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11410854 | Effect of crown ethers on structure, stability, activity, and enantioselectivity of subtilisin Carlsberg in organic solvents. | Colyophilization or codrying of subtilisin Carlsberg with the crown ethers 18-crown-6, 15-crown-5, and 12-crown-4 substantially improved enzyme activity in THF, acetonitrile, and 1,4-dioxane in the transesterification reactions of N-acetyl-L-phenylalanine ethylester and 1-propanol and that of (+/-)-1-phenylethanol and ... |
11373723 | Photoinduced hydrogen evolution with peptide dendrimer-multi-Zn(II)-porphyrin, viologen, and hydrogenase. | To construct an artificial photosynthetic system, multi-Zn(II)-mesoporphyrins in peptide dendrimers were equipped as a photosensitizer of photoinduced hydrogen evolution in a four-component system (electron donor, photosensitizer, electron carrier, and catalyst), so that hydrogen was evolved effectively by the dendrime... |
11481344 | Clathrin-dependent and -independent internalization of plasma membrane sphingolipids initiates two Golgi targeting pathways. | Sphingolipids (SLs) are plasma membrane constituents in eukaryotic cells which play important roles in a wide variety of cellular functions. However, little is known about the mechanisms of their internalization from the plasma membrane or subsequent intracellular targeting. We have begun to study these issues in human... |
11473115 | Identification of a critical lysine residue in apolipoprotein B-100 that mediates noncovalent interaction with apolipoprotein(a). | We have previously shown that lipoprotein(a) (Lp(a)) assembly involves an initial noncovalent interaction between sequences within apolipoprotein(a) (apo(a)) kringle IV types 5-8 and the amino terminus of apolipoprotein B-100 (sequences between amino acids 680 and 781 in apoB-100), followed by formation of a disulfide ... |
11468386 | General rules for the packing of hydrogen-bonded crystals as derived from the analysis of squaric acid anions: aminoaromatic nitrogen base co-crystals. | Preparation and single-crystal X-ray structure determination of three co-crystals of hydrogen squarate, HSQ(-), with 2-aminopyrimidine, 3-aminopyridine and 4-aminopyridine, and one of squarate, SQ(2-), with 8-aminoquinoline are reported. Their crystal packings are analyzed and discussed in terms of the intermolecular O... |
11468383 | Crystal engineering in the gem-alkynol family: the key role of water in the structure of 2,3,5,6-tetrabromo-trans-1,4-diethynyl-cyclohexa-2,5-diene-1,4-diol dihydrate determined by X-ray and neutron diffraction at 150 K. | The structure of the title compound has been determined using low-temperature (150 K) single-crystal X-ray and neutron diffraction data. Crystals adopt the uncommon space group P4(2)/ncm and display a complex set of intermolecular interactions in which the water molecules play the crucial role: the water O-atom [O2(w)]... |
11468381 | Basic forms of supramolecular self-assembly organized by parallel and antiparallel hydrogen bonds in the racemic crystal structures of six disubstituted and trisubstituted cyclopentane derivatives. | A selection of stereoisomeric 2-hydroxy-1-cyclopentanecarboxamides, a 4-tert-butyl derivative and three tert-butyl derivatives of the respective carboxylic acid were subjected to X-ray crystallography. The optically active molecules (I)--(VI) form racemic crystals. Each racemic structure is basically determined by two ... |
11468378 | Correction of the space group of [Ni(bipy)(2)(ONO(2))(2)] x 2(pyrene). | The crystal structure of [Ni(bipy)(2)(ONO(2))(2)] x2(pyrene), poly[[[bis(nitrato-O)nickel(II)]bis(mu-4,4'-bipyridyl-N,N'] bis(pyrene)], was originally reported in space group Pn [Biradha et al. (1999). Chem. Commun. pp. 1327--1328]. Reasons are given for changing the space group to P2(1)/n. Consequently, incorrect desc... |
11470923 | Molecular determinants for CC-chemokine recognition by a poxvirus CC-chemokine inhibitor. | Poxviruses express a family of secreted proteins that bind with high affinity to chemokines and antagonize the interaction with their cognate G protein-coupled receptors (GPCRs). These viral inhibitors are novel in structure and, unlike cellular chemokine receptors, are able to specifically interact with most, if not a... |
11470915 | Insulin alters heterogeneous nuclear ribonucleoprotein K protein binding to DNA and RNA. | The interaction of the multimodular heterogeneous nuclear ribonucleoprotein (hnRNP) K protein with many of its protein and nucleic acid partners is regulated by extracellular signals. Acting as a docking platform, K protein could link signal-transduction pathways to DNA- and RNA-directed processes such as transcription... |
11470911 | Paradoxical intrathymic positive selection in mice with only a covalently presented agonist peptide. | The Y-Ae mAb and the 1H3.1 alphabeta T cell antigen receptor (TCR) are both specific for the I-Ealpha52-68 peptide bound to the I-A(b) major histocompatibility complex (MHC) class II molecule. Antigen-presenting cells (APCs) from I-A(b+) mice with a natural or transgenic (Tg) I-Ealpha chain activate mature 1H3.1 T cell... |
11470896 | Evolutionary self-organization of cell-free genetic coding. | Genetic encoding provides a generic construction scheme for biomolecular functions. This paper addresses the key problem of coevolution and exploitation of the multiple components necessary to implement a replicable genetic encoding scheme. Extending earlier results on multicomponent replication, the necessity of spati... |
11470894 | Effects of DNA sequence and structure on binding of RecA to single-stranded DNA. | Fluorescence anisotropy is used to follow the binding of RecA to short single-stranded DNA (ssDNA) sequences (39 bases) at low DNA and RecA concentration where the initial phase of polymerization occurs. We observe that RecA condensation is extremely sensitive to minute changes in DNA sequences. RecA binds strongly to ... |
11466321 | Agonist-dependent traffic of raft-associated Ras and Raf-1 is required for activation of the mitogen-activated protein kinase cascade. | Stimulation of HIRcB fibroblasts with insulin leads to accumulation of active components of the mitogen-activated protein kinase cascade in endocytic compartments. However, the factors that regulate the mobilization of these components through the endocytic pathway and the relevance of this event to cellular signaling ... |
11457834 | Activation of mitogen-activated protein kinase by membrane-targeted Raf chimeras is independent of raft localization. | Binding of proteins to the plasma membrane can be achieved with various membrane targeting motifs, including combinations of fatty acids, isoprenoids, and basic domains. In this study, we investigate whether attachment of different membrane targeting motifs influences the signaling capacity of membrane-bound signal tra... |
11447281 | Sir3-dependent assembly of supramolecular chromatin structures in vitro. | Baculovirus-expressed recombinant Sir3p (rSir3p) has been purified to near homogeneity, and its binding to naked DNA, mononucleosomes, and nucleosomal arrays has been characterized in vitro. At stoichiometric levels rSir3p interacts with intact nucleosomal arrays, mononucleosomes, and naked DNA, as evidenced by formati... |
11447273 | 4-Hydroxytamoxifen binds to and deactivates the estrogen-related receptor gamma. | The estrogen-related receptors (ERR alpha, ERR beta, and ERR gamma) form a family of orphan nuclear receptors that share significant amino acid identity with the estrogen receptors, but for which physiologic roles remain largely unknown. By using a peptide sensor assay, we have identified the stilbenes diethylstilbestr... |
11445568 | Analysis of the minimal amyloid-forming fragment of the islet amyloid polypeptide. An experimental support for the key role of the phenylalanine residue in amyloid formation. | The development of type II diabetes was shown to be associated with the formation of amyloid fibrils consisted of the islet amyloid polypeptide (IAPP or amylin). Recently, a short functional hexapeptide fragment of IAPP (NH(2)-NFGAIL-COOH) was found to form fibrils that are very similar to those formed by the full-leng... |
11443257 | p-methyltetrahomodioxacalix[4]arene. | The title compound, 7,13,21,27-tetramethyl-3,17-dioxapentacyclo[23.3.1.1(5,9).1(11,15).1(9,23)]ditriaconta-1(29),5,7,9(30),11(31),-12,14,19(32),20,22,25,27-dodecaene-29,30,31,32-tetraol, C34H36O6, assumes in the solid state a very distorted cone-like conformation stabilized by intramolecular simple and bifurcated hydro... |
11443247 | A novel hydrogen-bonded microporous framework constructed from two different metal complexes. | A hydrogen-bonded coordination supramolecule, (meso-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane-kappa4N)nickel(II) [N,N-o-phenylenebis(oxamato)-kappa4O,N,N',O']nickelate(II) dihydrate, [Ni(C16H36N4)][Ni(C10H4N2O6)]*2H2O or [Ni(meso-cth)][Ni(opba)]*2H2O, has been prepared and characterized by X-ray cryst... |
11438695 | Location and properties of metal-binding sites on the human prion protein. | Although a functional role in copper binding has been suggested for the prion protein, evidence for binding at affinities characteristic of authentic metal-binding proteins has been lacking. By presentation of copper(II) ions in the presence of the weak chelator glycine, we have now characterized two high-affinity bind... |
29712330 | Molecular Paneling by Coordination: An M<sub>15</sub> L<sub>6</sub> Hexahedral Molecular Capsule having Clefts for Reversible Guest Inclusion. | Only one positional isomer is obtained from the assembly of 21 small components. A triangular molecular panel with five coordination sites is assembled upon complexation with [Pd<sup>II</sup> (en)] (en=ethylenediamine) into a unique M<sub>15</sub> L<sub>6</sub> hexahedral coordination capsule (see X-ray structure). The... |
29712328 | Synthesis of a Nanoporous Polymer with Hexagonal Channels from Supramolecular Discotic Liquid Crystals. | Hydrogen-bonding interactions between a benzotri(imidazole) derivative and a polymerizable alkoxybenzoic acid result in the formation of a supramolecular hexagonal columnar liquid crystal. Light-induced polymerization followed by removal of the benzotri(imidazole) core produces a porous polymer with hexagonal channels. |
29712320 | Nematic Dendrimers Based on Carbosilazane Cores. | The controlled synthesis of nematic nanophase-separated materials poses an attractive synthetic challenge. The use of carbosilazane multipodes and dendrimers (such as 1) in conjunction with laterally attached mesogens allows the systematic investigation of the structure-property relationships of room-temperature nemati... |
29712318 | A Cyclic Hexapeptide Containing L-Proline and 6-Aminopicolinic Acid Subunits Binds Anions in Water. | A neutral receptor that binds anions by hydrogen bonds even in water is the cyclopeptide reported in this article. This property results from the particular structure of the complex in which the anions are effectively shielded from the surrounding solvent, as can be seen in the iodide complex shown. |
29712317 | Zeosil Nanoslabs: Building Blocks in nPr<sub>4</sub> N<sup>+</sup> -Mediated Synthesis of MFI Zeolite. | Tetrapropylammonium (TPA)-containing precursors are the building blocks in the crystallization of silica. In the first steps slab-shaped silicalite nanoparticles are formed by ordered combination of the precursors. These nanoslabs have MFI-type zeolite framework topology and play a key role in TPA-ion-mediated zeolite ... |
29712310 | A Novel Hemiporphyrazine Comprising Three Isoindolediimine and Three Thiadiazole Units. | Incorporation of three metal ions (Ni or Cu) in the macrocyclic ring and the formation of hexamers following a 3+3 approach are novel features of the hemiporphyrazines (one example shown) formed by the condensation of 2,5-diamino-1,3,4-triazole with isoindolediimines. This is in contrast to the corresponding reactions ... |
29712308 | Noncovalent Assembly of [2]Rotaxane Architectures. | Reversible zinc-pyridine coordination and hydrogen-bonding interactions have been used to assemble a [2]rotaxane from three components. Cooperativity in the macrocyclization process that results in the porphyrin dimer makes the system exceptionally stable. However, the kinetic lability of the zinc-porphyrin interaction... |
29712301 | Unprecedented Seven- and Eight-Connected Lanthanide Coordination Networks. | Eight-coordinate metal-ion nodes are linked through 4,4-bipyridine-N,N'-dioxide (L) ligands to form the first examples of eight- and seven-connected coordination networks. Thus, whereas [La(L)<sub>4</sub> ](CF<sub>3</sub> SO<sub>3</sub> )<sub>3</sub> adopts an eight-connected body-centered hypercubic CsCl-like lattice,... |
29712291 | A Synthetic Pore-Mediated Transmembrane Transport of Glutamic Acid. | Transported to the other side: Cyclic D,L-α-peptides self-assemble in lipid bilayers into transmembrane ion channels that may allow efficient transport of glutamic acid. The molecular transport is size/shape selective, as evidenced by the high transport rates observed with cyclodecapeptide-based transmembrane pores but... |
29712289 | Self-Assembly of Pyramidal Tetrapalladium Complexes with a Halide at the Apex. | Halide ions act as the template for the self-assembly of tetrapalladium macrocyclic pyramidal structures. These undergo easy inversion in which the halide ion apparently jumps across the macrocycle. |
29712282 | Exceptionally Long (≥2.9 Å) C-C Bonds between [TCNE]<sup>-</sup> Ions: Two-Electron, Four-Center π*-π* C-C Bonding in π-[TCNE]<sub>2</sub><sup>2</sup>. | Attractive interaction with the cation overcomes the electrostatic repulsion between two tetracyanoethylene radical anions, [TCNE]<sup>.-</sup> , and leads to the formation of a diamagnetic dimer [TCNE]<sub>2</sub><sup>2-</sup> , for example, in [K(glyme)]<sub>2</sub> [TCNE]<sub>2</sub> . The bonding is described as tw... |
29712279 | Novel Amide-Based Molecular Knots: Complete Enantiomeric Separation, Chiroptical Properties, and Absolute Configuration. | By comparison of experimental and theoretical CD curves the absolute configurations of chromatographically baseline-separated enantiomers of new trefoil molecular knots could be determined. From the results of syntheses with differently substituted starting materials, conclusions can be drawn about the knot-formation m... |
29712276 | Synthesis of a Remarkably Stable Dehydro[14]annulene. | The substituents at the peri positions of dehydro[14]annulenes 1 have a dramatic effect on the stability of these macrocycles, and lead to derivatives that are stable even at elevated temperatures (up to 190°C). |
29712270 | The First Inorganic "Tennis Ball" Encapsulating an Anion. | New balls please! Reaction of Cu(BF<sub>4</sub> )<sub>2</sub> with [(dach)Pt<sup>II</sup> ] (dach=trans (±)-1,2-diaminocyclohexane) and bis(ethylthio)methylenepropanedioate (BETMP) gave [{(dach)Pt(BETMP)}<sub>2</sub> Cu(BF<sub>4</sub> )<sub>2</sub> ] (1; shown schematically). Dimerization of 1 in methanol leads to the ... |
29712269 | Working Supramolecular Machines Trapped in Glass and Mounted on a Film Surface. | Two surface-tethered nanomachines have been constructed at a supramolecular level by employing cylinders of the π-electron deficient tetracationic cyclophane, cyclobis(paraquat-p-phenylene) (blue), inside which polyether pistons incorporating π-electron rich dioxynaphthalene units (red and pink) can be induced to move ... |
23696532 | Ordered nanostructures of a [2]catenane through self-assembly at surfaces--an STM study with sub-molecular resolution. | Model molecular machines can be prepared in solution; their requirements are still more restrictive when anchored onto a surface. Large two-dimensional crystals of [2]catenane were formed on HOPG through self-assembly--the picture shows a 15×15 nm(2) STM image of the surface-bound structure. A comparison with related s... |
23696531 | Colloidal organization and clusters: self-assembly of polyoxometalate-surfactant complexes towards three-dimensional organized structures. | Increased hydrophobicity of well-defined polyoxometalate clusters is possible through complexation with cationic surfactants in a one-pot reaction. The clusters, of toroid and spherical shape and colloidal dimensions, then organized into ordered, supramolecular assemblies, as shown schematically, are similar to classic... |
23105309 | Adenosine and its role in asthma. | Endogenous adenosine formed from ADP and AMP by the action of ATPase and 5'-nucleotidase is known to cause bronchoconstriction and asthma in humans. It has been suggested that this action of adenosine is due to its binding to specific purino receptors in the mast cells in the lungs and consequent release of mediators w... |
19003330 | Inhibition of hepatoma cell invasion beneath mesothelial-cell monolayer by sera from tea- and related component-treated rats and their modes of action. | The bioavailability and action of teas on the invasion of a rat ascites hepatoma cell line, AH109A, were determined and their modes of action were by co-culturing the cancer cells with a rat mesentery-derived mesothelial-cell (M-cell) monolayer in the presence of sera from rats orally given teas and their component, (-... |
19003316 | Effect of hypoosmotic pressure on cell growth and antibody production in recombinant Chinese hamster ovary cell culture. | To determine the response of recombinant Chinese hamster ovary (rCHO) cells subjected to hypoosmotic pressure, rCHO cells (CS13*-1.0) producing a chimeric antibody were cultivated in the hypoosmolar medium resulting from NaCl subtraction. At hypoosmotic pressure, CS13*-1.0 cells displayed decreased specific growth rate... |
19003311 | Lysine: Is it worth more? | Lysine, an essential cationic amino acid, has a positively charged R group. The structure of lysine is given as (H(3)N(+)-)CH(-COO(-))-CH(2)-CH(2)-CH(2)-CH(2)-N(+)H(3).While the anabolic role(s) of the molecule has been in focus for quite a few decades now, its biological properties, e.g. role in cellular proliferation... |
18049526 | Dendrimer molecules with record large two-photon absorption cross section. | We report what is to our knowledge a record high value for an intrinsic two-photon absorption (TPA) cross section, sigma(2) = 11 x 10(-47)> cm>(4)> s photon(-1) molecule(-1), measured with femtosecond pulses in a new dendrimer molecule comprising 29 repeat units of 4, 4(?)-bis(diphenylamino)stilbene chromophore. We mea... |
11443654 | Noncovalent Synthesis Using Hydrogen Bonding. | Hydrogen bonds are like human beings in the sense that they exhibit typical grouplike behavior. As an individual they are feeble, easy to break, and sometimes hard to detect. However, when acting together they become much stronger and lean on each other. This phenomenon, which in scientific terms is called cooperativit... |
11427027 | Effect of Particle Size on the Sticking Probability. | In the literature the transport of particles toward an oppositely charged collector in stagnation point flow is described theoretically with the Smoluchowski-Levich solution of the convective-diffusion equation. Using optical reflectometry, the initial adsorption rate in the case of adsorption of negatively charged pol... |
11880926 | Neurogenic inflammation of gingivomucosal tissue in streptozotocin-diabetic rat. | Previously it was assumed that nerve fibres are involved in the neurogenic inflammation induced by mechanical or chemical irriations. It has been also suggested that in diabetes mellitus the unmyelinated small diameter fibers are impaired as a result of diabetic neuropathy. Therefore, our aim was to study the alteratio... |
11683375 | Identification of a novel V1-type AVP receptor based on the molecular recognition theory. | <h4>Background</h4>The molecular recognition theory predicts that binding domains of peptide hormones and their corresponding receptor binding domains evolved from complementary strands of genomic DNA, and that a process of selective evolutionary mutational events within these primordial domains gave rise to the high a... |
11548860 | Ofloxacin/beta-cyclodextrin complexation. | Ofloxacin (OFX) is a fluorquinolone characterized by photochemical instability. With the goal to improve its photostability in aqueous solutions, the complexation of ofloxacin with beta-cyclodextrin was investigated. The complexes showed a water solubility enhancement of approximately 2.6 times; nevertheless, the photo... |
11548859 | Influence of the preparation method on the physicochemical properties of tolbutamide/cyclodextrin binary systems. | Tolbutamide (TBM) was found to form an inclusion complex with beta cyclodextrin (beta-CD) in solution and in solid state. Inclusion complex formation between tolbutamide and beta-cyclodextrin in aqueous solution was studied by phase solubility and spectral shift methods. The apparent stability constant Ks calculated by... |
11547900 | Molecular properties and involvement of heparanase in cancer progression and mammary gland morphogenesis. | Tumor spread involves degradation of various components of the extracellular matrix and blood vessel wall. Among these is heparan sulfate proteoglycan, which plays a key role in the self-assembly, insolubility and barrier properties of basement membranes and extracellular matrices. Expression of an endoglycosidase (hep... |
11529502 | Friedrich Miescher Prize awardee lecture review. A conserved family of nuclear export receptors mediates the exit of messenger RNA to the cytoplasm. | The distinguishing feature of eukaryotic cells is the segregation of RNA biogenesis and DNA replication in the nucleus, separate from the cytoplasmic machinery for protein synthesis. As a consequence, messenger RNAs (mRNAs) and all cytoplasmic RNAs from nuclear origin need to be transported from their site of synthesis... |
11529500 | Trans-Golgi network sorting. | The trans-Golgi network (TGN) is a major secretory pathway sorting station that directs newly synthesized proteins to different subcellular destinations. The TGN also receives extracellular materials and recycled molecules from endocytic compartments. In this review, we summarize recent progress on understanding TGN st... |
11521907 | Factorial design of electrolyte systems for the separation of fatty acids by capillary electrophoresis. | In this work, a capillary zone electrophoretic methodology using UV indirect detection (224 nm) for the analysis of fatty acids (FAs) in saponified oils is proposed. The electrolyte consisted of a 5 mmol l(-1) phosphate buffer, pH 7. containing 4 mmol l(-1) sodium dodecylbenzenesulfonate (SDBS) as chromophore, 4 mmol l... |
11521905 | Characterization of highly sulfated cyclodextrins. | A class of highly sulfated cyclodextrins (HS-CDs) was developed for enantiomeric separation of chiral compounds by capillary electrophoresis (CE). The HS-CDs were produced by a facile single-step direct sulfation of cyclodextrin using sulfur trioxide-trimethylamine complex in dimethylformamide. Characterization of the ... |
11521902 | Use of beta-cyclodextrin in the capillary zone electrophoretic separation of the components of clandestine heroin preparations. | The present paper describes the methodological optimization and validation of a capillary zone electrophoresis method for the rapid determination of heroin, secondary products and additives present in clandestine heroin samples, by using 20 mM beta-cyclodextrins in phosphate buffer, pH 3.23. Applied potential was 15 kV... |
11521900 | Determination of apparent binding constants of drugs by capillary electrophoresis using beta-cyclodextrin as ligand and three different linear plotting methods. | Capillary electrophoretic estimation of apparent binding constants (Kapp) for naproxen, salbutamol, indomethacine and procaine with beta-cyclodextrin is presented. While with naproxen and indomethacine this approach was straightforward and gave well compatible results by three different linearization plots (double reci... |
11521897 | Enantiomeric separation of R,S-naproxen by conventional and nano-liquid chromatography with methyl-beta-cyclodextrin as a mobile phase additive. | Chiral separations of R,S-naproxen mixtures were obtained on an achiral column (ODS) with methyl-beta-cyclodextrin as a mobile phase additive using conventional and nano-LC. The optimised mobile phase composition was 20 mmol l(-1) methyl-beta-cyclodextrin, 20% (v/v) acetonitrile, and 50 mmol l(-1) sodium acetate buffer... |
11518567 | Carotenoid incorporation into natural membranes from artificial carriers: liposomes and beta-cyclodextrins. | Liposomes and beta-cyclodextrin (beta-CD) have been used as carriers for the incorporation of three dietary carotenoids (beta-carotene (BC), lutein (LUT) and canthaxanthin (CTX)) into plasma, mitochondrial, microsomal and nuclear membrane fractions from pig liver cells or the retinal epithelial cell line D407. The upta... |
11518192 | Expression of GRK2 is increased in the left ventricles of cardiomyopathic hamsters. | Reduced beta-adrenergic responsiveness in the heart is a characteristic feature of heart failure. G protein-coupled receptor kinase 2 (GRK2) phosphorylates beta-adrenoceptors in an agonist-dependent manner, causing receptor uncoupling and desensitisation. Elevated levels of both GRK2 mRNA and activity have been shown t... |
11516154 | A novel plastid-targeted J-domain protein in Arabidopsis thaliana. | Arabidopsis cDNAs encoding ATJ11, the smallest known J-domain protein, have been isolated and characterized. The precursor protein of 161 amino acid residues was synthesized in vitro and imported by isolated pea chloroplasts where it was localized to the stroma and cleaved to a mature protein of 125 amino acid residues... |
11510547 | Quantitative determination of amygdalin epimers by cyclodextrin-modified micellar electrokinetic chromatography. | A new capillary electrophoresis method was developed for the quantitative determination of the amygdalin epimers, amygdalin and neoamygdalin, which are biologically significant constituents in the crude drugs, namely Persicae Semen and Armeniacae Semen. The effects of surfactants, additives and other analytical paramet... |
11510545 | Mechanistic study of enantiomeric recognition of primary amino compounds using an achiral crown ether with cyclodextrin by capillary electrophoresis and nuclear magnetic resonance. | A model and theoretical equations are presented to investigate the enantiomeric recognition mechanism of primary amino compounds using an achiral crown ether with cyclodextrin by capillary electrophoresis (CE) and nuclear magnetic resonance (NMR). Association constants were calculated from CE and 1H NMR experiment resu... |
11510532 | Molecular recognition in imprinted polymers: thermodynamic investigation of analyte binding using microcalorimetry. | This study aimed at elucidating the interaction mechanism between an imprinted polymer and its template in aqueous environment with thermodynamic aspects. The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) was chosen as a model template to imprint a co-polymer of 4-vinylpyridine (4-VP) and ethyleneglycol dimethacryla... |
11504061 | Determination of pesticides in drinking water by micellar electrokinetic capillary chromatography. | A new analytical procedure using a two-step sample preconcentration (solid-phase extraction (SPE) and field-amplified sample stacking) prior to separation by micellar electrokinetic capillary chromatography was developed for the determination of 14 pesticides such as aldicarb, carbofuran, isoproturon, chlorotoluron, me... |
11504050 | Separation of chlorophenoxyacetic acids and chlorophenols by using capillary zone electrophoresis. | In this study, the choice of electrolyte systems for the separation and detection of a range of chlorophenoxyacetic acids and chlorophenols by means of capillary zone electrophoresis (CZE) is discussed. A series of acetate buffers over the buffering capacity pH range 4.03-5.5 were initially chosen for the separation. I... |
11504048 | Sol-gel technique for the preparation of beta-cyclodextrin derivative stationary phase in open-tubular capillary electrochromatography. | A novel open-tubular capillary electrochromatography (OT-CEC) column coated with 2,6-dibutyl-beta-cyclodextrin (DB-beta-CD) was prepared using sol-gel technique. In the sol-gel approach, owing to the three-dimensional network of sol-gel and the strong chemical bond between the stationary phase and the surface of capill... |
11504044 | Interaction between 18-crown-6-tetracarboxylic acid and positional substituents of enantiomers and simultaneous separation of positional enantiomers of methyl-DL-tryptophans by capillary electrophoresis. | 18-Crown-6-tetracarboxylic acid (18C6H4) is a chiral selector with high selectivity for the enantioseparation of solutes bearing the primary amine function. This work presents the simultaneous separation of positional enantiomers of methyl-DL-tryptophans by using 18C6H4 as an additive to the background electrolyte. Sep... |
11501675 | Activity against Mycobacterium tuberculosis with concomitant induction of cellular immune responses by a tetraaza-macrocycle with acetate pendant arms. | The novel tetraaza-macrocyclic compound 3,7,11-tris(carboxymethyl)-3,7,11,17-tetraaza-bicyclo[11.3.1]heptadeca-1(17),13,15-triene, abbreviated as ac3py14, was investigated for its activity against Mycobacterium tuberculosis and for induction of protective cellular immune responses. Perspective results show that ac3py14... |
11500972 | Src homology-2 domain binding assays by scintillation proximity and surface plasmon resonance. | Various SH2 competitive binding assays, based on different techniques, have been described in the literature to identify and characterize SH2 ligands. The consideration that most reported methods show experimental limitations associated with assay parameters has prompted us to base our Src-SH2 inhibitor discovery progr... |
11500971 | IgM expressed by leukemic CD5(+) B cells binds mouse immunoglobulin light chain. | Mouse immunoglobulin (Ig) molecules have previously been shown to bind to the surface of CD5(+) B cells from patients with B-cell chronic lymphocytic leukemia (B-CLL). The results indicated that surface IgM was involved in the interaction and suggested the phenomenon was an example of the polyreactive binding capacity ... |
11500970 | Localization of the large subunit of replication factor C near the 5' end of DNA primers. | Replication factor C (RFC) is a heteropentameric sliding clamp loader protein essential for processive synthesis of DNA by eukaryotic DNA polymerases delta and epsilon. To study the interaction of RFC with 3' and 5' ends of the DNA primer, we have developed chemical photocrosslinking assay using a synthetic DNA gap and... |
11500969 | Binding of synthetic peptides by a human monoclonal IgM with an unusual combining site structure. | Using X-ray crystallography, a human monoclonal IgM cryoglobulin (Mez) was found to have an unusual combining site topography. Analysis of the unliganded Fv at 2.6 A resolution revealed that the HCDR3 had partitioned the active site into two compartments [Ramsland PA et al. 2000. Mol. Immunol. 37: 295-310]. The two cav... |
11500968 | BIACORE J: a new platform for routine biomolecular interaction analysis. | SPR biosensor technology continues to evolve. The recently released platform from Biacore AB (Uppsala, Sweden), BIACORE J, is designed for the routine analysis of biomolecular interactions. Using an antibody-protein A and a ligand-receptor system, we demonstrate the utility of BIACORE J in determining active concentrat... |
11500967 | Direct monitoring of molecular recognition processes using fluorescence enhancement at colloid-coated microplates. | Direct monitoring of recognition processes at the molecular level is a valuable tool for studying reaction kinetics to assess affinity constants (e.g. drugs to receptors) and for designing rapid single step immunoassays. Methods currently used to gain information about binding processes predominantly depend on surface ... |
11500966 | Statistical analysis of atomic contacts at RNA-protein interfaces. | Forty-five crystals of complexes between proteins and RNA molecules from the Protein Data Bank have been statistically surveyed for the number of contacts between RNA components (phosphate, ribose and the four bases) and amino acid side chains. Three groups of complexes were defined: the tRNA synthetases; the ribosomal... |
11499924 | Expression of mouse anticreatine kinase (MAK33) monoclonal antibody in the yeast Hansenula polymorpha. | The methylotrophic yeast Hansenula polymorpha HM1-39 (ura 3 and leu 2) was used as a host strain for the expression of the Fab fragment of the MAK33 monoclonal antibody. The MAK33 antibody reacts specifically with creatine kinase-M. The cDNA of kappa and gamma chains were inserted between the FMD or MOX promoter and th... |
11496956 | Oral delivery of biologically active parathyroid hormone. | <h4>Purpose</h4>Parathyroid hormone (PTH), the only drug known to stimulate bone formation. is a peptide therapeutic indicated in the treatment of osteoporosis. Unfortunately, PTH is only effective when dosed by injection because it has no oral bioavailability. Herein we report the oral absorption of PTH in rats and mo... |
11496953 | A new colorimetric assay for studying and rapid screening of membrane penetration enhancers. | <h4>Purpose</h4>This work aims to demonstrate a novel chemical assay for rapid screening and analysis of the mode of action of membrane interaction by penetration enhancers.<h4>Methods</h4>The new bio-mimetic membrane assembly, consisting of supramolecular aggregates of lipids and conjugated polydiacetylene, undergoes ... |
11496951 | Interactions between oligonucleotides and cationic polymers investigated by fluorescence correlation spectroscopy. | <h4>Purpose</h4>To evaluate whether fluorescence correlation spectroscopy (FCS) can be used to characterize the complexation between oligonucleotides and cationic polymers.<h4>Methods</h4>The features of the complexes between rhodamine labeled oligonucleotides (Rh-ONs) and poly(2-dimethylamino)ethyl methacrylate (pDMAE... |
11495437 | Synthesis and characterization of linear, hyperbranched, and dendrimer-like polymers constituted of the same repeating unit. | The synthesis of a linear polymer that includes both P=N and P=S double bonds, and P-O and P-C single bonds is reported by using two different paths that involve deprotection reactions and the Staudinger reaction. The preparation of hyperbranched polymers made up of OC6H4P(Ph)2=N-P=S repeating units is also described. ... |
11495428 | High-spin iron(II) as a semitransparent partner for tuning europium(III) luminescence in heterodimetallic d-f complexes. | The segmental ligand 2-[6-(N,N-diethylcarbamoyl)pyridin-2-yl]-1,1'-dimethyl-5,5'-methylene-2'-(6-methylpyridine-2-yl)bis[1H-benzimidazole] (L3) reacts with a stoichiometric mixture of LnIII (Ln = La, Eu, Gd) and M(II) (M = Zn, Fe) in acetonitrile to produce selectively the heterodimetallic triple-stranded helicates (HH... |
11495426 | Novel chiral macrocycles containing two electronically interacting arylene chromophores. | Novel chiral macrocycles consisting of two rigid oligoarylene rods and two chiral spiroindane clips have been synthesized by condensation of spiroindane diols and CF3-activated alpha-omega-difluorooligoaryls. Since a broad variety of planar aromatic macrocycles is known, our non-planar, chiral rings represent a new cla... |
11487971 | Chiral separation of verapamil and some of its metabolites by HPLC and CE. | HPLC and CE assays were developed for chiral separations of verapamil and its metabolites in serum samples. Three chiral HPLC columns (Chiralcel OJ, Chiralpak AD and Chiralcel OD-R) were tested in normal and reverse-phase modes. All HPLC analyses were performed with fluorescence detection at 276 and 310 nm. CE was real... |
11486962 | Ferrocene-cyclam: a redox-active macrocycle for the complexation of transition metal ions and a study on the influence of the relative permittivity on the coulombic interaction between metal cations. | The reaction of 1,1'-ferrocene-bis(methylenepyridinium) salt with 1,4,8,11-tetraazacyclotetradecane-5,12-dione, followed by LiAlH4 reduction results in the formation of FcCyclam. Metal complexes of FcCyclam with M2+ = Co2+, Ni2+, Cu2+, and Zn2+ were synthesized from FcCyclam and the respective metal triflates. The comp... |
11486957 | Helical molecular programming: supramolecular double helices by dimerization of helical oligopyridine-dicarboxamide strands. | Helically preorganized oligopyridine-dicarboxamide strands are found to undergo dimerization into double helical supramolecular architectures. Dimerization of single helical strands with five or seven pyridine rings has been characterized by NMR and mass spectrometry in various solvent/ temperature conditions. Solution... |
11486950 | A liquid-crystalline silsesquioxane dendrimer exhibiting chiral nematic and columnar mesophases. | A hexadecamer, first-generation, octasilsesquioxane liquid-crystalline dendrimer was synthesized by a platinum-catalyzed hydrosilylation reaction of the parent first-generation vinyl octasilsesquioxane dendrimer with a modified, laterally substituted mesogen. The structure and purity of the octasilsesquioxane substrate... |
11486947 | Point-dipole approximation of the exciton coupling model versus type of bonding and of excitons in porphyrin supramolecular structures. | The application of the exciton coupling model to interacting porphyrin chromophores is discussed. Covalently bonded systems and ionic or electrostatically bonded homoassociates require different orientations of the transition dipole moments in order to explain the experimental results: according to the symmetry of the ... |
11486892 | Macroporous copolymer matrix. IV. Expanded bed adsorption application. | Macroporous crosslinked hydroxyethyl methacrylate-ethylene dimethacrylate copolymeric beads (HEG beads) were synthesized by suspension polymerization in the presence of a pore generating agent. These beads were coupled to alpha-cyclodextrin through a urethane spacer. These modified copolymer beads (affinity-HEG beads) ... |
11485736 | Crystal structure of the IL-10/IL-10R1 complex reveals a shared receptor binding site. | Interleukin 10 (IL-10) is a dimeric cytokine that plays a central role in suppressing inflammatory responses. These activities are dependent on the interaction of IL-10 with its high-affinity receptor (IL-10R1). This intermediate complex must subsequently recruit the low-affinity IL-10R2 chain before cell signaling can... |
11485618 | Lipid rafts and HIV pathogenesis: host membrane cholesterol is required for infection by HIV type 1. | In a previous study we showed that budding of HIV-1 particles occurs at highly specialized membrane microdomains known as lipid rafts. These microdomains are characterized by a distinct lipid composition that includes high concentrations of cholesterol, sphingolipids, and glycolipids. Since cholesterol is known to play... |
11478636 | Enantioselective molecular sensing of aromatic amines using tetra-(S)-di-2-naphthylprolinol calix[4]arene. | This paper presents new analytical data, and evidence of the fluorescence quenching mechanism involved in enantioselective signals obtained with the chiral host tetra-(S)-di-2-naphthylprolinol calix[4]arene. Excellent selectivity is obtained with phenylglycinol and norephidrine in methanol, and samples of unknown enant... |
11473447 | Cyclopeptides from the bark of Discaria americana. | Two new cyclopeptides, named discarene C (1) and discarene D (2), have been isolated from the bark of Discaria americana, along with seven known cyclopeptide alkaloids. The structures of the new compounds were determined by spectroscopic methods, mainly NMR. The stereochemistry of the ring amino acid residues have been... |
11471805 | Ion chromatography on chelating stationary phases: separation of alkali metals. | Analytical 250x4.6 mm I.D. columns packed with iminodiacetic acid (IDA) derivatised silica were used to separate alkali metal ions and the ammonium ion in combination with non-suppressed conductivity detection. The addition of 2.5-10 mmol/l of the macrocyclic crown ether 18-crown-6 to the nitric acid eluent resulted in... |
11471804 | Determination of the UV filters worldwide authorised in sunscreens by high-performance liquid chromatography. Use of cyclodextrins as mobile phase modifier. | Simultaneous determination of organic UV filters worldwide authorised in sunscreen formulations was performed by HPLC with UV spectrophotometric detection. The filters determined were: benzophenone-4, benzophenone-3, butyl methoxydibenzoylmethane, octyl dimethyl PABA, octyl methoxycinnamate, homosalate and octyl salicy... |
11471711 | Fluorometric study of the inclusion interaction of beta-cyclodextrin derivatives with tetraphenylporphyrin and its analytical application. | The effects of native beta-cyclodextrin (beta-CD) and four kinds of alkylated beta-cyclodextrin (beta-CDs), i.e. heptakis (2,6-di-O-isobutyl-beta-cyclodextrin) (I), heptakis (2,6-di-O-octyl-beta-cyclodextrin) (II), heptakis (2,6-di-O-dodecyl-beta-cyclodextrin) (III), and heptakis (2,6-di-O-hexadecyl-beta-cyclodextrin) ... |
11471710 | Spectroscopic studies on molecular recognition capabilities of a nucleolipid bearing thymine headgroup to adenosine. | The Langmuir-Blodgett (LB) films of octadecanoyl ester of 1-(2-carboxyethyl) thymine deposited from pure water and aqueous adenosine subphases were investigated by ultraviolet-visible (UV-vis), Fourier transform infrared-attenuated total reflection (FTIR-ATR), and Fourier transform surface-enhanced Raman scattering (FT... |
11470819 | Residual Cajal bodies in coilin knockout mice fail to recruit Sm snRNPs and SMN, the spinal muscular atrophy gene product. | Cajal bodies (CBs) are nuclear suborganelles involved in the biogenesis of small nuclear ribonucleoproteins (snRNPs). In addition to snRNPs, they are highly enriched in basal transcription and cell cycle factors, the nucleolar proteins fibrillarin (Fb) and Nopp140 (Nopp), the survival motor neuron (SMN) protein complex... |
11470817 | Regulation of limb patterning by extracellular microfibrils. | To elucidate the contribution of the extracellular microfibril-elastic fiber network to vertebrate organogenesis, we generated fibrillin 2 (Fbn2)-null mice by gene targeting and identified a limb-patterning defect in the form of bilateral syndactyly. Digit fusion involves both soft and hard tissues, and is associated w... |
11467563 | Immobilized fluorescent cyclodextrin on a cellulose membrane as a chemosensor for molecule detection. | Dansylglycine-modified cyclodextrin (DnsC4-beta-CD) was prepared as a fluorescent host that is capable of being immobilized on a cellulose membrane (DnsC4-beta-CD membrane). DnsC4-beta-CD immobilized on the cellulose membrane decreased its fluorescence intensity with increasing concentration of guest molecules, indicat... |
11467553 | Chromatographic probing of electrostatic potential. | Electrostatic potential in the vicinity of the surface of a cation-exchange resin has been evaluated by modeling chromatographic retention. Binary mixtures of K+ and its crown ether complex in methanol are used as mobile phases, and two types of solutes, that is, cationic and crown ether probes, have been examined. The... |
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