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8890914 | Structure and energetics of the glucoamylase-isomaltose transition-state complex probed by using modeling and deoxygenated substrates coupled with site-directed mutagenesis. | Molecular recognition, site-directed mutagenesis, and molecular modeling are combined to describe hydrogen bonds important for formation and catalysis of the Aspergillus niger glucomylase-isomaltose complex. This analysis of the energetics of the transition-state complex identified OH-4', -6', and -4 as critical for is... |
8890772 | The apolipoprotein E allele epsilon 4 does not correlate with the number of senile plaques or neurofibrillary tangles in patients with Alzheimer's disease. | <h4>Background and objectives</h4>Apolipoprotein E (apoE) has been implicated in regenerative processes in the brain after trauma, as well as in the pathogenesis of Alzheimer's disease. Inheritance of a specific apo epsilon allele (apo epsilon 4) determines in part the risk and the mean age at onset of Alzheimer's dise... |
8889198 | Scanning force microscopy reveals ellipsoid shape of chicken erythrocyte nucleosomes. | Scanning force microscopy was used to investigate the conformation of hypotonic spread chicken erythrocyte nucleosomes. Nucleosomal chains were prepared in low-salt conditions and fixed before centrifugation onto glass coverslips and air drying. The images of single nucleosomes were isolated by image processing, and th... |
8889194 | New fluorescent octadecapentaenoic acids as probes of lipid membranes and protein-lipid interactions. | The chemical and spectroscopic properties of the new fluorescent acids all(E)-8, 10, 12, 14, 16-octadecapentaenoic acid (t-COPA) and its (8Z)-isomer (c-COPA) have been characterized in solvents of different polarity, synthetic lipid bilayers, and lipid/protein systems. These compounds are reasonably photostable in solu... |
8889190 | Thermodynamics of hydrogen bond and hydrophobic interactions in cyclodextrin complexes. | Values of K, delta G(o), delta H(o), delta S(o) and delta C(po) for the binding reaction of small organic ligands forming 1:1 complexes with either alpha- or beta-cyclodextrin were obtained by titration calorimetry from 15 degrees C to 45 degrees C. A hydrogen bond or hydrophobic interaction was introduced by adding a ... |
8889178 | Interactions of phage P22 tails with their cellular receptor, Salmonella O-antigen polysaccharide. | Bacteriophage P22 binds to its cell surface receptor, the repetitive O-antigen structure in Salmonella lipopolysaccharide, by its six homotrimeric tailspikes. Receptor binding by soluble tailspikes and the receptor-inactivating endorhamnosidase activity of the tailspike protein were studied using octa- and dodecasaccha... |
8889177 | Hydrogen bonding stabilizes globular proteins. | It is clear that intramolecular hydrogen bonds are essential to the structure and stability of globular proteins. It is not clear, however, whether they make a net favorable contribution to this stability. Experimental and theoretical studies are at odds over this important question. Measurements of the change in confo... |
8889175 | Turbidimetric studies of Limulus coagulin gel formation. | The turbidity during trypsin-induced coagulin gel formation was studied over a range of wavelengths. The range of wavelengths used (686-326 nm) also made it possible to investigate the dependence of turbidity on wavelength (the wavelength exponent). Using the results from that work, and structural information on coagul... |
8889168 | Spectral broadening of interacting pigments: polarized absorption by photosynthetic proteins. | Excitonic interaction between pigment molecules is largely responsible for the static and dynamic spectroscopic properties of photosynthetic pigment-proteins. This paper provides a new description of its effect on polarized absorption spectroscopy, in particular on circular dichroism (CD). We investigate excitonic spec... |
8889161 | Structure and interactive properties of highly fluorinated phospholipid bilayers. | Because liposomes containing fluoroalkylated phospholipids are being developed for in vivo drug delivery, the structure and interactive properties of several fluoroalkylated glycerophosphocholines (PCs) were investigated by x-ray diffraction/osmotic stress, dipole potential, and hydrophobic ion binding measurements. Th... |
8886021 | Refolding of SDS- and thermally denatured MM-creatine kinase using cyclodextrins. | We have tried to refold thermally-denatured MM-CK using detergent and cyclodextrins as protein folding assistants. This procedure, named artificial chaperone-assisted refolding, has been extensively tested to refold carbonic anhydrase B. Here, we describe a study which shows that this procedure can be applied to refold... |
8880527 | Direct activity of recombinant human lactoferrin against Helicobacter pylori. | We report the activity of recombinant human lactoferrin against Helicobacter pylori. Lactoferrin exerted a time- and dose-dependent action against 8 of the 13 clinical isolates of H. pylori tested in vitro. These results highlight a potential therapeutic use for lactoferrin against H.pylori infection. |
8880522 | Survey of enterococcal susceptibility patterns in Belgium. | A national surveillance study was performed in order to identify the enterococci causing important infections, to determine their susceptibilities to first-choice agents for treatment, and to characterize the phenotypes and genotypes of the glycopeptide-resistant strains. A total of 472 isolates were collected between ... |
8879219 | The importance of leukotrienes in airway inflammation in a mouse model of asthma. | Inhalation of antigen in immunized mice induces an infiltration of eosinophils into the airways and increased bronchial hyperreactivity as are observed in human asthma. We employed a model of late-phase allergic pulmonary inflammation in mice to address the role of leukotrienes (LT) in mediating airway eosinophilia and... |
8878427 | Direct preconditioning of cultured chick ventricular myocytes. Novel functions of cardiac adenosine A2a and A3 receptors. | Preconditioning with brief ischemia before a sustained period of ischemia reduces infarct size in the perfused heart. A cultured chick ventricular myocyte model was developed to investigate the role of adenosine receptor subtypes in cardiac preconditioning. Brief hypoxic exposure, termed preconditioning hypoxia, prior ... |
8876229 | On the molecular mechanism of chloroquine's antimalarial action. | Chloroquine is thought to exert its antimalarial effect by preventing the polymerization of toxic heme released during proteolysis of hemoglobin in the Plasmodium digestive vacuole. The mechanism of this blockade has not been established. We incubated cultured parasites with subinhibitory doses of [3H]chloroquine and [... |
8876190 | Transposition of DNase hypersensitive chromatin to the nuclear periphery coincides temporally with nerve growth factor-induced up-regulation of gene expression in PC12 cells. | To test the hypothesis that the nonrandom organization of the contents of interphase nuclei represents a compartmentalization of function, we examined the relative, spatial relationship of small nuclear ribonucleoproteins (snRNPs) and of DNase I hypersensitive chromatin (DHC) in rat pheochromocytoma cells. In controls,... |
8876188 | Transbilayer inhibition of protein kinase C by the lipophosphoglycan from Leishmania donovani. | Lipophosphoglycan (LPG), the predominant molecule on the surface of the parasite Leishmania donovani, has previously been shown to be a potent inhibitor of protein kinase C (PKC) isolated from rat brain. The mechanism by which LPG inhibits PKC was further investigated in this study. LPG was found to inhibit the PKC alp... |
8876186 | Interplay of structure and disorder in cochaperonin mobile loops. | Protein-protein interactions typically are characterized by highly specific interfaces that mediate binding with precisely tuned affinities. Binding of the Escherichia coli cochaperonin GroES to chaperonin GroEL is mediated, at least in part, by a mobile polypeptide loop in GroES that becomes immobilized in the GroEL/G... |
8876174 | RNA replication by Q beta replicase: a working model. | Two classes of RNA ligands that bound to separate, high affinity nucleic acid binding sites on Q beta replicase were previously identified. RNA ligands to the two sites, referred to as site I and site II, were used to investigate the molecular mechanism of RNA replication employed by the four-subunit replicase. Replica... |
8876160 | Engineering human immunodeficiency virus 1 protease heterodimers as macromolecular inhibitors of viral maturation. | Dimerization of human immunodeficiency virus type 1 protease (HIV-1 PR) monomers is an essential prerequisite for viral proteolytic activity and the subsequent generation of infectious virus particles. Disruption of the dimer interface inhibits this activity as does formation of heterodimers between wild-type and defec... |
8876143 | Early events in poliovirus infection: virus-receptor interactions. | The interaction of poliovirus with its cell receptor initiates conformational changes that lead to uncoating of the viral RNA. Three types of genetic analyses have been used to study the poliovirus-receptor interaction: (i) mutagenesis of the poliovirus receptor (PVR), (ii) selection of viral mutants resistant to neutr... |
8873613 | Effect of geldanamycin on the kinetics of chaperone-mediated renaturation of firefly luciferase in rabbit reticulocyte lysate. | Renaturation of thermally denatured firefly luciferase in rabbit reticulocyte lysate (RRL) requires hsp90, hsc70, and other as yet unidentified RRL components [Schumacher, R.J., et al. (1994) J. Biol. Chem. 269, 9493-9499]. Benzoquinonoid ansamycins (BAs) have recently been shown to specifically bind hsp90 and inhibit ... |
8871560 | Purification and biochemical analyses of a monomeric form of Tn5 transposase. | The binding of transposase (Tnp) to the specific Tn5 end sequences is the first dedicated reaction during transposition. In this study, comparative DNA-binding analyses were performed using purified full-length Tnp and a C-terminal deletion variant (delta369) that lacks the putative dimerization domain. The shape of th... |
8870668 | High-yield production of functionally active human serum transferrin using a baculovirus expression system, and its structural characterization. | Recently, there has been much interest in expressing recombinant human serum transferrin (HST) and mutants thereof for structural and functional studies. We have developed a baculovirus expression system for the rapid and efficient production of large quantities of HST (> 20 mg/l). Like native HST, the recombinant prot... |
8870664 | Distinct biochemical properties of the native members of the G12 G-protein subfamily. Characterization of G alpha 12 purified from rat brain. | G12 and G13 are insufficiently characterized pertussis toxin-insensitive G-proteins. Here, we describe the isolation of G alpha 12 from rat brain membranes. G alpha 12 was purified to apparent homogeneity by three steps of conventional chromatography, followed by two cycles of subunit-exchange chromatography on immobil... |
8870656 | Reconstitution of mammalian pyruvate dehydrogenase and 2-oxoglutarate dehydrogenase complexes: analysis of protein X involvement and interaction of homologous and heterologous dihydrolipoamide dehydrogenases. | Optimal conditions for rapid and efficient reconstitution of pyruvate dehydrogenase complex (PDC) activity are demonstrated by using an improved method for the dissociation of the multienzyme complex into its constituent E1 (substrate-specific 2-oxoacid decarboxylase) and E3 (dihydrolipoamide dehydrogenase) components ... |
8870640 | Cation-pi bonding and amino-aromatic interactions in the biomolecular recognition of substituted ammonium ligands. | Cation-pi bonds and amino-aromatic interactions are known to be important contributors to protein architecture and stability, and their role in ligand-protein interactions has also been reported. Many biologically active amines contain substituted ammonium moieties, and cation-pi bonding and amino-aromatic interactions... |
8863792 | Synthesis and structure-activity relationship of pyrazolo[3,4-d]pyrimidines: potent and selective adenosine A1 receptor antagonists. | A series of 12 substituted 1-phenylpyrazolo[3,4-d]pyrimidines were synthesized and evaluated for rat brain adenosine A1 and A2a receptor binding affinity. Substituents at C-4 and C-6 were varied in order to define these regions in terms of molecular recognition by the receptor subtypes. At C-4, the effects of a mercapt... |
8863790 | Derivatives of the triazoloquinazoline adenosine antagonist (CGS15943) are selective for the human A3 receptor subtype. | The adenosine antagonist 9-chloro-2-(2-furanyl)[1,2,4]triazolo[1,5-c]quinazolin-5-amine (CGS15943) binds to human A3 receptors with high affinity (Ki = 14 nM), while it lacks affinity at rat A3 receptors. Acylated derivatives of the 5-amino group and other modifications were prepared in an effort to provide A3 subtype ... |
8855964 | RNA folding topology and intermolecular contacts in the AMP-RNA aptamer complex. | We report below on the NMR structural characterization of the complex between AMP and a 40-mer RNA aptamer in aqueous solution. Resonance assignments are based on multinuclear multidimensional NMR studies on complexes uniformly 13C, 15N-labeled with either AMP or the RNA aptamer. AMP binds to an internal loop (labeled ... |
8855937 | Nonpolar interactions of thrombin and its inhibitors at the fibrinogen recognition exosite: thermodynamic analysis. | Nonpolar interactions play a major role in the association of the fibrinogen recognition exosite of thrombin with the C-terminal fragment (55-65), Asp-Phe-Glu-IIe-Pro-Glu-Glu-Tyr-Leu-Gln, of hirudin, which is a naturally occurring thrombin inhibitor. The thermodynamic details (free energy, enthalpy, entropy, and heat c... |
8855818 | Sublingual testosterone replacement improves muscle mass and strength, decreases bone resorption, and increases bone formation markers in hypogonadal men--a clinical research center study. | To study the effects of androgen replacement therapy on muscle mass and strength and bone turnover markers in hypogonadal men, we administered sublingual testosterone (T) cyclodextrin (SLT; 5 mg, three times daily) to 67 hypogonadal men (baseline serum T, < 8.4 nmol/L) recruited from 4 centers in the U.S.: Torrance (n ... |
8855804 | Testosterone replacement therapy improves mood in hypogonadal men--a clinical research center study. | The effect of testosterone (T) replacement on changes in mood was studied for 60 days in 51 hypogonadal men. All patients were withdrawn from their prior T replacement for at least 6 weeks before enrollment. Of these patients, 18 received T enanthate 200 mg im every 20 days, 16 received sublingual T cyclodextrin (SLT) ... |
8855239 | Targeting nucleic acid secondary structures by antisense oligonucleotides designed through in vitro selection. | Using an in vitro selection approach, we have isolated oligonucleotides that can bind to a DNA hairpin structure. Complex formation of these oligonucleotides with the target hairpin involves some type of triple-stranded structure with noncanonical interaction, as indicated by bandshift assays and footprinting studies. ... |
8855218 | Cation-pi interactions in aromatics of biological and medicinal interest: electrostatic potential surfaces as a useful qualitative guide. | The cation-pi interaction is an important, general force for molecular recognition in biological receptors. Through the sidechains of aromatic amino acids, novel binding sites for cationic ligands such as acetylcholine can be constructed. We report here a number of calculations on prototypical cation-pi systems, emphas... |
8855217 | Acyl tunichlorins: a new class of nickel chlorins isolated from the Caribbean tunicate Trididemnum solidum. | A new class of nickel-containing chlorins (acyl tunichlorins) has been isolated from the Caribbean tunicate Trididemnum solidum. The structures of 28 of these nickel (II) hydroporphyrins were elucidated using mass spectrometry, one- and two-dimensional NMR spectroscopy, and chemical degradation/derivatization. Unique s... |
8849689 | Genetic mapping of genes for twelve nuclear-encoded polypeptides associated with the thylakoid membranes in Beta vulgaris L. | Thylakoid membranes of chloroplasts are composed of approx. 75 polypeptide species. Nearly 60% originate in nuclear genes, the remainder in plastid genes. In order to localize representatives of the nuclear-encoded gene complement in a eukaryotic plant genome (sugar beet, Beta vulgaris L.), we have investigated the RFL... |
8843142 | Chiral separations by nonaqueous capillary electrophoresis. | This paper reports successful chiral separations of pharmaceutical racemic amines by nonaqueous capillary electrophoresis (NACE) using beta- and gamma-cyclodextrins (CDs) and various derivatives of beta-CDs. The results in three organic solvents, formamide (FA), N-methylformamide (NMF), and N,N-dimethylformamide (DMF) ... |
8843136 | Combining avidin-biotin chemistry with matrix-assisted laser desorption/ionization mass spectrometry. | Molecular recognition based on the high affinity of avidin for biotin has been combined with matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The rich chemistry of biotinylation reagents underlies the development of a mass tracer method for the rapid and sensitive analysis of biotinylated analyte ... |
8830697 | Functional analysis of the Pseudomonas aeruginosa autoinducer PAI. | A series of structural analogs of the Pseudomonas aeruginosa autoinducer [PAI, N-3-oxo-dodecanoyl homoserine lactone] were obtained and tested for their ability to act as autoinducers in stimulating the expression of the gene for elastase (lasB) by measuring beta-galactosidase production from a lasB-lacZ gene fusion in... |
8830694 | "Division potential" in Escherichia coli. | The phenotype of a minC mutant has been reexamined and found to correspond closely to the quantitative predictions of Teather et al. (R. M. Teather, J. F. Collins, and W. D. Donachie, J. Bacteriol. 118:407-413, 1974). We confirm that the number of septa formed per generation per cell length is fixed and independent of ... |
8824615 | Gene overexpression, purification, and identification of a desulfurization enzyme from Rhodococcus sp. strain IGTS8 as a sulfide/sulfoxide monooxygenase. | The oxidation of dibenzothiophene to dibenzothiophene sulfone has been linked to the enzyme encoded by the sox/dszC gene from Rhodococcus sp. strain IGTS8 (S. A. Denome, C. Oldfield, L. J. Nash, and K. D. Young, J. Bacteriol. 176:6707-6717, 1994; C. S. Piddington, B. R. Kovacevich, and J. Rambosek, Appl. Environ. Micro... |
8824603 | Evidence that an N-terminal S-layer protein fragment triggers the release of a cell-associated high-molecular-weight amylase in Bacillus stearothermophilus ATCC 12980. | During growth on starch medium, the S-layer-carrying Bacillus stearothermophilus ATCC 12980 and an S-layer-deficient variant each secreted three amylases, with identical molecular weights of 58,000, 122,000, and 184,000, into the culture fluid. Only the high-molecular-weight amylase (hmwA) was also identified as cell a... |
8824260 | Manganese-based superoxide dismutase mimetics inhibit neutrophil infiltration in vivo. | In a previous study (Hardy et al. (1994) J. Biol. Chem. 269, 18535-18540), we observed that the manganese-based superoxide dismutase mimetic Mn(II)-dichloro(1,4,7,10,13-pentaazacyclopentadecane) (MnPAM) inhibited neutrophil-mediated cell injury in vitro. We have extended these studies with the low molecular weight supe... |
8823367 | Evidence of the involvement of phosphatidylinositol 3-kinase in the migration, actin stress fiber formation, and alpha v beta 3-integrin-mediated adherence of human melanoma cells. | Tumor invasion and formation of metastases are major obstacles for a successful therapy of melanomas. Metastasis is thought to require multiple steps such as alpha v beta 3-integrin-mediated adhesion, proteolytic digestion of extracellular matrix by metalloproteinase-2, and reorganization of the actin cytoskeleton. To ... |
8816474 | The Drosophila P-element KP repressor protein dimerizes and interacts with multiple sites on P-element DNA. | Drosophila P elements are mobile DNA elements that encode an 87-kDa transposase enzyme and transpositional repressor proteins. One of these repressor proteins is the 207-amino-acid KP protein which is encoded by a naturally occurring P element with an internal deletion. To study the molecular mechanisms by which KP rep... |
8816400 | Supramolecular complexes of MHC class I, MHC class II, CD20, and tetraspan molecules (CD53, CD81, and CD82) at the surface of a B cell line JY. | The results of previous biochemical studies indicated that a fraction of MHC class II proteins is associated with four proteins of the tetraspan family, CD37, CD53, CD81, and CD82, and possibly with other membrane components, at the surface of JY B lymphoma cells. In the present communication we used a biophysical tech... |
8810344 | Factor VIII C2 domain missense mutations exhibit defective trafficking of biologically functional proteins. | The half-life of coagulation factor VIII (FVIII) in plasma is prolonged by noncovalent interaction with von Willebrand factor (vWF). Antibody inhibition data indicate that epitopes within the carboxyl terminus of the FVIII light chain play a role in vWF binding. Analysis of hemophilia A patient DNA samples have identif... |
8794388 | Cytotoxic T-lymphocyte clones specific for an immunodominant epitope display discerning antagonistic response to naturally occurring Epstein-Barr virus variants. | In the present study we have identified Epstein-Barr virus isolates which encode variant sequences within an HLA B35-restricted immunodominant cytotoxic T-lymphocyte (CTL) epitope that act as natural antagonists and can inhibit CTL activity on the wild-type epitope. This effect can be demonstrated if the wild-type epit... |
8794354 | A hydrophobic heptad repeat of the core protein of woodchuck hepatitis virus is required for capsid assembly. | The capsid particle of hepadnaviruses is assembled from its dimer precursors. However, the mechanism of the protein-protein interaction is still poorly understood. A small region in the capsid protein of woodchuck hepatitis virus (WHV) contains four hydrophobic residues, including leucine 101, leucine 108, valine 115, ... |
8794339 | CREB and CREB-binding proteins play an important role in the IE2 86-kilodalton protein-mediated transactivation of the human cytomegalovirus 2.2-kilobase RNA promoter. | The human cytomegalovirus (HCMV) immediate-early region 2 86-kDa protein (IE2 86) is the major transactivator of the promoter for the 2.2-kb class of early RNAs (open reading frame UL 112-113). Previously, we reported that a DNA segment on this promoter between nucleotides (nt) -113 and -59 was critical for activation ... |
8794322 | Lack of integrase can markedly affect human immunodeficiency virus type 1 particle production in the presence of an active viral protease. | The Gag-Pol polyprotein of human immunodeficiency virus type 1 is not required for efficient viral particle assembly or release. However, in this report we demonstrate that the synthesis of a truncated Gag-Pol precursor due to a premature termination codon in pol can reduce the ability of a full-length provirus to dire... |
8794310 | Adenovirus-pulsed dendritic cells stimulate human virus-specific T-cell responses in vitro. | Adenovirus infections cause significant morbidity and mortality in immunocompromised patients, yet little is known about the immune response to adenovirus infections. We established a system for the generation of a cytotoxic immune response to adenovirus in vitro. Cytotoxic T cells (CTLs) were derived from normal donor... |
8794305 | Activity of purified hepatitis C virus protease NS3 on peptide substrates. | The protease domain of the hepatitis C virus (HCV) protein NS3 was expressed in Escherichia coli, purified to homogeneity, and shown to be active on peptides derived from the sequence of the NS4A-NS4B junction. Experiments were carried out to optimize protease activity. Buffer requirements included the presence of dete... |
8794293 | Attachment and entry of recombinant Norwalk virus capsids to cultured human and animal cell lines. | Norwalk virus (NV) is the prototype strain of a group of noncultivable human caliciviruses responsible for epidemic outbreaks of acute gastroenteritis. While these viruses do not grow in tissue culture cells or animal models, expression of the capsid protein in insect cells results in the self-assembly of recombinant N... |
11607705 | Dendrimer-supported combinatorial chemistry. | A new methodology for the construction of combinatorial libraries is described. The approach, termed dendrimer-supported combinatorial chemistry (DCC), centers on the use of dendrimers as soluble supports. Salient features of DCC include solution phase chemistry, homogeneous purification, routine characterization of in... |
26964630 | Benzodiazepinen in perspectief (I): De GABAA-benzodiazepine-receptor. | In this first part of a review on recent insights into the structure and function of the γ-aminobuty rie acid type A - benzodiazepine receptor system, the γ-aminobutyric acid type A (GABAA) receptor and the different types of benzodiazepine (BDZ) receptors known at this moment are dicussed. GABAA- and BDZ receptors are... |
21619353 | Immobilization of crown ether carboxylic acids on silica gel and their use in column concentration of alkali metal cations from dilute aqueous solutions. | Eight crown ethers with pendent carboxylic acid groups are immobilized on silica gel and utilized for column concentration of alkali metal cations from dilute aqueous solutions. The column concentration selectivity and efficiency are found to be strongly influenced by (1) the cavity size of the crown ether unit, (2) co... |
16467911 | Modeling the maximum charge state of arginine-containing Peptide ions formed by electrospray ionization. | A model for the gas-phase proton transfer reactivity of multiply protonated molecules is used to quantitatively account for the maximum charge states of a series of arginine-containing peptide ions measured by Downard and Biemann (Int. J. Mass Spectrom. Ion Processes 1995, 148, 191-202). We find that our calculations a... |
11667481 | Selective Oxygen Transfers with Iron(III) Porphyrin Nitrite. | The reaction of octaethylporphyrin iron(III) chloride with potassium crown ether (18-crown-6) nitrite in N-methylpyrrolidone-1% acetic acid under argon generates the iron(III) nitrite salt (PFeNO(2)). The latter is a unique and selective oxygen atom transfer reagent. The reaction of a broad range of substrates (S) proc... |
11666748 | Electrochemistry and Spectral Characterization of Oxidized and Reduced (TPPBr(x)())FeCl Where TPPBr(x)() Is the Dianion of beta-Brominated-Pyrrole Tetraphenylporphyrin and x Varies from 0 to 8. | The electrochemistry and spectroelectrochemistry of (TPPBr(x)())FeCl (TPPBr(x)() is the dianion of beta-brominated-pyrrole tetraphenylporphyrin and x = 0-8) were examined in PhCN containing tetra-n-butylammonium perchlorate (TBAP) as supporting electrolyte. Each compound undergoes two reversible to quasireversible one-... |
11666744 | CO(2) Fixation by Novel Copper(II) and Zinc(II) Macrocyclic Complexes. A Solution and Solid State Study. | Solutions containing Zn(II) and Cu(II) complexes with [15]aneN(3)O(2) rapidly adsorb atmospheric CO(2) to give {[ZnL](3)(&mgr;(3)-CO(3))}.(ClO(4))(4) (2) and {[CuL](3)(&mgr;(3)-CO(3))}.(ClO(4))(4) (4) complexes. The crystal structures of both complexes have been solved (for 2, space group R3c, a, b = 22.300(5) Å, c = 1... |
9174968 | End point attached heparin affinity matrix. | Heparin is a highly sulfated long-chain glycosaminoglycan utilized extensively for its anticoagulation properties, which has found widespread use as a general affinity ligand. The polysaccharide is composed of repeating units of uronic acid and glucosamine with great variability in sequence within the chain. The high d... |
9174967 | Purification of an expressed insect transferrin from cell culture media using high-capacity Ni(2+)-dipicolylamine gel. | Vertebrate transferrin is a well characterized iron transport protein. In contrast, little is known concerning the role of transferrin in insects. Yet, study of iron metabolism in insects could give insights into strategies for insect control, particularly for insects that transmit disease. |
9174966 | Analysis of antibody selection by phage display utilizing anti-phenobarbital antibodies. | The generation of new antibodies for diagnostic applications using phage display could greatly decrease the time and expense of new assay development but, to be effective, the process must yield antibodies with desired specificity and affinity comparable to those obtained by monoclonal antibody technology. In order to ... |
9174965 | Interactions and applications of soluble heterobifunctional affinity chelating polymers in immobilized metal affinity chromatography. | The interaction of immobilized metal-chelating adsorbents with a dual heterobifunctional soluble polyethylene glycol (PEG) of the form X-PEG-Y is described, where X represents an affinity ligand and Y a chelating agent. The bifunctional PEG derivative used in this study was biotin-PEG-iminodiacetic acid (IDA). Affinity... |
9174964 | Well defined dye adsorbents for protein purification. | When activating a matrix with epichlorohydrin, the degree of activation can be controlled by the amount of epichlorohydrin added and the length of time of the reaction. The epoxy group can react with thiols and amines to produce N- and S-linked adsorbents for protein purification. The epoxy-activated gel may also react... |
9174963 | Purification and identification of ABA-binding proteins and antibody preparation. | Maize root membranes were extracted and the solubilized proteins were affinity-purified using an ABA-BSA-Sepharose 4B matrix. The retained proteins were eluted with 4M urea or 10(-4)M ABA. ABA could elute the binding proteins but other phytohormones, such as IAA or GA3, could not. ABA binding activity was detected in A... |
9174962 | Copper binding studies of lipases from different sources using image binding: mechanism of free copper and chelated copper. | Immobilized metal-ion affinity gel electrophoresis (IMAGE) has been demonstrated to be an efficient tool to study the binding of proteins to chelated transition metals such as Cu(II). IMAGE was exploited to isolate several lipases from different sources and so evaluate their affinities for iminodiacetic acid (IDA)-Cu(I... |
9174961 | Effect of immobilization on the penicillin binding and reactivity properties of DD-peptidase from Streptomyces R61. | An affinity gel matrix containing an enzyme (DD-peptidase) with specific beta-lactam binding properties was characterized with respect to its binding and reactivity behavior with penicillin. The data show that immobilization of DDP by reaction with the enzymes susceptible amino groups resulted in changes in catalytic a... |
9174960 | Diazotizable supports of potential interest as affinity chromatography matrices. | Immobilization of affinity ligands, proteins, enzymes and other functional groups by azo coupling is based on the high reactivity of the support-carrying diazonium groups towards both low- and high-molecular weight compounds containing certain groupings such as phenols, imidazole and some other heterocycles, thiols and... |
9174959 | Size-exclusion phases and repulsive protein--polymer interaction/recognition. | Size-dependent exclusion of macromolecules from gel matrices has long been discussed in terms of pore models. An alternate approach is to calculate the partition coefficient of the distributed species between the matrix material and the mobile phase assuming that the gel can be treated as a polymer solution of appropri... |
9174958 | Chiral recognition in adrenergic receptor binding mimics prepared by molecular imprinting. | Molecularly imprinted polymers were prepared against the adrenomimetic agents ephedrine and pseudoephedrine. These compounds each incorporate two chiral centres. The polymers were evaluated with respect to enantiodiscrimination of various adrenergic ligands. The selectivity of the polymeric binding sites for the imprin... |
9174957 | Oriented immobilization of restriction endonuclease EcoRI. | Two activated matrices have been developed to determine whether immobilization chemistry can be used to orient proteins on a support. Restriction endonuclease EcoRI from Escherichia coli RY13 (E.C.3.1.23.13) was used as a model in these studies. Thiol-activated Sephadex G-10 was used to couple the EcoRI endonuclease th... |
9174956 | Study of the nature of recognition in molecularly imprinted polymers. | In the present study molecularly imprinted polymers (MIPs) were prepared against a series of structurally related compounds containing various numbers of pyridyl groups. The goal, to increase understanding of the mechanisms of recognition in MIPs, was achieved by comparing the patterns of retention of the imprinted com... |
9174955 | Five-membered mercaptoheterocyclic ligands for thiophilic adsorption chromatography. | A series of five-membered mercaptoheterocyles containing at least two heteroatoms in their ring structure was investigated for their ability to specifically adsorb antibodies. The structures that contain at least one double bond adsorbed antibodies, while the saturated structure showed no protein interaction under the ... |
9174954 | New technologies for amperometric biosensors. | Amperomeric-based detectors have successfully been used as personal monitors for blood glucose levels. However, there is a desire to increase the number of compounds measured in a small blood sample, the speed of detection and enhance the reliability of the measurement. Furthermore, with the increasing use of microdial... |
9174953 | Biosensors in flow-injection systems for biomedical analysis, process and environmental monitoring. | This paper presents the construction of various biosensors using thin-film layers incorporated in flow injection devices, providing automated systems for biomedical analysis, process and environmental monitoring. A urease sensor has been developed in conjunction with a flow injection system for the automatic determinat... |
9174952 | Some recent developments in the preparation of novel recognition systems: a recognition site for the selective catalysis of an aldol condensation using molecular imprinting and specific affinity motifs for alpha-chymotrypsin using a phage display peptide library. | Molecular imprinting and phage display library technologies are rapidly being accepted as useful techniques for the generation of ligand-selective recognition motifs. The use of molecular imprinting to produce a novel type II aldolase mimic selective for the cobalt(II)-mediated aldol condensation of benzophenone and ac... |
9174951 | Novel method for coupling of poly(ethyleneglycol) to carboxylic acid moieties of proteins. | Lack of toxicity, excellent solubility and superb biocompatibility make polyethylene glycol (PEG) one of the most popular modifiers of biologicals. The most common method for attachment of PEG is based on modification of amino groups of proteins with methoxy- or succinimide-derivatives of PEG. In the case of proteins w... |
9174950 | Discriminatory recognition of membrane phospholipids by lysine-49-phospholipases A2 from Trimeresurus flavoviridis venom. | Basic proteins I and II (BP-I and BP-II) isolated from Trimeresurus flavoviridis venom, which are classified into a group of lysine-49-phospholipases A2 (Lys-49-PLA2), exhibited only limited lipolytic activity for the mixed micelles of various phospholipids. Based on the finding that BP-II elicits a strong contraction ... |
9174949 | Epitope contiguous chains and antibody recognition in HIV-1 synthetic peptide antigens. | Five peptides derived from human immuno deficiency virus (HIV-1) gp41 transmembrane protein have been synthesized: M9 (610-618), M12 (598-609), M15 (600-614), M21 (584-604) and M23 (587-609). These sequences partially overlap in the region vicinal to the immunodominant epitope CSGKLIC, between two cysteine residues 603... |
9174948 | 'Wiring' of lactate oxidase within a low-redox potential electron-conducting hydrogel. | Lactate electrodes based on electron-conducting hydrogels made by cross-linking lactate oxidase and the redox polymer formed upon complexing polyvinyl imidazole with [Os(dmo-bpy)2Cl]+/2+ (dmo-bpy = 4,4'-dimethoxy-2,2'-bipyridine) on vitreous carbon electrode surfaces were investigated. The redox potential of the hydrog... |
9174947 | The engineering of biomaterials exhibiting recognition and specificity. | Although synthetic materials are now widely used in implanted medical devices, they are not engineered for recognition and specificity. This article considers the design of polymer surfaces that might be specifically recognized and trigger normal healing pathways. The technological advances that will contribute to bior... |
9174946 | Affinity adsorption of Saccharomyces cerevisiae on concanavalin A perflurocarbon emulsions. | Perfluorocarbon affinity emulsions have been generated by immobilizing concanavalin A onto the surface of triazine-activated perfluorocarbon droplets. Immobilized concanavalin A densities of 0.1, 0.7 and 2.1 mg/ml were obtained by varying the concentration of cyanuric chloride used for activation. The affinity emulsion... |
9174945 | Intermolecular chiral recognition probed by enantiodifferential excited-state quenching kinetics. | Time-resolved chiroptical luminescence (TR-CL) measurements are used to study the kinetics of chirality-dependent excited-state quenching processes in aqueous solution. Experiments are carried out on samples that contain a racemic mixture of chiral luminophore molecules (L) in solution with a small, optically active co... |
9174944 | Multiple affinity domains for the detection, purification and immobilization of recombinant proteins. | Affinity systems based on specific molecular recognition are valuable tools for detection, purification and immobilization of recombinant proteins. Here, novel multipartite affinity fusion vectors were assembled and investigated to allow flexible binding and elution conditions. The rationale for the assembly of differe... |
9174943 | Application of perfluorocarbons in novel continuous counter-current protein chromatography. | In this work the development of a process capable of extracting proteins from particulate-containing solutions (such as fermentation broths) on a continuous basis, and in which absorbent and process streams are contacted counter-currently is described. The process consists of four stages, required for the loading, wash... |
9174942 | Sequence of bifurcations in an 'antigen-antibody' reaction. | The aperiodically singularly disturbed system of ordinary differential equations describing the process of the formation of the antibody complex initiated by antigen binding was analysed. The numerical and analytical examinations showed that there are solutions which correspond to primary Hopf bifurcation and subsequen... |
9174941 | Protein A mimetic peptide ligand for affinity purification of antibodies. | A peptide mimicking protein A for its ability to recognize the Fc immunoglobulin portion has been identified through screening of a synthetic multimeric peptide library. Screening of the multimeric library, composed of randomized synthetic tripeptide tetramers, has been carried out using a very simple assay, measuring ... |
9174940 | Immobilization of conalbumin onto polystyrene/divinylbenzene co-polymers: towards finding the best support for MAMC. | Immediately after the successful immobilization of conalbumin onto CNBr-activated Sepharose, efforts were begun to find a less expensive support and a more benign chemistry of activation. The potential of the Sepharose-conalbumin conjugate for decontamination of several metal-containing waste-waters has been establishe... |
9174939 | Synthesis and characterization of sol-gel phase-reversible hydrogels sensitive to glucose. | A new type of hydrogel capable of sol-gel phase-reversible transition by changes in the environmental glucose concentration has been synthesized. The hydrogel consists of vinylpyrrolidinone-allylglucose (VP/AG) copolymer and concanavalin A (Con A). The formation of the hydrogel is based on the specific interaction betw... |
9174938 | Dihydrofolate reductase synthesis in the presence of immobilized methotrexate. An approach to a continuous cell-free protein synthesis system. | Dihydrofolate reductase was synthesized in a batch system in the presence of the affinity ligand methotrexate, bound to various matrices. Two types of gel were used: commercial methotrexate-agarose with pores inaccessible for translation machinery and methotrexate-POROS with pores easily accessible for translation reac... |
9174937 | in vivo targeting of colloidal carriers by novel graft copolymers. | One of the major obstacles to the targeted delivery of colloidal carriers (nanocapsules) is the body's own defence mechanism in capturing foreign particles by the reticuloendothelial system (RES). This means that following intravenous administration, practically all nanometer size particles are captured by the RES (mai... |
9174936 | Effect of antibody orientation on immunosorbent performance. | The impact of antibody orientation on immunosorbent efficiency was quantitatively assessed. A pH-dependent murine monoclonal antibody (Mab) against human protein C (hPC), recombinant hPC (rhPC) and two different immobilization chemistries and matrices were used as model systems. The lysyl groups of the rhPC were covale... |
9174935 | Single nucleotide modulation of uridine to pseudouridine rearrangement in transfer RNA catalyzed by pseudouridine synthase I. | E. coli pseudouridine synthase I (PSUI) catalyzes the rearrangement of uridine residues in positions 38, 39 and 40 of tRNA transcripts to pseudouridine. These positions are located in the anticodon stem-loop of the tRNA molecule. Fourteen different E. coli tRNAs are substrates for the enzyme, whereas four other tRNAs w... |
9174934 | Cyclodextrin-aided capillary electrophoretic separation and laser-induced fluorescence detection of polynuclear aromatic hydrocarbons (PAHs). | Two neutral cyclodextrins (CDs), hydroxypropyl-beta-CD (HP beta OD) and methyl-beta-CD (M beta CD), and two negatively charged forms, carboxymethyl-beta-CD (CM beta CD) and sulfobutylether-beta-CD (SB beta CD), were used to demonstrate the principle of separation of hydrophobic and non-charged polynuclear aromatic hydr... |
9174933 | Polymer-shielded dye-affinity chromatography. | Polymer-shielded dye-affinity chromatography is a form of chromatography in which the dye matrix forms complexes with a nonionic, water-soluble polymer such as poly(vinylpyrrolidone) or poly(vinyl alcohol), prior to the column chromatography of a crude protein extract, the idea being that polymer shielding of the dye w... |
9174932 | Monitoring fibrinogen adsorption kinetics by interfacial TIRF rheometry. | The adsorption kinetics of purified fibrinogen to unmodified and aminopropylsilane-modified quartz glass surfaces were studied under pseudo-first order (binding-unit excess) conditions by the total internal reflection fluorescence (TIRF) method. Fluorescence in the adsorbed protein layer (350 nm) was excited by the eva... |
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