id stringlengths 4 8 | title stringlengths 1 642 | abstract stringlengths 50 17.9k |
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12793820 | Self-assembly of dialkyltin(IV) moieties and aromatic dicarboxylates to complexes with a polymeric or a discrete trinuclear macrocyclic structure in the solid state and a mixture of fast interchanging cyclooligomeric structures in solution. | It is well-known that the structures of trialkyltin(IV) carboxylates can be either monomeric, polymeric, or cyclooligomeric in the solid state. In contrast, all dialkyltin(IV) dicarboxylates characterized so far in the solid state have monomeric or polymeric structures, however, for some cases it has been proposed that... |
12793814 | Induced fit process in the selective distal binding of imidazoles in zinc(II) porphyrin receptors. | The respective affinities of various imidazole derivatives, imidazole (ImH), 2-methylimidazole (2-MeImH), 2-phenylimidazole (2-PhImH), N-methylimidazole (N-MeIm), 2-methylbenzimidazole (2-MeBzImH), and 4,5-dimethylbenzimidazole (4,5-Me(2)BzImH), for two phenanthroline (Phen) strapped zinc(II) porphyrin receptors porphe... |
12793811 | Influences of changes in multitopic tris(pyrazolyl)methane ligand topology on silver(I) supramolecular structures. | The reactions between silver tetrafluoroborate and the ligands 1,2,4,5-C(6)H(2)[CH(2)OCH(2)C(pz)(3)](4) (L1, pz = pyrazolyl ring), o-C(6)H(4)[CH(2)OCH(2)C(pz)(3)](2) (L2), and m-C(6)H(4)[CH(2)OCH(2)C(pz)(3)](2) (L3) yield coordination polymers of the formula (C(6)H(6)(-)(n)[CH(2)OCH(2)C(pz)(3)](n)(AgBF4)(m))( infinity ... |
12794399 | Lipid composition and lipopolysaccharide binding capacity of lipoproteins in plasma and lymph of patients with systemic inflammatory response syndrome and multiple organ failure. | <h4>Background</h4>Lipopolysaccharide (LPS), the major glycolipid component of Gram-negative bacterial outer membranes, is a potent endotoxin responsible for many of the directly or indirectly induced symptoms of infection. Lipoproteins (in particular, high-density lipoproteins) sequester LPS, thereby acting as a humor... |
12794908 | Photoinduced electron transfer between the interlocked components of porphyrin catenanes: effect of the presence of nonequivalent reduction sites on the charge recombination rate. | [2]Catenanes made up of several polyether-strapped porphyrin macrocycles interlinked with the cyclic electron acceptor cyclobis(paraquat-p-phenylene) were spectroscopically, photophysically, and electrochemically characterized. The catenanes exhibit very rich redox behavior due to the presence of several different and ... |
12794904 | Facile optical resolution of tert-butanethiosulfinate by molecular complexation with (R)-BINOL and study of chiral discrimination of the diastereomeric complexes. | An important synthon, tert-butanethiosulfinate (2), has been effectively resolved by forming molecular complexes with (R)-2,2'-dihydroxy-1,1'-binaphthyl (BINOL, 3) in high enantioselectivity (>99 % ee). The present procedure represents the first example of the resolution of thiosulfinate. The mechanism of chiral discri... |
12794899 | A molecular approach to self-assembly of trimethylsilylacetylene derivatives on gold. | We recently discovered that a linear multifunctional trimethylsilylacetylene (TMSA) compound forms long-range and highly stable self-assembled monolayers (SAMs) on reconstructed Au(111). To better understand the interactions governing self-assembly in this new system, we synthesized a series of homologue organosilanes ... |
12794895 | Synthesis and fluorescence ion-sensory properties of the first dehydropyridoannulene-type cyclophane with enforced exotopic metal ion binding sites. | The new twistophane 4 has been synthesised, which comprises a conjugated dehydropyridoannulene-type macrocyclic scaffold with outwardly projecting nitrogen-donor sites for the purpose of metal ion coordination. The macrocyclíc structure of 4 was assigned by using spectroscopic methods, and shown to exist in a twisted a... |
12794888 | Potassium selective calix[4]semitubes. | A new class of ionophore consisting of two calix[4]arene units linked through the lower rim by two ethylene chains, in combination with propyl ether and phenolic functional groups, has been developed. These calix[4]semitube molecules exhibit remarkable selectivity and fast complexation kinetics for potassium over all G... |
12794830 | A thrombin-cross-reactive anticardiolipin antibody binds to and inhibits the anticoagulant function of activated protein C. | <h4>Objective</h4>To test the hypotheses that some thrombin-reactive anticardiolipin antibodies (aCL) may bind to protein C (PC) and/or activated PC (APC), and that some of the PC- and APC-reactive aCL may inhibit PC activation and/or the function of APC.<h4>Methods</h4>We studied the reactivity of patient-derived mono... |
12790519 | A supramolecular "ship in bottle" strategy for enantiomeric selectivity in geminate radical pair recombination. | [reaction: see text] Reactions in which zeolites are modified with chiral inductors to serve as media for chiral induction are often limited by the propensity of both substrate and inductor to occupy the same supercage. Herein, we report a "ship in bottle" strategy utilizing the thermal decomposition of dioxetanes obta... |
12790620 | Highly regioselective ring opening of oxiranes with phenoxides in the presence of beta-cyclodextrin in water. | Highly regioselective ring opening of oxiranes to beta-hydroxy ethers with phenoxides has been achieved in impressive yields in the presence of beta-cyclodextrin as catalyst and water as solvent. |
12790587 | Inter- and innermolecular reactions of chloro(phenyl)carbene. | Supramolecular photolyses of 3-chloro-3-phenyl-3H-diazirine (8) were performed within cyclodextrin (CyD) hosts to determine whether these toroidal inclusion compounds could alter the reactivity of the ensuing carbene reaction intermediate, chloro(phenyl)carbene (9). Remarkably, no intramolecular products stemming from ... |
12790585 | Design and synthesis of tridentate facially chelating ligands of the [2.n.1]-(2,6)-pyridinophane family. | Syntheses are reported for tripyridine macrocycles 2 and 3 and some of their alkyl derivatives. The macrocycles are designed to stabilize to various extents coordinated d(8) metal precursors and d(6) alkane oxidative addition products (Pt(IV)), therefore allowing favorable kinetics and thermodynamics of (e.g., Pt(II)) ... |
12790569 | Molecular dynamics study of 2rotaxanes: influence of solvation and cation on co-conformation. | The conformational preference of a [2]rotaxane system has been examined by molecular dynamics simulations. The rotaxane wheel consists of two bridged binding components: a cis-dibenzo-18-crown-6 ether and a 1,3-phenyldicarboxamide, and the penetrating axle consists of a central isophthaloyl unit with phenyltrityl cappi... |
12791840 | Studies of epidemiology and seroprevalence of bovine noroviruses in Germany. | Jena virus (JV) is a bovine enteric calicivirus that causes diarrhea in calves. The virus is approximately 30 nm in diameter and has a surface morphology similar to the human Norwalk virus. The genome sequence of JV was recently described, and the virus has been assigned to the genus Norovirus of the family CALICIVIRID... |
12787643 | Drug complexation, in vitro release and cellular entry of dendrimers and hyperbranched polymers. | Highly branched, functionalized polymers have potential to act as efficient drug carrier systems. Dendrimers are ideal candidates among model hyperbranched polymers because of their well-defined structure and high density of functional groups. Using ibuprofen as a model drug, we studied the interaction between the drug... |
12787933 | Temperature dependence of fluid phase endocytosis coincides with membrane properties of pig platelets. | In previous studies we have shown that platelets take up low molecular weight molecules from the medium by fluid phase endocytosis, a phenomenon that we previously have used to load trehalose into human platelets, after which we have successfully freeze-dried them. We now extend those findings to a species to be used i... |
12783554 | Ion pairing and host-guest complexation in low dielectric constant solvents. | We report an equilibrium treatment for complexation of ionic species in low dielectric constant media that explicitly includes ion pairing of one of the components. Experimental validation was achieved through study of pseudorotaxane formation between dibenzylammonium salts and dibenzo-24-crown-8. In particular, we sho... |
12783548 | Characterization of supramolecular (H2O)18 water morphology and water-methanol (H2O)15(CH3OH)3 clusters in a novel phosphorus functionalized trimeric amino acid host. | Phosphorus functionalized trimeric alanine compounds (l)- and (d)-P(CH(2)NHCH(CH(3))COOH)(3) 2 are prepared in 90% yields by the Mannich reaction of Tris(hydroxymethyl)phosphine 1 with (l)- or (d)- Alanine in aqueous media. The hydration properties of (l)-2 and (d)-2 in water and water-methanol mixtures are described. ... |
12783543 | Shape-persistant macrocycles with terpyridine units: synthesis, characterization, and structure in the crystal. | The synthesis of a variety of shape-persistent macrocycles with either one (1a-d, 2) or two (opposing) terpyridine units (3, 4, 5a-c) and inner diameters of up to 2 nm is described. The sequences are mainly based on transition metal cross-coupling reactions and, whenever appropriate, compared with one another regarding... |
12783526 | Enantioselective cyclization of racemic supramolecular polymers. | Homochiral hydrogen-bonded cyclic assemblies are formed in dilute solutions of racemic supramolecular polymers based on the quadruple hydrogen bonding 2-ureido-4[1H]-pyrimidinone unit, as observed by 1H NMR and SEC experiments. Preorganization of the monomers and the combined binding strength of the eight hydrogen bond... |
12783523 | Manipulating supramolecular self-assembly via tailoring pendant group size of linear vinyl polymers. | In a series of poly[di(alkyl) vinylterephthalates] (PDAVTs) synthesized via radical polymerization, fine-tuning the size and shape of the side groups manipulated the supramolecular self-assembly and led to control over the formations between amorphous and 2D ordered hexagonal phases. To introduce the 2D long-range orde... |
12646045 | Glucoamylase starch-binding domain of Aspergillus niger B1: molecular cloning and functional characterization. | Carbohydrate-binding modules (CBMs) are protein domains located within a carbohydrate-active enzyme, with a discrete fold that can be separated from the catalytic domain. Starch-binding domains (SBDs) are CBMs that are usually found at the C-terminus in many amylolytic enzymes. The SBD from Aspergillus niger B1 (CMI CC... |
12782651 | Local spreading of MSL complexes from roX genes on the Drosophila X chromosome. | MSL proteins and noncoding roX RNAs form complexes to up-regulate hundreds of genes on the Drosophila male X chromosome, and make X-linked gene expression equal in males and females. Altering the ratio of MSL proteins to roX RNA dramatically changes X-chromosome morphology. In protein excess, the MSL complex concentrat... |
12783454 | Chiral analysis of amphetamine-type stimulants using reversed-polarity capillary electrophoresis/positive ion electrospray ionization tandem mass spectrometry. | Reversed-polarity (RP) capillary electrophoresis/positive ion electrospray ionization mass spectrometry (CE-ESI+ MS) and tandem mass spectrometry (MS/MS) were utilized for simultaneous chiral separation of nine amphetamine-type stimulants (ATS) (dl-norephedrine, dl-norpseudoephedrine, dl-ephedrine, dl-pseudoephedrine, ... |
12783453 | Cyclodextrin-modified micellar electrokinetic chromatography for the analysis of Esterom, a topical product consisting of hydrolyzed benzoylecgonine in propylene glycol. | Esterom, a new drug currently in human clinical trials, is a mixture of compounds in a propylene glycol vehicle. It is being evaluated as a topical treatment to aid in the relief of muscle pain and to increase range of motion. Benzoylecgonine is the major component of Esterom and there are at least nine other minor con... |
12778127 | Fibulins: a versatile family of extracellular matrix proteins. | Fibulins are a newly recognized family of extracellular matrix proteins. The five known members of the family share an elongated structure and many calcium-binding sites, owing to the presence of tandem arrays of epidermal growth factor-like domains. They have overlapping binding sites for several basement-membrane pro... |
12775701 | Electron microscopic analysis of membrane assemblies formed by the bacterial chemotaxis receptor Tsr. | The serine receptor (Tsr) from Escherichia coli is representative of a large family of transmembrane receptor proteins that mediate bacterial chemotaxis by influencing cell motility through signal transduction pathways. Tsr and other chemotaxis receptors form patches in the inner membrane that are often localized at th... |
12774312 | Overexpression of V-1 prevents nitric oxide-induced cell death: involvement of enhanced tetrahydrobiopterin biosynthesis. | Previously we reported that the synthesis of catecholamines, dopamine, and noradrenaline was enhanced by overexpression of V-1 protein, a neuronal protein active in the initial stage of development of the rat cerebellum, in the neuronal cell line PC12D, a model of dopamine cells (Yamakuni et al. [1998] J. Biol. Chem. 2... |
12773385 | Glycoprotein hormone receptors: determinants in leucine-rich repeats responsible for ligand specificity. | Glycoprotein hormone receptors [thyrotropin (TSHr), luteinizing hormone/chorionic gonadotropin (LH/CGr), follicle stimulating hormone (FSHr)] are rhodopsin-like G protein-coupled receptors with a large extracellular N-terminal portion responsible for hormone recognition and binding. In structural models, this ectodomai... |
12773382 | A cholesterol-regulated PP2A/HePTP complex with dual specificity ERK1/2 phosphatase activity. | The acute depletion of membrane cholesterol causes the concentration of pERK1/2 in caveola/raft lipid domains and the cytosol of human fibroblasts to dramatically increase. This increase could be caused by either the activation of MEK-1 or the inhibition of a pERK phosphatase. Here we describe the isolation of a high m... |
12773371 | Dendritic cell regulation of immune responses: a new role for interleukin 2 at the intersection of innate and adaptive immunity. | Dendritic cells are professional antigen-presenting cells able to initiate innate and adaptive immune responses against invading pathogens. In response to external stimuli dendritic cells undergo a complete genetic reprogramming that allows them to become, soon after activation, natural killer cell activators and subse... |
12774289 | Effect of constituting amino acid residue numbers on molecularly imprinted chiral recognition sites. | In the present study, the effect of constituting amino acid residue numbers of oligopeptide derivatives, which are candidate materials to construct molecular recognition sites, on chiral recognition ability was investigated. Chiral recognition sites were formed from oligopeptide derivatives, of which constituting amino... |
12771228 | In vitro analysis of nuclear mRNA export using molecular beacons for target detection. | A detailed molecular characterization of nuclear mRNA export will require an in vitro system, allowing a biochemical reconstitution of transport. To this end, an mRNA export assay has been developed using digitonin-permeabilized HeLa cells and 2'-O-methyl oligoribonucleotide molecular beacons for target detection. Thes... |
12771207 | Purification and characterisation of a novel DNA methyltransferase, M.AhdI. | We have cloned the M and S genes of the restriction-modification (R-M) system AhdI and have purified the resulting methyltransferase to homogeneity. M.AhdI is found to form a 170 kDa tetrameric enzyme having a subunit stoichiometry M2S2 (where the M and S subunits are responsible for methylation and DNA sequence specif... |
12771202 | Steric inhibition of human immunodeficiency virus type-1 Tat-dependent trans-activation in vitro and in cells by oligonucleotides containing 2'-O-methyl G-clamp ribonucleoside analogues. | We report the synthesis of a novel 2'-O-methyl (OMe) riboside phosphoramidite derivative of the G-clamp tricyclic base and incorporation into a series of small steric blocking OMe oligonucleotides targeting the apical stem-loop region of human immunodeficiency virus type 1 (HIV-1) trans- activation-responsive (TAR) RNA... |
12771198 | Syntheses and structural studies of calix[4]arene-nucleoside and calix[4]arene-oligonucleotide hybrids. | We have synthesized three types of calix[4]arene- nucleoside hybrid efficiently by amide bond formation between the amine functional groups of 1,3-diaminocalix[4]arene and the carboxyl groups of thymidine nucleoside derivatives. X-ray crystallography of a homocoupled calix[4]arene-nucleoside hybrid revealed an interest... |
12769588 | Symmetry and bonding in metalloporphyrins. A modern implementation for the bonding analyses of five- and six-coordinate high-spin iron(III)-porphyrin complexes through density functional calculation and NMR spectroscopy. | Bonding interactions between the iron and the porphyrin macrocycle of five- and six-coordinate high-spin iron(III)-porphyrin complexes are analyzed within the framework of approximate density functional theory with the use of the quantitative energy decomposition scheme in combination with removal of the vacant pi orbi... |
12769577 | Efficient macrocyclization of U-turn preorganized peptidomimetics: the role of intramolecular H-bond and solvophobic effects. | Simple peptidomimetic molecules derived from amino acids were reacted with meta- and para-bis(bromomethyl)benzene in acetonitrile to very efficiently yield macrocyclic structures. The cyclization reaction does not require high dilution techniques and seems to be insensitive to the size of the formed macrocycle. The ana... |
12769558 | Chemical formation of mononuclear univalent zinc in a microporous crystalline silicoaluminophosphate. | A host-guest compound containing mononuclear univalent Zn+ ions has been prepared through vapor reaction of metallic zinc with protons in the cages of SAPO-CHA, a silicoaluminophosphate molecular sieve. Unlike in fused ZnCl2 salt, the formed Zn+ species are associated with the molecular sieve walls, and this prevents t... |
12769550 | Constraints on supramolecular structure in amyloid fibrils from two-dimensional solid-state NMR spectroscopy with uniform isotopic labeling. | We show that strong constraints on supramolecular structure in amyloid fibrils can be obtained from solid-state nuclear magnetic resonance measurements on samples with uniformly 13C-labeled segments. The measurements exploit two-dimensional (2D) 13C-13C exchange spectroscopy in conjunction with high-speed magic angle s... |
12769721 | The bovine basic pancreatic trypsin inhibitor (Kunitz inhibitor): a milestone protein. | The pancreatic Kunitz inhibitor, also known as aprotinin, bovine basic pancreatic trypsin inhibitor (BPTI), and trypsin-kallikrein inhibitor, is one of the most extensively studied globular proteins. It has proved to be a particularly attractive and powerful tool for studying protein conformation as well as molecular b... |
12770901 | Mobility of taxol in microtubule bundles. | Mobility of taxol inside microtubules was investigated using fluorescence recovery after photobleaching on flow-aligned bundles. Bundles were made of microtubules with either GMPCPP or GTP at the exchangeable site on the tubulin dimer. Recovery times were sensitive to bundle thickness and packing, indicating that taxol... |
12770888 | The flexibility of DNA double crossover molecules. | Double crossover molecules are DNA structures containing two Holliday junctions connected by two double helical arms. There are several types of double crossover molecules, differentiated by the relative orientations of their helix axes, parallel or antiparallel, and by the number of double helical half-turns (even or ... |
12770863 | Connective tissue polarity unraveled by a markov-chain mechanism of collagen fibril segment self-assembly. | The well-established occurrence of pyroelectricity (Lang, 1966) in tissues of living organisms has found a first explanation by a Markov-chain mechanism taking place during collagen fibril self-assembly in extracytoplasmic channels. Recently reported biochemical findings on the longitudinal fusion reactivity of small f... |
12768576 | Sensitive CEST agents based on nucleic acid imino proton exchange: detection of poly(rU) and of a dendrimer-poly(rU) model for nucleic acid delivery and pharmacology. | It is shown that the exchange properties of the imino and hydroxyl protons of polyuridilic acid (poly(rU)) allow use of this compound as a chemical-exchange saturation transfer (CEST) contrast agent. A proton/proton sensitivity enhancement factor of over 5000 per imino proton allowed the detection of a few micromolar o... |
12768015 | A novel human antibody against human immunodeficiency virus type 1 gp120 is V1, V2, and V3 loop dependent and helps delimit the epitope of the broadly neutralizing antibody immunoglobulin G1 b12. | The V1/V2 and V3 loops are proximal to the CD4 binding site (CD4bs) of human immunodeficiency virus type 1 (HIV-1) gp120 and undergo conformational change upon CD4 receptor engagement by the HIV-1 envelope spike. Nearly all of the reported monoclonal antibodies (MAbs) against the CD4bs exhibit a very limited capacity t... |
12767984 | Cytolysis by CCR5-using human immunodeficiency virus type 1 envelope glycoproteins is dependent on membrane fusion and can be inhibited by high levels of CD4 expression. | T-tropic (X4) and dualtropic (R5X4) human immunodeficiency virus type 1 (HIV-1) envelope glycoproteins kill primary and immortalized CD4(+) CXCR4(+) T cells by mechanisms involving membrane fusion. However, because much of HIV-1 infection in vivo is mediated by M-tropic (R5) viruses whose envelope glycoproteins use CCR... |
12767195 | Electronic effects in 12-metallacrown-3 complexes. A theoretical and experimental study. | The Mulliken charges of the 12-metallacrown-3 complex [(C(6)H(6))Ru(C(5)H(3)NO(2))](3) were determined by a single point analysis at the HF level. For comparison, a Mulliken population analysis was carried out for the organic analogue 12-crown-3. The partial negative charges on the O-donor atoms of the metallamacrocycl... |
12767192 | Synthesis, structural investigation, and solid-state properties of iodine-doped zirconium diphthalocyanine, [ZrPc2]I3.I2. | Crystals of iodine-doped zirconium(IV) diphthalocyanine, [ZrPc(2)]I(3).I(2) (where Pc = C(32)H(16)N(8)), were grown directly in the reaction of pure zirconium powder with phthalonitrile under a stream of iodine at 260 degrees C. [ZrPc(2)]I(3).I(2) crystallizes in the space group P2(1)/m (No. 11) of the monoclinic syste... |
12767182 | Coordination properties of a diarylaza crown ether appended with a luminescent [Ru(bipy)3]2+ unit. | The [Ru(bipy)(2)(1)](PF(6))(2) (bipy refers to 2,2'-bipyridine) complex, comprising a ruthenium(II) tris(2,2'-bipyridine) luminophore covalently linked to a di[(o-triethyleneglycoxy)phenyl]amine crown ether 1, has been synthesized and fully characterized. The photophysical properties of this metal complex have been exa... |
12767169 | Structural properties of cyclopentanone-bridged bis-macrocyclic ligand dicopper(II) complexes in the solid and in solution: a successful test of the MM-EPR method. | The copper(II)-assisted condensation of 2,3,2-tet (3,7-diazanonane-1,9-diamine) with formaldehyde and cyclopentanone yields the mono- and bis-macrocyclic Mannich condensation products L(1) and L(2), as well as the Schiff-base product L(3), all with cyclam-type tetraaza macrocycles, coordinated to copper(II). The combin... |
12767245 | Structure of the ceramide moiety of GM1 ganglioside determines its occurrence in different detergent-resistant membrane domains in HL-60 cells. | To investigate the effect of the ceramide moiety of GM1 ganglioside on its association with detergent resistant membrane domains (DRMs) in human leukemia HL-60 cells, [(3)H] labeled GM1 molecular species (GM1s) with ceramides consisting of C18 sphingosine acetylated or acylated with C(8), C(12), C(14), C(16), C(18), C(... |
12767230 | Discovery and characterization of cooperative ligand binding in the adaptive region of interleukin-2. | The cytokine hormone interleukin-2 (IL-2) contains a highly adaptive region that binds small, druglike molecules. The binding properties of this adaptive region have been explored using a "tethering" method that relies on the formation of a disulfide bond between the protein and small-molecule ligands. Using tethering,... |
12767214 | The structure of a functional unit from the wall of a gastropod hemocyanin offers a possible mechanism for cooperativity. | Structure-function relationships in a molluscan hemocyanin have been investigated by determining the crystal structure of the Rapana thomasiana (gastropod) hemocyanin functional unit RtH2e in deoxygenated form at 3.38 A resolution. This is the first X-ray structure of an unit from the wall of the molluscan hemocyanin c... |
12766196 | Interaction of dendrimers (artificial proteins) with biological hydroxyapatite crystals. | This investigation sets out to mimic protein-crystal interaction during biomineralization with the use of artificial proteins (dendrimers). It is hypothesized that these interactions depend on the surface charge of hydroxyapatite crystals. This was investigated with the use of dendrimers with capped surfaces of differe... |
12763666 | Ligand-exchangeability of 2-coordinate phosphinegold(I) complexes with AuSP and AuNP cores showing selective antimicrobial activities against Gram-positive bacteria. Crystal structures of [Au(2-Hmpa)(PPh(3))] and [Au(6-Hmna)(PPh(3))] (2-H(2)mpa=2-mercaptopropionic acid, 6-H(2)mna=6-mercaptonicotinic acid). | Selective and effective antimicrobial activities against Gram-positive bacteria (B. subtilis and/or S. aureus) were found in 2-coordinate gold(I)-PPh(3) complexes with AuSP and AuNP cores, i.e. [Au(L)(PPh(3))] (HL=2-H(2)mna [H(2)mna=mercaptonicotinic acid] 3, D-H(2)pen [H(2)pen=penicillamine] 4, D,L-H(2)pen 5, 4-H(2)mb... |
12761389 | An electronic effect on protein structure. | The well-known preference of the peptide bond for the trans conformation has been attributed to steric effects. Here, we show that a proline residue with an N-formyl group (H(i-1)-C'(i-1)=O(i-1)), in which H(i-1) presents less steric hindrance than does O(i-1), likewise prefers a trans conformation. Thus, the preferenc... |
12761150 | Helicobacter pylori supernatants cause epithelial cytoskeletal disruption that is bacterial strain and epithelial cell line dependent but not toxin VacA dependent. | We show here that Helicobacter pylori broth culture supernatants disrupt the actin cytoskeleton of epithelial cell lines, leading to cell rounding and apoptosis through anoikis. We demonstrate that there are marked quantitative differences between strains and that there are different cell line sensitivities. By constru... |
12761138 | pH-regulated gene expression of the gastric pathogen Helicobacter pylori. | Colonization by the gastric pathogen Helicobacter pylori has been shown to be intricately linked to the development of gastritis, ulcers, and gastric malignancy. Little is known about mechanisms employed by the bacterium that help it adapt to the hostile environment of the human stomach. In an effort to extend our know... |
12757731 | Helical templating of oligopeptides by cyclodextrin dimers. | beta-cyclodextrin-based receptors were synthesized and tested for their ability to induce a helical fold in peptides bearing hydrophobic amino acid residues in the i, i+11- or i, i+14-positions. Circular dichroism experiments revealed that a dimeric beta-cylodextrin receptor synthesized from a [1,1'-biphenyl]-4,4'-dith... |
12648035 | Organization on the plasma membrane of the retinitis pigmentosa protein RP2: investigation of association with detergent-resistant membranes and polarized sorting. | Mutations in the retinitis pigmentosa protein gene RP2 account for up to 15% of X-linked retinitis pigmentosa. RP2 is a novel protein of unknown function, which is targeted to the plasma membrane by dual N-terminal acyl-modification. Dual-acylated proteins are targeted to lipid rafts, and some are subject to polarized ... |
12611589 | Polymorphic glutathione S-transferase subunit 3 of rat liver exhibits different susceptibilities to carbon tetrachloride: differences in their interactions with heat-shock protein 90. | Rat glutathione S-transferase (GST) subunit 3 gene has polymorphism, one type encoding Asn(198)-Cys(199) (NC type) and another encoding Lys(198)-Ser(199) (KS type). To examine whether the two types of GST 3-3 exhibit different susceptibilities to oxidative stress in vivo, rats were administered with CCl(4), a hepatotox... |
12611588 | Leucine-zipper-mediated homo- and hetero-dimerization of GIT family p95-ARF GTPase-activating protein, PIX-, paxillin-interacting proteins 1 and 2. | ADP-ribosylation factor GTPase-activating proteins (ARFGAPs) of the G-protein-coupled receptor kinase interactor 1/p95 paxillin kinase linker/p95-ARFGAP Pak-interacting exchange factor paxillin-binding protein (APP)-1 family are multidomain proteins, which interact functionally with both ARF and Rac GTPases. These prot... |
12758262 | Enhancement of the fluorescence and stability of o-phthalaldehyde-derived isoindoles of amino acids using hydroxypropyl-beta-cyclodextrin. | Addition of hydroxypropyl-beta-cyclodextrin to o-phthalaldehyde (OPA)-amino acid-thiol reaction mixtures is shown to cause significant enhancement of the fluorescence of the isoindole product for a wide range of amino acids, with the largest effects observed in the cases of glycine and lysine. The largest enhancement o... |
12756325 | Structural mimicry in the phage phi21 N peptide-boxB RNA complex. | We determined the solution structure of a 22-amino-acid peptide from the amino-terminal domain of the bacteriophage phi21 N protein in complex with its cognate 24-mer boxB RNA hairpin using heteronuclear magnetic resonance spectroscopy. The N peptide binds as an alpha-helix and interacts predominately with the major gr... |
12754250 | Synthesis and localization of the Salmonella SPI-1 type III secretion needle complex proteins PrgI and PrgJ. | An essential component of type III secretion systems (TTSS) is a supramolecular structure termed the needle complex. In Salmonella enterica, at least four proteins make up this structure: InvG, PrgH, PrgK, and PrgI. Another protein, PrgJ, is thought to play a role in the assembly of this structure, but its function is ... |
12753767 | Effect of chitosan on progesterone release from hydroxypropyl-beta-cyclodextrin complexes. | An inclusion complex composed of progesterone (Prog) and hydroxypropyl-beta-cyclodextrin (HPbetaCD) was prepared by the spray-drying and freeze-drying methods. Prog alone and its inclusion complex with HPbetaCD were incorporated into chitosan by spray-drying and freeze-drying. The inclusion complex was characterized by... |
12794333 | Two isomorphous complexes: dichloro[phthalocyaninato(2-)]tin(IV) and dichloro[phthalocyaninato(2-)]germanium(IV). | Isomorphous triclinic forms of dichloro[phthalocyaninato(2-)]tin(IV), [Sn(C(32)H(16)N(8))Cl(2)], and dichloro[phthalocyaninato(2-)]germanium(IV), [Sn(C(32)H(16)N(8))Cl(2)], and a monoclinic form of the latter have been obtained from the reaction of pure tin and germanium powder, respectively, with phthalonitrile under ... |
12777392 | Initiation and transduction of stretch-induced RhoA and Rac1 activation through caveolae: cytoskeletal regulation of ERK translocation. | The Rho family small GTPases play a crucial role in mediating cellular responses to stretch. However, it remains unclear how force is transduced to Rho signaling pathways. We investigated the effect of stretch on the activation and caveolar localization of RhoA and Rac1 in neonatal rat cardiomyocytes. In unstretched ca... |
12777633 | A role for Z-DNA binding in vaccinia virus pathogenesis. | The N-terminal domain of the E3L protein of vaccinia virus has sequence similarity to a family of Z-DNA binding proteins of defined three-dimensional structure and it is necessary for pathogenicity in mice. When other Z-DNA-binding domains are substituted for the similar E3L domain, the virus retains its lethality afte... |
12777631 | Viral assembly of oriented quantum dot nanowires. | The highly organized structure of M13 bacteriophage was used as an evolved biological template for the nucleation and orientation of semiconductor nanowires. To create this organized template, peptides were selected by using a pIII phage display library for their ability to nucleate ZnS or CdS nanocrystals. The success... |
12777622 | Breakdown of chlorophyll: a nonenzymatic reaction accounts for the formation of the colorless "nonfluorescent" chlorophyll catabolites. | Senescent higher plants degrade their chlorophylls (Chls) to polar colorless tetrapyrrolic Chl catabolites, which accumulate in the vacuoles. In extracts from degreened leaves of the tree Cercidiphyllum japonicum an unpolar catabolite of this type was discovered. This tetrapyrrole was named Cj-NCC-2 and was found to be... |
12972565 | Host but not parasite cholesterol controls Toxoplasma cell entry by modulating organelle discharge. | Host cell cholesterol is implicated in the entry and replication of an increasing number of intracellular microbial pathogens. Although uptake of viral particles via cholesterol-enriched caveolae is increasingly well described, the requirement of cholesterol for internalization of eukaryotic pathogens is poorly underst... |
12776251 | IBD5 is a general risk factor for inflammatory bowel disease: replication of association with Crohn disease and identification of a novel association with ulcerative colitis. | Inflammatory bowel disease (IBD) refers to complex chronic relapsing autoimmune disorders of the gastrointestinal tract that have been traditionally classified into Crohn disease (CD) and ulcerative colitis (UC). We have previously reported that genetic variation within a 250-kb haplotype (IBD5) in the 5q31 cytokine ge... |
12773479 | Binding of the CC-chemokine RANTES to syndecan-1 and syndecan-4 expressed on HeLa cells. | It is believed that proteoglycans influence biological properties of chemokines. We show that the CC chemokine RANTES binds not only to high-affinity binding sites on CCR5-positive HeLa cells but also to low-affinity binding sites on HeLa cells expressing or lacking RANTES G protein-coupled receptors. Coimmunoprecipita... |
12774216 | Construction of a toroidal model for the magainin pore. | Magainins are natural peptides that selectively kill bacteria at concentrations that are harmless to animal cells. Due to a positive charge and distinct hydrophobic moment, magainins in the alpha-helical conformation interact favorably with bacterial membrane lipids. These interactions lead to the formation of large op... |
12771141 | Structural basis of Synercid (quinupristin-dalfopristin) resistance in Gram-positive bacterial pathogens. | Synercid, a new semisynthetic streptogramin-derived antibiotic containing dalfopristin and quinupristin, is used in treatment of life-threatening infections caused by glycopeptide-resistant Enterococcus faecium and other bacterial pathogens. However, dissemination of genes encoding virginiamycin acetyltransferases, enz... |
12771375 | Peripheral heme substituents control the hydrogen-atom abstraction chemistry in cytochromes P450. | We elucidate the hydroxylation of camphor by cytochrome P450 with the use of density functional and mixed quantum mechanics/molecular mechanics methods. Our results reveal that the enzyme catalyzes the hydrogen-atom abstraction step with a remarkably low free-energy barrier. This result provides a satisfactory explanat... |
12771181 | Cbl-b negatively regulates B cell antigen receptor signaling in mature B cells through ubiquitination of the tyrosine kinase Syk. | Members of the Cbl family of molecular adaptors play key roles in regulating tyrosine kinase-dependent signaling in a variety of cellular systems. Here we provide evidence that in B cells Cbl-b functions as a negative regulator of B cell antigen receptor (BCR) signaling during the normal course of a response. In B cell... |
12766225 | Uniform polarity microtubule assemblies imaged in native brain tissue by second-harmonic generation microscopy. | Microtubule (MT) ensemble polarity is a diagnostic determinant of the structure and function of neuronal processes. Here, polarized MT structures are selectively imaged with second-harmonic generation (SHG) microscopy in native brain tissue. This SHG is found to colocalize with axons in both brain slices and cultured n... |
12761410 | Mechanism of the first-order phase transition of an acylurea derivative: observation of intermediate stages of transformation with a detailed temperature-resolved single-crystal diffraction method. | The process of the first-order solid-to-solid phase transition of 1-ethyl-3-(4-methylpentanoyl)urea (1) was observed by means of a detailed temperature-resolved single-crystal diffraction method, which resembles watching a series of stop-motion photographs. The transition consists of two elementary processes, one supra... |
12761407 | Structure of lithium benzilate hemihydrate solved by simulated annealing and difference Fourier synthesis from powder data. | The crystal structure of lithium benzilate hemihydrate (C(14)H(11)O(3)(-)Li(+).0.5H(2)O) was solved from synchrotron powder diffraction data. This compound crystallizes in the monoclinic space group P2(1)/a. The structure was solved via the direct space search for two benzilate fragments using the simulated-annealing p... |
12763753 | Nucleotide coronary vasodilation in guinea pig hearts. | The role of P1 receptors and P2Y1 receptors in coronary vasodilator responses to adenine nucleotides was examined in the isolated guinea pig heart. Bolus arterial injections of nucleotides were made in hearts perfused at constant pressure. Peak increase in flow was measured before and after addition of purinoceptor ant... |
12794355 | Two bis(ammonium) 1,5-naphthalenedisulfonate salts. | The title compounds, bis(ammonium) naphthalene-1,5-disulfonate, 2NH(4)(+).C(10)H(6)O(6)S(2)(2-), and bis[1-(hydroxymethyl)-3,5,7-triaza-1-azoniatricyclo[3.3.1.1(3,7)]decane] 1,5-naphthalenedisulfonate, 2C(7)H(15)N(4)O(+).C(10)H(6)O(6)S(2)(2-), were prepared from the acid-promoted reaction of hexamethylenetetramine. In ... |
12794349 | Dispiro[adamantane-2,2'-1',3',6',9',11',14'-hexathiacyclohexadecane-10',2"-adamantane]. | The conformational features of the title compound, C(28)H(44)S(6), are compared with previously reported analogous macrocycles. The type of substituent affects considerably the conformation of the macrocycle. A (1)H NMR titration of the title compound with AgBF(4) indicated the formation of the 1:1 complex, which was n... |
12786133 | Brownian particles in supramolecular polymer solutions. | The Brownian motion of colloidal particles embedded in solutions of hydrogen-bonded supramolecular polymers has been studied using dynamic light scattering. At short times, the motion of the probe particles is diffusive with a diffusion coefficient equal to that in pure solvent. At intermediate time scales the particle... |
12756237 | Macrophage podosomes assemble at the leading lamella by growth and fragmentation. | Podosomes are actin- and fimbrin-containing adhesions at the leading edge of macrophages. In cells transfected with beta-actin-ECFP and L-fimbrin-EYFP, quantitative four-dimensional microscopy of podosome assembly shows that new adhesions arise at the cell periphery by one of two mechanisms; de novo podosome assembly, ... |
12749771 | Genome wide identification of regulatory motifs in Bacillus subtilis. | <h4>Background</h4>To explain the vastly different phenotypes exhibited by the same organism under different conditions, it is essential that we understand how the organism's genes are coordinately regulated. While there are many excellent tools for predicting sequences encoding proteins or RNA genes, few algorithms ex... |
12750469 | Structure of the coat protein in fd filamentous bacteriophage particles determined by solid-state NMR spectroscopy. | The atomic resolution structure of fd coat protein determined by solid-state NMR spectroscopy of magnetically aligned filamentous bacteriophage particles differs from that previously determined by x-ray fiber diffraction. Most notably, the 50-residue protein is not a single curved helix, but rather is a nearly ideal st... |
12748066 | Nicotinic acetylcholine receptor alpha 7 regulates cAMP signal within lipid rafts. | Neuronal nicotinic acetylcholine receptors (nAChRs) are made of multiple subunits with diversified functions. The nAChR alpha 7-subunit has a property of high Ca2+ permeability and may have specific functions and localization within the plasma membrane as a signal transduction molecule. In PC-12 cells, fractionation by... |
12743371 | Exponential growth by cross-catalytic cleavage of deoxyribozymogens. | We have designed an autocatalytic cycle based on the highly efficient 10-23 RNA-cleaving deoxyribozyme that is capable of exponential amplification of catalysis. In this system, complementary 10-23 variants were inactivated by circularization, creating deoxyribozymogens. Upon linearization, the enzymes can act on their... |
12743366 | Golgi-dependent transport of cholesterol to the Chlamydia trachomatis inclusion. | Cholesterol, a lipid not normally found in prokaryotes, was identified in purified Chlamydia trachomatis elementary bodies and in the chlamydial parasitophorous vacuole (inclusion) membrane of infected HeLa cells. Chlamydiae obtained eukaryotic host cell cholesterol both from de novo synthesis or low-density lipoprotei... |
12740026 | Profilin is required for viral morphogenesis, syncytium formation, and cell-specific stress fiber induction by respiratory syncytial virus. | <h4>Background</h4>Actin is required for the gene expression and morphogenesis of respiratory syncytial virus (RSV), a clinically important Pneumovirus of the Paramyxoviridae family. In HEp-2 cells, RSV infection also induces actin stress fibers, which may be important in the immunopathology of the RSV disease. Profili... |
12736264 | CCHX zinc finger derivatives retain the ability to bind Zn(II) and mediate protein-DNA interactions. | Classical (CCHH) zinc fingers are among the most common protein domains found in eukaryotes. They function as molecular recognition elements that mediate specific contact with DNA, RNA, or other proteins and are composed of a betabetaalpha fold surrounding a single zinc ion that is ligated by two cysteine and two histi... |
12724830 | Size and shape of mineralites in young bovine bone measured by atomic force microscopy. | Atomic force microscopy (AFM) was used to obtain three-dimensional images of isolated mineralites extracted from young postnatal bovine bone. The mean mineralite size is 9 nm x 6 nm x 2.0 nm, significantly shorter and thicker than the mineralites of mature bovine bone measured by the same technique. Mineralites of the ... |
12734401 | Contributions of molecular binding events and cellular compliance to the modulation of leukocyte adhesion. | The interaction of leukocyte function-associated antigen-1 (LFA-1) and intercellular adhesion molecule-1 (ICAM-1) is central to the regulation of adhesion in leukocytes. In this report, we investigated the mechanisms by which phorbol myristate acetate (PMA) promotes LFA-1-dependent cell adhesion. The adhesion of PMA-st... |
12925777 | Inhibition of a Golgi complex lysophospholipid acyltransferase induces membrane tubule formation and retrograde trafficking. | Recent studies have suggested that formation of Golgi membrane tubules involves the generation of membrane-associated lysophospholipids by a cytoplasmic Ca2+-independent phospholipase A2 (PLA2). Herein, we provide additional support for this idea by showing that inhibition of lysophospholipid reacylation by a novel Gol... |
12925765 | Distinct mechanisms of agonist-induced endocytosis for human chemokine receptors CCR5 and CXCR4. | Desensitization of the chemokine receptors, a large class of G protein-coupled receptors, is mediated in part by agonist-driven receptor endocytosis. However, the exact pathways have not been fully defined. Here we demonstrate that the rate of ligand-induced endocytosis of CCR5 in leukocytes and expression systems is s... |
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