra of proteins demonstrated that the α-helical content decreased with increasing metformin concentration. The zeta potential and resonance light scattering (RLS) diagrams provided that lower drug concentration induced metformin aggregation on gHSA surface as compare to HSA. The increase in polarizability was one of the important factors for the enhancement of RLS and the formation of drug/protein complexes. The zeta potential results suggested that both hydrophobic and electrostatic interactions played important roles in the protein-metformin complex formation. Site marker experiments and molecular modeling showed that the metformin bound to subdomain IIIA (Sudlow's site II) on HSA and gHSA.

  9. Synthesis of 25-hydroxyvitamin D sub 3 3. beta. -3 prime -(N-(4-azido-2-nitrophenyl)amino)propyl ether, a second-generation photoaffinity analogue of 25-hydroxyvitamin D sub 3 : Photoaffinity labeling of rat serum vitamin D binding protein

    SciTech Connect

    Ray, R.; Holick, M.F. ); Bouillon, R.; Van Baelen, H. )

    1991-05-14

    Vulnerability of 25-hydroxy-(26,27-{sup 3}H)vitamin D{sub 3} 3{beta}-N-(4-azido-2-nitrophenyl)glycinate, a photoaffinity analogue of 25-hydroxyvitamin D{sub 3} (25-OH-D{sub 3}) toward standard conditions of carboxymethylationin promoted the authors to synthesize 25-hydroxyvitamin D{sub 3} 3{beta}-3{prime}-(N-(4-azido-2-nitrophenyl)amino)propyl ether (25-ANE), a hydrolytically stable photoaffinity analogue of 25-OH-D{sub 3}, and 25-hydroxyvitamin D{sub 3} 3{beta}-3{prime}-(N-(4-azido-2-nitro-(3,5-{sup 3}H)phenyl)amino)propyl ether ({sup 3}H-25-ANE), the radiolabeled counterpart of 25-ANE competes for the 25-OH-D{sub 3} binding site in rat serum vitamin D binding protein (rDBP). On the other hand, UV exposure of a sample of purified rat DBP (rDBP), preincubated in the dark with {sup 3}H-25-ANE, covalently labeled the protein. However, very little covalent labeling was observed in the absence of UV light or in the presence of a large excess of 25-OH-D{sub 3}. These results provide strong evidence for the covalent labeling of the 25-OH-D{sub 3} binding site in rDPB by {sup 3}H-25-ANE.

  10. Binding of transition metals to S100 proteins

    PubMed Central

    Gilston, Benjamin A.; Skaar, Eric P.; Chazin, Walter J.

    2016-01-01

    The S100 proteins are a unique class of EF-hand Ca2+ binding proteins distributed in a cell-specific, tissue-specific, and cell cycle-specific manner in humans and other vertebrates. These proteins are distinguished by their distinctive homodimeric structure, both intracellular and extracellular functions, and the ability to bind transition metals at the dimer interface. Here we summarize current knowledge of S100 protein binding of Zn2+, Cu2+ and Mn2+ ions, focusing on binding affinities, conformational changes that arise from metal binding, and the roles of transition metal binding in S100 protein function. PMID:27430886

  11. Improved rapid methods for the determination of iron content and binding capacity of serum.

    PubMed

    BEALE, R N; BOSTROM, J O; TAYLOR, R F

    1962-03-01

    Improved methods are described for the determination of serum iron (SeFe) and latent iron-binding capacity under controlled conditions of pH. As before, no precipitation or heating of the serum is required, and controls are not used. Unbuffered sulphonated bathophenanthroline is employed for colour development. Statistical data for 40 normals are presented and comparisons with other data are given; the effects of ageing of serum are studied.

  12. [Binding of epirubicin to human plasma protein and erythrocytes: interaction with the cytoprotective amifostine].

    PubMed

    Pernkopf, I; Tesch, G; Dempe, K; Kletzl, H; Schüller, J; Czejka, M

    1996-11-01

    The in vitro binding rate of epirubicin (EPR) to different plasma proteins, control serum, red blood cells and whole blood was investigated without and with the cytoprotective agent amifostine. The binding rate of EPR to plasma proteins fractions and red blood cells dependend on the concentration of the matrix components. EPR was bound more than 90% to human serum alpha-globulin (alpha-HSG), to human serum albumine (HSA) and human serum beta-globuline (beta-HSG) at 80 to 90%, in the case of human serum gamma-globulin (gamma-HSG) the binding rate amounted 75%. The binding rate of EPR to RBCs in whole blood samples reached 38%. Within the observed concentration range of proteins (1-40 micrograms/ml, depending on the protein concentration) AMI caused a reduction of the protein-bound amount of EPR in the range from 2 to 19% of HSA, 4 to 20 in the case of beta-HSG, 2 to 32% in the case of alpha-HSG and 17 to 21% for gamma-HSG. In the whole blood samples the binding of EPR to proteins dropped from 45 to 32% and RBC-partitioning from 38 to 32%. Two compounds with free thiol groups, cystein and glutathione, were compared with AMI in regard to lowering the binding rate of EPR to HSA: the effect was exactly in the same order of magnitude: -17% for AMI, -21.0% for cystein and -20.8% for glutahion (p < 0.002). For a negative control, cystin and phenylalanin were tested, too: both compounds showed no influence on the protein binding of EPR: 63.8% binding rate in the control group, 65.2% in the presence of cystin and 64.6% in the presence of phenylalanin (statistically not significant). The present results indicate, that binding of EPR to serum proteins is reduced in the presence of AMI by interaction of the thiol-group with the protein and that the thiophosphoric ester bond in the test solution must cleave rapidly.

  13. Characterization of interactions between polyphenolic compounds and human serum proteins by capillary electrophoresis.

    PubMed

    Diniz, Andréa; Escuder-Gilabert, Laura; Lopes, Norberto P; Villanueva-Camañas, Rosa María; Sagrado, Salvador; Medina-Hernández, María José

    2008-05-01

    The interaction of ten natural polyphenolic compounds (chlorogenic acid, apigenin, catechin, epicatechin, flavanone, flavone, quercetin, rutin, vicenin-2 and vitexin) with human serum albumin and mixtures of human serum albumin and α(1)-acid glycoprotein under near physiological conditions is studied by capillary electrophoresis-frontal analysis. Furthermore, the binding of these polyphenolic compounds to total plasmatic proteins is evaluated using ultrafiltration and capillary electrophoresis. In spite of the relatively small differences in the chemical structures of the compounds studied, large differences were observed in their binding behaviours to plasmatic proteins. The hydrophobicity, the presence/absence of some functional groups, steric hindrance and spatial arrangement seem to be key factors in the affinity of natural polyphenols towards plasmatic proteins.

  14. Binding of the bioactive component Aloe dihydroisocoumarin with human serum albumin

    NASA Astrophysics Data System (ADS)

    Zhang, Xiu-Feng; Xie, Ling; Liu, Yang; Xiang, Jun-Feng; Tang, Ya-Lin

    2008-11-01

    Aloe dihydroisocoumarin, one of new components isolated from Aloe vera, can scavenge reactive oxygen species. In order to explore the mechanism of drug action at a molecular level, the binding of Aloe dihydroisocoumarin with human serum albumin (HSA) has been investigated by using fluorescence, ultraviolet (UV), circular dichroism (CD) and Fourier transform infrared (FT-IR) spectroscopy, fluorescence dynamics, and molecular dynamic docking for the first time. We observed a quenching of fluorescence of HSA in the presence of Aloe dihydroisocoumarin and also analyzed the quenching results using the Stern-Volmer equation and obtained high affinity binding to HSA. An isoemissive point at 414 nm is seen, indicating that the quenching of HSA fluorescence depends on the formation of Aloe dihydroisocoumarin-HSA complex, which is further confirmed by fluorescence dynamic result. From the CD and FT-IR results, it is apparent that the interaction of Aloe dihydroisocoumarin with HSA causes a conformational change of the protein, with the gain of α-helix, β-sheet and random coil stability and the loss of β-turn content. Data obtained by fluorescence spectroscopy, fluorescence dynamics, CD, and FTIR experiments along with the docking studies suggest that Aloe dihydroisocoumarin binds to residues located in subdomain IIA of HSA.

  15. Spectroscopic and molecular modeling evidence of clozapine binding to human serum albumin at subdomain IIA

    NASA Astrophysics Data System (ADS)

    Wu, Xinhu; Liu, Jianjun; Wang, Qiang; Xue, Weiwei; Yao, Xiaojun; Zhang, Yan; Jin, Jing

    2011-09-01

    Various spectroscopy and molecular docking methods were used to examine the binding of Clozapine (CLZ) to human serum albumin (HSA) in this paper. By monitoring the intrinsic fluorescence of single Trp214 residue and performing Dansylamide (DNSA) displacement measurement, the specific binding of CLZ in the vicinity of Sudlow's Site I of HSA has been clarified. An apparent distance of 27.3 Å between the Trp214 and CLZ was obtained via fluorescence resonance energy transfer (FRET) method. In addition, the changes in the secondary structure of HSA after its complexation with CLZ ligand were studied with CD spectroscopy, which indicate that CLZ does not has remarkable effect on the structure of the protein. Moreover, thermal denaturation experiment shows that the HSA-CLZ complexes are conformationally more stable. Finally, the binding details between CLZ and HSA were further confirmed by molecular docking studies, which revealed that CLZ was bound at subdomain IIA through multiple interactions, such as hydrophobic effect, van der Waals forces and hydrogen bonding.

  16. Spectroscopic and molecular modeling evidence of clozapine binding to human serum albumin at subdomain IIA.

    PubMed

    Wu, Xinhu; Liu, Jianjun; Wang, Qiang; Xue, Weiwei; Yao, Xiaojun; Zhang, Yan; Jin, Jing

    2011-09-01

    Various spectroscopy and molecular docking methods were used to examine the binding of Clozapine (CLZ) to human serum albumin (HSA) in this paper. By monitoring the intrinsic fluorescence of single Trp214 residue and performing Dansylamide (DNSA) displacement measurement, the specific binding of CLZ in the vicinity of Sudlow's Site I of HSA has been clarified. An apparent distance of 27.3 Å between the Trp214 and CLZ was obtained via fluorescence resonance energy transfer (FRET) method. In addition, the changes in the secondary structure of HSA after its complexation with CLZ ligand were studied with CD spectroscopy, which indicate that CLZ does not has remarkable effect on the structure of the protein. Moreover, thermal denaturation experiment shows that the HSA-CLZ complexes are conformationally more stable. Finally, the binding details between CLZ and HSA were further confirmed by molecular docking studies, which revealed that CLZ was bound at subdomain IIA through multiple interactions, such as hydrophobic effect, van der Waals forces and hydrogen bonding.

  17. Placental Vitamin D-Binding Protein Expression in Human Idiopathic Fetal Growth Restriction

    PubMed Central

    Wookey, Alice F.; Chollangi, Tejasvy; Yong, Hannah E. J.

    2017-01-01

    Vitamin D-binding protein is a multifunctional serum protein with multiple actions related to normal health. Vitamin D-binding protein transports vitamin D and influences the metabolism of this key hormone but it also has additional immunomodulatory and actin-clearing properties. We investigated whether vitamin D-binding protein expression is altered in fetal growth restriction-associated placental dysfunction. Protein was extracted from 35 placentae derived from 17 healthy control subjects and 18 gestation-matched subjects with fetal growth restriction (FGR). FGR subjects were further subdivided as idiopathic (n = 9) and nonidiopathic (n = 9). Vitamin D-binding protein and 25(OH) vitamin D were measured by ELISA and normalized to protein concentration. The results showed significantly reduced levels of placental vitamin D-binding protein (control versus FGR, p < 0.05, Student's t-test) that were strongly associated with idiopathic fetal growth restriction (p < 0.01, Kruskal-Wallis), whereas levels of vitamin D-binding protein were not associated with placental 25(OH) vitamin D stores (p = 0.295, Pearson's correlation). As such, vitamin D-binding protein may be a factor in unexplained placental dysfunction associated with idiopathic fetal growth restriction and may potentially serve as a biomarker of this disease. PMID:28293436

  18. Phosphorylation of native porcine olfactory binding proteins.

    PubMed

    Nagnan-Le Meillour, Patricia; Le Danvic, Chrystelle; Brimau, Fanny; Chemineau, Philippe; Michalski, Jean-Claude

    2009-07-01

    The identification of various isoforms of olfactory binding proteins is of major importance to elucidate their involvement in detection of pheromones and other odors. Here, we report the characterization of the phosphorylation of OBP (odorant binding protein) and Von Ebner's gland protein (VEG) from the pig, Sus scrofa. After labeling with specific antibodies raised against the three types of phosphorylation (Ser, Thr, Tyr), the phosphate-modified residues were mapped by using the beta-elimination followed by Michael addition of dithiothreitol (BEMAD) method. Eleven phosphorylation sites were localized in the pOBP sequence and nine sites in the VEG sequence. OBPs are secreted by Bowman's gland cells in the extracellular mucus lining the nasal cavity. After tracking the secretion pathway in the rough endoplasmic reticulum of these cells, we hypothesize that these proteins may be phosphorylated by ectokinases that remain to be characterized. The existence of such a regulatory mechanism theoretically increases the number of OBP variants, and it suggests a more specific role for OBPs in odorant coding than the one of odorant solubilizer and transporter.

  19. Modulation of linoleic acid-binding properties of human serum albumin by divalent metal cations.

    PubMed

    Nemashkalova, Ekaterina L; Permyakov, Eugene A; Permyakov, Sergei E; Litus, Ekaterina A

    2017-03-16

    Human serum albumin (HSA) is an abundant multiligand carrier protein, linked to progression of Alzheimer's disease (AD). Blood HSA serves as a depot of amyloid β (Aβ) peptide. Aβ peptide-buffering properties of HSA depend on interaction with its ligands. Some of the ligands, namely, linoleic acid (LA), zinc and copper ions are involved into AD progression. To clarify the interplay between LA and metal ion binding to HSA, the dependence of LA binding to HSA on Zn(2+), Cu(2+), Mg(2+) and Ca(2+) levels and structural consequences of these interactions have been explored. Seven LA molecules are bound per HSA molecule in the absence of the metal ions. Zn(2+) binding to HSA causes a loss of one bound LA molecule, while the other metals studied exert an opposite effect (1-2 extra LA molecules are bound). In most cases, the observed effects are not related to the metal-induced changes in HSA quaternary structure. However, the Zn(2+)-induced decline in LA capacity of HSA could be due to accumulation of multimeric HSA forms. Opposite to Ca(2+)/Mg(2+)-binding, Zn(2+) or Cu(2+) association with HSA induces marked changes in its hydrophobic surface. Overall, the divalent metal ions modulate LA capacity and affinity of HSA to a different extent. LA- and Ca(2+)-binding to HSA synergistically support each other. Zn(2+) and Cu(2+) induce more pronounced changes in hydrophobic surface and quaternary structure of HSA and its LA capacity. A misbalanced metabolism of these ions in AD could modify interactions of HSA with LA, other fatty acids and hydrophobic substances, associated with AD.

  20. Revision of the biodistribution of uranyl in serum: is fetuin-A the major protein target?

    PubMed

    Basset, Christian; Averseng, Olivier; Ferron, Pierre-Jean; Richaud, Nicolas; Hagège, Agnès; Pible, Olivier; Vidaud, Claude

    2013-05-20

    Uranium is a natural actinide present as uranyl U(VI) species in aqueous environments. Its toxicity is considered to be chemical rather than radiotoxicological. Whatever the route of entry, uranyl reaches the blood, is partly eliminated via the kidneys, and accumulated in the bones. In serum, its speciation mainly involves carbonate and proteins. Direct identification of labile uranyl-protein complexes is extremely difficult because of the complexity of this matrix. Thus, until now the biodistribution of the metal in serum has not been described, and therefore, little is known about the metal transport mechanisms leading to bone accumulation. A rapid screening method based on a surface plasmon resonance (SPR) technique was used to determine the apparent affinities for U(VI) of the major serum proteins. A first biodistribution of uranyl was obtained by ranking the proteins according to the criteria of both their serum concentrations and affinities for this metal. Despite its moderate concentration in serum, fetuin-A (FETUA) was shown to exhibit an apparent affinity within the 30 nM range and to carry more than 80% of the metal. This protein involved in bone mineralization aroused interest in characterizing the U(VI) and FETUA interaction. Using complementary chromatographic and spectroscopic approaches, we demonstrated that the protein can bind 3 U(VI) at different binding sites exhibiting Kd from ∼30 nM to 10 μM. Some structural modifications and functional properties of FETUA upon uranyl complexation were also controlled. To our knowledge, this article presents the first identification of a uranyl carrier involved in bone metabolism along with the characterization of its metal binding sites.

  1. Novel stereospecificity of the L-arabinose-binding protein

    NASA Astrophysics Data System (ADS)

    Quiocho, Florante A.; Vyas, Nand K.

    1984-08-01

    Tertiary structure refinement at 1.7 Å resolution of the liganded form of L-arabinose-binding protein from Escherichia coli has revealed a novel binding site geometry which accommodates both α- and β-anomers of L-arabinose. This detailed structure analysis provides new understanding of protein-sugar interaction, the process by which the binding protein minimizes the difference in the stability of the two bound sugar anomers, and the roles of periplasmic binding proteins in active transport

  2. Surface plasmon resonance and circular dichroism characterization of cucurbitacins binding to serum albumins for early pharmacokinetic profiling.

    PubMed

    Fabini, Edoardo; Fiori, Giovana Maria Lanchoti; Tedesco, Daniele; Lopes, Norberto Peporine; Bertucci, Carlo

    2016-04-15

    Cucurbitacins are a group of tetracyclic triterpenoids, known for centuries for their anti-cancer and anti-inflammatory properties, which are being actively investigated over the past decades in order to elucidate their mechanism of action. In perspective of being used as therapeutic molecules, a pharmacokinetic characterization is crucial to assess the affinity toward blood carrier proteins and extrapolate distribution volumes. Usually, pharmacokinetic data are first collected on animal models and later translated to humans; therefore, an early characterization of the interaction with carrier proteins from different species is highly desirable. In the present study, the interactions of cucurbitacins E and I with human and rat serum albumins (HSA and RSA) were investigated by means of surface plasmon resonance (SPR)-based optical biosensing and circular dichroism (CD) spectroscopy. Active HSA and RSA sensor chip surfaces were prepared through an amine coupling reaction protocol, and the equilibrium dissociation constants (Kd) for the different cucurbitacins-serum albumins complexes were then determined by SPR analysis. Further information on the binding of cucurbitacins to serum albumins was obtained by CD competition experiments with biliverdin, a specific marker binding to subdomain IB of HSA. SPR data unveiled a previously unreported binding event between CucI and HSA; the determined binding affinities of both compounds were slightly higher for RSA with respect to HSA, even though all the compounds can be ranked as high-affinity binders for both carriers. CD analysis showed that the two cucurbitacins modify the binding of biliverdin to serum albumins through opposite allosteric modulation (positive for HSA, negative for RSA), confirming the need for caution in the translation of pharmacokinetic data across species.

  3. Sulfadiazine binds and unfolds bovine serum albumin: an in vitro study.

    PubMed

    Al-Lohedan, Hamad A; Sajih Ali, Mohd

    2013-11-01

    Sulfonamide derivatives, such as sulfadiazine (SD) are used as antibiotics and, very recently, anti-amyloid properties of these have been reported. We have evaluated binding of SD with bovine serum albumin (BSA) followed by unfolding of protein. Studies were accomplished at physiological conditions of temperature (37 °C) and pH (7.4), employing UV, fluorescence, circular dichroism (CD) and Fourier transform infra-red (FTIR) spectroscopies. In presence of drug, UV spectrum of BSA was altered from the spectrum of native BSA due to the interaction between albumin and drug. Excitation of protein at 295 nm showed that fluorescence quenching of BSA by SD is a result of the formation of SD–BSA complex. The data were analyzed using Stern–Volmer and Lineweaver–Burk methods. From both methods it was evaluated that the quenching involved in BSA–SD binding was static. BSA had only one binding site for SD. Synchronous fluorescence spectra have shown a red shift and advocated that hydrophobicity around both Trp and Tyr residues was decreased. CD results revealed that the conformation of macromolecule remain undisturbed at low concentrations (up to 20 μM of the SD) and there was small perturbation in the secondary structure from 20 to 50 μM of SD followed by a large change and consequent unfolding on further increase in the drug concentration. Both synchronous and CD measurements were consistent to each other. FTIR spectra revealed the shifting of amide I band which is also an indication of conformational change of the protein.

  4. Fish protein decreases serum cholesterol in rats by inhibition of cholesterol and bile acid absorption.

    PubMed

    Hosomi, Ryota; Fukunaga, Kenji; Arai, Hirofumi; Kanda, Seiji; Nishiyama, Toshimasa; Yoshida, Munehiro

    2011-05-01

    Fish protein has been shown to decrease serum cholesterol content by inhibiting absorption of cholesterol and bile acid in laboratory animals, though the mechanism underlying this effect is not yet fully understood. The purpose of this study was to elucidate the mechanism underlying the inhibition of cholesterol and bile acid absorption following fish protein intake. Male Wistar rats were divided into 2 dietary groups of 7 rats each, 1 group receiving a diet consisting of 20% casein and the other receiving a diet consisting of 10% casein and 10% fish protein. Both experimental diets also contained 0.5% cholesterol and 0.1% sodium cholate. After the rats had been on their respective diets for 4 wk, their serum and liver cholesterol contents and fecal cholesterol, bile acid, and nitrogen excretion contents were measured. Fish protein consumption decreased serum and liver cholesterol content and increased fecal cholesterol and bile acid excretion and simultaneously increased fecal nitrogen excretion. In addition, fish protein hydrolyzate prepared by in vitro digestion had lower micellar solubility of cholesterol and higher binding capacity for bile acids compared with casein hydrolyzate. These results suggest that the hypocholesterolemic effect of fish protein is mediated by increased fecal cholesterol and bile acid excretion, which is due to the digestion products of fish protein having reduced micellar solubility of cholesterol and increased bile acid binding capacity.

  5. Serum CRP protein as a differential marker in cancer.

    PubMed

    Juan, Hu; Qijun, Wang; Junlan, Liu

    2012-11-01

    The objective of this study was to measure the serum concentrations of C-reactive protein (CRP) in cancer patients and compare with those of immune disease patients and healthy individuals for discriminatory analysis. For this purpose, automatic systems for special protein analysis (Type: Drcon Diognostica Tarbox) was used to measure serum CRP concentrations in 276 cancer patients (Group A), 110 immune disease patients (Group B), 161 phlogistic patients (Group C), and 125 age-matched healthy individuals (Group D). Our data show that serum CRP concentrations in Group A were significantly higher than those in Groups B and D, whereas CRP concentrations in Group B were higher than those in Group D. The differences of serum CRP concentrations between Groups A and B as well as between Groups B and D were significant (P < 0.01). We, therefore, concluded that the measurement of serum CRP concentrations was a fast and accurate method to distinguish between cancer and immune disease patients.

  6. Binding studies of lophirone B with bovine serum albumin (BSA): Combination of spectroscopic and molecular docking techniques

    NASA Astrophysics Data System (ADS)

    Chaves, Otávio Augusto; da Silva, Veridiana A.; Sant'Anna, Carlos Maurício R.; Ferreira, Aurélio B. B.; Ribeiro, Tereza Auxiliadora N.; de Carvalho, Mário G.; Cesarin-Sobrinho, Dari; Netto-Ferreira, José Carlos

    2017-01-01

    The interaction between the transport protein bovine serum albumin (BSA) and the natural product lophirone B, was investigated by spectroscopic techniques combined with a computational method (molecular docking). From the KSV and kq values it was concluded that lophirone B quenches the fluorescence of BSA by dynamic and static mechanisms. The Ka values, of the order of 104 M-1, and the number of binding sites (n ≈ 1), indicate that the binding is moderate and there is just one main binding site in BSA for lophirone B. The negative ΔG° values are in accordance with the spontaneity of the process and the positive ΔH° and ΔS° values indicate that the binding is entropically driven; the main binding forces for the association BSA:lophirone B are probably lipophilic interactions. Circular dichroism (CD) studies show there is not a significant perturbation on the secondary structure of the albumin upon the binding process. In order to better understand the spectroscopic results, a computational method was applied: molecular docking suggests Trp-213 site, as the main binding site for the ligand. Lophirone B seems to be exposed to the aqueous media as well as accommodated inside the protein cavity, resulting in a moderate affinity for the albumin. The Arg-198, His-287, Lys-294 and Lys-439 residues are interacting via hydrogen bonding with lophirone B, whereas the interaction with Trp-213 residue occurs through a lipophilic interaction.

  7. Interaction of Serum Proteins with Surface of Hemodialysis Fiber Membranes

    NASA Astrophysics Data System (ADS)

    Afrin, Rehana; Shirako, Yuji; Kishimoto, Kikuo; Ikai, Atsushi

    2012-08-01

    The poly(vinyl pyrrolidone)-covered hydrophilic surface of hollow-fiber membranes (fiber membrane, hereafter) for hemodialysis was mechanically probed using modified tips on an atomic force microscope (AFM) with covalent crosslinkers and several types of serum protein. The retraction part of many of the force extension (F-E) curves obtained with AFM tips coated with serum albumin had a long and smooth extension up to 200-300 nm indicating forced elongation of poly(vinyl pyrrolidone) chains. When fibrinogen-coated tips were used, long extension F-E curves up to 500 nm with multiple peaks were obtained in addition to smooth curves most likely reflecting the unfolding of fibrinogen molecules. The results indicated that individual polymer chains had a significant affinity toward serum proteins. The adhesion frequency of tips coated with serum proteins was lower on the poly(vinyl pyrrolidone) surface than on the uncoated hydrophobic polysulfone surface.

  8. Reversible binding of ethacrynic acid to human serum albumin: difference circular dichroism study.

    PubMed

    Bertucci, C; Nanni, B; Salvadori, P

    1999-01-01

    The reversible binding of ethacrynic acid was characterized by a difference circular dichroism method. A 2/1 stoichiometry was determined for the [drug]/[HSA] (human serum albumin) complex. The reversible binding of ethacrynic acid to HSA determines direct competition with ligands that selectivity bind to site II and to the fatty acid site. Furthermore, indirect competition was shown for ligands for site I (anti-cooperative) and to site III (cooperative).

  9. Gene encoding herbicide safener binding protein

    SciTech Connect

    Walton, Jonathan D.; Scott-Craig, John S.

    1999-01-01

    The cDNA encoding safener binding protein (SafBP), also referred to as SBP1, is set forth in FIG. 5 and SEQ ID No. 1. The deduced amino acid sequence is provided in FIG. 5 and SEQ ID No. 2. Methods of making and using SBP1 and SafBP to alter a plant's sensitivity to certain herbicides or a plant's responsiveness to certain safeners are also provided, as well as expression vectors, transgenic plants or other organisms transfected with said vectors and seeds from said plants.

  10. Measuring Binding Affinity of Protein-Ligand Interaction Using Spectrophotometry: Binding of Neutral Red to Riboflavin-Binding Protein

    ERIC Educational Resources Information Center

    Chenprakhon, Pirom; Sucharitakul, Jeerus; Panijpan, Bhinyo; Chaiyen, Pimchai

    2010-01-01

    The dissociation constant, K[subscript d], of the binding of riboflavin-binding protein (RP) with neutral red (NR) can be determined by titrating RP to a fixed concentration of NR. Upon adding RP to the NR solution, the maximum absorption peak of NR shifts to 545 nm from 450 nm for the free NR. The change of the absorption can be used to determine…

  11. Crystal structure of equine serum albumin in complex with cetirizine reveals a novel drug binding site.

    PubMed

    Handing, Katarzyna B; Shabalin, Ivan G; Szlachta, Karol; Majorek, Karolina A; Minor, Wladek

    2016-03-01

    Serum albumin (SA) is the main transporter of drugs in mammalian blood plasma. Here, we report the first crystal structure of equine serum albumin (ESA) in complex with antihistamine drug cetirizine at a resolution of 2.1Å. Cetirizine is bound in two sites--a novel drug binding site (CBS1) and the fatty acid binding site 6 (CBS2). Both sites differ from those that have been proposed in multiple reports based on equilibrium dialysis and fluorescence studies for mammalian albumins as cetirizine binding sites. We show that the residues forming the binding pockets in ESA are highly conserved in human serum albumin (HSA), and suggest that binding of cetirizine to HSA will be similar. In support of that hypothesis, we show that the dissociation constants for cetirizine binding to CBS2 in ESA and HSA are identical using tryptophan fluorescence quenching. Presence of lysine and arginine residues that have been previously reported to undergo nonenzymatic glycosylation in CBS1 and CBS2 suggests that cetirizine transport in patients with diabetes could be altered. A review of all available SA structures from the PDB shows that in addition to the novel drug binding site we present here (CBS1), there are two pockets on SA capable of binding drugs that do not overlap with fatty acid binding sites and have not been discussed in published reviews.

  12. Chick neural retina adhesion and survival molecule is a retinol-binding protein

    SciTech Connect

    Schubert, D.; LaCorbiere, M.; Esch, F.

    1986-01-01

    A 20,000-D protein called purpurin has recently been isolated from the growth-conditioned medium of cultured embryonic chick neural retina cells. Purpurin is a constituent of adherons and promotes cell-adheron adhesion by interacting with a cell surface heparan sulfate proteoglycan. It also prolongs the survival of cultured neural retina cells. This paper shows that purpurin is a secretory protein that has sequence homology with a human protein synthesized in the liver that transports retinol in the blood, the serum retinol-binding protein (RBP). Purpurin binds (/sup 3/H)retinol, and both purpurin and chick serum RBP stimulate the adhesion of neural retina cells, although the serum protein is less active than purpurin. Purpurin and the serum RBP are, however, different molecules, for the serum protein is approx.3.000 D larger than purpurin and has different silver-staining characteristics. Finally, purpurin supports the survival of dissociated ciliary ganglion cells, indicating that RBPs can act as ciliary neurotrophic factors.

  13. Computational characterization of how the VX nerve agent binds human serum paraoxonase 1.

    PubMed

    Fairchild, Steven Z; Peterson, Matthew W; Hamza, Adel; Zhan, Chang-Guo; Cerasoli, Douglas M; Chang, Wenling E

    2011-01-01

    Human serum paraoxonase 1 (HuPON1) is an enzyme that can hydrolyze various chemical warfare nerve agents including VX. A previous study has suggested that increasing HuPON1's VX hydrolysis activity one to two orders of magnitude would make the enzyme an effective countermeasure for in vivo use against VX. This study helps facilitate further engineering of HuPON1 for enhanced VX-hydrolase activity by computationally characterizing HuPON1's tertiary structure and how HuPON1 binds VX. HuPON1's structure is first predicted through two homology modeling procedures. Docking is then performed using four separate methods, and the stability of each bound conformation is analyzed through molecular dynamics and solvated interaction energy calculations. The results show that VX's lone oxygen atom has a strong preference for forming a direct electrostatic interaction with HuPON1's active site calcium ion. Various HuPON1 residues are also detected that are in close proximity to VX and are therefore potential targets for future mutagenesis studies. These include E53, H115, N168, F222, N224, L240, D269, I291, F292, and V346. Additionally, D183 was found to have a predicted pKa near physiological pH. Given D183's location in HuPON1's active site, this residue could potentially act as a proton donor or accepter during hydrolysis. The results from the binding simulations also indicate that steered molecular dynamics can potentially be used to obtain accurate binding predictions even when starting with a closed conformation of a protein's binding or active site.

  14. Neurodegeneration and RNA-binding proteins.

    PubMed

    De Conti, Laura; Baralle, Marco; Buratti, Emanuele

    2017-03-01

    In the eukaryotic nucleus, RNA-binding proteins (RBPs) play a very important role in the life cycle of both coding and noncoding RNAs. As soon as they are transcribed, in fact, all RNA molecules within a cell are bound by distinct sets of RBPs that have the task of regulating its correct processing, transport, stability, and function/translation up to its final degradation. These tasks are particularly important in cells that have a complex RNA metabolism, such as neurons. Not surprisingly, therefore, recent findings have shown that the misregulation of genes involved in RNA metabolism or the autophagy/proteasome pathway plays an important role in the onset and progression of several neurodegenerative diseases. In this article, we aim to review the recent advances that link neurodegenerative processes and RBP proteins. WIREs RNA 2017, 8:e1394. doi: 10.1002/wrna.1394 For further resources related to this article, please visit the WIREs website.

  15. Identification of actin binding protein, ABP-280, as a binding partner of human Lnk adaptor protein.

    PubMed

    He, X; Li, Y; Schembri-King, J; Jakes, S; Hayashi, J

    2000-08-01

    Human Lnk (hLnk) is an adaptor protein with multiple functional domains that regulates T cell activation signaling. In order to identify cellular Lnk binding partners, a yeast two-hybrid screening of human spleen cDNA library was carried out using human hLnk as bait. A polypeptide sequence identical to the C-terminal segment of the actin binding protein (ABP-280) was identified as a hLnk binding protein. The expressed hLnk and the FLAG tagged C-terminal 673 amino acid residues of ABP-280 or the endogenous ABP-280 in COS-7 cells could be co-immunoprecipitated using antibodies either to hLnk, FLAG or ABP-280, respectively. Furthermore, immunofluorescence confocal microscope showed that hLnk and ABP-280 co-localized at the plasma membrane and at juxtanuclear region of COS-7 cells. In Jurkat cells, the endogenous hLnk also associates with the endogenous ABP-280 indicating that the association of these two proteins is physiological. The interacting domains of both proteins were mapped using yeast two-hybrid assays. Our results indicate that hLnk binds to the residues 2006-2454 (repeats 19-23C) of ABP-280. The domain in hLnk that associates with ABP-280 was mapped to an interdomain region of 56 amino acids between pleckstrin homology and Src homology 2 domains. These results suggest that hLnk may exert its regulatory role through its association with ABP-280.

  16. 1HNMR study of methotrexate serum albumin (MTX SA) binding in rheumatoid arthritis

    NASA Astrophysics Data System (ADS)

    Sułkowska, A.; Maciążek-Jurczyk, M.; Bojko, B.; Równicka, J.; Sułkowski, W. W.

    2008-11-01

    Rheumatoid arthritis (RA) is an immunologically depended disease. It is characterized by a chronic, progressive inflammatory process. Methotrexate (4-amino-10-methylfolic acid, MTX) is the modifying drug used to treat RA. The aim of the presented studies is to determine the low affinity binding site of MTX in bovine (BSA) and human (HSA) serum albumin with the use of proton nuclear magnetic resonance ( 1HNMR) spectroscopy. The analysis of 1HNMR spectra of MTX in the presence of serum albumin (SA) allows us to observe the interactions between aromatic rings of the drug and the rings of amino acids located in the hydrophobic subdomains of the protein. On the basis of the chemical shifts σ [ppm] and the relaxation times T1 [s] of drug protons the hydrophobic interaction between MTX-SA and the stoichiometric molar ratio of the complex was evaluated. This work is a part of a spectroscopic study on MTX-SA interactions [A. Sułkowska, M. Maciążek, J. Równicka, B. Bojko, D. Pentak, W.W. Sułkowski, J. Mol. Struct. 834-836 (2007) 162-169].

  17. Immunoreactivity and bioactivity of lipopolysaccharide-binding protein in normal and heat-inactivated sera.

    PubMed Central

    Mészáros, K; Aberle, S; White, M; Parent, J B

    1995-01-01

    The lipopolysaccharide (LPS)-potentiating effect of serum is due to LPS-binding protein (LBP), which facilitates the binding of LPS to CD14 receptors. We observed a remarkable heat sensitivity of recombinant LBP and various sera with respect to both immunoreactivity (measured by enzyme-linked immunosorbent assay) and bioactivity (potentiation of LPS induction of tumor necrosis factor in monocytes). Human sera were more active and more heat sensitive than fetal bovine sera. The commonly practiced heat inactivation of human serum (56 degrees C, 30 min) resulted in a 70% loss of bioactivity, which caused an apparent decrease in the potency of LPS. PMID:7806380

  18. Detection of serum proteins by native polyacrylamide gel electrophoresis using Blue Sepharose CL-6B-containing stacking gels.

    PubMed

    Muratsubaki, Haruhiro; Satake, Kaoru; Yamamoto, Yasuhisa; Enomoto, Keiichiro

    2002-08-15

    Analysis of serum proteins by native polyacrylamide gel electrophoresis is difficult because albumin is abundant in serum and interferes with the resolution of other proteins, especially alpha-antitrypsin which has mobility that is very similar to that of albumin. We present here a method in which serum proteins are separated by polyacrylamide gel electrophoresis using stacking gels containing Blue Sepharose CL-6B, which has a high affinity for albumin, lipoproteins, kinases, and pyridine-nucleotide-dependent oxidoreductases. During electrophoresis, proteins that bind to Blue Sepharose CL-6B stay in the stacking gel and do not migrate into the separating gel. As a consequence, certain proteins, including alpha(1)-antitrypsin, can be detected as clear bands. This method overcomes the requirement for fractionation of serum samples prior to electrophoresis to remove albumin and allows the simultaneous analysis of many samples.

  19. Predicting human plasma protein binding of drugs using plasma protein interaction QSAR analysis (PPI-QSAR).

    PubMed

    Li, Haiyan; Chen, Zhuxi; Xu, Xuejun; Sui, Xiaofan; Guo, Tao; Liu, Wei; Zhang, Jiwen

    2011-09-01

    A novel method, named as the plasma protein-interaction QSAR analysis (PPI-QSAR) was used to construct the QSAR models for human plasma protein binding. The intra-molecular descriptors of drugs and inter-molecular interaction descriptors resulted from the docking simulation between drug molecules and human serum albumin were included as independent variables in this method. A structure-based in silico model for a data set of 65 antibiotic drugs was constructed by the multiple linear regression method and validated by the residual analysis, the normal Probability-Probability plot and Williams plot. The R(2) and Q(2) values of the entire data set were 0.87 and 0.77, respectively, for the training set were 0.86 and 0.72, respectively. The results indicated that the fitted model is robust, stable and satisfies all the prerequisites of the regression models. Combining intra-molecular descriptors with inter-molecular interaction descriptors between drug molecules and human serum albumin, the drug plasma protein binding could be modeled and predicted by the PPI-QSAR method successfully.

  20. [Modification of placenta blood serum proteins under low temperature effect].

    PubMed

    Fal'ko, O V; Zemlianskikh, N G; Lipina, O V; Prokopiuk, O S

    2013-01-01

    Changes in environmental physical and chemical factors upon freeze-thawing and low temperature storage of biological samples can result in impairments of protein structures. This work specifies spontaneous and diamide-induced protein aggregations of placenta blood serum stored at -20 degrees and -196 degrees C during 2 years with SDS-PAGE. It was shown that storage of placenta blood serum at low temperatures did not cause any quantitative and qualitative changes in fraction distribution of proteins denatured with SDS in comparison to the native samples which were not frozen. Application of beta-mercaptoethanol revealed that placenta blood serum proteins upon freeze-thawing did not form spontaneous aggregates linked by disulphide bridges. Oxidation of amino acid sulfhydryl groups induced by diamide and accompanied by high molecular aggregate formation proved to be a quite effective way for indirect estimation of structural changes in protein upon low temperature effects. In samples thawed after low temperature storage the protein aggregation with 4 microM diamide was significantly higher than in native serum. These discrepancies between native and frozen-thawed samples are stipulated by impairments of protein structure under low temperature and increased in accessibility of reactive SH-groups of proteins for oxidation with diamide. Structural changes in placenta blood serum proteins, which caused by low temperatures and revealed by elevated sensibility to diamide-induced aggregate formation, did not depend on temperature (-20 degrees and -196 degrees C) and storage terms (2 years and 3 weeks). They reflect protein reaction to freeze-thawing processes and could be sequence of ice crystal formation which takes place in unprotected media.

  1. Regulation of amantadine hydrochloride binding with IIA subdomain of human serum albumin by fatty acid chains.

    PubMed

    Yang, Feng; Lee, Philbert; Ma, Zhiyuan; Ma, Li; Yang, Guoping; Wu, Xiaoyang; Liang, Hong

    2013-01-01

    Human serum albumin (HSA) is a major protein component of blood plasma that has been exploited to bind and transport a wide variety of endogenous and exogenous organic compounds. Although anionic drugs readily associate with the IIA subdomain of HSA, most cationic drugs poorly associate with HSA at this subdomain. In this study, we propose to improve the association between cationic drugs and HSA by modifying HSA with fatty acid chains. For our experiments, we tested amantadine hydrochloride, a cationic drug with antiviral and antiparkinsonian effects. Our results suggest that extensive myristoylation of HSA can help stabilize the interaction between amantadine and HSA in vitro. Our X-ray crystallography data further elucidate the structural basis of this regulation. Additionally, our crystallography data suggest that anionic drugs, with a functional carboxylate group, may enhance the association between amantadine and HSA by a mechanism similar to myristoylation. Ultimately, our results provide critical structural insight into this novel association between cationic drugs and the HSA IIA subdomain, raising the tempting possibility to fully exploit the unique binding capacity of HSA's IIA subdomain to achieve simultaneous delivery of anionic and cationic drugs.

  2. Binding interaction of quinclorac with bovine serum albumin: A biophysical study

    NASA Astrophysics Data System (ADS)

    Han, Xiao-Le; Mei, Ping; Liu, Yi; Xiao, Qi; Jiang, Feng-Lei; Li, Ran

    2009-10-01

    Quinclorac (QUC) is a new class of highly selective auxin herbicides. The interaction between QUC and bovine serum albumin (BSA) was investigated by fluorescence spectroscopy, synchronous fluorescence, three-dimensional fluorescence, CD spectroscopy and UV-vis absorption spectroscopy under simulative physiological condition. It was proved that the probable quenching mechanism of BSA by quinclorac was dynamic quenching. The Stern-Volmer quenching model has been successfully applied and the activation energy of the interaction as much as 8.03 kJ mol -1, corresponding thermodynamic parameters Δ Hθ, Δ Sθ and Δ Gθ were calculated. The results indicated that the acting forces between QUC and BSA were mainly hydrogen bonding and van der Waals forces. According to the Förster non-radiation energy transfer theory, the average binding distance between donor (BSA) and acceptor (QUC) was obtained ( r = 3.12 nm). The alterations of protein secondary structure in the presence of QUC were confirmed by the evidences from three-dimensional fluorescence, synchronous fluorescence and CD spectroscopy. Furthermore, the site marker competitive experiments indicated that the binding of QUC to BSA primarily took place in Sudlow site I.

  3. Comparison of the Folding Mechanism of Highly Homologous Proteins in the Lipid-binding Protein Family

    EPA Science Inventory

    The folding mechanism of two closely related proteins in the intracellular lipid binding protein family, human bile acid binding protein (hBABP) and rat bile acid binding protein (rBABP) were examined. These proteins are 77% identical (93% similar) in sequence Both of these singl...

  4. Spectroscopic characterization of effective components anthraquinones in Chinese medicinal herbs binding with serum albumins

    NASA Astrophysics Data System (ADS)

    Bi, Shuyun; Song, Daqian; Kan, Yuhe; Xu, Dong; Tian, Yuan; Zhou, Xin; Zhang, Hanqi

    2005-11-01

    The interactions of serum albumins such as human serum albumin (HSA) and bovine serum albumin (BSA) with emodin, rhein, aloe-emodin and aloin were assessed employing fluorescence quenching and absorption spectroscopic techniques. The results obtained revealed that there are relatively strong binding affinity for the four anthraquinones with HSA and BSA and the binding constants for the interactions of anthraquinones with HSA or BSA at 20 °C were obtained. Anthraquinone-albumin interactions were studied at different temperatures and in the presence of some metal ions. And the competition binding of anthraquinones with serum albumins was also discussed. The Stern-Volmer curves suggested that the quenching occurring in the reactions was the static quenching process. The binding distances and transfer efficiencies for each binding reactions were calculated according to the Föster theory of non-radiation energy transfer. Using thermodynamic equations, the main action forces of these reactions were also obtained. The reasons of the different binding affinities for different anthraquinone-albumin reactions were probed from the point of view of molecular structures.

  5. The alternative complement pathway control protein H binds to immune complexes and serves their detection

    SciTech Connect

    Nydegger, U.E.; Corvetta, A.; Spaeth, P.J.; Spycher, M.

    1983-01-01

    During solubilization of immune complexes C3b becomes fixed to the immunoglobulin part and serves as a receptor for the alternative complement pathway control protein H. The H-C3b immune complex interaction can be made detectable using 4% polyethyleneglycol to separate free from bound /sup 125/I-H. Tetanus toxoid (Te)/anti-Te complexes kept soluble with fresh serum and containing 125 IU of specific antibody bound 18% of /sup 125/I-H; when fresh serum was chelated with 10 mM EDTA, /sup 125/I-H binding was only 5%. On sucrose density gradients, the H-binding material sedimented in the range of 12 to 30 S. In 36 serum samples from rheumatoid arthritis (RA) patients and in 12 serum samples from patients with systemic lupus erythematosus (SLE), /sup 125/I-H binding was significantly elevated to 9.5 +/- 4.7% (mean +/- 1 SD) and 13.3 +/- 5.6%, respectively, while /sup 125/I-H binding by 36 normal human sera was 4 +/- 2%. RA samples (17/36, 47%) and SLE samples (9/12, 75%) had H-binding values increased by more than 2 SD above the normal mean. The serum samples were also assessed for conglutinin- and C1q-binding activities; a significant correlation between H and C1q binding was observed (P less than 0.001); there was no correlation between H and conglutinin binding. Although binding to immune complexes through its interaction with C3b, H clearly detects a population of complexes other than conglutinin, thus expanding the possibilities of further characterizing pathological complexes.

  6. Comparison of rabbit androgen binding protein with testosterone estradiol binding globulin--I. Physical and chemical properties.

    PubMed

    Cheng, S L; Kotite, N; Musto, N A

    1984-12-01

    Rabbit epididymal androgen binding protein (rbABP) and serum testosterone estradiol binding globulin (rbTeBG) were purified and their physicochemical properties compared. Both proteins bound dihydrotestosterone (DHT) with high affinity. Both contained two components, Heavy (H) and Light (L), and their molecular weights and pI values were comparable. rbABP and rbTeBG were different with regard to their ConA-Sepharose binding property. rbABP was not bound by ConA-Sepharose while rbTeBG was found and retained by this lectin; thus, rbABP and rbTeBG differed in their carbohydrate structure. Peptide mapping on SDS-PAGE indicated that the H components of rbABP and rbTeBG were distinct even though they showed a high degree of homology. By contrast, the L components of these two proteins appeared to be identical. The structure of the steroid binding sites of these two proteins was analyzed by peptide mapping of [1,2(3)H]17 beta hydroxy-androsta-4,6-dien-3-one photoaffinity labeled protein. The size distribution of radioactive peptide fragments generated appeared to be identical for these two proteins. However, the distribution of labeled peptides was slightly different when examined by high pressure liquid chromatography (HPLC). The observations suggest that the differences between rbABP and rbTeBG might reside not only in carbohydrate moieties but also in their amino acid sequences.

  7. Technical advance: identification of plant actin-binding proteins by F-actin affinity chromatography

    NASA Technical Reports Server (NTRS)

    Hu, S.; Brady, S. R.; Kovar, D. R.; Staiger, C. J.; Clark, G. B.; Roux, S. J.; Muday, G. K.

    2000-01-01

    Proteins that interact with the actin cytoskeleton often modulate the dynamics or organization of the cytoskeleton or use the cytoskeleton to control their localization. In plants, very few actin-binding proteins have been identified and most are thought to modulate cytoskeleton function. To identify actin-binding proteins that are unique to plants, the development of new biochemical procedures will be critical. Affinity columns using actin monomers (globular actin, G-actin) or actin filaments (filamentous actin, F-actin) have been used to identify actin-binding proteins from a wide variety of organisms. Monomeric actin from zucchini (Cucurbita pepo L.) hypocotyl tissue was purified to electrophoretic homogeneity and shown to be native and competent for polymerization to actin filaments. G-actin, F-actin and bovine serum albumin affinity columns were prepared and used to separate samples enriched in either soluble or membrane-associated actin-binding proteins. Extracts of soluble actin-binding proteins yield distinct patterns when eluted from the G-actin and F-actin columns, respectively, leading to the identification of a putative F-actin-binding protein of approximately 40 kDa. When plasma membrane-associated proteins were applied to these columns, two abundant polypeptides eluted selectively from the F-actin column and cross-reacted with antiserum against pea annexins. Additionally, a protein that binds auxin transport inhibitors, the naphthylphthalamic acid binding protein, which has been previously suggested to associate with the actin cytoskeleton, was eluted in a single peak from the F-actin column. These experiments provide a new approach that may help to identify novel actin-binding proteins from plants.

  8. Screening serum hepatocellular carcinoma-associated proteins by SELDI-based protein spectrum analysis

    PubMed Central

    Cui, Jie-Feng; Liu, Yin-Kun; Zhou, Hai-Jun; Kang, Xiao-Nan; Huang, Cheng; He, Yi-Feng; Tang, Zhao-You; Uemura, Toshimasa

    2008-01-01

    AIM: To find out potential serum hepatocellular carcinoma (HCC)-associated proteins with low molecular weight and low abundance by SELDI-based serum protein spectra analysis, that will have much application in the diagnosis or differentiated diagnosis of HCC, as well as giving a better understanding of the mechanism of hepato-carcinogenesis. METHODS: Total serum samples were collected with informed consent from 81 HCC patients with HBV(+)/cirrhosis(+), 36 cirrhosis patients and 43 chronic hepatitis B patients. Serum protein fingerprint profiles were first generated by selected WCX2 protein chip capture integrating with SELDI-TOF-MS, then normalized and aligned by Ciphergen SELDI Software 3.1.1 with Biomarker Wizard. Comparative analysis of the intensity of corresponding protein fingerprint peaks in normalized protein spectra, some protein peaks with significant difference between HCC and cirrhosis or chronic hepatitis B were found. RESULTS: One hundred and twenty-eight serum protein peaks between 2000 and 30 000Da were identified under the condition of signal-to-noise > 5 and minimum threshold for cluster > 20%. Eighty-seven of these proteins were showed significant differences in intensity between HCC and cirrhosis (P < 0.05). Of the above differential proteins, 45 proteins had changes greater than two-fold, including 15 upregulated proteins and 30 downregulated proteins in HCC serum. Between HCC and chronic hepatitis B, 9 of 52 differential proteins (P < 0.05) had intensities of more than two-fold, including 2 upregulated proteins and 7 downregulated proteins in HCC serum. Between cirrhosis and chronic hepatitis B, 28 of 79 significant differential proteins (P < 0.05) changes greater than two-fold in intensity, including 17 upregulated proteins and 11 downregulated proteins in cirrhosis serum. For the analysis of these leading differential proteins in subtraction difference mode among three diseases, the five common downregulated proteins in HCC serum (M/Z 2870

  9. Serum immune-related proteins are differentially expressed during hibernation in the American black bear.

    PubMed

    Chow, Brian A; Donahue, Seth W; Vaughan, Michael R; McConkey, Brendan; Vijayan, Mathilakath M

    2013-01-01

    Hibernation is an adaptation to conserve energy in the face of extreme environmental conditions and low food availability that has risen in several animal phyla. This phenomenon is characterized by reduced metabolic rate (∼25% of the active basal metabolic rate in hibernating bears) and energy demand, while other physiological adjustments are far from clear. The profiling of the serum proteome of the American black bear (Ursus americanus) may reveal specific proteins that are differentially modulated by hibernation, and provide insight into the remarkable physiological adaptations that characterize ursid hibernation. In this study, we used differential gel electrophoresis (DIGE) analysis, liquid chromatography coupled to tandem mass spectrometry, and subsequent MASCOT analysis of the mass spectra to identify candidate proteins that are differentially expressed during hibernation in captive black bears. Seventy serum proteins were identified as changing by ±1.5 fold or more, out of which 34 proteins increased expression during hibernation. The majority of identified proteins are involved in immune system processes. These included α2-macroglobulin, complement components C1s and C4, immunoglobulin μ and J chains, clusterin, haptoglobin, C4b binding protein, kininogen 1, α2-HS-glycoprotein, and apoplipoproteins A-I and A-IV. Differential expression of a subset of these proteins identified by proteomic analysis was also confirmed by immunodetection. We propose that the observed serum protein changes contribute to the maintenance of the hibernation phenotype and health, including increased capacities for bone maintenance and wound healing during hibernation in bears.

  10. BindML/BindML+: Detecting Protein-Protein Interaction Interface Propensity from Amino Acid Substitution Patterns.

    PubMed

    Wei, Qing; La, David; Kihara, Daisuke

    2017-01-01

    Prediction of protein-protein interaction sites in a protein structure provides important information for elucidating the mechanism of protein function and can also be useful in guiding a modeling or design procedures of protein complex structures. Since prediction methods essentially assess the propensity of amino acids that are likely to be part of a protein docking interface, they can help in designing protein-protein interactions. Here, we introduce BindML and BindML+ protein-protein interaction sites prediction methods. BindML predicts protein-protein interaction sites by identifying mutation patterns found in known protein-protein complexes using phylogenetic substitution models. BindML+ is an extension of BindML for distinguishing permanent and transient types of protein-protein interaction sites. We developed an interactive web-server that provides a convenient interface to assist in structural visualization of protein-protein interactions site predictions. The input data for the web-server are a tertiary structure of interest. BindML and BindML+ are available at http://kiharalab.org/bindml/ and http://kiharalab.org/bindml/plus/ .

  11. The influence of fatty acids on theophylline binding to human serum albumin. Comparative fluorescence study

    NASA Astrophysics Data System (ADS)

    Maciążek-Jurczyk, M.; Sułkowska, A.; Bojko, B.; Równicka-Zubik, J.; Szkudlarek-Haśnik, A.; Zubik-Skupień, I.; Góra, A.; Dubas, M.; Korzonek-Szlacheta, I.; Wielkoszyński, T.; Żurawiński, W.; Sosada, K.

    2012-04-01

    Theophylline, popular diuretic, is used to treat asthma and bronchospasm. In blood it forms complexes with albumin, which is also the main transporter of fatty acids. The aim of the present study was to describe the influence of fatty acids (FA) on binding of theophylline (Th) to human serum albumin (HSA) in the high affinity binding sites. Binding parameters have been obtained on the basis of the fluorescence analysis. The data obtained for the complex of Th and natural human serum albumin (nHSA) obtained from blood of obese patients qualified for surgical removal of stomach was compared with our previous studies on the influence of FA on the complex of Th and commercially available defatted human serum albumin (dHSA).

  12. Alpha-amylase inhibitor, CS-1036 binds to serum amylase in a concentration-dependent and saturable manner.

    PubMed

    Honda, Tomohiro; Kaneno-Urasaki, Yoko; Ito, Takashi; Kimura, Takako; Matsushima, Nobuko; Okabe, Hiromi; Yamasaki, Atsushi; Izumi, Takashi

    2014-03-01

    (2R,3R,4R)-4-hydroxy-2-(hydroxymethyl)pyrrolidin-3-yl 4-O-(6-deoxy-β-D-glucopyranosyl)-α-D-glucopyranoside (CS-1036), which is an α-amylase inhibitor, exhibited biphasic and sustained elimination with a long t1/2 (18.4-30.0 hours) in rats and monkeys, but exhibited a short t1/2 (3.7-7.9 hours) in humans. To clarify the species differences in the t1/2, the plasma protein binding of CS-1036 was evaluated by ultrafiltration. A concentration-dependent and saturable plasma protein binding of CS-1036 was observed in rats and monkeys with the dissociation rate constant (KD) of 8.95 and 27.2 nM, and maximal binding capacity (Bmax) of 52.8 and 22.1 nM, respectively. By the assessments of the recombinant amylase and immunoprecipitation, the major binding protein of CS-1036 in rats was identified as salivary amylase (KD 5.64 nM). CS-1036 also showed concentration-dependent and saturable binding to human salivary and pancreatic amylase, with similar binding affinity in rats. However, the protein binding of CS-1036 was constant in human plasma (≤10.2%) due to the lower serum amylase level compared with rats and monkeys. From the calculation of the unbound fraction (fu) in plasma based on in vitro KD and Bmax, the dose-dependent increase in fu after oral administration is speculated to lead to a dose-dependent increase in total body clearance and a high area under the curve/dose at lower doses, such as 0.3 mg/kg in rats.

  13. Neuronal calcium-binding proteins and schizophrenia.

    PubMed

    Eyles, D W; McGrath, J J; Reynolds, G P

    2002-09-01

    Calcium-binding proteins (CBPs) such as calbindin, parvalbumin and calretinin are used as immunohistochemical markers for discrete neuronal subpopulations. They are particularly useful in identifying the various subpopulations of GABAergic interneurons that control output from prefrontal and cingulate cortices as well as from the hippocampus. The strategic role these interneurons play in regulating output from these three crucial brain regions has made them a focus for neuropathological investigation in schizophrenia. The number of pathological reports detailing subtle changes in these CBP-containing interneurons in patients with schizophrenia is rapidly growing. These proteins however are more than convenient neuronal markers. They confer survival advantages to neurons and can increase the neuron's ability to sustain firing. These properties may be important in the subtle pathophysiology of nondegenerative phenomena such as schizophrenia. The aim of this review is to introduce the reader to the functional properties of CBPs and to examine the emerging literature reporting alterations in these proteins in schizophrenia as well as draw some conclusions about the significance of these findings.

  14. Investigating protein haptenation mechanisms of skin sensitisers using human serum albumin as a model protein.

    PubMed

    Aleksic, Maja; Pease, Camilla K; Basketter, David A; Panico, Maria; Morris, Howard R; Dell, Anne

    2007-06-01

    Covalent modification of skin proteins by electrophiles is a key event in the induction of skin sensitisation but not skin irritation although the exact nature of the binding mechanisms has not been determined empirically for the vast majority of sensitisers. It is also unknown whether immunologically relevant protein targets exist in the skin contributing to effecting skin sensitisation. To determine the haptenation mechanism(s) and spectra of amino acid reactivity in an intact protein for two sensitisers expected to react by different mechanisms, human serum albumin (HSA) was chosen as a model protein. The aim of this work was also to verify for selected non-sensitisers and irritants that no protein haptenation occurs even under forcing conditions. HSA was incubated with chemicals and the resulting complexes were digested with trypsin and analysed deploying matrix-assisted laser desorption/ionization mass spectrometry, reverse phase high performance liquid chromatography and nano-electrospray tandem mass spectrometry. The data confirmed that different residues (lysine, cysteine, histidine and tyrosine) are covalently modified in a highly selective and differential manner by the sensitisers 2,4-dinitro-1-chlorobenzene and phenyl salicylate. Additionally, non-sensitisers 2,4-dichloro-1-nitrobenzene, butyl paraben and benzaldehyde and irritants benzalkonium chloride and sodium dodecyl sulphate did not covalently modify HSA under any conditions. The data indicate that covalent haptenation is a prerequisite of skin sensitisation but not irritation. The data also suggest that protein modifications are targeted to certain amino acids residing in chemical microenvironments conducive to reactivity within an intact protein. Deriving such information is relevant to our understanding of antigen formation in the immunobiology of skin sensitisation and in the development of in vitro protein haptenation assays.

  15. Connecting simulated, bioanalytical, and molecular docking data on the stereoselective binding of (±)-catechin to human serum albumin.

    PubMed

    Sabela, Myalowenkosy I; Gumede, Njabulo J; Escuder-Gilabert, Laura; Martín-Biosca, Yolanda; Bisetty, Khirsna; Medina-Hernández, María-Jose; Sagrado, Salvador

    2012-02-01

    The stereoselective binding of the frequently ingested nutraceutical (±)-catechin, with demonstrated differential biological activity between enantiomers, to human serum albumin (HSA), with the largest complexation and enantioselectivity potential among the plasmatic proteins, is studied by combining simulations to optimize the experimental design, robust in vitro electrokinetic chromatographic data, and molecular docking-chiral recognition estimates. Methodological and mathematical drawbacks in previous reports on (±)-catechin-HSA are detected and eliminated. Recent and novel direct equations extracted from the classical interaction model allows advantageous univariate mathematical data treatment, providing the first evidence of quantitative (±)-catechin-HSA enantioselectivity. Also, the binding site in HSA of the enantiomers is approached, and both the experimental enantioselectivity and the main binding site information are contrasted with a molecular docking approach.

  16. Suppression of severe lesions, myonecrosis and hemorrhage, caused by Protobothrops flavoviridis venom with its serum proteins.

    PubMed

    Chijiwa, Takahito; So, Shuhei; Hattori, Shosaku; Yoshida, Aichi; Oda-Ueda, Naoko; Ohno, Motonori

    2013-12-15

    Protobothrops flavoviridis serum proteins precipitated with ammonium sulfate were chromatographed on a DEAE-Toyopearl 650M column at pH 7.5 with stepwise increase or with linear gradient of NaCl concentration. Peaks 3 and 4 serum proteins, obtained by linear gradient elution and named Fr(de3) and Fr(de4), contained Habu serum factors (HSF) and phospholipase A2 (PLA2) inhibitors (PfPLI), respectively. The serum proteins eluted at 0.2 M NaCl by stepwise elution, named Fr(0.2NaCl), effectively suppressed myonecrosis and hemorrhage caused by P. flavoviridis venom in rat or mouse thigh muscles. The Fr(0.2NaCl) were fractionated by HPLC and the fractions, after SDS-PAGE, underwent far-western blot analysis with PLA2 ([Asp(49)]PLA2) and BPI ([Lys(49)]PLA2) as the probes. Four PfPLIs, namely, PfαPLI-A, PfαPLI-B, PfγPLI-A and PfγPLI-B, were identified together with their selective binding specificities to PLA2 species. In addition, a new 9 kDa protein, which is specifically bound to BPI, was found. Suppression of P. flavoviridis venom-induced severe lesions, such as myonecrosis, hemorrhage and edema, with its serum proteins was histopathologically observed in the present work for the first time. The cooperative use of P. flavoviridis antivenom and its serum proteins as medication for P. flavoviridis snake bites is discussed.

  17. Glycan Masking of Plasmodium vivax Duffy Binding Protein for Probing Protein Binding Function and Vaccine Development

    PubMed Central

    Janes, Joel; Gurumoorthy, Sairam; Gibson, Claire; Melcher, Martin; Chitnis, Chetan E.; Wang, Ruobing; Schief, William R.; Smith, Joseph D.

    2013-01-01

    Glycan masking is an emerging vaccine design strategy to focus antibody responses to specific epitopes, but it has mostly been evaluated on the already heavily glycosylated HIV gp120 envelope glycoprotein. Here this approach was used to investigate the binding interaction of Plasmodium vivax Duffy Binding Protein (PvDBP) and the Duffy Antigen Receptor for Chemokines (DARC) and to evaluate if glycan-masked PvDBPII immunogens would focus the antibody response on key interaction surfaces. Four variants of PVDBPII were generated and probed for function and immunogenicity. Whereas two PvDBPII glycosylation variants with increased glycan surface coverage distant from predicted interaction sites had equivalent binding activity to wild-type protein, one of them elicited slightly better DARC-binding-inhibitory activity than wild-type immunogen. Conversely, the addition of an N-glycosylation site adjacent to a predicted PvDBP interaction site both abolished its interaction with DARC and resulted in weaker inhibitory antibody responses. PvDBP is composed of three subdomains and is thought to function as a dimer; a meta-analysis of published PvDBP mutants and the new DBPII glycosylation variants indicates that critical DARC binding residues are concentrated at the dimer interface and along a relatively flat surface spanning portions of two subdomains. Our findings suggest that DARC-binding-inhibitory antibody epitope(s) lie close to the predicted DARC interaction site, and that addition of N-glycan sites distant from this site may augment inhibitory antibodies. Thus, glycan resurfacing is an attractive and feasible tool to investigate protein structure-function, and glycan-masked PvDBPII immunogens might contribute to P. vivax vaccine development. PMID:23853575

  18. Activation of the Complement Classical Pathway (C1q Binding) by Mesophilic Aeromonas hydrophila Outer Membrane Protein

    PubMed Central

    Merino, Susana; Nogueras, Maria Mercedes; Aguilar, Alicia; Rubires, Xavier; Albertí, Sebastian; Benedí, Vicente Javier; Tomás, Juan M.

    1998-01-01

    The mechanism of killing of Aeromonas hydrophila serum-sensitive strains in nonimmune serum by the complement classical pathway has been studied. The bacterial cell surface component that binds C1q more efficiently was identified as a major outer membrane protein of 39 kDa, presumably the porin II described by D. Jeanteur, N. Gletsu, F. Pattus, and J. T. Buckley (Mol. Microbiol. 6:3355–3363, 1992), of these microorganisms. We have demonstrated that the purified form of porin II binds C1q and activates the classical pathway in an antibody-independent manner, with the subsequent consumption of C4 and reduction of the serum total hemolytic activity. Activation of the classical pathway has been observed in human nonimmune serum and agammaglobulinemic serum (both depleted of factor D). Binding of C1q to other components of the bacterial outer membrane, in particular to rough lipopolysaccharide, could not be demonstrated. Activation of the classical pathway by this lipopolysaccharide was also much less efficient than activation by the outer membrane protein. The strains possessing O-antigen lipopolysaccharide bind less C1q than the serum-sensitive strains, because the outer membrane protein is less accessible, and are resistant to complement-mediated killing. Finally, a similar or identical outer membrane protein (presumably porin II) that binds C1q was shown to be present in strains from the most common mesophilic Aeromonas O serogroups. PMID:9673268

  19. Calcyclin Binding Protein/Siah-1 Interacting Protein Is a Hsp90 Binding Chaperone

    PubMed Central

    Góral, Agnieszka; Bieganowski, Paweł; Prus, Wiktor; Krzemień-Ojak, Łucja; Kądziołka, Beata; Fabczak, Hanna; Filipek, Anna

    2016-01-01

    The Hsp90 chaperone activity is tightly regulated by interaction with many co-chaperones. Since CacyBP/SIP shares some sequence homology with a known Hsp90 co-chaperone, Sgt1, in this work we performed a set of experiments in order to verify whether CacyBP/SIP can interact with Hsp90. By applying the immunoprecipitation assay we have found that CacyBP/SIP binds to Hsp90 and that the middle (M) domain of Hsp90 is responsible for this binding. Furthermore, the proximity ligation assay (PLA) performed on HEp-2 cells has shown that the CacyBP/SIP-Hsp90 complexes are mainly localized in the cytoplasm of these cells. Using purified proteins and applying an ELISA we have shown that Hsp90 interacts directly with CacyBP/SIP and that the latter protein does not compete with Sgt1 for the binding to Hsp90. Moreover, inhibitors of Hsp90 do not perturb CacyBP/SIP-Hsp90 binding. Luciferase renaturation assay and citrate synthase aggregation assay with the use of recombinant proteins have revealed that CacyBP/SIP exhibits chaperone properties. Also, CacyBP/SIP-3xFLAG expression in HEp-2 cells results in the appearance of more basic Hsp90 forms in 2D electrophoresis, which may indicate that CacyBP/SIP dephosphorylates Hsp90. Altogether, the obtained results suggest that CacyBP/SIP is involved in regulation of the Hsp90 chaperone machinery. PMID:27249023

  20. Fluorescent protein-based detection of unconjugated bilirubin in newborn serum

    PubMed Central

    Iwatani, Sota; Nakamura, Hajime; Kurokawa, Daisuke; Yamana, Keiji; Nishida, Kosuke; Fukushima, Sachiyo; Koda, Tsubasa; Nishimura, Noriyuki; Nishio, Hisahide; Iijima, Kazumoto; Miyawaki, Atsushi; Morioka, Ichiro

    2016-01-01

    Increased serum levels of unconjugated bilirubin are associated with the development of brain damage in newborns. In current clinical settings, there are no methods for directly determining serum levels of unconjugated bilirubin. UnaG, a fluorescent protein from Japanese eel muscle that specifically binds to unconjugated bilirubin was used in this study. Linear regression analysis was carried out to compare unconjugated bilirubin levels measured by UnaG and conventional bilirubin oxidase methods. Unconjugated bilirubin levels in the serum of newborns who were untreated or treated with phototherapy were compared. Effects of interfering factors in the serum (conjugated bilirubin, hemoglobin, and lipid) on unconjugated bilirubin concentration measured by the UnaG method were also evaluated. Unconjugated bilirubin levels measured by the UnaG method were highly correlated with those determined by the bilirubin oxidase assay. Unconjugated bilirubin levels determined by bilirubin oxidase and UnaG assays were similar in serum samples containing conjugated bilirubin. The performance of the UnaG assay was unaffected by phototherapy and the presence of serum hemoglobin and lipid emulsion. These results demonstrate the clinical applicability of the UnaG method for direct measurement of unconjugated bilirubin levels in newborn serum. PMID:27324682

  1. Characterizing the morphology of protein binding patches.

    PubMed

    Malod-Dognin, Noël; Bansal, Achin; Cazals, Frédéric

    2012-12-01

    Let the patch of a partner in a protein complex be the collection of atoms accounting for the interaction. To improve our understanding of the structure-function relationship, we present a patch model decoupling the topological and geometric properties. While the geometry is classically encoded by the atomic positions, the topology is recorded in a graph encoding the relative position of concentric shells partitioning the interface atoms. The topological-geometric duality provides the basis of a generic dynamic programming-based algorithm comparing patches at the shell level, which may favor topological or geometric features. On the biological side, we address four questions, using 249 cocrystallized heterodimers organized in biological families. First, we dissect the morphology of binding patches and show that Nature enjoyed the topological and geometric degrees of freedom independently while retaining a finite set of qualitatively distinct topological signatures. Second, we argue that our shell-based comparison is effective to perform atomic-level comparisons and show that topological similarity is a less stringent than geometric similarity. We also use the topological versus geometric duality to exhibit topo-rigid patches, whose topology (but not geometry) remains stable upon docking. Third, we use our comparison algorithms to infer specificity-related information amidst a database of complexes. Finally, we exhibit a descriptor outperforming its contenders to predict the binding affinities of the affinity benchmark. The softwares developed with this article are availablefrom http://team.inria.fr/abs/vorpatch_compatch/.

  2. Prediction of zinc finger DNA binding protein.

    PubMed

    Nakata, K

    1995-04-01

    Using the neural network algorithm with back-propagation training procedure, we analysed the zinc finger DNA binding protein sequences. We incorporated the characteristic patterns around the zinc finger motifs TFIIIA type (Cys-X2-5-Cys-X12-13-His-X2-5-His) and the steroid hormone receptor type (Cys-X2-5-Cys-X12-15-Cys-X2-5-Cys-X15-16-Cys-X4-5-Cys-X8-10- Cys-X2-3-Cys) in the neural network algorithm. The patterns used in the neural network were the amino acid pattern, the electric charge and polarity pattern, the side-chain chemical property and subproperty patterns, the hydrophobicity and hydrophilicity patterns and the secondary structure propensity pattern. Two consecutive patterns were also considered. Each pattern was incorporated in the single layer perceptron algorithm and the combinations of patterns were considered in the two-layer perceptron algorithm. As for the TFIIIA type zinc finger DNA binding motifs, the prediction results of the two-layer perceptron algorithm reached up to 96.9% discrimination, and the prediction results of the discriminant analysis using the combination of several characters reached up to 97.0%. As for the steroid hormone receptor type zinc finger, the prediction results of neural network algorithm and the discriminant analyses reached up to 96.0%.

  3. Penicillin-binding proteins in Actinobacteria.

    PubMed

    Ogawara, Hiroshi

    2015-04-01

    Because some Actinobacteria, especially Streptomyces species, are β-lactam-producing bacteria, they have to have some self-resistant mechanism. The β-lactam biosynthetic gene clusters include genes for β-lactamases and penicillin-binding proteins (PBPs), suggesting that these are involved in self-resistance. However, direct evidence for the involvement of β-lactamases does not exist at the present time. Instead, phylogenetic analysis revealed that PBPs in Streptomyces are distinct in that Streptomyces species have much more PBPs than other Actinobacteria, and that two to three pairs of similar PBPs are present in most Streptomyces species examined. Some of these PBPs bind benzylpenicillin with very low affinity and are highly similar in their amino-acid sequences. Furthermore, other low-affinity PBPs such as SCLAV_4179 in Streptomyces clavuligerus, a β-lactam-producing Actinobacterium, may strengthen further the self-resistance against β-lactams. This review discusses the role of PBPs in resistance to benzylpenicillin in Streptomyces belonging to Actinobacteria.

  4. Serum levels of bone Gla-protein in inhabitants exposed to environmental cadmium

    SciTech Connect

    Kido, T.; Honda, R.; Tsuritani, I.; Ishizaki, M.; Yamada, Y.; Nakagawa, H.; Nogawa, K.; Dohi, Y. )

    1991-01-01

    Serum levels of bone Gla-protein (BGP)--the vitamin K-dependent CA2(+)-binding protein--were evaluated in 76 cadmium (Cd)-exposed subjects with renal tubular dysfunction (32 men, 44 women) and 133 nonexposed subjects (53 men, 80 women). Serum BGP levels were higher in the Cd-exposed subjects than in nonexposed subjects. Significant correlations between BGP and each index measured by bone microdensitometry (MD), serum alkaline phosphatase activity, and Cd in blood and urine were found. For all of the Cd-exposed and nonexposed men and women, BGP showed a significant standard partial regression coefficient (multiple regression analysis) with the metacarpal index (MCI), which was one of the MD indicators. Bone Gla-protein also correlated significantly with urinary beta 2-microglobulin in the men and with serum creatinine in the women. Serum BGP values strongly reflect the degree of bone damage and also reflect, although less strongly, the degree of renal damage induced by exposure to Cd.

  5. Serum iron, total iron binding capacity, plasma copper and hemoglobin types in anemic and poikilocytic calves.

    PubMed Central

    McGillivray, S R; Searcy, G P; Hirsch, V M

    1985-01-01

    Ninety-eight calves were studied to determine if anemia and poikilocytosis were related to iron or copper status or hemoglobin type. No significant differences were found in serum iron, total iron binding capacity, marrow iron, plasma copper or hemoglobin type between affected and normal calves. Poikilocytes were strongly inversely correlated (-0.9177) with age. Calves less than six weeks of age had more poikilocytes, lower serum iron, higher total iron binding capacity, less adult hemoglobin and more neonatal and fetal hemoglobin than calves greater than six weeks of age. Images Fig. 1. PMID:2412677

  6. Identification of a phage-encoded immunoglobulin-binding protein from invasive Neisseria meningitidis†

    PubMed Central

    Müller, Maike G.; Ing, Jessica Y.; Cheng, Mike Kai-Wick; Flitter, Becca A.; Moe, Gregory R.

    2013-01-01

    Immunoglobulin (Ig)-binding proteins are employed by a variety of organisms to evade the immune system. We now report for the first time that meningococcal strains from several capsular groups exhibit Ig-binding activity that is dependent on human serum factors. A protein mediating Ig binding was identified as T and B cell stimulating protein B (TspB) by immunoprecipitation and by mass spectroscopic analysis of tryptic peptides. Recombinant TspB and derivatives verified Ig binding, with a preference for human IgG2 Fc, and localized the IgG-binding region to a highly conserved subdomain of TspB. Antiserum produced in mice against the conserved subdomain, detected the presence of TspB on the cell surface by flow cytometry when bacteria were grown in the presence of human serum. By fluorescence microscopy, we observed formation of an extracellular matrix having characteristics of a biofilm containing TspB, human IgG, DNA, and large aggregates of bacteria. TspB is encoded by gene ORF6 in prophage DNA, which others have shown is associated with invasive meningococcal strains. Knocking out ORF6 genes eliminated IgG binding and formation of large bacterial aggregates in biofilm. Reintroduction of a wild-type ORF6 gene by phage transduction restored the phenotype. The results show that TspB mediated IgG binding and aggregate/biofilm formation triggered by factors in human serum. As has been observed for other Ig-binding proteins, the activities mediated by TspB may provide protection against immune responses, which is in accordance with the association of prophage DNA carrying ORF6 with invasive meningococcal strains. PMID:23926326

  7. Effects of pH and ionic strength on the thermodynamics of human serum albumin-photosensitizer binding

    PubMed Central

    Jones, Cecil L.; Dickson, TiReJe; Hayes, Ronald; Thomas, Lana

    2013-01-01

    Fluorescence spectroscopy was used to measure the effects of pH and ionic strength on thermodynamic parameters governing the interaction of human serum albumin with zinc phthalocyanine tetrasulfonic acid. Fluorescence emission of zinc phthalocyanine increases at 686 nm with increasing concentrations of the protein. The non-linear correlation between protein concentration and emission of the photosensitizer was fitted using Chipman’s analysis to calculate the binding affinities. The standard enthalpy and entropy changes were estimated from van’t Hoff analysis of data that were acquired from temperature ramping studies. Results show that reaction is primarily driven by solution dynamics and that the change in enthalpy for the system becomes increasingly unfavorable with increasing pH and ionic strength. The effect of ionic strength on the entropy change for binding is shown to be significantly greater than the effects of pH. The interplay between entropy and enthalpy changes is demonstrated. PMID:24058218

  8. Protein function annotation by local binding site surface similarity.

    PubMed

    Spitzer, Russell; Cleves, Ann E; Varela, Rocco; Jain, Ajay N

    2014-04-01

    Hundreds of protein crystal structures exist for proteins whose function cannot be confidently determined from sequence similarity. Surflex-PSIM, a previously reported surface-based protein similarity algorithm, provides an alternative method for hypothesizing function for such proteins. The method now supports fully automatic binding site detection and is fast enough to screen comprehensive databases of protein binding sites. The binding site detection methodology was validated on apo/holo cognate protein pairs, correctly identifying 91% of ligand binding sites in holo structures and 88% in apo structures where corresponding sites existed. For correctly detected apo binding sites, the cognate holo site was the most similar binding site 87% of the time. PSIM was used to screen a set of proteins that had poorly characterized functions at the time of crystallization, but were later biochemically annotated. Using a fully automated protocol, this set of 8 proteins was screened against ∼60,000 ligand binding sites from the PDB. PSIM correctly identified functional matches that predated query protein biochemical annotation for five out of the eight query proteins. A panel of 12 currently unannotated proteins was also screened, resulting in a large number of statistically significant binding site matches, some of which suggest likely functions for the poorly characterized proteins.

  9. The effect of structural alterations of three mammalian serum albumins on their binding properties

    NASA Astrophysics Data System (ADS)

    Równicka-Zubik, J.; Sułkowski, L.; Maciążek-Jurczyk, M.; Sułkowska, A.

    2013-07-01

    The binding of piroxicam (PIR) to human (HSA), bovine (BSA) and sheep (SSA) serum albumin in native and destabilized/denaturated state was studied by the fluorescence quenching technique. Quenching of the intrinsic fluorescence of three analyzed serum albumins was observed due to selective exciting of tryptophanyl and tyrosil residues at 295 nm and 280 nm. Based on fluorescence emission spectra the quenching (KQ) and binding constants (Ka) were determined. The results showed that PIR is bound mainly in IIA subdomain of HSA and is additionally able to interact with tyrosil groups located in subdomains IB, IIB or IIIA. PIR interacts only with tryptophanyl residues of BSA and SSA [Trp-214, Trp-237 (IIA) and Trp-135, Trp-158 (IB)]. The presence of denaturating factors modified the mechanism of fluorescence quenching of SSA by PIR. Linear Scatchard plots suggest that HSA, BSA and SSA bind PIR in one class of binding sites.

  10. An ent-kaurene that inhibits mitotic chromosome movement and binds the kinetochore protein ran-binding protein 2.

    PubMed

    Rundle, Natalie T; Nelson, Jim; Flory, Mark R; Joseph, Jomon; Th'ng, John; Aebersold, Ruedi; Dasso, Mary; Andersen, Raymond J; Roberge, Michel

    2006-08-22

    Using a chemical genetics screen, we have identified ent-15-oxokaurenoic acid (EKA) as a chemical that causes prolonged mitotic arrest at a stage resembling prometaphase. EKA inhibits the association of the mitotic motor protein centromeric protein E with kinetochores and inhibits chromosome movement. Unlike most antimitotic agents, EKA does not inhibit the polymerization or depolymerization of tubulin. To identify EKA-interacting proteins, we used a cell-permeable biotinylated form that retains biological activity to isolate binding proteins from living cells. Mass spectrometric analysis identified six EKA-binding proteins, including Ran-binding protein 2, a kinetochore protein whose depletion by small interfering RNA causes a similar mitotic arrest phenotype.

  11. Preparation of protein imprinted materials by hierarchical imprinting techniques and application in selective depletion of albumin from human serum

    PubMed Central

    Liu, Jinxiang; Deng, Qiliang; Tao, Dingyin; Yang, Kaiguang; Zhang, Lihua; Liang, Zhen; Zhang, Yukui

    2014-01-01

    Hierarchical imprinting was developed to prepare the protein imprinted materials, as the artificial antibody, for the selective depletion of HSA from the human serum proteome. Porcine serum albumin (PSA) was employed as the dummy template for the fabrication of the recognition sites. To demonstrate the advantages of the hierarchical imprinting, molecularly imprinted polymers prepared by hierarchical imprinting technique (h-MIPs) were compared with those obtained by bulk imprinting (b-MIPs), in terms of the binding capacity, adsorption kinetics, selectivity and synthesis reproducibility. The binding capacity of h-MIPs could reach 12 mg g−1. And saturation binding could be reached in less than 20 min for the h-MIPs. In the protein mixture, h-MIPs exhibit excellent selectivity for PSA, with imprinting factors as about 3.6, much higher than those for non-template proteins. For the proteomic application, the identified protein group number in serum treated by h-MIPs was increased to 422, which is 21% higher than that obtained from the original serum, meanwhile the identified protein group number for the Albumin Removal kit was only 376. The results demonstrate that protein imprinted polymers prepared by hierarchical imprinting technique, might become the artificial antibodies for the selective depletion of high abundance proteins in proteome study. PMID:24976158

  12. Preparation of protein imprinted materials by hierarchical imprinting techniques and application in selective depletion of albumin from human serum

    NASA Astrophysics Data System (ADS)

    Liu, Jinxiang; Deng, Qiliang; Tao, Dingyin; Yang, Kaiguang; Zhang, Lihua; Liang, Zhen; Zhang, Yukui

    2014-06-01

    Hierarchical imprinting was developed to prepare the protein imprinted materials, as the artificial antibody, for the selective depletion of HSA from the human serum proteome. Porcine serum albumin (PSA) was employed as the dummy template for the fabrication of the recognition sites. To demonstrate the advantages of the hierarchical imprinting, molecularly imprinted polymers prepared by hierarchical imprinting technique (h-MIPs) were compared with those obtained by bulk imprinting (b-MIPs), in terms of the binding capacity, adsorption kinetics, selectivity and synthesis reproducibility. The binding capacity of h-MIPs could reach 12 mg g-1. And saturation binding could be reached in less than 20 min for the h-MIPs. In the protein mixture, h-MIPs exhibit excellent selectivity for PSA, with imprinting factors as about 3.6, much higher than those for non-template proteins. For the proteomic application, the identified protein group number in serum treated by h-MIPs was increased to 422, which is 21% higher than that obtained from the original serum, meanwhile the identified protein group number for the Albumin Removal kit was only 376. The results demonstrate that protein imprinted polymers prepared by hierarchical imprinting technique, might become the artificial antibodies for the selective depletion of high abundance proteins in proteome study.

  13. Probing the binding of (+)-catechin to bovine serum albumin by isothermal titration calorimetry and spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Li, Xiangrong; Hao, Yongbing

    2015-07-01

    In this study, the interaction between (+)-catechin and bovine serum albumin (BSA) was investigated using isothermal titration calorimetry (ITC), in combination with fluorescence spectroscopy, UV-vis absorption spectroscopy, and Fourier transform infrared (FT-IR) spectroscopy. Thermodynamic investigations reveal that the electrostatic interaction and hydrophobic interaction are the major binding forces in the binding of (+)-catechin to BSA. The binding of (+)-catechin to BSA is synergistically driven by enthalpy and entropy. Fluorescence experiments suggest that (+)-catechin can quench the fluorescence of BSA through a static quenching mechanism. The obtained binding constants and the equilibrium fraction of unbound (+)-catechin show that (+)-catechin can be stored and transported from the circulatory system to reach its target organ. Binding site I is found to be the primary binding site for (+)-catechin. Additionally, as shown by the UV-vis absorption, synchronous fluorescence spectroscopy and FT-IR, (+)-catechin may induce conformational and microenvironmental changes of BSA.

  14. Interaction between curcumin and human serum albumin in the presence of excipients and the effect of binding on curcumin photostability.

    PubMed

    Vukićević, Milica; Tønnesen, Hanne Hjorth

    2016-01-01

    Curcumin (Cur) is known to bind to human serum albumin (HSA) which may lead to a reduced phototoxic effect of the compound in the presence of serum or saliva. The influence of excipients on the Cur-HSA binding was studied by HSA florescence quenching and Cur absorption and emission spectroscopy in the presence and absence of the selected excipients. Photostabilty of Cur in the presence of HSA was evaluated, as well as the effect of excipients on HSA bound Cur photodegradation. Cyclodextrins (CDs) (2-hydroxypropyl-β-cyclodextrin and 2-hydroxypropyl-γ-cyclodextrin) and polymers (polyethylene glycol 400, PEG 400 and Pluronic F-127, PF-127) were selected for the study. CDs and PF-127 seem to decrease Cur binding to HSA, probably through competitive binding. Cur was still bound to HSA in polyethylene glycol (PEG) solutions at the highest investigated concentration (5% w/v). However, high PEG concentration appears to have effect on the protein conformation, as shown by the fluorescence quenching study. Low Cur photostability in the presence of HSA could be improved by the addition of hydroxylpropyl-γ-cyclodextrin (HPγCD) to the samples, whereas PEG and PF-127 showed no effect.

  15. RNA-Binding Proteins in Trichomonas vaginalis: Atypical Multifunctional Proteins.

    PubMed

    Figueroa-Angulo, Elisa E; Calla-Choque, Jaeson S; Mancilla-Olea, Maria Inocente; Arroyo, Rossana

    2015-11-26

    Iron homeostasis is highly regulated in vertebrates through a regulatory system mediated by RNA-protein interactions between the iron regulatory proteins (IRPs) that interact with an iron responsive element (IRE) located in certain mRNAs, dubbed the IRE-IRP regulatory system. Trichomonas vaginalis, the causal agent of trichomoniasis, presents high iron dependency to regulate its growth, metabolism, and virulence properties. Although T. vaginalis lacks IRPs or proteins with aconitase activity, possesses gene expression mechanisms of iron regulation at the transcriptional and posttranscriptional levels. However, only one gene with iron regulation at the transcriptional level has been described. Recently, our research group described an iron posttranscriptional regulatory mechanism in the T. vaginalis tvcp4 and tvcp12 cysteine proteinase mRNAs. The tvcp4 and tvcp12 mRNAs have a stem-loop structure in the 5'-coding region or in the 3'-UTR, respectively that interacts with T. vaginalis multifunctional proteins HSP70, α-Actinin, and Actin under iron starvation condition, causing translation inhibition or mRNA stabilization similar to the previously characterized IRE-IRP system in eukaryotes. Herein, we summarize recent progress and shed some light on atypical RNA-binding proteins that may participate in the iron posttranscriptional regulation in T. vaginalis.

  16. Effect of serum albumin presence on the binding constant of metronidazole to the phospholipid membranes fluorescence study

    NASA Astrophysics Data System (ADS)

    Sułkowska, A.

    1999-05-01

    The experiment was designed to test the possibility of entrapping the drug metronidazole into liposome vesicles in order to use liposome vesicles as a drug carrier. We estimated the effect of size of the liposome and the presence of serum albumin on the leakage of the drug. Some interactions between the lipid membrane surface and serum albumin were demonstrated. As the effects of lipid composition and physical states in membranes on protein adsorption and binding are poorly understood, it is difficult to estimate the protein interaction with the lipid membrane surface. The fluorescence quenching technique was used in this investigation. The fluorescence of serum albumin tryptophanyl residues is reduced by the presence of metronidazole. When incorporated into liposomes, metronidazole reduces the fluorescence of tryptophanyl residues of BSA to a lesser extent. The least effect of metronidazole on the fluorescence of albumin is shown when the drug is incorporated into large liposomes (450 nm). Larger liposomes are less susceptible to the presence of serum albumin than the smaller ones. Large size of the liposomes is necessary to retain their stability in plasma.

  17. Identification of a fibronectin-binding protein from Staphylococcus epidermidis.

    PubMed

    Williams, Rachel J; Henderson, Brian; Sharp, Lindsay J; Nair, Sean P

    2002-12-01

    Staphylococcus epidermidis has been reported to bind to a number of host cell extracellular matrix proteins, including fibronectin. Here we report the identification of a fibronectin-binding protein from S. epidermidis. A phage display library of S. epidermidis genomic DNA was constructed and panned against immobilized fibronectin. A number of phagemid clones containing overlapping inserts were identified, and one of these clones, pSE109FN, contained a 1.4-kb insert. Phage pSE109FN was found to bind to fibronectin but not to collagen, fibrinogen, laminin, or vitronectin. However, pSE109FN also bound to heparin, hyaluronate, and plasminogen, although to a lesser extent than it bound to fibronectin. Analysis of The Institute for Genomic Research S. epidermidis genome sequence database revealed a 1.85-kb region within a putative 30.5-kb open reading frame, to which the overlapping DNA inserts contained within the fibronectin-binding phagemids mapped. We have designated the gene encoding the fibronectin-binding domain embp. A recombinant protein, Embp32, which encompassed the fibronectin-binding domain of Embp, blocked the binding of S. epidermidis, but not the binding of Staphylococcus aureus, to fibronectin. In contrast, a recombinant protein, FnBPB[D1-D4], spanning the fibronectin-binding domain of the S. aureus fibronectin-binding protein FnBPB, blocked binding of S. aureus to fibronectin but had a negligible effect on the binding of S. epidermidis.

  18. Bacterial periplasmic sialic acid-binding proteins exhibit a conserved binding site

    SciTech Connect

    Gangi Setty, Thanuja; Cho, Christine; Govindappa, Sowmya; Apicella, Michael A.; Ramaswamy, S.

    2014-07-01

    Structure–function studies of sialic acid-binding proteins from F. nucleatum, P. multocida, V. cholerae and H. influenzae reveal a conserved network of hydrogen bonds involved in conformational change on ligand binding. Sialic acids are a family of related nine-carbon sugar acids that play important roles in both eukaryotes and prokaryotes. These sialic acids are incorporated/decorated onto lipooligosaccharides as terminal sugars in multiple bacteria to evade the host immune system. Many pathogenic bacteria scavenge sialic acids from their host and use them for molecular mimicry. The first step of this process is the transport of sialic acid to the cytoplasm, which often takes place using a tripartite ATP-independent transport system consisting of a periplasmic binding protein and a membrane transporter. In this paper, the structural characterization of periplasmic binding proteins from the pathogenic bacteria Fusobacterium nucleatum, Pasteurella multocida and Vibrio cholerae and their thermodynamic characterization are reported. The binding affinities of several mutations in the Neu5Ac binding site of the Haemophilus influenzae protein are also reported. The structure and the thermodynamics of the binding of sugars suggest that all of these proteins have a very well conserved binding pocket and similar binding affinities. A significant conformational change occurs when these proteins bind the sugar. While the C1 carboxylate has been identified as the primary binding site, a second conserved hydrogen-bonding network is involved in the initiation and stabilization of the conformational states.

  19. [Blood prealbumin: comparison of 2 methods of assay and correlation with the retinol binding protein].

    PubMed

    Romette, J; Mallet, B; Di Constanzo, J

    1984-01-01

    Prealbumin was determined by radial immunodiffusion and laser immunonephelometry methods in serum or plasma from 86 adult subjects. Both methods were reliable in physiologic prealbumin range but immunonephelometry only was reliable for lower levels. Physiologic prealbumin level was 346 +/- 67 mg/l in adult males and 319 +/- 48 mg/l in adult females; no difference was noted for retinol binding protein (60 +/- 14 mg/l). When prealbumin and retinol binding protein levels were low, no close correlation was noted in their variations.

  20. Ultrasensitive protein detection in blood serum using gold nanoparticle probes by single molecule spectroscopy

    NASA Astrophysics Data System (ADS)

    Chen, Jiji; Wang, Chungang; Irudayaraj, Joseph

    2009-07-01

    A one-step rapid and ultrasensitive immunoassay capable of detecting proteins in blood serum is developed using gold nanoprobes and fluorescence correlation spectroscopy (FCS). In this approach we take advantage of the inherent photoluminescence property of gold nanoparticles (GNPs) to develop a fluorophore-free assay to observe binding entities by monitoring the diffusion of bound versus unbound molecules in a limited confocal volume. 40-nm GNPs conjugated separately with rabbit anti-IgG (Fc) and goat anti-IgG (Fab) when incubated in blood serum containing IgG forms a sandwich structure constituting dimers and oligomers that can be differentiated by to detect IgG in blood serum at a limit of detection (LOD) of 5 pg/ml. The novelty of integrating GNPs with FCS to develop a sensitive blood immunoassay brings single molecule methods one step closer to the clinic.

  1. Changes in serum protein profiles of chickens with tibial dyschondroplasia

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Differences in serum protein profiles were analyzed to identify biomarkers associated with a poultry leg problem named tibial dyschondroplasia (TD) that can cause lameness. We used a bead-based affinity matrix containing a combinatorial library of hexapeptides (ProteoMinerTM) to deplete high abundan...

  2. Amyloid-related serum component (protein ASC) IN LEPROSY PATIENTS.

    PubMed Central

    Kronvall, G; Husby, G; Samuel, D; Bjune, G; Wheate, H

    1975-01-01

    The presence of amyloid-related serum component, protein ASC, in serum samples from 63 leprosy patients was investigated. Protein ASC was detected in 38% of the patients. A correlation to the disease spectrum of leprosy was apparent: polar lepromatous cases, 64% positive; borderline lepromatous, 50%; borderline tuberculoid, 36%; subpolar tuberculoid, 17%; and polar tuberculoid, negative. Antibody activity against the a antigen of Mycobacterium leprae was also determined, showing a similar correlation to the disease spectrum. Serum samples from 23 apparently healthy Ethiopians serving as controls showed a protein ASC incidence of 22%. This figure is significantly higher than the frequency found by others among healthy Norwegian blood donors. Immunoglobulin M levels among patients were elevated in the borderline lepromatous and poplar lepromatous groups. The three tuberculoid groups did not differ in this respect from the control group but were all elevated as compared to a normal Caucasian serum pool. Although raised immunoglobulin M levels seemed to parallel increased frequencies of protein ASC in the patient groups as well as in controls, this correlation might be only secondary to a primary derangement in T-cell function. PMID:804451

  3. Discovery of binding proteins for a protein target using protein-protein docking-based virtual screening.

    PubMed

    Zhang, Changsheng; Tang, Bo; Wang, Qian; Lai, Luhua

    2014-10-01

    Target structure-based virtual screening, which employs protein-small molecule docking to identify potential ligands, has been widely used in small-molecule drug discovery. In the present study, we used a protein-protein docking program to identify proteins that bind to a specific target protein. In the testing phase, an all-to-all protein-protein docking run on a large dataset was performed. The three-dimensional rigid docking program SDOCK was used to examine protein-protein docking on all protein pairs in the dataset. Both the binding affinity and features of the binding energy landscape were considered in the scoring function in order to distinguish positive binding pairs from negative binding pairs. Thus, the lowest docking score, the average Z-score, and convergency of the low-score solutions were incorporated in the analysis. The hybrid scoring function was optimized in the all-to-all docking test. The docking method and the hybrid scoring function were then used to screen for proteins that bind to tumor necrosis factor-α (TNFα), which is a well-known therapeutic target for rheumatoid arthritis and other autoimmune diseases. A protein library containing 677 proteins was used for the screen. Proteins with scores among the top 20% were further examined. Sixteen proteins from the top-ranking 67 proteins were selected for experimental study. Two of these proteins showed significant binding to TNFα in an in vitro binding study. The results of the present study demonstrate the power and potential application of protein-protein docking for the discovery of novel binding proteins for specific protein targets.

  4. Partial characterization of GTP-binding proteins in Neurospora

    SciTech Connect

    Hasunuma, K.; Miyamoto-Shinohara, Y.; Furukawa, K.

    1987-08-14

    Six fractions of GTP-binding proteins separated by gel filtration of a mycelial extract containing membrane components of Neurospora crassa were partially characterized. (/sup 35/S)GTP gamma S bound to GTP-binding protein was assayed by repeated treatments with a Norit solution and centrifugation. The binding of (/sup 35/S)GTP gamma S to GTP-binding proteins was competitively prevented in the presence of 0.1 to 1 mM GTP but not in the presence of ATP. These GTP-binding proteins fractionated by the gel column had Km values of 20, 7, 4, 4, 80 and 2 nM. All six fractions of these GTP-binding proteins showed the capacity to be ADP-ribosylated by pertussis toxin.

  5. Beer consumption and changes in stability of human serum proteins.

    PubMed

    Gorinstein, S; Caspi, A; Goshev, I; Moncheva, S; Zemser, M; Weisz, M; Libman, I; Lerner, H T; Trakhtenberg, S; Martín-Belloso, O

    2001-03-01

    The aim of this study was to evaluate the influence of beer consumption (BC) on the functional and structural properties of human serum proteins (HSP). Thirty-eight volunteers (after coronary bypass) were divided into two groups: experimental (EG) and control (CG). Nineteen volunteers of the EG consumed 330 mL per day of beer (about 20 g of alcohol) for 30 consecutive days. The CG volunteers consumed mineral water instead of beer. Blood samples were collected from EG and CG patients before and after the experiment. Albumin (Alb), globulin (Glo), and methanol-precipitable proteins (MPP) from human serum were denatured with 8 M urea. Fluorescence and electrophoresis were employed in order to elucidate urea-induced conformational changes and structural behavior of proteins. The measured fluorescence emission spectra were used to estimate the stability of native and denatured protein fractions before and after BC. It was found that before BC the fractions most stable to urea denaturation were Glo, Alb, and MPP fractions. After BC in most of the beer-consuming patients (EG) some changes in native and denatured protein fractions were detected: a tendency to lower stability and minor structural deviations. These qualitative changes were more profound in MPP than in Alb and Glo. Thus, Glo is more resistible to alcohol influence than Alb, which in turn is more resistible than MPP. No serum protein changes were detected in patients of CG.

  6. [Electrophoretic studies of serum protein fractions in horses with laminitis].

    PubMed

    Edinger, H; Miller, I; Stanek, C; Gemeiner, M

    1992-10-01

    The spectrum of serum proteins was evaluated in 46 horses affected with spontaneous laminitis and correlations between the severity of the disease and changes of the protein pattern were analyzed. The investigation was made in two groups; group A consisted of 21 horses of various breeds (warmblood, thoroughbred, standardbred) and group B of 25 ponys. Each group was subdivided according to the severity of the disease, using the OBEL-grade (OG) classification system. Serum proteins were separated by different one- and two-dimensional electrophoretic methods. Sera analysed by cellulose acetate electrophoresis showed a significant difference in the alpha 1-globulin fraction between OG II and OG IV affected horses. An increasing severity of the disease was correlated with a decrease of the alpha 1-globulins. The other protein fractions didn't show a uniform tendency. In group B there was a significant difference in the alpha 1-globulin fractions of OG II and OG III and in the beta 2-globulin fractions of OG I and OG II affected ponys. The acute phase proteins C3c, C4, Hp and fibronectin could be determined in a preliminary study in horse serum using the cross-reactivity of antibodies against the homologous human proteins.

  7. Magnetic core/shell Fe3O4/Au nanoparticles for studies of quinolones binding to protein by fluorescence spectroscopy.

    PubMed

    Jin, Rui; Song, Daqian; Xiong, Huixia; Ai, Lisha; Ma, Pinyi; Sun, Ying

    2016-03-01

    Magnetic core/shell Fe3O4/Au nanoparticles were used in the determination of drug binding to bovine serum albumin (BSA) using a fluorescence spectroscopic method. The binding constants and number of binding sites for protein with drugs were calculated using the Scatchard equation. Because of their superparamagnetic and biocompatible characteristics, magnetic core/shell Fe3O4/Au nanoparticles served as carrier proteins for fixing proteins. After binding of the protein to a drug, the magnetic core/shell Fe3O4/Au nanoparticles-protein-drug complex was separated from the free drug using an applied magnetic field. The free drug concentration was obtained directly by fluorescence spectrometry and the proteins did not influence the drug determination. So, the achieved number of binding sites should be reliable. The binding constant and site number for ciprofloxacin (CPFX) binding to BSA were 2.055 × 10(5) L/mol and 31.7, and the corresponding values for norfloxacin (NOR) binding to BSA were 1.383 × 10(5) L/mol and 38.8. Based on the achieved results, a suitable method was proposed for the determination of binding constants and the site number for molecular interactions. The method was especially suitable for studies on the interactions of serum albumin with the active ingredients of Chinese medicine.

  8. Exploring NMR ensembles of calcium binding proteins: Perspectives to design inhibitors of protein-protein interactions

    PubMed Central

    2011-01-01

    Background Disrupting protein-protein interactions by small organic molecules is nowadays a promising strategy employed to block protein targets involved in different pathologies. However, structural changes occurring at the binding interfaces make difficult drug discovery processes using structure-based drug design/virtual screening approaches. Here we focused on two homologous calcium binding proteins, calmodulin and human centrin 2, involved in different cellular functions via protein-protein interactions, and known to undergo important conformational changes upon ligand binding. Results In order to find suitable protein conformations of calmodulin and centrin for further structure-based drug design/virtual screening, we performed in silico structural/energetic analysis and molecular docking of terphenyl (a mimicking alpha-helical molecule known to inhibit protein-protein interactions of calmodulin) into X-ray and NMR ensembles of calmodulin and centrin. We employed several scoring methods in order to find the best protein conformations. Our results show that docking on NMR structures of calmodulin and centrin can be very helpful to take into account conformational changes occurring at protein-protein interfaces. Conclusions NMR structures of protein-protein complexes nowadays available could efficiently be exploited for further structure-based drug design/virtual screening processes employed to design small molecule inhibitors of protein-protein interactions. PMID:21569443

  9. Monitoring drug-serum protein interactions for early ADME prediction through Surface Plasmon Resonance technology.

    PubMed

    Fabini, Edoardo; Danielson, U Helena

    2017-03-28

    Many molecules fail to reach the market due to poor pharmacokinetic (PK) properties, rendering the potential drug virtually unavailable for the primary target despite efficient administration to the body. PK properties of endogenous and exogenous compounds in mammals are dependent, among other factors, on their ability to interact with serum proteins. The extent of binding can greatly influence their ADME (adsorption, distribution, metabolism and execration) profile. Reliable and cost-effective bioavailability studies, early in the drug discovery process, can lead to an improvement of the success rate for compounds entering clinical trials. Optical biosensors based on surface plasmon resonance (SPR) detection emerged as an efficient approach to obtain large amounts of information about the binding of small molecules to serum proteins. Simple, automated and fast assays provide a good throughput, versatility and highly informative data output, rendering the methodology particularly suited for early screening. The ability to provide basic information on PK can be easily coupled to structure-activity relationship analysis. In this review, features of the technology and its employment for the study of serum protein-small molecule interactions are presented and discussed.

  10. Increased (/sup 125/I)trypsin-binding in serum from cystic fibrosis patients

    SciTech Connect

    Cox, K.L.; Frates, R.C. Jr.; Sheikholislam, B.M.; Iwahashi-Hosoda, C.K.

    1982-01-01

    The capacities of normal and cystic fibrosis (CF) sera to bind to exogenous human (/sup 125/I)trypsin were compared. Sera from eight older CF patients bound significantly more exogenous human (/sup 125/I)trypsin than did sera from eight normal subjects (p less than 0.001). Disregarding the increased trypsin-binding (TB) of CF sera, serum immunoreactive trypsinogen (SIRT) levels were not detectable in these eight older CF patients. However, when SIRT levels were corrected for TB, four CF patients had normal SIRT concentrations and four had low but detectable SIRT levels. As compared to five normal newborns' sera, serum from a newborn with CF had normal TB and the SIRT levels were very high. In conclusion, increased TB in CF serum lowers results of SIRT assays. Therefore, unless SIRT levels are corrected for TB, results obtained from currently available SIRT kits may be invalid.

  11. Determination of energies and sites of binding of PFOA and PFOS to human serum albumin.

    PubMed

    Salvalaglio, Matteo; Muscionico, Isabella; Cavallotti, Carlo

    2010-11-25

    Structure and energies of the binding sites of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) to human serum albumin (HSA) were determined through molecular modeling. The calculations consisted of a compound approach based on docking, followed by molecular dynamics simulations and by the estimation of the free binding energies adopting WHAM-umbrella sampling and semiempirical methodologies. The binding sites so determined are common either to known HSA fatty acids sites or to other HSA sites known to bind to pharmaceutical compounds such as warfarin, thyroxine, indole, and benzodiazepin. Among the PFOA binding sites, five have interaction energies in excess of -6 kcal/mol, which become nine for PFOS. The calculated binding free energy of PFOA to the Trp 214 binding site is the highest among the PFOA complexes, -8.0 kcal/mol, in good agreement with literature experimental data. The PFOS binding site with the highest energy, -8.8 kcal/mol, is located near the Trp 214 binding site, thus partially affecting its activity. The maximum number of ligands that can be bound to HSA is 9 for PFOA and 11 for PFOS. The calculated data were adopted to predict the level of complexation of HSA as a function of the concentration of PFOA and PFOS found in human blood for different levels of exposition. The analysis of the factors contributing to the complex binding energy permitted to outline a set of guidelines for the rational design of alternative fluorinated surfactants with a lower bioaccumulation potential.

  12. SONAR Discovers RNA-Binding Proteins from Analysis of Large-Scale Protein-Protein Interactomes.

    PubMed

    Brannan, Kristopher W; Jin, Wenhao; Huelga, Stephanie C; Banks, Charles A S; Gilmore, Joshua M; Florens, Laurence; Washburn, Michael P; Van Nostrand, Eric L; Pratt, Gabriel A; Schwinn, Marie K; Daniels, Danette L; Yeo, Gene W

    2016-10-20

    RNA metabolism is controlled by an expanding, yet incomplete, catalog of RNA-binding proteins (RBPs), many of which lack characterized RNA binding domains. Approaches to expand the RBP repertoire to discover non-canonical RBPs are currently needed. Here, HaloTag fusion pull down of 12 nuclear and cytoplasmic RBPs followed by quantitative mass spectrometry (MS) demonstrates that proteins interacting with multiple RBPs in an RNA-dependent manner are enriched for RBPs. This motivated SONAR, a computational approach that predicts RNA binding activity by analyzing large-scale affinity precipitation-MS protein-protein interactomes. Without relying on sequence or structure information, SONAR identifies 1,923 human, 489 fly, and 745 yeast RBPs, including over 100 human candidate RBPs that contain zinc finger domains. Enhanced CLIP confirms RNA binding activity and identifies transcriptome-wide RNA binding sites for SONAR-predicted RBPs, revealing unexpected RNA binding activity for disease-relevant proteins and DNA binding proteins.

  13. Actin binding proteins, spermatid transport and spermiation*

    PubMed Central

    Qian, Xiaojing; Mruk, Dolores D.; Cheng, Yan-Ho; Tang, Elizabeth I.; Han, Daishu; Lee, Will M.; Wong, Elissa W. P.; Cheng, C. Yan

    2014-01-01

    The transport of germ cells across the seminiferous epithelium is composed of a series of cellular events during the epithelial cycle essential to the completion of spermatogenesis. Without the timely transport of spermatids during spermiogenesis, spermatozoa that are transformed from step 19 spermatids in the rat testis fail to reach the luminal edge of the apical compartment and enter the tubule lumen at spermiation, thereby entering the epididymis for further maturation. Step 19 spermatids and/or sperms that remain in the epithelium will be removed by the Sertoli cell via phagocytosis to form phagosomes and be degraded by lysosomes, leading to subfertility and/or infertility. However, the biology of spermatid transport, in particular the final events that lead to spermiation remain elusive. Based on recent data in the field, we critically evaluate the biology of spermiation herein by focusing on the actin binding proteins (ABPs) that regulate the organization of actin microfilaments at the Sertoli-spermatid interface, which is crucial for spermatid transport during this event. The hypothesis we put forth herein also highlights some specific areas of research that can be pursued by investigators in the years to come. PMID:24735648

  14. Informing the Human Plasma Protein Binding of ...

    EPA Pesticide Factsheets

    The free fraction of a xenobiotic in plasma (Fub) is an important determinant of chemical adsorption, distribution, metabolism, elimination, and toxicity, yet experimental plasma protein binding data is scarce for environmentally relevant chemicals. The presented work explores the merit of utilizing available pharmaceutical data to predict Fub for environmentally relevant chemicals via machine learning techniques. Quantitative structure-activity relationship (QSAR) models were constructed with k nearest neighbors (kNN), support vector machines (SVM), and random forest (RF) machine learning algorithms from a training set of 1045 pharmaceuticals. The models were then evaluated with independent test sets of pharmaceuticals (200 compounds) and environmentally relevant ToxCast chemicals (406 total, in two groups of 238 and 168 compounds). The selection of a minimal feature set of 10-15 2D molecular descriptors allowed for both informative feature interpretation and practical applicability domain assessment via a bounded box of descriptor ranges and principal component analysis. The diverse pharmaceutical and environmental chemical sets exhibit similarities in terms of chemical space (99-82% overlap), as well as comparable bias and variance in constructed learning curves. All the models exhibit significant predictability with mean absolute errors (MAE) in the range of 0.10-0.18 Fub. The models performed best for highly bound chemicals (MAE 0.07-0.12), neutrals (MAE 0

  15. Plasma protein binding: from discovery to development.

    PubMed

    Bohnert, Tonika; Gan, Liang-Shang

    2013-09-01

    The importance of plasma protein binding (PPB) in modulating the effective drug concentration at pharmacological target sites has been the topic of significant discussion and debate amongst drug development groups over the past few decades. Free drug theory, which states that in absence of energy-dependent processes, after steady state equilibrium has been attained, free drug concentration in plasma is equal to free drug concentration at the pharmacologic target receptor(s) in tissues, has been used to explain pharmacokinetics/pharmacodynamics relationships in a large number of cases. Any sudden increase in free concentration of a drug could potentially cause toxicity and may need dose adjustment. Free drug concentration is also helpful to estimate the effective concentration of drugs that potentially can precipitate metabolism (or transporter)-related drug-drug interactions. Disease models are extensively validated in animals to progress a compound into development. Unbound drug concentration, and therefore PPB information across species is very informative in establishing safety margins and guiding selection of First in Human (FIH) dose and human efficacious dose. The scope of this review is to give an overview of reported role of PPB in several therapeutic areas, highlight cases where PPB changes are clinically relevant, and provide drug metabolism and pharmacokinetics recommendations in discovery and development settings.

  16. Investigation of ketoprofen binding to human serum albumin by spectral methods

    NASA Astrophysics Data System (ADS)

    Bi, Shuyun; Yan, Lili; Sun, Yantao; Zhang, Hanqi

    2011-01-01

    The binding of ketoprofen with human serum albumin (HSA) was studied by fluorescence and absorption spectroscopic methods. Quenching of fluorescence of HSA was found to be a static quenching process. At 288.15, 298.15, 308.15 and 318.15 K, the binding constants and binding sites were obtained. The effects of Cu 2+, Al 3+, Ca 2+, Pb 2+ and K + on the binding at 288.15 K were also studied. The thermodynamic parameters, Δ H, Δ G and Δ S were got and the main sort of acting force between ketoprofen and HSA was studied. Based on the Förster's theory of non-radiation energy transfer, the binding average distance, r, between the acceptor (ketoprofen) and the donor (HSA) was calculated.

  17. Chronic Manganism: Preliminary Observations on Glucose Tolerance and Serum Proteins

    PubMed Central

    Hassanein, M.; Ghaleb, H. A.; Haroun, E. A.; Hegazy, M. R.; Khayyal, M. A. H.

    1966-01-01

    An intravenous glucose tolerance test was carried out in 11 patients with chronic manganese poisoning. Prolonged reactionary hypoglycaemia was observed. The underlying mechanism is discussed. It may be due to a disturbance of the hypothalamo-pituitary-adrenal axis. In seven of these patients total serum proteins were estimated and were separated electrophoretically. The albumin: globulin ratios were lower in patients than in controls. There were significant reductions in serum albumin concentrations and increases in concentrations of α1 and β globulins. PMID:5904101

  18. Elucidation of binding mechanism and identification of binding site for an anti HIV drug, stavudine on human blood proteins.

    PubMed

    Sandhya, B; Hegde, Ashwini H; Seetharamappa, J

    2013-05-01

    The binding of stavudine (STV) to two human blood proteins [human hemoglobin (HHb) and human serum albumin (HSA)] was studied in vitro under simulated physiological conditions by spectroscopic methods viz., fluorescence, UV absorption, resonance light scattering, synchronous fluorescence, circular dichroism (CD) and three-dimensional fluorescence. The binding parameters of STV-blood protein were determined from fluorescence quenching studies. Stern-Volmer plots indicated the presence of static quenching mechanism in the interaction of STV with blood proteins. The values of n close to unity indicated that one molecule of STV bound to one molecule of blood protein. The binding process was found to be spontaneous. Analysis of thermodynamic parameters revealed the presence of hydrogen bond and van der Waals forces between protein and STV. Displacement experiments indicated the binding of STV to Sudlow's site I on HSA. Secondary structures of blood proteins have undergone changes upon interaction with STV as evident from the reduction of α-helices (from 46.11% in free HHb to 38.34% in STV-HHb, and from 66.44% in free HSA to 52.26% in STV-HSA). Further, the alterations in secondary structures of proteins in the presence of STV were confirmed by synchronous and 3D-fluorescence spectral data. The distance between the blood protein (donor) and acceptor (STV) was found to be 5.211 and 5.402 nm for STV-HHb and STV-HSA, respectively based on Föster's non-radiative energy transfer theory. Effect of some metal ions was also investigated. The fraction of STV bound to HSA was found to be 87.8%.

  19. Crystal structure of CbpF, a bifunctional choline-binding protein and autolysis regulator from Streptococcus pneumoniae

    PubMed Central

    Molina, Rafael; González, Ana; Stelter, Meike; Pérez-Dorado, Inmaculada; Kahn, Richard; Morales, María; Campuzano, Susana; Campillo, Nuria E; Mobashery, Shahriar; García, José L; García, Pedro; Hermoso, Juan A

    2009-01-01

    Phosphorylcholine, a crucial component of the pneumococcal cell wall, is essential in bacterial physiology and in human pathogenesis because it binds to serum components of the immune system and acts as a docking station for the family of surface choline-binding proteins. The three-dimensional structure of choline-binding protein F (CbpF), one of the most abundant proteins in the pneumococcal cell wall, has been solved in complex with choline. CbpF shows a new modular structure composed both of consensus and non-consensus choline-binding repeats, distributed along its length, which markedly alter its shape, charge distribution and binding ability, and organizing the protein into two well-defined modules. The carboxy-terminal module is involved in cell wall binding and the amino-terminal module is crucial for inhibition of the autolytic LytC muramidase, providing a regulatory function for pneumococcal autolysis. PMID:19165143

  20. RNA binding protein and binding site useful for expression of recombinant molecules

    DOEpatents

    Mayfield, Stephen P.

    2006-10-17

    The present invention relates to a gene expression system in eukaryotic and prokaryotic cells, preferably plant cells and intact plants. In particular, the invention relates to an expression system having a RB47 binding site upstream of a translation initiation site for regulation of translation mediated by binding of RB47 protein, a member of the poly(A) binding protein family. Regulation is further effected by RB60, a protein disulfide isomerase. The expression system is capable of functioning in the nuclear/cytoplasm of cells and in the chloroplast of plants. Translation regulation of a desired molecule is enhanced approximately 100 fold over that obtained without RB47 binding site activation.

  1. RNA binding protein and binding site useful for expression of recombinant molecules

    DOEpatents

    Mayfield, Stephen

    2000-01-01

    The present invention relates to a gene expression system in eukaryotic and prokaryotic cells, preferably plant cells and intact plants. In particular, the invention relates to an expression system having a RB47 binding site upstream of a translation initiation site for regulation of translation mediated by binding of RB47 protein, a member of the poly(A) binding protein family. Regulation is further effected by RB60, a protein disulfide isomerase. The expression system is capable of functioning in the nuclear/cytoplasm of cells and in the chloroplast of plants. Translation regulation of a desired molecule is enhanced approximately 100 fold over that obtained without RB47 binding site activation.

  2. Immobilized purified folate-binding protein: binding characteristics and use for quantifying folate in erythrocytes

    SciTech Connect

    Hansen, S.I.; Holm, J.; Nexo, E.

    1987-08-01

    Purified folate-binding protein from cow's milk was immobilized on monodisperse polymer particles (Dynospheres) activated by rho-toluenesulfonyl chloride. Leakage from the spheres was less than 0.1%, and the binding properties were similar to those of the soluble protein with regard to dissociation, pH optimum for binding pteroylglutamic acid, and specificity for binding various folate derivatives. We used the immobilized folate-binding protein as binding protein in an isotope-dilution assay for quantifying folate in erythrocytes. The detection limit was 50 nmol/L and the CV over a six-month period was 2.3% (means = 1.25 mumol/L, n = 15). The reference interval, for folate measured in erythrocytes of 43 blood donors, was 0.4-1.5 mumol/L.

  3. Acyl-CoA binding proteins: multiplicity and function.

    PubMed

    Gossett, R E; Frolov, A A; Roths, J B; Behnke, W D; Kier, A B; Schroeder, F

    1996-09-01

    The physiological role of long-chain fatty acyl-CoA is thought to be primarily in intermediary metabolism of fatty acids. However, recent data show that nM to microM levels of these lipophilic molecules are potent regulators of cell functions in vitro. Although long-chain fatty acyl-CoA are present at several hundred microM concentration in the cell, very little long-chain fatty acyl-CoA actually exists as free or unbound molecules, but rather is bound with high affinity to membrane lipids and/or proteins. Recently, there is growing awareness that cytosol contains nonenzymatic proteins also capable of binding long-chain fatty acyl-CoA with high affinity. Although the identity of the cytosolic long-chain fatty acyl-CoA binding protein(s) has been the subject of some controversy, there is growing evidence that several diverse nonenzymatic cytosolic proteins will bind long-chain fatty acyl-CoA. Not only does acyl-CoA binding protein specifically bind medium and long-chain fatty acyl-CoA (LCFA-CoA), but ubiquitous proteins with multiple ligand specificities such as the fatty acid binding proteins and sterol carrier protein-2 also bind LCFA-CoA with high affinity. The potential of these acyl-CoA binding proteins to influence the level of free LCFA-CoA and thereby the amount of LCFA-CoA bound to regulatory sites in proteins and enzymes is only now being examined in detail. The purpose of this article is to explore the identity, nature, function, and pathobiology of these fascinating newly discovered long-chain fatty acyl-CoA binding proteins. The relative contributions of these three different protein families to LCFA-CoA utilization and/or regulation of cellular activities are the focus of new directions in this field.

  4. 1-Anilino-8-naphthalene sulfonate anion-protein binding depends primarily on ion pair formation.

    PubMed Central

    Matulis, D; Lovrien, R

    1998-01-01

    The ANS- (1-anilino-8-naphthalene sulfonate) anion is strongly, dominantly bound to cationic groups of water-soluble proteins and polyamino acids through ion pair formation. This mode of ANS- binding, broad and pH dependent, is expressed by the quite rigorous stoichiometry of ANS- bound with respect to the available summed number of H+ titrated lysine, histidine, and arginine groups. By titration calorimetry, the integral or overall enthalpies of ANS- binding to four proteins, bovine serum albumin, lysozyme, papain, and protease omega, were arithmetic sums of individual ANS(-)-polyamino acid sidechain binding enthalpies (polyhistidine, polyarginine, polylysine), weighted by numbers of such cationic groups of each protein (additivity of binding enthalpies). ANS- binding energetics to both classes of macromolecules, cationic proteins and synthetic cationic polyamino acids, is reinforced by the organic moiety (anilinonaphthalene) of ANS-. In a much narrower range of binding, where ANS- is sometimes assumed to act as a hydrophobic probe, ANS- may become fluorescent. However, the broad overall range is sharply dependent on electrostatic, ion pair formation, where the organic sulfonate group is the major determinant of binding. PMID:9449342

  5. SCOWLP classification: Structural comparison and analysis of protein binding regions

    PubMed Central

    Teyra, Joan; Paszkowski-Rogacz, Maciej; Anders, Gerd; Pisabarro, M Teresa

    2008-01-01

    Background Detailed information about protein interactions is critical for our understanding of the principles governing protein recognition mechanisms. The structures of many proteins have been experimentally determined in complex with different ligands bound either in the same or different binding regions. Thus, the structural interactome requires the development of tools to classify protein binding regions. A proper classification may provide a general view of the regions that a protein uses to bind others and also facilitate a detailed comparative analysis of the interacting information for specific protein binding regions at atomic level. Such classification might be of potential use for deciphering protein interaction networks, understanding protein function, rational engineering and design. Description Protein binding regions (PBRs) might be ideally described as well-defined separated regions that share no interacting residues one another. However, PBRs are often irregular, discontinuous and can share a wide range of interacting residues among them. The criteria to define an individual binding region can be often arbitrary and may differ from other binding regions within a protein family. Therefore, the rational behind protein interface classification should aim to fulfil the requirements of the analysis to be performed. We extract detailed interaction information of protein domains, peptides and interfacial solvent from the SCOWLP database and we classify the PBRs of each domain family. For this purpose, we define a similarity index based on the overlapping of interacting residues mapped in pair-wise structural alignments. We perform our classification with agglomerative hierarchical clustering using the complete-linkage method. Our classification is calculated at different similarity cut-offs to allow flexibility in the analysis of PBRs, feature especially interesting for those protein families with conflictive binding regions. The hierarchical

  6. Probing the binding of an endocrine disrupting compound-Bisphenol F to human serum albumin: Insights into the interactions of harmful chemicals with functional biomacromolecules

    NASA Astrophysics Data System (ADS)

    Pan, Fang; Xu, Tianci; Yang, Lijun; Jiang, Xiaoqing; Zhang, Lei

    2014-11-01

    Bisphenol F (BPF) as an endocrine disrupting compounds (EDCs) pollutant in the environment poses a great threat to human health. To evaluate the toxicity of BPF at the protein level, the effects of BPF on human serum albumin (HSA) were investigated at three temperatures 283, 298, and 308 K by multiple spectroscopic techniques. The experimental results showed that BPF effectively quenched the intrinsic fluorescence of HSA via static quenching. The number of binding sites, the binding constant, the thermodynamic parameters and the binding subdomain were measured, and indicated that BPF could spontaneously bind with HSA on subdomain IIA through H-bond and van der Waals interactions. Furthermore, the conformation of HSA was demonstrably changed in the presence of BPF. The work provides accurate and full basic data for clarifying the binding mechanisms of BPF with HSA in vivo and is helpful for understanding its effect on protein function during its transportation and distribution in blood.

  7. Protein-Polyelectrolyte Coacervation: Morphology Diagram, Binding Affinity, and Protein Separation

    NASA Astrophysics Data System (ADS)

    Hoagland, David; Du, Xiaosong; Dubin, Paul

    2014-03-01

    For aqueous mixtures of negatively charged polysaccharide, hyaluronic acid (HA), and globular protein, either bovine serum albumin (BSA) or beta-lactoglobulin (BLG), a pH-ionic strength (I) morphology diagram, with regions of homogeneous solution, soluble complex, coacervation, precipitation, and redissolution, was developed by pH titrations performed at fixed I. The systems are models for coacervation, or liquid-liquid phase separation, between flexible and compact solutes of opposite charge. Protein charge here is tuned by pH, and titration keeps the mixtures close to equilibrium. At high I, only homogeneous solution is observed, as true at high and low pH. Diagrams for the proteins differ because HA affinity for BSA is higher than for BLG, traced to BSA's greater charge patchiness and higher net charge; isothermal solution titration calorimetry finds a factor of two difference in binding energy. Dependences of transition pH on protein charge Z and solution I offer additional insights into interactions underlying morphology transitions. At optimal conditions, the affinity disparity is sufficient to achieve highly selective BSA coacervation in a 1:1 protein mixture, suggesting coacervation to separate similar proteins under mild, non-denaturing conditions. Funding: NSF CBET-1133289, NSF (UMass MRSEC).

  8. Serum proteins are extracted along with monolayer cells in plasticware and interfere with protein analysis

    PubMed Central

    Hong, Xin; Meng, Yuling; Kalkanis, Steven N.

    2016-01-01

    Washing and lysing monolayer cells directly from cell culture plasticware is a commonly used method for protein extraction. We found that multiple protein bands were enriched in samples with low cell numbers from the 6-well plate cultures. These proteins contributed to the overestimation of cell proteins and led to the uneven protein loading in Western blotting analysis. In Coomassie blue stained SDS-PAGE gels, the main enriched protein band is about 69 kDa and it makes up 13.6% of total protein from 104 U251n cells. Analyzed by mass spectrometry, we identified two of the enriched proteins: bovine serum albumin and bovine serum transferrin. We further observed that serum proteins could be extracted from other cell culture plates, dishes and flasks even after washing the cells 3 times with PBS. A total of 2.3 mg of protein was collected from a single well of the 6-well plate. A trace amount of the protein band was still visible after washing the cells 5 times with PBS. Thus, serum proteins should be considered if extracting proteins from plasticware, especially for samples with low cell numbers. PMID:27631018

  9. Binding of suprofen to human serum albumin. Role of the suprofen carboxyl group.

    PubMed

    Maruyama, T; Lin, C C; Yamasaki, K; Miyoshi, T; Imai, T; Yamasaki, M; Otagiri, M

    1993-03-09

    The binding of suprofen (SP), a non-steroidal anti-inflammatory drug of the arylpropionic acid class, and its methyl ester derivative (SPM) to human serum albumin (HSA) was studied by dialysis and spectroscopic techniques. In spite of the remarkable differences in the physicochemical properties of SP and SPM, the binding of each molecule to HSA was quantitatively very similar. Thermodynamic analysis suggests that the interaction of SP with HSA may be caused by electrostatic as well as hydrophobic forces, whereas the interactions with SPM may be explained by hydrophobic and van der Waals forces. Similarities in the difference UV absorption spectra between ligand-detergent micelle and -HSA systems indicate that the SP and SPM molecules are inserted into a hydrophobic crevice on HSA. The same studies suggest that the carboxyl group of SP interacts with a cationic sub-site which is closely associated with the SP binding site. Proton relaxation rate measurements indicate that the thiophen ring and propanoate portion of the SP molecule is the major binding site for HSA. The locations of SP and SPM binding sites were identified by using fluorescence probes which bind to a known site on HSA. The displacement data implied that SP primarily binds to Site II, while the high affinity site of SPM as well as low affinity site of SP are at the warfarin binding site in the Site I area. From binding data with chemically modified HSA derivatives, it is likely that highly reactive tyrosine (Tyr) and lysine (Lys) residues, which may be Tyr-411 and Lys-195, are specifically involved in SP binding. In contrast, these two residues are clearly separated from the SPM binding site. The binding of SP and SPM is independent of conformational changes on HSA that accompany N-B transition. There is evidence that the carboxyl group may play a crucial role in the high affinity binding processes of SP to HSA.

  10. Thiophilic interaction chromatography of serum albumins.

    PubMed

    Bourhim, Mustapha; Rajendran, Anita; Ramos, Yanira; Srikrishnan, Thamarapu; Sulkowski, Eugene

    2008-07-01

    An investigation of the binding of native and recombinant human serum albumin and bovine serum albumin on three thiophilic gels, PyS, 2S, and 3S was performed. In addition to these proteins, we studied serum albumins from several species such as goat, rabbit, guinea pig, rat, hamster, baboon, and pig. Our results reveal that recombinant human serum albumin (rHSA) binds completely to PyS whereas native human serum albumin and bovine serum albumin bind only partially to PyS. The binding affinities of rHSA, human serum albumin and bovine serum albumin to 2S and 3S gels are less than their binding to PyS. Serum albumins from goat, rabbit, guinea pig, rat, hamster, baboon, and pig bind much stronger to 3S gel than human and bovine serum albumins. The binding of pig and hamster serum albumins is stronger than that of rat, goat, baboon, and rabbit.

  11. Characterization of the DNA binding properties of polyomavirus capsid protein

    NASA Technical Reports Server (NTRS)

    Chang, D.; Cai, X.; Consigli, R. A.; Spooner, B. S. (Principal Investigator)

    1993-01-01

    The DNA binding properties of the polyomavirus structural proteins VP1, VP2, and VP3 were studied by Southwestern analysis. The major viral structural protein VP1 and host-contributed histone proteins of polyomavirus virions were shown to exhibit DNA binding activity, but the minor capsid proteins VP2 and VP3 failed to bind DNA. The N-terminal first five amino acids (Ala-1 to Lys-5) were identified as the VP1 DNA binding domain by genetic and biochemical approaches. Wild-type VP1 expressed in Escherichia coli (RK1448) exhibited DNA binding activity, but the N-terminal truncated VP1 mutants (lacking Ala-1 to Lys-5 and Ala-1 to Cys-11) failed to bind DNA. The synthetic peptide (Ala-1 to Cys-11) was also shown to have an affinity for DNA binding. Site-directed mutagenesis of the VP1 gene showed that the point mutations at Pro-2, Lys-3, and Arg-4 on the VP1 molecule did not affect DNA binding properties but that the point mutation at Lys-5 drastically reduced DNA binding affinity. The N-terminal (Ala-1 to Lys-5) region of VP1 was found to be essential and specific for DNA binding, while the DNA appears to be non-sequence specific. The DNA binding domain and the nuclear localization signal are located in the same N-terminal region.

  12. Carbene footprinting accurately maps binding sites in protein-ligand and protein-protein interactions.

    PubMed

    Manzi, Lucio; Barrow, Andrew S; Scott, Daniel; Layfield, Robert; Wright, Timothy G; Moses, John E; Oldham, Neil J

    2016-11-16

    Specific interactions between proteins and their binding partners are fundamental to life processes. The ability to detect protein complexes, and map their sites of binding, is crucial to understanding basic biology at the molecular level. Methods that employ sensitive analytical techniques such as mass spectrometry have the potential to provide valuable insights with very little material and on short time scales. Here we present a differential protein footprinting technique employing an efficient photo-activated probe for use with mass spectrometry. Using this methodology the location of a carbohydrate substrate was accurately mapped to the binding cleft of lysozyme, and in a more complex example, the interactions between a 100 kDa, multi-domain deubiquitinating enzyme, USP5 and a diubiquitin substrate were located to different functional domains. The much improved properties of this probe make carbene footprinting a viable method for rapid and accurate identification of protein binding sites utilizing benign, near-UV photoactivation.

  13. Carbene footprinting accurately maps binding sites in protein-ligand and protein-protein interactions

    NASA Astrophysics Data System (ADS)

    Manzi, Lucio; Barrow, Andrew S.; Scott, Daniel; Layfield, Robert; Wright, Timothy G.; Moses, John E.; Oldham, Neil J.

    2016-11-01

    Specific interactions between proteins and their binding partners are fundamental to life processes. The ability to detect protein complexes, and map their sites of binding, is crucial to understanding basic biology at the molecular level. Methods that employ sensitive analytical techniques such as mass spectrometry have the potential to provide valuable insights with very little material and on short time scales. Here we present a differential protein footprinting technique employing an efficient photo-activated probe for use with mass spectrometry. Using this methodology the location of a carbohydrate substrate was accurately mapped to the binding cleft of lysozyme, and in a more complex example, the interactions between a 100 kDa, multi-domain deubiquitinating enzyme, USP5 and a diubiquitin substrate were located to different functional domains. The much improved properties of this probe make carbene footprinting a viable method for rapid and accurate identification of protein binding sites utilizing benign, near-UV photoactivation.

  14. Investigation of alginate binding to germanium and polystyrene substrata conditioned with mussel adhesive protein

    SciTech Connect

    Suci, P.A.; Geesey, G.G.

    1995-06-15

    Binding of alginate from Macrocystis pyrifera (kelp) to germanium and polystyrene substrata conditioned with mussel adhesive protein (MAP) from Mytilis edulis, to germanium substrata conditioned with bovine serum albumin (BSA) and polylysine, and to germanium substrata coated with aminopropyltriethoxysilane (APS) was investigated using attenuated total reflection Fourier transform infrared spectrometry. Binding of alginate to MAP appears to be proportional to surface coverage for levels tested. Distinct spectral features appear in the region associated with pyranose ring vibrations upon binding of alginate to MAP, polylysine, and APS, indicating that lysine residues play a prominent role in promoting irreversible adsorption with perturbation of pyranose ring atoms. BSA does not appear to enhance alginate adsorption over that observed on clean germanium and no new spectral features appear as a result of binding. The level of irreversible binding of alginate to germanium and polystyrene substrata conditioned with MAP is similar.

  15. Standardisation of the quantitation of serum amyloid A protein (SAA) in human serum.

    PubMed

    Godenir, N L; Jeenah, M S; Coetzee, G A; Van der Westhuyzen, D R; Strachan, A F; De Beer, F C

    1985-11-07

    An adequate method for standardising the quantitation of serum amyloid A protein (SAA) in human serum was developed. Acute phase high density lipoprotein3 (HDL3) was used as a standard. The concentration of the SAA in the standard was determined by the use of purified SAA. After protein determination, various concentrations of purified SAA were run on SDS-polyacrylamide gel together with the HDL3 standard containing an unknown amount of SAA amongst the apolipoproteins. From the standard curve obtained by pyridine extraction (Coomassie blue colour yield at A605 nm) the concentration of SAA in the HDL3 standard was determined. An established immunoradiometric assay (IRMA) for SAA was standardised with the HDL3. SAA concentrations in normal and acute phase sera were determined.

  16. Binding of reactive brilliant red to human serum albumin: insights into the molecular toxicity of sulfonic azo dyes.

    PubMed

    Li, W Y; Chen, F F; Wang, Shi-Long

    2010-05-01

    The non-covalent interaction of reactive brilliant red (RBR) as a representative of sulfonic azo compounds with human serum albumin (HSA) was investigated by a combination of UV-VIS spectrometry, fluorophotometry, circular dichroism (CD) and isothermal titration calorimetry (ITC) technique. The thermodynamic characterization of the interaction was performed. The saturation binding numbers of RBR on peptide chains were determined and the effects of electrolytes and temperature were investigated. The ionic interaction induced a combination of multiple non-covalent bonds including hydrogen bonds, hydrophobic interactions and van der Waals force. A three-step binding model of RBR was revealed. The binding of RBR molecules might occur on the external surface of HSA via electric interaction when the mole ratio of RBR to HSA was less than 40 and RBR molecules entered the hydrophobic intracavity of HSA when ratio was more than 40. Moreover, RBR binding resulted in a conformational change in the structure of HSA or even the precipitation of HSA and inhibited its function accordingly. The possible binding site and the conformational transition of HSA were hypothesized and illustrated. This work provides a new insight into non-covalent interactions between sulfonic azo compounds and proteins, which may be further used to investigate the potential toxicity mechanism of azo dyes.

  17. Binding interaction of ramipril with bovine serum albumin (BSA): Insights from multi-spectroscopy and molecular docking methods.

    PubMed

    Shi, Jie-Hua; Pan, Dong-Qi; Jiang, Min; Liu, Ting-Ting; Wang, Qi

    2016-11-01

    The binding interaction between a typical angiotensin-converting enzyme inhibitor (ACEI), ramipril, and a transport protein, bovine serum albumin (BSA), was studied in vitro using UV-vis absorption spectroscopy, steady-state fluorescence spectroscopic titration, synchronous fluorescence spectroscopy, three dimensional fluorescence spectroscopy, circular dichroism and molecular docking under the imitated physiological conditions (pH=7.4). The experimental results suggested that the intrinsic fluorescence of BSA was quenched by ramipril thought a static quenching mechanism, indicating that the stable ramipril-BSA complex was formed by the intermolecular interaction. The number of binding sites (n) and binding constant of ramipril-BSA complex were about 1 and 3.50×10(4)M(-1) at 298K, respectively, suggesting that there was stronger binding interaction of ramipril with BSA. The thermodynamic parameters together with molecular docking study revealed that both van der Waal's forces and hydrogen bonding interaction dominated the formation of the ramipril-BSA complex and the binding interaction of BSA with ramipril is enthalpy-driven processes due to |ΔH°|>|TΔS°| and ΔG°<0. The spatial distance between ramipril and BSA was calculated to be 3.56nm based on Förster's non-radiative energy transfer theory. The results of the competitive displacement experiments and molecular docking confirmed that ramipril inserted into the subdomain IIA (site I) of BSA, resulting in a slight change in the conformation of BSA but BSA still retained its secondary structure α-helicity.

  18. Identification of a common hyaluronan binding motif in the hyaluronan binding proteins RHAMM, CD44 and link protein.

    PubMed Central

    Yang, B; Yang, B L; Savani, R C; Turley, E A

    1994-01-01

    We have previously identified two hyaluronan (HA) binding domains in the HA receptor, RHAMM, that occur near the carboxyl-terminus of this protein. We show here that these two HA binding domains are the only HA binding regions in RHAMM, and that they contribute approximately equally to the HA binding ability of this receptor. Mutation of domain II using recombinant polypeptides of RHAMM demonstrates that K423 and R431, spaced seven amino acids apart, are critical for HA binding activity. Domain I contains two sets of two basic amino acids, each spaced seven residues apart, and mutation of these basic amino acids reduced their binding to HA--Sepharose. These results predict that two basic amino acids flanking a seven amino acid stretch [hereafter called B(X7)B] are minimally required for HA binding activity. To assess whether this motif predicts HA binding in the intact RHAMM protein, we mutated all basic amino acids in domains I and II that form part of these motifs using site-directed mutagenesis and prepared fusion protein from the mutated cDNA. The altered RHAMM protein did not bind HA, confirming that the basic amino acids and their spacing are critical for binding. A specific requirement for arginine or lysine residues was identified since mutation of K430, R431 and K432 to histidine residues abolished binding. Clustering of basic amino acids either within or at either end of the motif enhanced HA binding activity while the occurrence of acidic residues between the basic amino acids reduced binding. The B(X7)B motif, in which B is either R or K and X7 contains no acidic residues and at least one basic amino acid, was found in all HA binding proteins molecularly characterized to date. Recombinant techniques were used to generate chimeric proteins containing either the B(X7)B motifs present in CD44 or link protein, with the amino-terminus of RHAMM (amino acids 1-238) that does not bind HA. All chimeric proteins containing the motif bound HA in transblot analyses

  19. Binding of benzodiazepine drugs to bovine serum albumin: A second derivative spectrophotometric study

    NASA Astrophysics Data System (ADS)

    Omran, Ahmed A.; El-Sayed, Abdel-Aziz; Shehata, Ahmed

    2011-12-01

    The binding constants ( K values) of three benzodiazepine drugs to bovine serum albumin were determined by a second derivative spectrophotometric method. Despite the sample and reference samples were prepared in the same way to maintain the same albumin content in each sample and reference pair, the absorption spectra show that the baseline compensation was incomplete because of the strong background signals caused by bovine serum albumin. Accordingly, further quantitative spectral information could not be obtained from these absorption spectra. On the other hand, the calculated second derivative spectra clearly show isosbestic points indicating the complete removal of the residual background signal effects. Using the derivative intensity differences (Δ D values) of the studied benzodiazepine drugs before and after the addition of albumin, the binding constants were calculated and obtained with R.S.D. of less than 8%. The interactions of drugs with bovine serum albumin were investigated using Scatchard's plot. In addition, the consistency between the fractions of bound benzodiazepine calculated from the obtained K values and the experimental values were established. The results indicate that the second derivative method can be advantageously applicable to the determination of binding constants of drugs to serum albumin without prior separation. Moreover, the validity of the proposed method was confirmed.

  20. Binding studies of L-tryptophan to human serum albumin with nanogold-structured sensor by piezoelectric quartz crystal impedance analysis.

    PubMed

    Long, Yumei; Yao, Shouzhuo; Chen, Jinhua

    2011-12-01

    Nanogold-modified sensor was constructed and applied to study the binding of L-tryptophan to human serum albumin (HSA) in situ by piezoelectric quartz crystal impedance (PQCI) analysis. It was interesting that the as-prepared nanogold modified sensor was more sensitive and biocompatible than bare gold electrode. The frequency changes due to protein adsorption on the nanogold-modified sensor might be described as a sum of two exponential functions and detailed explanation was given. Additionally, the kinetics of the binding process was also investigated. The binding constant (K) and the number of binding site (n) for the binding process without competitor are fitted to be 1.07 x 10(4) (mol l(-1))(-1) s(-1) and 1.13, respectively, and 2.24 x 10(3) (mol l-(1))(-1) s(-1) and 1.18, respectively for the binding process with competitor.

  1. Molecular simulations of multimodal ligand-protein binding: elucidation of binding sites and correlation with experiments.

    PubMed

    Freed, Alexander S; Garde, Shekhar; Cramer, Steven M

    2011-11-17

    Multimodal chromatography, which employs more than one mode of interaction between ligands and proteins, has been shown to have unique selectivity and high efficacy for protein purification. To test the ability of free solution molecular dynamics (MD) simulations in explicit water to identify binding regions on the protein surface and to shed light on the "pseudo affinity" nature of multimodal interactions, we performed MD simulations of a model protein ubiquitin in aqueous solution of free ligands. Comparisons of MD with NMR spectroscopy of ubiquitin mutants in solutions of free ligands show a good agreement between the two with regard to the preferred binding region on the surface of the protein and several binding sites. MD simulations also identify additional binding sites that were not observed in the NMR experiments. "Bound" ligands were found to be sufficiently flexible and to access a number of favorable conformations, suggesting only a moderate loss of ligand entropy in the "pseudo affinity" binding of these multimodal ligands. Analysis of locations of chemical subunits of the ligand on the protein surface indicated that electrostatic interaction units were located on the periphery of the preferred binding region on the protein. The analysis of the electrostatic potential, the hydrophobicity maps, and the binding of both acetate and benzene probes were used to further study the localization of individual ligand moieties. These results suggest that water-mediated electrostatic interactions help the localization and orientation of the MM ligand to the binding region with additional stability provided by nonspecific hydrophobic interactions.

  2. An odorant-binding protein as a new allergen from Siberian hamster (Phodopus sungorus).

    PubMed

    Torres, J A; Pastor-Vargas, C; de las Heras, M; Vivanco, F; Cuesta, Javier; Sastre, J

    2012-01-01

    A case of anaphylaxis following a bite from a Siberian hamster (SH; Phodopus sungorus) is described. Skin prick tests with hair, urine and salivary gland extracts from SH were positive, while the tests were negative for hair extracts from other rodents. IgE immunoblotting with the patient serum revealed 3 IgE-binding bands of about 18, 21 and 23 kDa. When the patient's serum was preincubated with rabbit, mouse and gerbil hair extracts, no inhibition of the 3 SH IgE-binding bands was demonstrated. Proteins extracted from the 3 bands were analyzed by N-terminal sequencing and matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry, and peptides were sequenced. IgE-binding bands were identified as being an odorant-binding protein belonging to the lipocalin family. Analysis of the 3 IgE-binding bands found in the hair, urine and salivary glands of SH showed a new allergenic protein lacking cross-reactivity with allergens from other rodents. The 3 bands likely correspond to isoforms of a single allergen.

  3. Fluorimetric studies on the binding of 4-(dimethylamino)cinnamic acid with micelles and bovine serum albumin.

    PubMed

    Singh, T Sanjoy; Mitra, Sivaprasad

    2008-09-01

    The constrained photophysics of intramolecular charge transfer (ICT) probe 4-(dimethylamino)cinnamic acid (DMACA) was studied in different surfactant systems as well as in presence of model water soluble protein bovine serum albumin (BSA). Binding of the probe in ionic micelles like sodium dodecyl sulfate (SDS) and cetyl trimethyl ammonium bromide (CTAB) causes an increase in ICT fluorescence intensity, whereas, in non-ionic TritonX-100 (TX-100) the intensity decreases with a concomitant increase in emission from locally excited (LE) state. The observations were explained in terms of the different binding affinity, location of the probe and also the nature of specific hydrogen bonding interaction in the excited state nonradiative relaxation process of DMACA. The ICT fluorescence emission yield decreases in BSA due to the locking in of the probe buried in the hydrophobic pocket of the protein structure. SDS induced uncoiling of protein and massive cooperative binding between BSA and SDS is manifested by the release of probe molecules in relatively free aqueous environment.

  4. Identification of an imidazoline binding protein: Creatine kinase and an imidazoline-2 binding site

    PubMed Central

    Kimura, Atsuko; Tyacke, Robin J.; Robinson, James J.; Husbands, Stephen M.; Minchin, Michael C.W.; Nutt, David J.; Hudson, Alan L.

    2009-01-01

    Drugs that bind to imidazoline binding proteins have major physiological actions. To date, three subtypes of such proteins, I1, I2 and I3, have been proposed, although characterisations of these binding proteins are lacking. I2 binding sites are found throughout the brain, particularly dense in the arcuate nucleus of the hypothalamus. Selective I2 ligands demonstrate antidepressant-like activity and the identity of the proteins that respond to such ligands remained unknown until now. Here we report the isolation of a ∼ 45 kDa imidazoline binding protein from rabbit and rat brain using a high affinity ligand for the I2 subtype, 2-BFI, to generate an affinity column. Following protein sequencing of the isolated ∼ 45 kDa imidazoline binding protein, we identified it to be brain creatine kinase (B-CK). B-CK shows high binding capacity to selective I2 ligands; [3H]-2-BFI (5 nM) specifically bound to B-CK (2330 ± 815 fmol mg protein− 1). We predicted an I2 binding pocket near the active site of B-CK using molecular modelling. Furthermore, B-CK activity was inhibited by a selective I2 irreversible ligand, where 20 μM BU99006 reduced the enzyme activity by 16%, confirming the interaction between B-CK and the I2 ligand. In summary, we have identified B-CK to be the ∼ 45 kDa imidazoline binding protein and we have demonstrated the existence of an I2 binding site within this enzyme. The importance of B-CK in regulating neuronal activity and neurotransmitter release may well explain the various actions of I2 ligands in brain and the alterations in densities of I2 binding sites in psychiatric disorders. PMID:19410564

  5. Fibrinogen and Fibronectin Binding Activity and Immunogenic Nature of Choline Binding Protein M

    PubMed Central

    AFSHAR, Davoud; POURMAND, Mohammad Reza; JEDDI-TEHRANI, Mahmood; SABOOR YARAGHI, Ali Akbar; AZARSA, Mohammad; SHOKRI, Fazel

    2016-01-01

    Background: Choline-binding proteins (CBPs) are a group of surface-exposed proteins, which play crucial and physiological roles in Streptococcus pneumoniae. The novel member of CBPs, choline-binding protein M (CbpM) may have binding activity to plasma proteins. This study aimed to clone and express CbpM and demonstrate its interaction with plasma proteins and patients’ sera. Methods: The total length of cbpM gene was cloned in pET21a vector and expressed in BL21 expression host. Verification of recombinant protein was evaluated by Western blot using anti-His tag monoclonal antibody. Binding ability of the recombinant protein to plasma proteins and the interaction with patients’ sera were assessed by Western blot and ELISA methods. Results: The cbpM gene was successfully cloned into pET21a and expressed in BL21 host. Binding activity to fibronectin and fibrinogen and antibody reaction of CbpM to patients’ sera was demonstrated by Western blot and ELISA methods, respectively. Conclusion: CbpM is one of the pneumococcal surface-exposed proteins, which mediates pneumococcal binding to fibronectin and fibrinogen proteins. PMID:28053927

  6. Stabilization of Human Serum Albumin by the Binding of Phycocyanobilin, a Bioactive Chromophore of Blue-Green Alga Spirulina: Molecular Dynamics and Experimental Study.

    PubMed

    Radibratovic, Milica; Minic, Simeon; Stanic-Vucinic, Dragana; Nikolic, Milan; Milcic, Milos; Cirkovic Velickovic, Tanja

    2016-01-01

    Phycocyanobilin (PCB) binds with high affinity (2.2 x 106 M-1 at 25°C) to human serum albumin (HSA) at sites located in IB and IIA subdomains. The aim of this study was to examine effects of PCB binding on protein conformation and stability. Using 300 ns molecular dynamics (MD) simulations, UV-VIS spectrophotometry, CD, FT-IR, spectrofluorimetry, thermal denaturation and susceptibility to trypsin digestion, we studied the effects of PCB binding on the stability and rigidity of HSA, as well as the conformational changes in PCB itself upon binding to the protein. MD simulation results demonstrated that HSA with PCB bound at any of the two sites showed greater rigidity and lower overall and individual domain flexibility compared to free HSA. Experimental data demonstrated an increase in the α-helical content of the protein and thermal and proteolytic stability upon ligand binding. PCB bound to HSA undergoes a conformational change to a more elongated conformation in the binding pockets of HSA. PCB binding to HSA stabilizes the structure of this flexible transport protein, making it more thermostable and resistant to proteolysis. The results from this work explain at molecular level, conformational changes and stabilization of HSA structure upon ligand binding. The resultant increased thermal and proteolytic stability of HSA may provide greater longevity to HSA in plasma.

  7. Stabilization of Human Serum Albumin by the Binding of Phycocyanobilin, a Bioactive Chromophore of Blue-Green Alga Spirulina: Molecular Dynamics and Experimental Study

    PubMed Central

    Stanic-Vucinic, Dragana; Nikolic, Milan; Milcic, Milos; Cirkovic Velickovic, Tanja

    2016-01-01

    Phycocyanobilin (PCB) binds with high affinity (2.2 x 106 M-1 at 25°C) to human serum albumin (HSA) at sites located in IB and IIA subdomains. The aim of this study was to examine effects of PCB binding on protein conformation and stability. Using 300 ns molecular dynamics (MD) simulations, UV-VIS spectrophotometry, CD, FT-IR, spectrofluorimetry, thermal denaturation and susceptibility to trypsin digestion, we studied the effects of PCB binding on the stability and rigidity of HSA, as well as the conformational changes in PCB itself upon binding to the protein. MD simulation results demonstrated that HSA with PCB bound at any of the two sites showed greater rigidity and lower overall and individual domain flexibility compared to free HSA. Experimental data demonstrated an increase in the α-helical content of the protein and thermal and proteolytic stability upon ligand binding. PCB bound to HSA undergoes a conformational change to a more elongated conformation in the binding pockets of HSA. PCB binding to HSA stabilizes the structure of this flexible transport protein, making it more thermostable and resistant to proteolysis. The results from this work explain at molecular level, conformational changes and stabilization of HSA structure upon ligand binding. The resultant increased thermal and proteolytic stability of HSA may provide greater longevity to HSA in plasma. PMID:27959940

  8. Concentration-dependent Cu(II) binding to prion protein

    NASA Astrophysics Data System (ADS)

    Hodak, Miroslav; Lu, Wenchang; Bernholc, Jerry

    2008-03-01

    The prion protein plays a causative role in several neurodegenerative diseases, including mad cow disease in cattle and Creutzfeldt-Jakob disease in humans. The normal function of the prion protein is unknown, but it has been linked to its ability to bind copper ions. Experimental evidence suggests that copper can be bound in three distinct modes depending on its concentration, but only one of those binding modes has been fully characterized experimentally. Using a newly developed hybrid DFT/DFT method [1], which combines Kohn-Sham DFT with orbital-free DFT, we have examined all the binding modes and obtained their detailed binding geometries and copper ion binding energies. Our results also provide explanation for experiments, which have found that when the copper concentration increases the copper binding mode changes, surprisingly, from a stronger to a weaker one. Overall, our results indicate that prion protein can function as a copper buffer. 1. Hodak, Lu, Bernholc, JCP, in press.

  9. Leukocyte protease binding to nucleic acids promotes nuclear localization and cleavage of nucleic acid binding proteins.

    PubMed

    Thomas, Marshall P; Whangbo, Jennifer; McCrossan, Geoffrey; Deutsch, Aaron J; Martinod, Kimberly; Walch, Michael; Lieberman, Judy

    2014-06-01

    Killer lymphocyte granzyme (Gzm) serine proteases induce apoptosis of pathogen-infected cells and tumor cells. Many known Gzm substrates are nucleic acid binding proteins, and the Gzms accumulate in the target cell nucleus by an unknown mechanism. In this study, we show that human Gzms bind to DNA and RNA with nanomolar affinity. Gzms cleave their substrates most efficiently when both are bound to nucleic acids. RNase treatment of cell lysates reduces Gzm cleavage of RNA binding protein targets, whereas adding RNA to recombinant RNA binding protein substrates increases in vitro cleavage. Binding to nucleic acids also influences Gzm trafficking within target cells. Preincubation with competitor DNA and DNase treatment both reduce Gzm nuclear localization. The Gzms are closely related to neutrophil proteases, including neutrophil elastase (NE) and cathepsin G. During neutrophil activation, NE translocates to the nucleus to initiate DNA extrusion into neutrophil extracellular traps, which bind NE and cathepsin G. These myeloid cell proteases, but not digestive serine proteases, also bind DNA strongly and localize to nuclei and neutrophil extracellular traps in a DNA-dependent manner. Thus, high-affinity nucleic acid binding is a conserved and functionally important property specific to leukocyte serine proteases. Furthermore, nucleic acid binding provides an elegant and simple mechanism to confer specificity of these proteases for cleavage of nucleic acid binding protein substrates that play essential roles in cellular gene expression and cell proliferation.

  10. Cooperative binding modes of Cu(II) in prion protein

    NASA Astrophysics Data System (ADS)

    Hodak, Miroslav; Chisnell, Robin; Lu, Wenchang; Bernholc, Jerry

    2007-03-01

    The misfolding of the prion protein, PrP, is responsible for a group of neurodegenerative diseases including mad cow disease and Creutzfeldt-Jakob disease. It is known that the PrP can efficiently bind copper ions; four high-affinity binding sites located in the octarepeat region of PrP are now well known. Recent experiments suggest that at low copper concentrations new binding modes, in which one copper ion is shared between two or more binding sites, are possible. Using our hybrid Thomas-Fermi/DFT computational scheme, which is well suited for simulations of biomolecules in solution, we investigate the geometries and energetics of two, three and four binding sites cooperatively binding one copper ion. These geometries are then used as inputs for classical molecular dynamics simulations. We find that copper binding affects the secondary structure of the PrP and that it stabilizes the unstructured (unfolded) part of the protein.

  11. Mn(II) binding to human serum albumin: a ¹H-NMR relaxometric study.

    PubMed

    Fanali, Gabriella; Cao, Yu; Ascenzi, Paolo; Fasano, Mauro

    2012-12-01

    Human serum albumin (HSA) displays several metal binding sites, participating to essential and toxic metal ions disposal and transport. The major Zn(II) binding site, called Site A, is located at the I/II domain interface, with residues His67, Asn99, His247, and Asp249 contributing with five donor atoms to the metal ion coordination. Additionally, one water molecule takes part of the octahedral coordination geometry. The occurrence of the metal-coordinated water molecule allows the investigation of the metal complex geometry by water (1)H-NMR relaxation, provided that the diamagnetic Zn(II) is replaced by the paramagnetic Mn(II). Here, the (1)H-NMR relaxometric study of Mn(II) binding to HSA is reported. Mn(II) binding to HSA is modulated by Zn(II), pH, and myristate through competitive inhibition and allosteric mechanisms. The body of results indicates that the primary binding site of Zn(II) corresponds to the secondary binding site of Mn(II), i.e. the multimetal binding site A. Excess Zn(II) completely displaces Mn(II) from its primary site suggesting that the primary Mn(II) site corresponds to the secondary Zn(II) site. This uncharacterized site is functionally-linked to FA1; moreover, metal ion binding is modulated by myristate and pH. Noteworthy, water (1)H-NMR relaxometry allowed a detailed analysis of thermodynamic properties of HSA-metal ion complexes.

  12. Serum protein adsorption and excretion pathways of metal nanoparticles

    PubMed Central

    Vinluan, Rodrigo D; Zheng, Jie

    2015-01-01

    While the synthesis of metal nanoparticles (NPs) with fascinating optical and electronic properties have progressed dramatically and their potential biomedical applications were also well demonstrated in the past decade, translation of metal NPs into the clinical practice still remains a challenge due to their severe accumulation in the body. Herein, we give a brief review on size-dependent material properties of metal NPs and their potential biomedical applications, followed by a summary of how structural parameters such as size, shape and charge influence their interactions with serum protein adsorption, cellular uptake and excretion pathways. Finally, the future challenges in minimizing serum protein adsorption and expediting clinical translation of metal NPs were also discussed. PMID:26377047

  13. Exploring the binding mechanism of 5-hydroxy-3',4',7-trimethoxyflavone with bovine serum albumin: Spectroscopic and computational approach.

    PubMed

    Sudha, A; Srinivasan, P; Thamilarasan, V; Sengottuvelan, N

    2016-03-15

    The current study was carried out to investigate the binding mechanism of a potential flavonoid compound 5-hydroxy-3',4',7-trimethoxyflavone (HTMF) with bovine serum albumin (BSA) using ultraviolet-visible, fluorescence, circular dichroism (CD) spectral measurements along with molecular docking and molecular dynamics (MD) simulation. It was confirmed from fluorescence spectra that the intrinsic fluorescence of BSA was robustly quenched by HTMF through a static quenching mechanism. The number of binding sites (n) for HTMF binding on BSA was found to be about one. The thermodynamic parameters estimated from the van't Hoff plot specified that hydrophobic force was the predominant force in the HTMF-BSA complex and there also exist hydrogen bonds and electrostatic interactions. The effect of HTMF on the BSA conformation examined using CD studies revealed that there is a decrease in the helical content of BSA upon HTMF interaction. The results of molecular docking study shed light on the binding mode which exposed that HTMF bind within the hydrophobic pocket of the subdomain IIIA of BSA. The stability of HTMF-BSA complex with respect to free protein was analyzed from the molecular dynamic studies. The electronic structure analysis of HTMF was achieved by using density functional theory (DFT) calculations at B3LYP/6-31G** level to support its antioxidant role. The results of computational analysis are in good consistence with the experimental data and the present findings suggested that HTMF exhibits a good binding propensity to BSA protein which will be helpful for the drug design.

  14. Investigation of the binding of Salvianolic acid B to human serum albumin and the effect of metal ions on the binding

    NASA Astrophysics Data System (ADS)

    Chen, Tingting; Cao, Hui; Zhu, Shajun; Lu, Yapeng; Shang, Yanfang; Wang, Miao; Tang, Yanfeng; Zhu, Li

    2011-10-01

    The studies on the interaction between HSA and drugs have been an interesting research field in life science, chemistry and clinical medicine. There are also many metal ions present in blood plasma, thus the research about the effect of metal ions on the interaction between drugs and plasma proteins is crucial. In this study, the interaction of Salvianolic acid B (Sal B) with human serum albumin (HSA) was investigated by the steady-state, synchronous fluorescence and circular dichroism (CD) spectroscopies. The results showed that Sal B had a strong ability to quench the intrinsic fluorescence of HSA through a static quenching mechanism. Binding parameters calculated showed that Sal B was bound to HSA with the binding affinities of 10 5 L mol -1. The thermodynamic parameters studies revealed that the binding was characterized by positive enthalpy and positive entropy changes, and hydrophobic interactions were the predominant intermolecular forces to stabilize the complex. The specific binding distance r (2.93 nm) between donor (HSA) and acceptor (Sal B) was obtained according to Förster non-radiative resonance energy transfer theory. The synchronous fluorescence experiment revealed that Sal B cannot lead to the microenvironmental changes around the Tyr and Trp residues of HSA, and the binding site of Sal B on HSA is located in hydrophobic cavity of subdomain IIA. The CD spectroscopy indicated the secondary structure of HSA is not changed in the presence of Sal B. Furthermore, The effect of metal ions (e.g. Zn 2+, Cu 2+, Co 2+, Ni 2+, Fe 3+) on the binding constant of Sal B-HSA complex was also discussed.

  15. The RNA-binding protein Gemin5 binds directly to the ribosome and regulates global translation

    PubMed Central

    Francisco-Velilla, Rosario; Fernandez-Chamorro, Javier; Ramajo, Jorge; Martinez-Salas, Encarnación

    2016-01-01

    RNA-binding proteins (RBPs) play crucial roles in all organisms. The protein Gemin5 harbors two functional domains. The N-terminal domain binds to snRNAs targeting them for snRNPs assembly, while the C-terminal domain binds to IRES elements through a non-canonical RNA-binding site. Here we report a comprehensive view of the Gemin5 interactome; most partners copurified with the N-terminal domain via RNA bridges. Notably, Gemin5 sediments with the subcellular ribosome fraction, and His-Gemin5 binds to ribosome particles via its N-terminal domain. The interaction with the ribosome was lost in F381A and Y474A Gemin5 mutants, but not in W14A and Y15A. Moreover, the ribosomal proteins L3 and L4 bind directly with Gemin5, and conversely, Gemin5 mutants impairing the binding to the ribosome are defective in the interaction with L3 and L4. The overall polysome profile was affected by Gemin5 depletion or overexpression, concomitant to an increase or a decrease, respectively, of global protein synthesis. Gemin5, and G5-Nter as well, were detected on the polysome fractions. These results reveal the ribosome-binding capacity of the N-ter moiety, enabling Gemin5 to control global protein synthesis. Our study uncovers a crosstalk between this protein and the ribosome, and provides support for the view that Gemin5 may control translation elongation. PMID:27507887

  16. Serum proteins of Canada goose (Branta canadensis) subspecies

    USGS Publications Warehouse

    Morgan, R.P.; Sulkin, S.T.; Henny, C.J.

    1977-01-01

    Serum proteins from nine subspecies of Canada Geese (Brunta canadensis) were analyzed through the use of column and slab acrylamide electrophoresis. Variation was minimal within a subspecies, although all the subspecies were closely related. B. c. leucopareia appeared to be the most distinct subspecies, while maxima and moffitti were the most similar. Our preliminary findings suggest that the electrophoresis techniques are sensitive enough to identify some of the subspecies; however, baseline data from breeding ranges of all subspecies are required.

  17. The metallomics approach: use of Fe(II) and Cu(II) footprinting to examine metal binding sites on serum albumins.

    PubMed

    Duff, Michael R; Kumar, Challa V

    2009-11-01

    Metal binding to serum albumins is examined by oxidative protein-cleavage chemistry, and relative affinities of multiple metal ions to particular sites on these proteins were identified using a fast and reliable chemical footprinting approach. Fe(ii) and Cu(ii), for example, mediate protein cleavage at their respective binding sites on serum albumins, in the presence of hydrogen peroxide and ascorbate. This metal-mediated protein-cleavge reaction is used to evaluate the binding of metal ions, Na(+), Mg(2+), Ca(2+), Al(3+), Cr(3+), Mn(2+), Co(2+), Ni(2+), Zn(2+), Cd(2+), Hg(2+), Pb(2+), and Ce(3+) to albumins, and the relative affinities (selectivities) of the metal ions are rapidly evaluated by examining the extent of inhibition of protein cleavage. Four distinct systems Fe(II)/BSA, Cu(II)/BSA, Fe(II)/HSA and Cu(II)/HSA are examined using the above strategy. This metallomics approach is novel, even though the cleavage of serum albumins by Fe(II)/Cu(II) has been reported previously by this laboratory and many others. The protein cleavage products were analyzed by SDS PAGE, and the intensities of the product bands quantified to evaluate the extent of inhibition of the cleavage and thereby evaluate the relative binding affinities of specific metal ions to particular sites on albumins. The data show that Co(II) and Cr(III) showed the highest degree of inhibition, across the table, followed by Mn(II) and Ce(III). Alakali metal ions and alkaline earth metal ions showed very poor affinity for these metal sites on albumins. Thus, metal binding profiles for particular sites on proteins can be obtained quickly and accurately, using the metallomics approach.

  18. Specific Changes of Serum Proteins in Parkinson's Disease Patients

    PubMed Central

    Lu, Wenwen; Wan, Xinhua; Liu, Bin; Rong, Xianfang; Zhu, Lei; Li, Pingping; Li, Jiang; Wang, Ling; Cui, Liying; Wang, Xiaoliang

    2014-01-01

    The aim of this study is to identify and validate protein change in the serum from PD patients. We used serum samples from 21 PD patients and 20 age-matched normal people as control to conduct a comparative proteomic study. We performed 2-DE and analyzed the differentially expressed protein spots by LC-MS/MS. In PD group 13 spots were shown to be differentially expressed compared to control group. They were identified as 6 proteins. Among these, 3 proteins were confirmed by Western blot analysis. It showed that the frequency of fibrinogen γ-chain (FGG) appeared 70% in PD, which could not be detected in control group. The protein of inter-alpha-trypsin inhibitor heavy chain H4 (ITI-H4) was found to exist two forms in serum. The full size (120 kDa) of the protein was increased and the fragmented ITI-H4 (35 kDa) was decreased in PD group. The ratio of full size ITI-H4 to fragmented ITI-H4 in PD patients was 3.85±0.29-fold higher than in control group. Furthermore, fragmented Apo A-IV (∼26 kDa) was mainly detected in control group, while it was rare to be found in PD group. Above findings might be useful for diagnosis of PD. When the expressions of FGG and 120 kDa ITI-H4 are increase, as well as ∼26 kDa Apo A-IV disappear would provide strong evidence for PD. PMID:24769800

  19. Salt modulates the stability and lipid binding affinity of the adipocyte lipid-binding proteins

    NASA Technical Reports Server (NTRS)

    Schoeffler, Allyn J.; Ruiz, Carmen R.; Joubert, Allison M.; Yang, Xuemei; LiCata, Vince J.

    2003-01-01

    Adipocyte lipid-binding protein (ALBP or aP2) is an intracellular fatty acid-binding protein that is found in adipocytes and macrophages and binds a large variety of intracellular lipids with high affinity. Although intracellular lipids are frequently charged, biochemical studies of lipid-binding proteins and their interactions often focus most heavily on the hydrophobic aspects of these proteins and their interactions. In this study, we have characterized the effects of KCl on the stability and lipid binding properties of ALBP. We find that added salt dramatically stabilizes ALBP, increasing its Delta G of unfolding by 3-5 kcal/mol. At 37 degrees C salt can more than double the stability of the protein. At the same time, salt inhibits the binding of the fluorescent lipid 1-anilinonaphthalene-8-sulfonate (ANS) to the protein and induces direct displacement of the lipid from the protein. Thermodynamic linkage analysis of the salt inhibition of ANS binding shows a nearly 1:1 reciprocal linkage: i.e. one ion is released from ALBP when ANS binds, and vice versa. Kinetic experiments show that salt reduces the rate of association between ANS and ALBP while simultaneously increasing the dissociation rate of ANS from the protein. We depict and discuss the thermodynamic linkages among stability, lipid binding, and salt effects for ALBP, including the use of these linkages to calculate the affinity of ANS for the denatured state of ALBP and its dependence on salt concentration. We also discuss the potential molecular origins and potential intracellular consequences of the demonstrated salt linkages to stability and lipid binding in ALBP.

  20. Phenanthrene binding by humic acid-protein complexes as studied by passive dosing technique.

    PubMed

    Zhao, Jian; Wang, Zhenyu; Ghosh, Saikat; Xing, Baoshan

    2014-01-01

    This work investigated the binding behavior of phenanthrene by humic acids (HA-2 and HA-5), proteins (bovine serum albumin (BSA)), lysozyme and pepsin), and their complexes using a passive dosing technique. All sorption isotherms were fitted well with Freundlich model and the binding capability followed an order of HA-5 > HA-2 > BSA > pepsin > lysozyme. In NaCl solution, phenanthrene binding to HA-BSA complexes was much higher than the sum of binding to individual HA and BSA, while there was no enhancement for HA-pepsin. Positively charged lysozyme slightly lowered phenanthrene binding on both HAs due to strong aggregation of HA-lysozyme complexes, leading to reduction in the number of binding sites. The binding enhancement by HA-BSA was observed under all tested ion species and ionic strengths. This enhancement can be explained by unfolding of protein, reduction of aggregate size and formation of HA-BSA complexes with favorable conformations for binding phenanthrene.

  1. Evaluation of enantioselective binding of propanocaine to human serum albumin by ultrafiltration and electrokinetic chromatography under intermediate precision conditions.

    PubMed

    Martínez-Gómez, María Amparo; Escuder-Gilabert, Laura; Villanueva-Camañas, Rosa María; Sagrado, Salvador; Medina-Hernández, María José

    2012-03-15

    Stereoselectivity in protein binding can have a significant effect on the pharmacokinetic and pharmacodynamic properties of chiral drugs. In this paper, the enantioselective binding of propanocaine (PRO) enantiomers to human serum albumin (HSA), the most relevant plasmatic protein in view of stereoselectivity, has been evaluated by incubation and ultrafiltration of racemic PRO-HSA mixtures and chiral analysis of the bound and unbound fractions by electrokinetic chromatography using HSA as chiral selector. Experimental conditions for the separation of PRO enantiomers using HSA as chiral selector and electrokinetic chromatography have been optimised. Affinity constants and protein binding in percentage (PB) were obtained for both enantiomers of PRO, as well as the enantioselectivity (ES) to HSA. Data were obtained in two independent working sessions (days). The influence of the session and fraction processed factors were examined. A univariate direct-estimation approach was used facilitating outliers' identification and statistical comparison. Non-linear fitting of data was used to verify the stoichiometry and affinity estimations obtained by the direct approach. Robust statistics were applied to obtain reliable estimations of uncertainty, accounting for the factors (day and processed fraction), thus representing intermediate precision conditions. Mimicking in vivo experimental conditions, information unapproachable by in vivo experiments was obtained for PRO enantiomers interacting with HSA. For the first (E1) and the second (E2) eluted PRO enantiomers the results were: 1:1 stoichiometry, medium affinity constants, logK(E1)=3.20±0.16 and log K(E2)=3.40±0.14, medium protein binding percentage, PB=48.7 and 60.1% for E1 and E2, respectively, and moderate but significant enantioselectivity, ES=K(E2)/K(E1)=1.5±0.3.

  2. Identification of transferrin as the main binding site for protactinium in rat blood serum.

    PubMed

    Taylor, D M; Farrow, L C

    1987-01-01

    The distribution of 233Pa in rat serum at periods between 5 and 50 min after i.v. injection of a solution of protactinium chloride was studied by gel chromatography. Sequential analysis of sera on Sephacryl S-300 and DEAE-Sephadex showed that 233Pa was associated only with the transferrin fraction of the serum proteins. This finding was confirmed by iso-electric focusing electrophoresis. In the cytosol fractions prepared from the liver and kidneys of the 233Pa injected rats the nuclide was also shown to be protein bound.

  3. Elevated serum levels in human pregnancy of a molecule immunochemically similar to eosinophil granule major basic protein

    PubMed Central

    1983-01-01

    We have shown that serum levels of a molecule immunochemically similar to eosinophil granule major basic protein (MBP) are elevated in pregnant women throughout gestation. MBP levels increase during gestation and plateau at approximately 7,500 ng/ml by the 20th wk (greater than 10-fold above normal). Levels return to normal after delivery, with a T1/2 of 13.7 d. The MBP in pregnancy serum is remarkably similar to the eosinophil granule MBP in that: (a) pregnancy MBP fully inhibits the binding of radiolabeled MBP standard in a double antibody radioimmunoassay; (b) this inhibition reaction is specific for human MBP because pregnancy serum produces no inhibition of the binding of radiolabeled guinea pig MBP in the guinea pig MBP radioimmunoassay; (c) in a two-site immunoradiometric assay for MBP, slopes of dose- response curves for pregnancy serum, purified MBP, and serum from a patient with hypereosinophilic syndrome are identical, and maximal binding is comparable; (d) reduction and alkylation of pregnancy sera increases measured MBP 100-fold, as previously shown for eosinophil granule MBP in serum; and (e) the MBP in pregnancy serum demonstrates the same pattern of heat lability as has been previously reported for MBP. Four observations have raised the possibility that the eosinophil is not the source of the MBP in pregnancy serum: (a) no correlation between serum MBP level and peripheral blood eosinophil count exists in pregnant women, in contrast to previous studies of patients with eosinophilia; (b) levels of three other eosinophil-associated proteins are normal or low in pregnancy sera, whereas the serum levels of these proteins are elevated in patients with eosinophilia; (c) the slopes of dose-response curves for pregnancy sera and MBP standards differ in the double antibody radioimmunoassay; and (d) the molecule in pregnancy serum elutes from Sephadex G-50 columns at the void volume, while eosinophil granule MBP and the MBP in serum of patients with

  4. Discovery and verification of serum differential expression proteins for pulmonary tuberculosis.

    PubMed

    Li, Cuiping; He, Xiao; Li, Hongtao; Zhou, Yi; Zang, Ning; Hu, Shuixiu; Zheng, Yanyan; He, Min

    2015-09-01

    Pulmonary tuberculosis (PTB) is a chronic disease and has remained a severe threat to public health. Valuable biomarkers for improving the detection rate are crucial for controlling this disease. The purpose of this study was to discover potential biomarkers in sera from PTB patients compared with pneumonia patients and normal healthy controls. A total of 336 human serum specimens were enrolled in this study. Differentially expressed proteins were identified using iTRAQ method combining with MALDI-TOF-MS. Data was analyzed using relative bioinformatics methods. Potential biomarkers were further validated by IHC, ELISA and Western blot. As a result, 489 non-redundant proteins were identified in the sera, and 159 of which could be quantified by calculating their iTRAQ ratios. Compared to the controls, 26 differentially expressed proteins were recognized among PTB patients, including 16 overexpressed proteins and 10 downregulated proteins. Analysis of their functional interactions revealed that 12 proteins appeared in the center of the functional network. One of these key proteins, sex hormone binding globulin (SHBG), was found to be significantly elevated among PTB patients as compared with the controls examined by IHC, ELISA and Western blot. This result was consistent with the iTRAQ result. An independent blinded testing set to examine serum SHBG by ELISA achieved an accuracy of 78.74%, sensitivity of 75.6% and specificity of 91.5% in diagnosing PTB. In summary, iTRAQ in combination with MALDI-TOF-MS technology can efficiently screen differentially expressed proteins in sera from the PTB patients. SHBG is suggested to be a possible and novel serum biomarker for PTB.

  5. Fluorescence quenching studies on binding fluoreno-9-spiro-oxazolidinedione to human serum albumin.

    PubMed

    Gonzalez-Jimenez, J; Jacquotte, H; Cayre, I

    1992-11-16

    Human serum albumin fluorescence quenching by fluorene-9-spiro-oxazolidinedione has been analyzed as a function of temperature. Such temperature dependence suggests that the mechanism of the quenching process is static in origin. This type of quenching implies that a non-fluorescent complex between oxazolidinedione and serum albumin has been formed and following the Stern-Volmer relationship we have calculated the binding constant. Thermodynamic parameters were also determined. The positive and large values of entropy and the negative value for enthalpy suggest that both hydrophobic and electrostatic interactions may play an important role in the stabilization of the complex. Finally, the irreversible changes in the spectral properties of HSA are interpreted in binding terms.

  6. Protein-binding affinity of leucaena condensed tannins of differing molecular weights.

    PubMed

    Huang, Xiao Dan; Liang, Juan Boo; Tan, Hui Yin; Yahya, Rosiyah; Long, Ruijun; Ho, Yin Wan

    2011-10-12

    Depending on their source, concentration, chemical structure, and molecular weight, condensed tannins (CTs) form insoluble complexes with protein, which could lead to ruminal bypass protein, benefiting animal production. In this study, CTs from Leuceana leucocephala hybrid were fractionated into five fractions by a size exclusion chromatography procedure. The molecular weights of the CT fractions were determined using Q-TOF LC-MS, and the protein-binding affinities of the respective CT fractions were determined using a protein precipitation assay with bovine serum albumin (BSA) as the standard protein. The calculated number-average molecular weights (M(n)) were 1348.6, 857.1, 730.1, 726.0, and 497.1, and b values (the b value represents the CT quantity that is needed to bind half of the maximum precipitable BSA) of the different molecular weight fractions were 0.381, 0.510, 0.580, 0.636, and 0.780 for fractions 1, 2, 3, 4, and 5, respectively. The results indicated that, in general, CTs of higher molecular weight fractions have stronger protein-binding affinity than those of lower molecular weights. However, the number of hydroxyl units within the structure of CT polymers also affects the protein-binding affinity.

  7. Induced binding of proteins by ammonium sulfate in affinity and ion-exchange column chromatography.

    PubMed

    Arakawa, Tsutomu; Tsumoto, Kouhei; Ejima, Daisuke; Kita, Yoshiko; Yonezawa, Yasushi; Tokunaga, Masao

    2007-04-10

    In general, proteins bind to affinity or ion-exchange columns at low salt concentrations, and the bound proteins are eluted by raising the salt concentration, changing the solvent pH, or adding competing ligands. Blue-Sepharose is often used to remove bovine serum albumin (BSA) from samples, but when we applied BSA to Blue-Sepharose in 20 mM phosphate, pH 7.0, 50%-60% of the protein flowed through the column; however, complete binding of BSA was achieved by the addition of 2 M ammonium sulfate (AS) to the column equilibration buffer and the sample. The bound protein was eluted by decreasing the AS concentration or by adding 1 M NaCl or arginine. AS at high concentrations resulted in binding of BSA even to an ion-exchange column, Q-Sepharose, at pH 7.0. Thus, although moderate salt concentrations elute proteins from Blue-Sepharose or ion-exchange columns, proteins can be bound to these columns under extreme salting-out conditions. Similar enhanced binding of proteins by AS was observed with an ATP-affinity column.

  8. Structure and Function of Nematode RNA-Binding Proteins

    PubMed Central

    Kaymak, Ebru; Wee, L.M.; Ryder, Sean P.

    2010-01-01

    RNA-binding proteins are critical effectors of gene expression. They guide mRNA localization, translation, and stability, and potentially play a role in regulating mRNA synthesis. The structural basis for RNA recognition by RNA-binding proteins is the key to understanding how they target specific transcripts for regulation. Compared to other metazoans, nematode genomes contain a significant expansion in several RNA-binding protein families, including Pumilio-FBF (PUF), TTP-like zinc finger (TZF), and argonaute-like (AGO) proteins. Genetic data suggest that individual members of each family have distinct functions, presumably due to sequence variations that alter RNA binding specificity or protein interaction partners. In this review, we highlight example structures and identify the variable regions that likely contribute to functional divergence in nematodes. PMID:20418095

  9. Guardian of Genetic Messenger-RNA-Binding Proteins

    PubMed Central

    Anji, Antje; Kumari, Meena

    2016-01-01

    RNA in cells is always associated with RNA-binding proteins that regulate all aspects of RNA metabolism including RNA splicing, export from the nucleus, RNA localization, mRNA turn-over as well as translation. Given their diverse functions, cells express a variety of RNA-binding proteins, which play important roles in the pathologies of a number of diseases. In this review we focus on the effect of alcohol on different RNA-binding proteins and their possible contribution to alcohol-related disorders, and discuss the role of these proteins in the development of neurological diseases and cancer. We further discuss the conventional methods and newer techniques that are employed to identify RNA-binding proteins. PMID:26751491

  10. Guardian of Genetic Messenger-RNA-Binding Proteins.

    PubMed

    Anji, Antje; Kumari, Meena

    2016-01-06

    RNA in cells is always associated with RNA-binding proteins that regulate all aspects of RNA metabolism including RNA splicing, export from the nucleus, RNA localization, mRNA turn-over as well as translation. Given their diverse functions, cells express a variety of RNA-binding proteins, which play important roles in the pathologies of a number of diseases. In this review we focus on the effect of alcohol on different RNA-binding proteins and their possible contribution to alcohol-related disorders, and discuss the role of these proteins in the development of neurological diseases and cancer. We further discuss the conventional methods and newer techniques that are employed to identify RNA-binding proteins.

  11. Familial abnormalities of thyroxine binding proteins: some problems of recognition and interpretation.

    PubMed Central

    Neild, J E; Byfield, P G; Lalloz, M R; Tait, D; Marigold, J H; Croft, D N; Slavin, B M

    1985-01-01

    A three generation family study was carried out after inappropriate treatment with radioactive iodine of a 50 year old woman with a raised serum total thyroxine concentration and free thyroxine index. Subsequent investigations showed that she and five members of her family had raised thyroxine binding globulin concentrations. Free thyroxine and free triiodothyronine concentrations were normal. Problems encountered in the recognition of this thyroxine binding protein disorder are discussed. Clinicians and clinical biochemists should be aware of these pitfalls and thus avoid further incorrect treatment on the basis of biochemical findings, even though free hormone estimations are now becoming readily available. PMID:3919066

  12. Development of porcine ficolin-alpha monoclonal and polyclonal antibodies for determining the binding capacity of multiple GlcNAc-binding proteins to bacterial danger components.

    PubMed

    Nahid, M Abu; Ross, Steven J; Umiker, Benjamin R; Li, Huapeng; Sugii, Sunji; Bari, Latiful

    2016-02-01

    Ficolins are a group of oligomeric defense proteins assembled from collagen-like stalks and fibrinogen-like domains that have common biochemical specificity for N-acetyl-d-glucose amine (GlcNAc) and can function as opsonins. In this report, GlcNAc-binding protein (GBP) purified from porcine nonimmune serum was biochemically characterized as ficolin-α. Ficolin-α was used as an immunogen to generate both rabbit polyclonal and murine monoclonal anti-ficolin-α antibodies, which are not yet commercially available. GBPs have been shown to be present in many animals, including humans; however, their functions are largely unknown. GBPs from chicken, dog, horse, bovine, and human sera were isolated using various chromatography methods. Interestingly, anti-ficolin-α antibody showed cross-reaction with those animal sera GBPs. Furthermore, anti-ficolin-α antibody was reactive with the GlcNAc eluate of Escherichia coli O26-bound and Salmonella-bound porcine serum proteins. Functionally, GBPs and bacteria-reactive pig serum proteins were able to bind with pathogen-associated molecular patterns such as lipopolysaccharides and lipoteichoic acids. Our studies demonstrate that ficolin-α specific antibody was reactive with GBPs from many species as well as bacteria-reactive serum proteins. These proteins may play important roles in innate immunity by sensing danger components that can lead to antibacterial activity.

  13. Suppression of serum iron-binding capacity and bone marrow cellularity in pigs fed aflatoxin

    SciTech Connect

    Harvey, R.B.; Clark, D.E.; Huff, W.E.; Kubena, L.F.; Corrier, D.E.; Phillips, I.D.

    1988-04-01

    Flavus-parasiticus species of the genus Aspergillus are recognized as the primary producers of aflatoxins B/sub 1/, B/sup 2/, G/sup 1/, and G/sup 2/, hereafter referred to as aflatoxin (AF). The effects of feeding AF-contaminated diets to growing and finishing pigs have been described with changes in clinical performance, serum biochemistry, histology, and hematology attributed to aflatoxicosis. However, most of these studies evaluated AF-induced changes for a single AF dosage at a given point in time. The present study was designed to characterize how various AF dosages influence bone marrow histology, hematology, prothrombin and activated thromboplastin times, serum amino acids, and serum iron binding capacity during aflatoxicosis in growing pigs.

  14. Suppression of serum iron-binding capacity and bone marrow cellularity in pigs fed aflatoxin

    SciTech Connect

    Harvey, R.B.; Clark, D.E.; Huff, W.E.; Kubena, L.F.; Corrier, D.E. ); Phillips, T.D. )

    1988-05-01

    Flavus-parasiticus species of the genus Aspergillus are recognized as the primary producers of aflatoxins B{sub 1}, B{sub 2}, G{sub 1}, and G{sub 2}, hereafter referred to as aflatoxin (AF). The effects of feeding AF-contaminated diets to growing and finishing pigs have been described with changes in clinical performance, serum biochemistry, histology, and hematology attributed to aflatoxicosis. However, most of these studies evaluated AF-induced changes for a single AF dosage at a given point in time. The present study was designed to characterize how various AF dosages influence bone marrow histology, hematology, prothrombin and activated thromboplastin times, serum amino acids, and serum iron binding capacity during aflatoxicosis in growing pigs.

  15. Binding of mitomycin C to blood proteins: A spectroscopic analysis and molecular docking

    NASA Astrophysics Data System (ADS)

    Jang, Jongchol; Liu, Hui; Chen, Wei; Zou, Guolin

    2009-06-01

    Mitomycin C (MMC) was the first recognized bioreductive alkylating agent, and has been widely used clinically for antitumor therapy. The binding of MMC to two human blood proteins, human serum albumin (HSA) and human hemoglobin (HHb), have been investigated by fluorescence quenching, synchronous fluorescence, circular dichroism (CD) spectroscopy and molecular docking methods. The fluorescence data showed that binding of MMC to proteins caused strong fluorescence quenching of proteins through a static quenching way, and each protein had only one binding site for the drug. The binding constants of MMC to HSA and HHb at 298 K were 2.71 × 10 4 and 2.56 × 10 4 L mol -1, respectively. Thermodynamic analysis suggested that both hydrophobic interaction and hydrogen bonding played major roles in the binding of MMC to HSA or HHb. The CD spectroscopy indicated that the secondary structures of the two proteins were not changed in the presence of MMC. The study of molecular docking showed that MMC was located in the entrance of site I of HSA, and in the central cavity of HHb.

  16. A spectroscopic investigations of anticancer drugs binding to bovine serum albumin

    NASA Astrophysics Data System (ADS)

    Bakkialakshmi, S.; Chandrakala, D.

    2012-03-01

    The binding of anticancer drugs (i) Uracil (U), (ii) 5-Fluorouracil (5FU) and (iii) 5-Chlorouracil (5ClU), to bovine serum albumin (BSA) at two levels of temperature was studied by the fluorescence of quenching method. UV/Vis, time-resolved fluorescence, Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H NMR) and scanning electron microscope (SEM) analyses were also made. Binding constants (Ka) and binding sites (n) at various levels of temperature were calculated. The obtained binding sites were found to be equal to one for all the three quenchers (U, 5FU and 5ClU) at two different temperature levels. Thermodynamic parameters ΔH, ΔG and ΔS have been calculated and were presented in tables. Change in FTIR absorption intensity shows strong binding of anticancer drugs to BSA. Changes in chemical shifts of NMR and fluorescence lifetimes of the drugs indicate the presence of interaction and binding of BSA to anticancer drugs. 1H NMR spectra and SEM photographs also conform this binding.

  17. Distinctive serum protein profiles involving abundant proteins in lung cancer patients based upon antibody microarray analysis

    PubMed Central

    Gao, Wei-Min; Kuick, Rork; Orchekowski, Randal P; Misek, David E; Qiu, Ji; Greenberg, Alissa K; Rom, William N; Brenner, Dean E; Omenn, Gilbert S; Haab, Brian B; Hanash, Samir M

    2005-01-01

    Background Cancer serum protein profiling by mass spectrometry has uncovered mass profiles that are potentially diagnostic for several common types of cancer. However, direct mass spectrometric profiling has a limited dynamic range and difficulties in providing the identification of the distinctive proteins. We hypothesized that distinctive profiles may result from the differential expression of relatively abundant serum proteins associated with the host response. Methods Eighty-four antibodies, targeting a wide range of serum proteins, were spotted onto nitrocellulose-coated microscope slides. The abundances of the corresponding proteins were measured in 80 serum samples, from 24 newly diagnosed subjects with lung cancer, 24 healthy controls, and 32 subjects with chronic obstructive pulmonary disease (COPD). Two-color rolling-circle amplification was used to measure protein abundance. Results Seven of the 84 antibodies gave a significant difference (p < 0.01) for the lung cancer patients as compared to healthy controls, as well as compared to COPD patients. Proteins that exhibited higher abundances in the lung cancer samples relative to the control samples included C-reactive protein (CRP; a 13.3 fold increase), serum amyloid A (SAA; a 2.0 fold increase), mucin 1 and α-1-antitrypsin (1.4 fold increases). The increased expression levels of CRP and SAA were validated by Western blot analysis. Leave-one-out cross-validation was used to construct Diagonal Linear Discriminant Analysis (DLDA) classifiers. At a cutoff where all 56 of the non-tumor samples were correctly classified, 15/24 lung tumor patient sera were correctly classified. Conclusion Our results suggest that a distinctive serum protein profile involving abundant proteins may be observed in lung cancer patients relative to healthy subjects or patients with chronic disease and may have utility as part of strategies for detecting lung cancer. PMID:16117833

  18. Predicting protein-binding RNA nucleotides with consideration of binding partners.

    PubMed

    Tuvshinjargal, Narankhuu; Lee, Wook; Park, Byungkyu; Han, Kyungsook

    2015-06-01

    In recent years several computational methods have been developed to predict RNA-binding sites in protein. Most of these methods do not consider interacting partners of a protein, so they predict the same RNA-binding sites for a given protein sequence even if the protein binds to different RNAs. Unlike the problem of predicting RNA-binding sites in protein, the problem of predicting protein-binding sites in RNA has received little attention mainly because it is much more difficult and shows a lower accuracy on average. In our previous study, we developed a method that predicts protein-binding nucleotides from an RNA sequence. In an effort to improve the prediction accuracy and usefulness of the previous method, we developed a new method that uses both RNA and protein sequence data. In this study, we identified effective features of RNA and protein molecules and developed a new support vector machine (SVM) model to predict protein-binding nucleotides from RNA and protein sequence data. The new model that used both protein and RNA sequence data achieved a sensitivity of 86.5%, a specificity of 86.2%, a positive predictive value (PPV) of 72.6%, a negative predictive value (NPV) of 93.8% and Matthews correlation coefficient (MCC) of 0.69 in a 10-fold cross validation; it achieved a sensitivity of 58.8%, a specificity of 87.4%, a PPV of 65.1%, a NPV of 84.2% and MCC of 0.48 in independent testing. For comparative purpose, we built another prediction model that used RNA sequence data alone and ran it on the same dataset. In a 10 fold-cross validation it achieved a sensitivity of 85.7%, a specificity of 80.5%, a PPV of 67.7%, a NPV of 92.2% and MCC of 0.63; in independent testing it achieved a sensitivity of 67.7%, a specificity of 78.8%, a PPV of 57.6%, a NPV of 85.2% and MCC of 0.45. In both cross-validations and independent testing, the new model that used both RNA and protein sequences showed a better performance than the model that used RNA sequence data alone in

  19. Recognition and binding of β-lactam antibiotics to bovine serum albumin by frontal affinity chromatography in combination with spectroscopy and molecular docking.

    PubMed

    Li, Qian; Zhang, Tianlong; Bian, Liujiao

    2016-03-01

    Serum albumins are the most abundant carrier proteins in blood plasma and participate in the binding and transportation of various exogenous and endogenous compounds in the body. This work was designed to investigate the recognition and binding of three typical β-lactam antibiotics including penicillin G (Pen G), penicillin V (Pen V) and cefalexin (Cef) with bovine serum albumin (BSA) by frontal affinity chromatography in combination with UV-vis absorption spectra, fluorescence emission spectra, binding site marker competitive experiment and molecular docking under simulated physiological conditions. The results showed that a BSA only bound with one antibiotic molecule in the binding process, and the binding constants for Pen G-BSA, Pen V-BSA and Cef-BSA complexes were 4.22×10(1), 4.86×10(2) and 3.32×10(3) (L/mol), respectively. All the three β-lactam antibiotics were mainly inserted into the subdomain IIA (binding site 1) of BSA by hydrogen bonds and Van der Waals forces. The binding capacity between the antibiotics and BSA was closely related to the functional groups and flexibility of side chains in antibiotics. This study provided an important insight into the molecular recognition and binding interaction of BSA with β-lactam antibiotics, which may be a useful guideline for the innovative clinical medications and new antibiotic designs with effective pharmacological properties.

  20. Protein-binding assays in biological liquids using microscale thermophoresis.

    PubMed

    Wienken, Christoph J; Baaske, Philipp; Rothbauer, Ulrich; Braun, Dieter; Duhr, Stefan

    2010-10-19

    Protein interactions inside the human body are expected to differ from the situation in vitro. This is crucial when investigating protein functions or developing new drugs. In this study, we present a sample-efficient, free-solution method, termed microscale thermophoresis, that is capable of analysing interactions of proteins or small molecules in biological liquids such as blood serum or cell lysate. The technique is based on the thermophoresis of molecules, which provides information about molecule size, charge and hydration shell. We validated the method using immunologically relevant systems including human interferon gamma and the interaction of calmodulin with calcium. The affinity of the small-molecule inhibitor quercetin to its kinase PKA was determined in buffer and human serum, revealing a 400-fold reduced affinity in serum. This information about the influence of the biological matrix may allow to make more reliable conclusions on protein functionality, and may facilitate more efficient drug development.

  1. Structural characteristics of green tea catechins for formation of protein carbonyl in human serum albumin.

    PubMed

    Ishii, Takeshi; Mori, Taiki; Ichikawa, Tatsuya; Kaku, Maiko; Kusaka, Koji; Uekusa, Yoshinori; Akagawa, Mitsugu; Aihara, Yoshiyuki; Furuta, Takumi; Wakimoto, Toshiyuki; Kan, Toshiyuki; Nakayama, Tsutomu

    2010-07-15

    Catechins are polyphenolic antioxidants found in green tea leaves. Recent studies have reported that various polyphenolic compounds, including catechins, cause protein carbonyl formation in proteins via their pro-oxidant actions. In this study, we evaluate the formation of protein carbonyl in human serum albumin (HSA) by tea catechins and investigate the relationship between catechin chemical structure and its pro-oxidant property. To assess the formation of protein carbonyl in HSA, HSA was incubated with four individual catechins under physiological conditions to generate biotin-LC-hydrazide labeled protein carbonyls. Comparison of catechins using Western blotting revealed that the formation of protein carbonyl in HSA was higher for pyrogallol-type catechins than the corresponding catechol-type catechins. In addition, the formation of protein carbonyl was also found to be higher for the catechins having a galloyl group than the corresponding catechins lacking a galloyl group. The importance of the pyrogallol structural motif in the B-ring and the galloyl group was confirmed using methylated catechins and phenolic acids. These results indicate that the most important structural element contributing to the formation of protein carbonyl in HSA by tea catechins is the pyrogallol structural motif in the B-ring, followed by the galloyl group. The oxidation stability and binding affinity of tea catechins with proteins are responsible for the formation of protein carbonyl, and consequently the difference in these properties of each catechin may contribute to the magnitude of their biological activities.

  2. HTLV-1 Tax Protein Stimulation of DNA Binding of bZIP Proteins by Enhancing Dimerization

    NASA Astrophysics Data System (ADS)

    Wagner, Susanne; Green, Michael R.

    1993-10-01

    The Tax protein of human T cell leukemia virus type-1 (HTLV-I) transcriptionally activates the HTLV-I promoter. This activation requires binding sites for activating transcription factor (ATF) proteins, a family of cellular proteins that contain basic region-leucine zipper (bZIP) DNA binding domains. Data are presented showing that Tax increases the in vitro DNA binding activity of multiple ATF proteins. Tax also stimulated DNA binding by other bZIP proteins, but did not affect DNA binding proteins that lack a bZIP domain. The increase in DNA binding occurred because Tax promotes dimerization of the bZIP domain in the absence of DNA, and the elevated concentration of the bZIP homodimer then facilitates the DNA binding reaction. These results help explain how Tax activates viral transcription and transforms cells.

  3. 9S binding protein for androgens and progesterone.

    PubMed

    Wilson, E M; Lea, O A; French, F S

    1977-05-01

    A steroid binding protein fraction with a sedimentation coefficient of approximately 9 S (molecular weight approximately equal to 200,000) has been identified in 105,000 X g supernatants of several androgen-responsive organs. Highest concentrations were found in epididymis and testis, but small amounts were detected in prostate, seminal vesicle, kidney, submandibular gland, and lung. The 9S protein binds [3H]dihydrotestosterone (17beta-hydroxy-5alpha-androstan-3-one) and [3H]progesterone (4-pregnene-3,20-dione) with equilibrium binding constants of approximately 10(5) M-1 and 10(6) M-1, respectively. The concentration of 9S binding sites in epididymis is approximately 10(-11) mol/mg of supernatant protein, which is at least 10(5) times greater than the concentration of androgen receptor. 9S binding protein appears to be a nonsecretory, intracellular protein and has properties different from the andorgen receptor. It is unretarded on DEAE-Sephadex chromatography at pH 8.0, and its sedimentation rate on sucrose gradients is not altered at high ionic strength (0.4 M KCl). Like the androgen receptor, its binding activity, which is maximal between pH 7 and 9.5, is heat labile, decreased by sulfhydryl reagents, and enhanced by 2-mercaptoethanol. It is suggested that because of its high concentration and low affinity, 9S binding protein may function in the intracellular accumulation of compartmentalization of androgens or progesterone.

  4. Solid-phase immunoradiometric assay for serum amyloid A protein using magnetisable cellulose particles.

    PubMed

    De Beer, F C; Dyck, R F; Pepys, M B

    1982-10-29

    An immunoradiometric assay for human serum amyloid A protein (SAA) was developed using magnetisable cellulose particles as the solid phase. Rabbit antiserum to to SAA was raised by immunization with SAA isolated from acute-phase serum by gel filtration in formic acid. The antiserum was rendered monospecific for SAA by solid-phase immunoabsorption with normal human serum, which contains only traces of SAA, and some was coupled covalently to the cellulose particles. Immunopurified anti-SAA antibodies were isolated from the monospecific anti-SAA serum by binding to, and elution from insolubilized acute-phase serum and were radiolabelled with 125I. The assay was calibrated with an acute phase serum which contained 6000 times more SAA than normal sera with the lowest detectable level of SAA, and an arbitrary value of 6000 U/l was assigned to this standard. Sera were tested in the native, undenatured state and there was no increase in SAA immunoreactivity following alkali treatment or heating. The assay range was from 1-2000 U/l so that all SAA levels above 6 U/l could be measured on a single (1:6) dilution of serum. The intra- and interassay coefficients of variation were 11.7 and 15.0% respectively. Among 100 healthy normal subjects (50 male, 50 female) the median SAA level was 9 U/l, range less than 1-100, with 93% below 20 U/l and only 2% below the lower limit of sensitivity of the assay (1 U/l).

  5. Protein surface-distribution and protein-protein interactions in the binding of peripheral proteins to charged lipid membranes.

    PubMed Central

    Heimburg, T; Marsh, D

    1995-01-01

    The binding of native cytochrome c to negatively charged lipid dispersions of dioleoyl phosphatidylglycerol has been studied over a wide range of ionic strengths. Not only is the strength of protein binding found to decrease rapidly with increasing ionic strength, but also the binding curves reach an apparent saturation level that decreases rapidly with increasing ionic strength. Analysis of the binding isotherms with a general statistical thermodynamic model that takes into account not only the free energy of the electrostatic double layer, but also the free energy of the surface distribution of the protein, demonstrates that the apparent saturation effects could arise from a competition between the out-of-plane binding reaction and the lateral in-plane interactions between proteins at the surface. It is found that association with nonlocalized sites results in binding isotherms that display the apparent saturation effect to a much more pronounced extent than does the Langmuir adsorption isotherm for binding to localized sites. With the model for nonlocalized sites, the binding isotherms of native cytochrome c can be described adequately by taking into account only the entropy of the surface distribution of the protein, without appreciable enthalpic interactions between the bound proteins. The binding of cytochrome c to dioleoyl phosphatidylglycerol dispersions at a temperature at which the bound protein is denatured on the lipid surface, but is nondenatured when free in solution, has also been studied. The binding curves for the surface-denatured protein differ from those for the native protein in that the apparent saturation at high ionic strength is less pronounced. This indicates the tendency of the denatured protein to aggregate on the lipid surface, and can be described by the binding isotherms for nonlocalized sites only if attractive interactions between the surface-bound proteins are included in addition to the distributional entropic terms. Additionally

  6. Cu(II) Bis(thiosemicarbazone) Radiopharmaceutical Binding to Serum Albumin: Further Definition of Species-Dependence and Associated Substituent Effects

    PubMed Central

    Basken, Nathan E.; Green, Mark A.

    2009-01-01

    Introduction The Cu-PTSM (pyruvaldehyde bis(N4-methylthiosemicarbazonato)copper(II)) and Cu-ATSM (diacetyl bis(N4-methylthiosemicarbazonato)copper(II)) radiopharmaceuticals exhibit strong, species-dependent binding to the IIA site of human serum albumin (HSA), while the related Cu-ETS (ethylglyoxal bis(thiosemicarbazonato)copper(II)) radiopharmaceutical appears to only exhibit non-specific binding to human and animal serum albumins. Methods To further probe the structural basis for the species-dependence of this albumin binding interaction, protein binding of these three radiopharmaceuticals was examined in solutions of albumin and/or serum from a broader array of mammalian species (rat, sheep, donkey, rabbit, cow, pig, dog, baboon, mouse, cat, elephant). We also evaluated the albumin binding of several copper(II) bis(thiosemicarbazone) chelates offering more diverse substitution of the ligand backbone. Results Cu-PTSM and Cu-ATSM exhibit a strong interaction with HSA that is not apparent with the albumins of other species, while the binding of Cu-ETS to albumin is much less species-dependent. The strong interaction of Cu-PTSM with HSA does not appear to simply correlate with variation, relative to the animal albumins, of a single amino acid lining HSA's IIA site. Those agents that selectively interact with HSA share the common feature of only methyl or hydrogen substitution at the carbon atoms of the diimine fragment of the ligand backbone. Conclusions The interspecies variations in albumin binding of Cu-PTSM and Cu-ATSM are not simply explained by unique amino acid substitutions in the IIA binding pocket of the serum albumins. However, the specific affinity for this region of HSA is disrupted when substituents bulkier than a methyl group appear on the imine carbons of the copper bis(thiosemicarbazone) chelate. PMID:19520290

  7. Paramagnetic Ligand Tagging To Identify Protein Binding Sites

    PubMed Central

    2015-01-01

    Transient biomolecular interactions are the cornerstones of the cellular machinery. The identification of the binding sites for low affinity molecular encounters is essential for the development of high affinity pharmaceuticals from weakly binding leads but is hindered by the lack of robust methodologies for characterization of weakly binding complexes. We introduce a paramagnetic ligand tagging approach that enables localization of low affinity protein–ligand binding clefts by detection and analysis of intermolecular protein NMR pseudocontact shifts, which are invoked by the covalent attachment of a paramagnetic lanthanoid chelating tag to the ligand of interest. The methodology is corroborated by identification of the low millimolar volatile anesthetic interaction site of the calcium senso