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Selective Binding (selective + binding)
Selected AbstractsSelective Binding of Steroids by 2,2,-Biquinoline-4,4,-dicarboxamide-Bridged Bis(,-cyclodextrin): Fluorescence Enhancement by Guest Inclusion.CHEMINFORM, Issue 31 2003Yu Liu No abstract is available for this article. [source] Selective Binding of Imidazolium Cations in Building Multi-Component LayersCHEMISTRY - A EUROPEAN JOURNAL, Issue 23 2010Irene Ling Abstract Addition of 1-alkyl-3-methylimidazolium (Cn -mim) cations 3,5 to a mixture of bis-phosphonium cation 2 and sodium p -sulfonatocalix[4]arene (1) in the presence of lanthanide ions results in the selective binding of an imidazolium cation into the cavity of the calixarene. The result is a multi-layered solid material with an inherently flexible interplay of the components. Incorporating ethyl-, n -butyl- or n -hexyl-mim cations into the multi-layers results in significant perturbation of the structure, the most striking effect is the tilting of the plane of the bowl-shaped calixarene relative to the plane of the multi-layer, with tilt angles of 7.2, 28.9 and 65.5°, respectively. The lanthanide ions facilitate complexation, but are not incorporated into the structures and, in all cases, the calixarene takes on a 5, charge, with one of the lower-rim phenolic groups deprotonated. ROESY NMR experiments and other 1H,NMR spectroscopy studies establish the formation of 1:1 supermolecules of Cn -mim and calixarene, regardless of the ratio of the two components, and indicate that the supermolecules undergo rapid exchange on the NMR spectroscopy timescale. [source] Tailoring Macromolecular Expression at Polymersome SurfacesADVANCED FUNCTIONAL MATERIALS, Issue 18 2009Adam Blanazs Abstract A series of amphiphilic ABC triblock copolymers are synthesized by atom transfer radical polymerization, wherein the ,A' and ,C' blocks are hydrophilic and the pH-sensitive ,B' block can be switched from hydrophilic in acidic solution to hydrophobic at pH 7. Careful addition of base to the molecularly dissolved copolymer in acidic solution readily induces the self-assembly of such triblock copolymers at around neutral pH to form pH-sensitive polymersomes (a.k.a. vesicles) with asymmetric membranes. By systematic variation of the relative volume fractions of the ,A' and ,C' blocks, the chemical nature of the polymer chains expressed at the interior or exterior corona of the polymersomes can be selected. Treatment of primary human dermal fibroblast cells with these asymmetric polymersomes demonstrates the biological consequences of such spatial segregation, with both polymersome cytotoxicity and endocytosis rates being dictated by the nature of the polymersome surface chemistry. The pH-sensitive nature of the polymersomes readily facilitates their dissociation after endocytosis due to the relatively low endosomal pH, which results in the rapid release of an encapsulated dye. Selective binding of anionic substrates such as DNA within the inner cationic polymersome volume, coupled with a biocompatible exterior, leads to potential gene delivery applications for these pH-sensitive asymmetric nanovectors. [source] In vitro expansion of DNA triplet repeats with bulge binders and different DNA polymerasesFEBS JOURNAL, Issue 18 2008Di Ouyang The expansion of DNA repeat sequences is associated with many genetic diseases in humans. Simple bulge DNA structures have been implicated as intermediates in DNA slippage within the DNA repeat regions. To probe the possible role of bulged structures in DNA slippage, we designed and synthesized a pair of simple chiral spirocyclic compounds [Xi Z, Ouyang D & Mu HT (2006) Bioorg Med Chem Lett16, 1180,1184], DDI-1A and DDI-1B, which mimic the molecular architecture of the enediyne antitumor antibiotic neocarzinostatin chromophore. Both compounds strongly stimulated slippage in various DNA repeats in vitro. Enhanced slippage synthesis was found to be synchronous for primer and template. CD spectra and UV thermal stability studies supported the idea that DDI-1A and DDI-1B exhibited selective binding to the DNA bulge and induced a significant conformational change in bulge DNA. The proposed mechanism for the observed in vitro expansion of long DNA is discussed. [source] Ly6 family member C4.4A binds laminins 1 and 5, associates with galectin-3 and supports cell migrationINTERNATIONAL JOURNAL OF CANCER, Issue 5 2005Claudia Paret Abstract C4.4A is a member of the Ly6 family, with low homology to uPAR. It has been detected mainly on metastasizing carcinoma cells and proposed to be involved in wound healing. So far, C4.4A has been observed as an orphan receptor, and its functional activity has not been explored. Using recombinant rat C4.4A (rrC4.4A) made in a eukaryotic expression system, we demonstrate by immunohistology that C4.4A ligands are strongly expressed in tissues adjacent to squamous epithelia of, e.g., tongue and esophagus, the expression pattern partly overlapping with laminin (LN) and complementing the C4.4A expression that is found predominantly on the basal layers of squamous epithelium. ELISA screening of several components of the extracellular matrix revealed selective binding of rrC4.4A to LN1 and LN5 and that transfection of the BSp73AS tumor line with C4.4A cDNA (BSp73AS-1B1) promoted LN1 and LN5 binding. Binding of BSp73AS-1B1 to LN5 and, less markedly, LN1 induced spreading, lamellipodia formation and migration. C4.4A also associates with galectin-3 in nontransformed tissues and tumor lines. There is evidence that the association of C4.4A with galectin-3 influences LN adhesion. C4.4A was described originally as a metastasis-associated molecule. Our findings that LN1 and LN5 are C4.4A ligands, that galectin-3 associates with C4.4A and that C4.4A ligand binding confers a migratory phenotype are well in line with the supposed metastasis association. © 2005 Wiley-Liss, Inc. [source] Aromatic,aromatic interaction of amitriptyline: Implication of overdosed drug detoxificationJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 2 2005Dong-Won Lee Abstract The objectives of this work are to explore the ,,, complexation of amitriptyline with , electron-deficient aromatic rings and demonstrate the feasibility of ,,, complexation for overdosed drug detoxification. Water-soluble oligochitosan was chemically modified with dinitrobenzenesulfonyl groups to induce selective binding toward amitriptyline through ,,, complexation. NMR studies showed that benzenesulfonyl and dinitrobenzenesulfonyl protons were upfield shifted by the addition of amitriptyline, indicating the formation of ,,, complexes. The ,,, complexation of amitriptyline is driven primarily by a desolvation driving force, whereas the magnitude of interaction is dictated by the complementrary electrostatic interaction. Isolated rat heart tests revealed that dinitrobenzenesulfonyl oligochitosan prevented the amitriptyline-induced cardiotoxicity and was itself not cardiotoxic. © 2004 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:373,381, 2005 [source] A novel missense mutation causing abnormal LMAN1 in a Japanese patient with combined deficiency of factor V and factor VIII,AMERICAN JOURNAL OF HEMATOLOGY, Issue 11 2009Takayuki Yamada Combined deficiency of coagulation factor V (FV) and factor VIII (FVIII) (F5F8D) is an inherited bleeding disorder characterized by a reduction in plasma concentrations of FV and FVIII. F5F8D is genetically linked to mutations in either LMAN1 or MCFD2. Here, we investigated the molecular basis of F5F8D in a Japanese patient, and identified a novel missense mutation (p.Trp67Ser, c.200G>C) in the LMAN1, but no mutation in the MCFD2. The amount of LMAN1 in Epstein-Barr virus-immortalized lymphoblasts from the patient was found to be almost the same as that in cells from a normal individual. Interestingly, an anti-MCFD2 antibody did not co-immunoprecipitate the mutant LMAN1 with MCFD2 in lymphoblasts from the patient, suggesting the affinity of MCFD2 for the mutant LMAN1 is weak or abolished by the binding of the anti-MCFD2 antibody. In addition, a Myc/6×His-tagged recombinant form of wild-type LMAN1 could bind to D-mannose, but that of the mutant could not. The p.Trp67Ser mutation was located in the carbohydrate recognition domain (CRD), which is thought to participate in the selective binding of LMAN1 to the D-mannose of glycoproteins as well as the EF-motif of MCFD2. Taken together, it was suggested that the p.Trp67Ser mutation might affect the molecular chaperone function of LMAN1, impairing affinity for D-mannose as well as for MCFD2, which may be responsible for F5F8D in the patient. This is the first report of F5F8D caused by a qualitative defect of LMAN1 due to a missense mutation in LMAN1. Am. J. Hematol. 2009. © 2009 Wiley-Liss, Inc. [source] Cranberry proanthocyanidins are cytotoxic to human cancer cells and sensitize platinum-resistant ovarian cancer cells to paraplatinPHYTOTHERAPY RESEARCH, Issue 8 2009Ajay P. Singh Abstract Polyphenolic extracts of the principal flavonoid classes present in cranberry were screened in vitro for cytotoxicity against solid tumor cells lines, identifying two fractions composed principally of proanthocyanidins (PACs) with potential anticancer activity. Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight Mass Spectrometry (MALDI-TOF-MS) analysis of the proanthocyanidins (PACs) fractions indicated the presence of A-type PACs with 1,4 linkages containing between 2,8 epicatechin units with a maximum of 1 epigallocatechin unit. PACs exhibited in vitro cytotoxicity against platinum-resistant human ovarian, neuroblastoma and prostate cancer cell lines (IC50 = 79,479 µg/mL) but were non-cytotoxic to lung fibroblast cells (IC50 > 1000 µg/ml). SKOV-3 ovarian cancer cells treated with PACs exhibited classic apoptotic changes. PACs acted synergistically with paraplatin in SKOV-3 cells. Pretreatment of SKOV-3 cells with PACs (106 µg/ml) resulted in a significant reduction of the paraplatin IC50 value. Similarly, in a BrdU incorporation assay, co-treatment of SKOV-3 cells with PACs and paraplatin revealed reduced cell proliferation at lower concentrations than with either individually. In SKOV-3 cell cultures co-treated with PAC-1 and paraplatin, an HPLC analysis indicated differential quantitative presence of various PAC oligomers such as DP-8, -9, -11 and -14 indicating either selective binding or uptake. Cranberry proanthocyanidins exhibit cell-line specific cytotoxicity, induce apoptotic markers and augment cytotoxicity of paraplatin in platinum-resistant SKOV-3 ovarian cancer cells. Copyright © 2009 John Wiley & Sons, Ltd. [source] Recombinant C1 inhibitor in brain ischemic injury,ANNALS OF NEUROLOGY, Issue 3 2009Raffaella Gesuete BD Objective C1 inhibitor (C1-INH) is an endogenous inhibitor of complement and kinin systems. We have explored the efficacy and the therapeutic window of the recently available human recombinant (rh) C1-INH on ischemic brain injury and investigated its mechanism of action in comparison with that of plasma-derived (pd) C1-INH. Methods rhC1-INH was administered intravenously to C57Bl/6 mice undergoing transient or permanent ischemia, and its protective effects were evaluated by measuring infarct volume and neurodegeneration. The binding profiles of rhC1-INH and pdC1-INH were assessed in vitro using surface plasmon resonance. Their localization in the ischemic brain tissue was determined by immunohistochemistry and confocal analysis. The functional consequences of rhC1-INH and pdC1-INH administration on complement activation were analyzed by enzyme-linked immunosorbent assay on plasma samples. Results rhC1-INH markedly reduced cerebral damage when administered up to 18 hours after transient ischemia and up to 6 hours after permanent ischemia, thus showing a surprisingly wide therapeutic window. In vitro rhC1-INH bound mannose-binding lectin (MBL), a key protein in the lectin complement pathway, with high affinity, whereas pdC1-INH, which has a different glycosylation pattern, did not. In the ischemic brain, rhC1-INH was confined to cerebral vessels, where it colocalized with MBL, whereas pdC1-INH diffused into the brain parenchyma. In addition, rhC1-INH was more active than pdC1-INH in inhibiting MBL-induced complement activation. Interpretation rhC1-INH showed a surprisingly wider time window of efficacy compared with the corresponding plasmatic protein. We propose that the superiority of rhC1-INH is due to its selective binding to MBL, which emerged as a novel target for stroke treatment. Ann Neurol 2009;66:332,342 [source] Adenosine binding to low-molecular-weight purine nucleoside phosphorylase: the structural basis for recognition based on its complex with the enzyme from Schistosoma mansoniACTA CRYSTALLOGRAPHICA SECTION D, Issue 1 2010Humberto M. Pereira Schistosomes are unable to synthesize purines de novo and depend exclusively on the salvage pathway for their purine requirements. It has been suggested that blockage of this pathway could lead to parasite death. The enzyme purine nucleoside phosphorylase (PNP) is one of its key components and molecules designed to inhibit the low-molecular-weight (LMW) PNPs, which include both the human and schistosome enzymes, are typically analogues of the natural substrates inosine and guanosine. Here, it is shown that adenosine both binds to Schistosoma mansoni PNP and behaves as a weak micromolar inhibitor of inosine phosphorolysis. Furthermore, the first crystal structures of complexes of an LMW PNP with adenosine and adenine are reported, together with those with inosine and hypoxanthine. These are used to propose a structural explanation for the selective binding of adenosine to some LMW PNPs but not to others. The results indicate that transition-state analogues based on adenosine or other 6-amino nucleosides should not be discounted as potential starting points for alternative inhibitors. [source] Fractionation of ,-Lactoglobulin from whey by mixed matrix membrane ion exchange chromatographyBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2009Syed M. Saufi Abstract Mixed matrix membranes (MMMs), which incorporate adsorptive particles during membrane casting, can be prepared simply and have performances that are competitive with other membrane chromatography materials. The application of MMM chromatography for fractionation of ,-Lactoglobulin from bovine whey is described in this article. MMM chromatography was prepared using ethylene vinyl alcohol polymer and lewatit anion exchange resin to form a flat sheet membrane. The membrane was characterized in terms of structure and its static and dynamic binding capacities were measured. The optimum binding for ,-Lactoglobulin was found to be at pH 6.0 using 20 mM sodium phosphate buffer. The MMM had a static binding capacity of 120 mg/g membrane (36 mg/mL membrane) and 90 mg/g membrane (27 mg/mL membrane) for ,-Lactoglobulin and ,-Lactalbumin, respectively. In batch fractionation of whey, the MMM showed selective binding towards ,-Lactoglobulin compared to other proteins. The dynamic binding capacity of ,-Lactoglobulin in whey solution was about 80 mg/g membrane (24 mg ,-Lac/mL of MMM), which is promising for whey fractionation using this technology. This is the first reported application of MMM chromatography to a dairy feed stream. Biotechnol. Bioeng. 2009;103: 138,147. © 2008 Wiley Periodicals, Inc. [source] Affibody-mediated transferrin depletion for proteomics applicationsBIOTECHNOLOGY JOURNAL, Issue 11 2007Caroline Grönwall Abstract An Affibody® (Affibody) ligand with specific binding to human transferrin was selected by phage display technology from a combinatorial protein library based on the staphylococcal protein A (SpA)-derived Z domain. Strong and selective binding of the selected Affibody ligand to transferrin was demonstrated using biosensor technology and dot blot analysis. Impressive specificity was demonstrated as transferrin was the only protein recovered by affinity chromatography from human plasma. Efficient Affibody-mediated capture of transferrin, combined with IgG- and HSA-depletion, was demonstrated for human plasma and cerebrospinal fluid (CSF). For plasma, 85% of the total transferrin content in the samples was depleted after only two cycles of transferrin removal, and for CSF, 78% efficiency was obtained in single-step depletion. These results clearly suggest a potential for the development of Affibody-based resins for the removal of abundant proteins in proteomics analyses. [source] The history of tocolysisBJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 2003Marc J.N.C. Keirse In 1950, the World Health Organisation (WHO) defined prematurity as a birthweight of 2500 g or less and in 1961 as a gestational age of less than 37 weeks. The time in between marks an era in which there was growing recognition of the importance of gestational age at birth and how to influence it. The latter was facilitated too by the development of tocography, which permitted some semi-objective measurement of uterine contractility. Along with it, came a growing interest in agents that could control uterine contractility beyond the earlier classical approaches of hormones and gastrointestinal spasmolytics. Hence, the early 1960s saw much research interest in agents, such as nylidrine, isoxsuprine, and orciprenaline that could suppress uterine contractility as one of their many beta-agonist properties. Subsequently, two approaches would be used to shift the balance towards uterine function over and above the influence on other bodily functions. One consisted of supplementing these drugs with agents, such as calcium antagonists and beta-receptor blockers that were hoped to suppress non-uterine actions. The other was a search for drugs in the same class with greater uterospecificity and more selective binding to uterine as opposed to other receptors. Neither of these approaches has ever fully fulfilled the hopes that were pinned on them, but they resulted in the availability of a large number of agents to suppress uterine contractility. The advent of prostaglandins as regulators of uterine contractility and the ability to suppress their biosynthesis saw another range of attempts to suppress uterine activity. They included aspirin, sodium salicylate, flufenamic acid, sulindac and indomethacin, but some were clearly based on a defective understanding of how uterine prostaglandin synthesis can be influenced. In the meantime, a flurry of other agents came and went, often more than once, testifying to the ingenuity of clinicians in trying to solve a problem that is poorly understood. Some, such as relaxin and ethanol, came and disappeared. Others, such as calcium antagonists, entered the scene as protectors against the non-uterine effects of other agents, went, and re-entered the scene in their own right. Still others, such as magnesium sulphate, came, lingered around, and became credited with effects in preterm labour that do not depend on affecting uterine contractility. Amidst this all arose the term tocolysis, coined in 1964 by Mosler from the Greek stems ,,,,' and ,,,,,,', to epitomise all of this ingenuity. [source] Selective Binding of Imidazolium Cations in Building Multi-Component LayersCHEMISTRY - A EUROPEAN JOURNAL, Issue 23 2010Irene Ling Abstract Addition of 1-alkyl-3-methylimidazolium (Cn -mim) cations 3,5 to a mixture of bis-phosphonium cation 2 and sodium p -sulfonatocalix[4]arene (1) in the presence of lanthanide ions results in the selective binding of an imidazolium cation into the cavity of the calixarene. The result is a multi-layered solid material with an inherently flexible interplay of the components. Incorporating ethyl-, n -butyl- or n -hexyl-mim cations into the multi-layers results in significant perturbation of the structure, the most striking effect is the tilting of the plane of the bowl-shaped calixarene relative to the plane of the multi-layer, with tilt angles of 7.2, 28.9 and 65.5°, respectively. The lanthanide ions facilitate complexation, but are not incorporated into the structures and, in all cases, the calixarene takes on a 5, charge, with one of the lower-rim phenolic groups deprotonated. ROESY NMR experiments and other 1H,NMR spectroscopy studies establish the formation of 1:1 supermolecules of Cn -mim and calixarene, regardless of the ratio of the two components, and indicate that the supermolecules undergo rapid exchange on the NMR spectroscopy timescale. [source] An Oligonucleotide-based Fluorescence Sensor for Mercury(II) in Aqueous SolutionsCHINESE JOURNAL OF CHEMISTRY, Issue 8 2009Huiwang WU Abstract A highly selective fluorescence sensor was developed for Hg(II) ion detection in aqueous solutions based on the selective binding of Hg(II) ions with a pair of thymine-thymine mismatch. The sensor consists of two DNA probes functionalized with a fluorophore (fluorescein, F) and a quencher (tetramethyl rhodamine, Q) moiety separately. This pair of DNA probes contains two pairs of thymine-thymine mismatches used to detect Hg(II) ions. In the presence of Hg(II) ions, thymine-Hg2+ -thymine was formed between thymine residues of probes. From that, the interaction of the two DNA probes increased. Thus, the DNA probes formed a double-stranded structure. Both the fluorophore and quencher were brought close to each other leading to the fluorescence resonance energy transfer (FRET) between F and Q. Under the optimum conditions, the sensor was used to detect the Hg(II) ions from 50 to 1000 nmol·L,1 with a regression equation y=5281.13,1650.56 lg[Hg2+] (R2=0.985). The linear range covers 100 to 500 nmol·L,1, and the limit of detection (LOD) is 79 nmol·L,1. The disturbance of some co-existing metal ions was explored, and no significant fluorescence quenching in the presence of 1.0 ,mol·L,1 other metal ions was observed. The fluorescence sensor has good sensitivity and selectivity for Hg(II) ions providing a rapid, simple and low cost method for the detection of mercury(II) ions in aqueous solutions. [source] | ||||||||||||||||