id stringlengths 4 8 | title stringlengths 1 642 | abstract stringlengths 50 17.9k |
|---|---|---|
23345769 | Domains and rafts in membranes - hidden dimensions of selforganization. | Both biomembranes and biomimetic membranes such as lipid bilayers withseveral components contain intramembrane domains and rafts.Macromolecules, which are anchored to the membrane but have no tendeney tocluster, induce curved nanodomains. Clustering of membrane componentsleads to larger domains which can grow up to a c... |
23345762 | Structural Characteristics in Protein Hydration Investigated by Cryogenic X-ray Crystal Structure Analyses. | Cryogenic X-ray crystallography has heen applied to investigate thehydration structures of proteins. The amount of hydration water moleculesidentified at cryogenic temperature is more than twice those at ambienttemperature, and the structural models of proteins with a lot of hydrationwater molecules have provided much ... |
19750207 | Monolayer Formation on Silicon and Mica Surfaces Rearranged from N-Hexadecanoyl-l-alanine Supramolecular Structures. | The rearrangements of N-hexadecanoyl-l-alanine supramolecular structures in water to form monolayers on silicon and mica surfaces have been investigated using atomic force microscopy. It is the first time that such a monolayer with the polar groups on the solid surface and the alkyl chains up is obtained through a rati... |
16290673 | A structural study of amphiphilic PAMAM (poly(amido amine)) dendrimers in Langmuir and Langmuir-Blodgett films. | Two amphiphilic PAMAM dendrimers are synthesized by attaching 12-hydroxydodecanoic acid (HA) chains to a poly(amido amine) (PAMAM) dendrimer core (including generation I and generation II). The limiting molecular area obtained from the surface pressure-area isotherm at the air/water interface suggests the edge-on confi... |
12596887 | Smooth muscle changes in the cephalic vein of renal failure patients before use as an arteriovenous fistula (AVF). | Complications in arteriovenous fistula (AVF) occur in up to 35% of renal failure patients on hemodialysis. The most frequent complication is thrombosis, usually from stenotic lesions in the venous outflow system. To study the pre-existing smooth muscle changes in the cephalic vein of these patients, we prospectively co... |
12579804 | [Chiral separation and preparation of three new antagonists of alpha 1-adrenoceptors by chiral mobile phase HPLC]. | <h4>Aim</h4>To establish new methods for the chiral separation and preparation of three new drugs, alfuzosin, terazosin and doxazosin.<h4>Methods</h4>By optimizing factors which affect the chiral separation, modifier of solvent, chiral additive, pH of mobile phase, modifier of organic base and stationary phase, the opt... |
12482108 | Pulsed estrogen therapy: from cellular mode of action to tissue effects. | Failure to achieve a uniform response to estrogen replacement therapy may be related to the dose or route of administration of estrogen. The established doctrines of estrogen replacement therapy are under scrutiny. Recent discoveries have prompted a complete re-evaluation of estrogen action at the biochemical, physiolo... |
12465491 | Two-dimensional molecular electronics circuits. | Addressing an array of bistable [2]rotaxanes through a two-dimensional crossbar arrangement provides the device element of a current-driven molecular electronic circuit. The development of the [2]rotaxane switches through an iterative, evolutionary process is described. The arrangement reported here allows both memory ... |
12455981 | Toxoplasma gondii cyclic GMP-dependent kinase: chemotherapeutic targeting of an essential parasite protein kinase. | The trisubstituted pyrrole 4-[2-(4-fluorophenyl)-5-(1-methylpiperidine-4-yl)-1H-pyrrol-3-yl]pyridine (compound 1) has in vivo activity against the apicomplexan parasites Toxoplasma gondii and Eimeria tenella in animal models. The presumptive molecular target of this compound in E. tenella is cyclic GMP-dependent protei... |
12428060 | Unmasking the anti-La/SSB response in sera from patients with Sjogren's syndrome by specific blocking of anti-idiotypic antibodies to La/SSB antigenic determinants. | <h4>Background</h4>Autoantigen La/SSB is molecular target of humoral autoimmunity in patients with primary Sjogren's Syndrome (pSS) and systemic lupus erythematosus (SLE). In this study, we investigated the existence and possible influence of anti-idiotypic response to anti-La/SSB antibodies.<h4>Materials and methods</... |
12391657 | Host-guest chemistry of the chromium-wheel complex [Cr8F8(tBuCO2)16]: prediction of inclusion capabilities by using an electrostatic potential distribution determined by modeling synchrotron X-ray structure factors at 16 K. | The structure and detailed electron density distribution (EDD) of the large octanuclear chromium-wheel host complex [Cr8F8(tBuCO2)16] (1) has been determined from synchrotron X-ray structure factors collected at 16(5) K. The complex has a central cavity with a minimum entry distance between carbon atoms of the pivalate... |
12391655 | Facile synthesis of optically functional, highly organized nanostructures: dye-surfactant complexes. | Multiply charged dye molecules can be precipitated from water by complexation with oppositely charged surfactants. It is shown that this complex formation occurs with 1:1 stoichiometry in a highly cooperative fashion. The resulting solids show either a gel-like or a supramolecular fibrillar morphology with a very high ... |
12391650 | First preparation of spacer-linked cyclic neooligoaminodeoxysaccharides. | The preparation of novel cyclic 1,4-butanediol-linked oligoaminodeoxysugars 3-5 and 7 is described which are potential binders to polynucleotides. Neooligosaccharides 3-5 are assembled by two consecutive metathesis protocols. In the first phase metathesis-mediated dimerization of an aminodeoxymonosaccharide which was e... |
12391646 | X-ray, 31P CP/MAS, and single-crystal NMR studies, and 31P DFT GIAO calculations of inclusion complexes of bis[6-O,6-O'-(1,2:3,4- diisopropylidene-alpha-D-galactopyranosyl)thiophosphoryl] disulfide: the importance of C-H...S=P contacts in the solid state. | Bis[6-O,6-O'-(1,2:3,4-diisopropylidene-alpha-D-galactopyranosyl) thiophosphoryl] disulfide shows a strong tendency to form inclusion compounds. The crystal and molecular structure of eight different solvates was established by X-ray analysis. The results indicate three different types of disulfide arrangements in the c... |
12220083 | Homotypic interactions of soluble and immobilized osteopontin. | Osteopontin (OPN) is an extracellular matrix protein found in bones and teeth, where it accumulates at matrix-matrix interfaces. We postulate that OPN interacts homotypically and heterotypically in the adhesion of apposing matrices. Using suspensions of OPN-coupled aldehyde/sulfate latex spheres, we measured the streng... |
12183121 | Test of a statistical model for molecular recognition in biological repertoires. | A chance encounter between members of a random repertoire and a molecular target is characteristic of different biological systems, including the immune and olfactory pathways as well as combinatorial libraries. In such systems, the affinity between the target and members of the repertoire is distributed with a probabi... |
12180335 | Control over calcium carbonate phase formation by dendrimer/surfactant templates. | Poly(propylene imine) dendrimers that are modified with long alkyl chains self-assemble to form well-defined aggregates. The geometry and surface chemistry of the dendrimer assemblies can be varied through the addition of surfactants. These dendrimer/surfactant aggregates can be tuned to template the formation of the d... |
12180333 | Supramolecular architecture and magnetic properties of copper(II) and nickel(II) porphyrinogen-TCNQ electron-transfer salts. | The compounds [Cu(Tz)-(MeOH)2](TCNQ)2 (1), [Ni(Tz)-(MeOH)2](TCNQ)2 (2), [Cu(Tz)2]-(TCNQ)7 (3) and [Ni(Tz)2](TCNQ)7 (4) (Tz = 2,7,12,17-tetramethyl-1,6,11,16-tetraazaporphyrinogen) were obtained by metathesis reaction of [M(Tz)](ClO4)2 with LiTCNQ and Et3NH(TCNQ)2, respectively. They were characterized by a combination ... |
12180331 | An unusual (10,3)-a racemic twofold interpenetrating network assembled from isolable tris(cyclopentadienyl)manganate and cesocene building blocks. | The syntheses and X-ray crystal structures of [([18]crown-6)2Cs](+)-[Cp3Mn]- (1), [([18]crown-6)2Cs](+)-[Cp'3Mn]- (2), [CsCp'] (3), [(CsCp')2-([18]crown-6)] (4), and Cs[MnCp3] (5), and the synthesis of Cs[MnCp'3] (6) are reported (Cp' = C5H4Me). The anions [Cp3Mn]- (1-) and [Cp'3Mn]- (2-) are characterized by eta 2 coo... |
12180322 | New scaffolds for supramolecular chemistry: upper-rim fully tethered 5-methyleneureido-5'-methyl-2,2'-bipyridyl cyclodextrins. | Seven upper-rim fully tethered cyclodextrins (URFT-CDs) have been synthesised in a good average coupling yield using the one-step "phosphine imide" approach and their metal complexation behaviour with lanthanides and transition metals was explored. We observed that the A-TE-E light conversion process (antennae effect) ... |
12179991 | Enantioseparation of novel COX-2 anti-inflammatory drugs by capillary electrophoresis using single and dual cyclodextrin systems. | A capillary electrophoresis method was developed for the enantioseparation of three novel cyclooxygenase-2 (COX-2) inhibitor drugs (E-6259, E-6036 and E-6087) with anti-inflammatory and analgesic activities using sulfobutyl ether-beta-cyclodextrin (SBE-beta-CD) as a chiral selector. The use of 50 mM sodium tetraborate ... |
12179972 | Enantioseparation of chiral sulfoxides and sulfinate esters by capillary electrophoresis. | Forty-one chiral sulfoxides and sulfinate esters were separated using sulfated beta-cyclodextrin and carboxymethyl beta-cyclodextrin as chiral selectors. Binding constants of some analytes to both chiral selectors were measured in order to examine and help explain the observed migration behavior and enantioselectivity ... |
12169026 | Critical appraisals of approaches for predictive designs in anticancer drugs. | The present review provides a critical appraisal of the most important areas in cancer drug research and, ultimately, in clinical oncology and therapy, with emphasis on the elucidation of possible predictive designs for the development of new anticancer drugs. These assessments encompass the well-established anticancer... |
12166748 | Study on the molecular recognitions of calix[n]arenes to 2,3-diaminonaphthalene by using fluorometric technique. | The molecular recognition properties of calixarenes to 2,3-diaminonaphthalene (DAN) were investigated. We found that the fluorescence emission of DAN has a blue shift after p-sulfonic sodium calix[4]arece (SSCA) was added to DAN. The proposed mechanism of the molecular recognition between SSCA and DAN indicates that DA... |
12164337 | Basement membrane type IV collagen molecules in the choroid plexus, pia mater and capillaries in the mouse brain. | We investigated the differential distribution of basement membrane type IV collagen a chains in the mouse brain by immunohistochemistry using a chain-specific monoclonal antibodies. Subendothelial basement membranes were found to contain alpha1 and alpha2 chains. Basement membranes surrounding smooth muscle cells on bl... |
12150562 | Use of full-column imaging capillary isoelectric focusing for the rapid determination of the operating conditions in the preparative-scale continuous free-flow isoelectric focusing separation of enantiomers. | A rapid, simple method is proposed here for the identification of the experimental conditions that lead to satisfactory preparative-scale isoelectric focusing enantiomer separations in continuous free-flow electrophoretic units. The method first calls for the use of a commercially available, full-column imaging capilla... |
12150560 | Stable homogeneous gel for molecular-sieving of DNA fragments in capillary electrophoresis. | A polyacrylamide gel crosslinked with allyl-beta-cyclodextrin can be used repeatedly for several weeks for the separation of DNA fragments, since bubbles are not generated during a run. Allyl-beta-cyclodextrin can easily be synthesized in one step from allylglycidylether and beta-cyclodextrin. The plate numbers for DNA... |
12146920 | Preparation and spectroscopic studies of an inclusion complex of adenine with beta-cyclodextrin in solution and in the solid state. | The interaction between adenine and beta-CD has been investigated in solution and in the solid state by several analytical techniques, primarily by 1H-NMR, 2D ROESY and fluorescence spectra, and secondarily by other important techniques, for example, Fourier transform infrared spectroscopy (FT-IR) and differential scan... |
12141558 | Determining eight colorants in milk beverages by capillary electrophoresis. | Milk beverages are popular because of their high nutritional value, and milk products that are enhanced with various fruit flavors are especially in high demand in Asia. Colorants are usually added to fruit flavored milk in order to increase its attraction and appearance, therefore, the detection and measurement of col... |
12141556 | Comparison of capillary electrophoresis and reversed-phase liquid chromatography for determination of the enantiomeric purity of an M3 antagonist. | The chiral separation of an M3 antagonist was investigated using capillary electrophoresis (CE) with various sulfated cyclodextrins and by reversed-phase liquid chromatography with derivatized cellulose, derivatized amylose, and two protein stationary phases. Operational parameters for each technique, such as the conce... |
12141563 | Liquid chromatographic resolution of racemic amines, amino alcohols and related compounds on a chiral crown ether stationary phase. | A chiral stationary phase (CSP) based on diphenyl-substituted 1,1'-binaphthyl crown ether was applied in resolving various racemic amines, amino alcohols and alpha-aminocarbonyl compounds including pharmaceutically important compounds such as amphetamine analogues, mexiletine, norepinephrine and norephedrine. The resol... |
12134827 | Development of a validated capillary electrophoresis method for enantiomeric purity testing of dexchlorpheniramine maleate. | A capillary zone electrophoresis method has been developed for the detection of 0.1% of (R)-levochlorpheniramine maleate in samples of (S)-dexchlorpheniramine maleate. Using 1.5 mM carboxymethyl-beta-cyclodextrin in an acidic background electrolyte, resolution values of more than 10 were obtained. Under these condition... |
12134824 | On-line coupling of capillary isotachophoresis and capillary zone electrophoresis for the determination of flavonoids in methanolic extracts of Hypericum perforatum leaves or flowers. | Five flavonoids (hyperoside, isoquercitrin, quercitrin, quercetin and rutin) were separated and determined in extracts of Hypericum perforatum leaves or flowers by capillary zone electrophoresis (CZE) with isotachophoretic (ITP) sample pre-treatment using on-line column coupling configuration. The background electrolyt... |
12115852 | Utility of nuclear magnetic resonance spectroscopy to characterize the structure of dexamethasone sodium phosphate inclusion complexes with cyclodextrins in solution and to analyze potential competitive effects. | The interaction between dexamethasone sodium phosphate (DSP) and four cyclodextrin (CyD) derivatives [2,6-di-O-beta-cyclodextrin (DIMEB), gamma-cyclodextrin (gamma-CyD), and hydroxypropyl-beta-cyclodextrin with either 2.7 or 4.6 degrees of substitution (HPbetaCyD 2.7 and HPbetaCyD 4.6, respectively)] was investigated b... |
12115841 | Characterization of the interaction of 2-hydroxypropyl-beta-cyclodextrin with itraconazole at pH 2, 4, and 7. | Phase-solubility techniques were used to assess the effect of pH on itraconazole complexation with 2-hydroxypropyl-beta-cyclodextrin (HPbetaCD). In addition, molecular modeling using beta-cyclodextrin as a surrogate for HPbetaCD was completed. Data suggested A(p)-type solubility relationships, indicating higher order c... |
12116135 | Enantioseparation of glutethimide and its 5-OH-metabolite in capillary electrophoresis and study of selector-selectand interactions using one-dimensional rotating frame nuclear Overhauser and exchange spectroscopy. | Enantioseparation of glutethimide (GT) and its 5-hydroxy metabolite (5-OH-GT) has been studied with several charged cyclodextrin (CD) derivatives. The emphasis was made on the enantiomer migration order of GT and simultaneous enantioseparation of GT and 5-OH-GT. The possible structural differences of GT complexes with ... |
12116130 | Separation of reboxetine enantiomers by means of capillary electrophoresis. | The novel antidepressant reboxetine, a selective norepinephrine reuptake inhibitor, is increasingly used in the treatment of different forms of major depression. Reboxetine is a chiral compound, and is marketed as a racemic mixture of (R,R)- and (S,S)-reboxetine; however, the pharmacokinetic and toxicological profiles ... |
12116127 | Modelling, optimisation and control of selectivity in the separation of aromatic bases by electrokinetic chromatography using a neutral cyclodextrin as a pseudostationary phase. | A simple mathematical model describing the separation of a series of aromatic bases by electrokinetic chromatography using beta-cyclodextrin (beta-CD) as a pseudostationary phase is described. The model takes into account changes in electrolyte pH and the different formation constants between the neutral and charged fo... |
12116122 | Capillary electrophoretic study of interactions of metal ions with crown ethers, a sulfated beta-cyclodextrin, and zwitterionic buffers present as additives in the background electrolyte. | Stability constants of K, Na, Ca, and Ba with 18-crown-6, K, Na, Li with sulfated beta-cyclodextrin and K, Li, Ca, Mg, Sr, and Ba ions with ([2-hydroxy-1,1-bis(hydroxymethyl) ethyl]-amino)-1-propanesulfonic acid (TAPS) were determined by capillary electrophoresis and computed using a general least squares minimizing pr... |
12116119 | Characterization of dendrimer properties by capillary electrophoresis and their use as pseudostationary phases. | The general properties of dendrimers and in particular their electrolytic characteristics that are relevant in electrokinetic separations, are described. In order to confirm theoretical considerations on commercial dendrimer charge and hydrodynamic radius, several capillary zone electrophoresis (CZE) experiments were p... |
12111790 | Acquired pulmonary alveolar proteinosis after umbilical cord blood transplantation for acute myeloid leukemia. | Pulmonary alveolar proteinosis (PAP) is a heterogeneous disease that occasionally develops with hematological malignancy. However, PAP in association with hematopoietic stem cell transplantation is quite rare. Here we present the first report of a patient who developed PAP after cord blood transplantation (CBT). A 45-y... |
12109108 | Changes in motion vs. bonding in positively vs. negatively cooperative interactions. | From a consideration of the interactions between non-covalent bonds, it is concluded that positively cooperative binding will occur with a benefit in enthalpy and a cost in entropy, and that negatively cooperative binding will occur with a cost in enthalpy and a benefit in entropy; experimental data support these concl... |
12109107 | Formation and manipulation of supramolecular structures of oligo(p-phenylenevinylene) terminated poly(propylene imine) dendrimers. | A third generation poly(propylene imine) dendrimer modified with pi-conjugated oligo(p-phenylenevinylene)s forms spherical and rod-like aggregates that can be manipulated by optical tweezers. |
12109095 | Calix[4]arene based dendrimers. | The synthesis of calix[4]arene based dendrimers containing up to seven calix[4]arene moieties is described, including the X-ray crystal structure of a tris-calix[4]arene branching derivative. |
12109086 | A novel dizinc bridged hydroxamate model for hydroxamate inhibited zinc hydrolases. | Reaction of Zn(OAc)(2).2H2O with tmen leads to the formation of [Zn(tmen)(OAc)2] (I) which reacts with benzohydroxamic acid to form Zn(BA)2.H2O (II) and the novel dizinc hydroxamate bridged complex [Zn2(mu-OAc)2(OAc)(mu-BA)(tmen)] (III), which may also be prepared by self-assembly and whose structure closely mimics tha... |
12109081 | Novel tungsten calix[8]arene complexes. | p-tert-Butylcalix[8]areneH8 reacts with WCl6 forming a number of new metallocalix[8]arenes, one of which is reduced to give the first example of a metal-metal triple bond supported by a large calixarene ligand; the degree of metallation and conformations adopted by the newly generated metallocalix[8]arene systems are d... |
12109066 | An unprecedented example of a cis-phosphonodithioato nickel(II) complex built by an extensive hydrogen bonding supramolecular network. | The P-N bond hydrolysis of the 4-methoxyphenyl-ammonium ethylamido-phosphonodithioato ligand during its complexation to NiII leads to the first example of phosphonodithioato nickel(II) complex having a cis configuration; this complex is stabilised in the solid state by an extensive and intricate network of hydrogen bon... |
12102529 | An assessment of the ability of the stay-green phenotype in lolium species to provide an improved protein supply for ruminants. | The stay-green phenotype results from a naturally occurring mutation in which senescent leaves retain their chlorophyll and the associated apoprotein, LHCPII. Protection of this protein pool could deliver grass with enhanced protein content and could decrease the extent of protein degradation by plant proteases in the ... |
12094933 | Enantiomer ratios, patterns and levels of toxaphene congeners in human milk from Germany. | High resolution gas chromatography (HRGC) coupled to quadrupole negative ion chemical ionization (NICI) mass spectrometry (MS) was used to investigate congener patterns, levels and enantiomer distribution of selected toxaphene congeners (#26, #41, #44, #50, #63, B7-1453) in human milk from Germany. #50 and #26 were the... |
12090296 | An experimental study on the perineurial window. | Neurological symptoms of herniated nerve fibers resulting from limited perineurial injury from sharp materials such as needles have become a recent topic in clinical practice. However, the mechanism of this disorder, which is known as a perineurial window, has not been clarified. To investigate the mechanism of nerve d... |
12088149 | Autoimmune epitopes in messenger RNA. | Patients with systemic autoimmune disorders produce autoantibodies against sequence-specific conformational RNA epitopes on U1 snRNA, 28S rRNA, and transfer RNAs. The molecular basis for immunological reactivity with these highly abundant and stable RNAs is not understood. Here, we report the existence of discrete RNA ... |
12084923 | Using deeply trapped intermediates to map the cytochrome c folding landscape. | Replacement of iron with cobalt(III) selectively introduces a deep trap in the folding-energy landscape of the heme protein cytochrome c. Remarkably, neither the protein structure nor the folding thermodynamics is perturbed by this metal-ion substitution, as shown by data from spectroscopic and x-ray diffraction experi... |
12084913 | Isolation of receptor-ligand pairs by capture of long-lived multivalent interaction complexes. | We have combined phage display and array screening for the rapid isolation of pairs of interacting polypeptides. Our strategy, named SAC (selection by avidity capture), is based on the avidity effect, the formation of highly stable complexes formed by multivalent interactions; in our case, between a receptor (multivale... |
12081328 | The peripheral benzodiazepine receptor in photodynamic therapy with the phthalocyanine photosensitizer Pc 4. | The peripheral benzodiazepine receptor (PBR) is an 18 kDa protein of the outer mitochondrial membrane that interacts with the voltage-dependent anion channel and may participate in formation of the permeability transition pore. The physiological role of PBR is reflected in the high-affinity binding of endogenous ligand... |
12081324 | Self-assembly of [Et,Et]-bacteriochlorophyll cF on highly oriented pyrolytic graphite revealed by scanning tunneling microscopy. | The chlorosomal light-harvesting antennae of green phototrophic bacteria consist of large supramolecular aggregates of bacteriochlorophyll c (BChl c). The supramolecular structure of (3(1)-R/S)-BChl c on highly oriented pyrolytic graphite (HOPG) and molybdenum disulfide (MoS2) has been investigated by scanning tunnelin... |
12079674 | Actin-binding proteins in the Arabidopsis genome database: properties of functionally distinct plant actin-depolymerizing factors/cofilins. | The plant actin cytoskeleton is a highly dynamic, fibrous structure essential in many cellular processes including cell division and cytoplasmic streaming. This structure is stimulus responsive, being affected by internal stimuli, by biotic and abiotic stresses mediated in signal transduction pathways by actin-binding ... |
12079671 | Roles for kinesin and myosin during cytokinesis. | Cytokinesis in higher plants involves the phragmoplast, a complex cytoplasmic structure that consists of microtubules (MTs), microfilaments (MFs) and membrane elements. Both MTs and MFs are essential for cell plate formation, although it is not clear which motor proteins are involved. Some candidate processes for motor... |
12080087 | Neurogenin 3 is essential for the proper specification of gastric enteroendocrine cells and the maintenance of gastric epithelial cell identity. | The notch signaling pathway is essential for the endocrine cell fate in various tissues including the enteroendocrine system of the gastrointestinal tract. Enteroendocrine cells are one of the four major cell types found in the gastric epithelium of the glandular stomach. To understand the molecular basis of enteroendo... |
12076155 | An enaminone-directed benzannulation/macrocyclization approach to cyclophane ring systems. | A straightforward and modular preparative approach to 1,3,5-triaroylbenzene-based functionalized cyclophane ring systems has been developed. The key cyclophane-forming macrocyclization reaction was accomplished during the course of a regioselective cross-benzannulation between bis(aryl ethynyl) ketone and enaminone rea... |
12076137 | Tricalixarenes and pentacalixarenes: synthesis and complexation studies. | Tricalix[4]arene 4, tricalix[5]arene 14, and pentacalix[4]arene 10 have been synthesized from O-alkylcalixarene mono- and dialdehydes by a two-step conversion to the corresponding monoethynyl ketones or diethynyl ketones followed by aryne trimerization in refluxing DMF containing a dialkylamine. The tricalixarenes 4 an... |
12074658 | Porphyrin-containing molecular capsules: metal mediated dimerization of a bis-porphyrin cavity. | [reaction] A self-complementary V-shaped bis-porphyrin cavity has been synthesized that is capable of dimerization to form a capsule structure. Self-assembly of the dimer occurs via metal ion coordination and produces an internal volume for guest encapsulation. |
12074654 | Chiral hybrid metal-organic dendrimers. | [structure: see text] New chiral terpyridines containing Frechét-type dendrons have been readily synthesized by coupling dendritic benzyl bromide and 4'-[6-(2,2'-dihydroxy-1,1'-binaphthyl)]-2,2':6'2' '-terpyridine. These chiral dendritic terpyridines were used to efficiently construct high molecular weight hybrid metal... |
12074649 | The first versatile synthetic approach to cofacial bis-porphyrins with calixarene spacers. | [structure: see text] A versatile stepwise synthetic approach to cofacial bis-porphyrin species with calix[4]arene spacers has been designed. The three examples described demonstrate that the method allows selection, in a tailor-made fashion, of the calix[4]arene conformation, the type of functionalization of the calix... |
12075024 | Global analysis of tandem aromatic octapeptide repeats: the significance of the aromatic-glycine motif. | <h4>Motivation</h4>Tandem peptide repeats play a key role in self-assembly and aggregation processes. A notable example is the occurrence of tandem peptide repeats in prionic proteins and their role in the aggregation process that leads to the formation of the prion. One of the structural characteristics that is eviden... |
12071750 | Selective substitution of corroles: nitration, hydroformylation, and chlorosulfonation. | This work demonstrates the feasibility and power of electrophilic substitution on the peripheral carbon atoms of triarylcorroles as a synthetic tool to new derivatives. The large difference in the reactivity of the various carbon atoms on the macrocycle was shown to be of electronic rather than steric origin. A careful... |
12071734 | Rational design to block amino acid editing of a tRNA synthetase. | Investigations in chemical biology have focused on the synthesis of custom-designed proteins with site-specific incorporation of novel amino acids. Their success requires stable production of misacylated tRNAs. Utilization of aminoacyl-tRNA synthetases has been hindered because of enzyme molecular recognition mechanism... |
12071724 | Coordination-driven self-assembly: solids with bidirectional porosity. | Coordination-driven self-assembly reactions have been used in the preparation of a variety of discrete supramolecular species, some of which have shown promise as synthetic receptors. Many highly ordered coordination polymers and porous networks have been prepared in a similar fashion. While a few of these solids are c... |
12069788 | A new spin on protein dynamics. | Site-directed spin labeling is a general method for investigating structure and conformational switching in soluble and membrane proteins. It will also be an important tool for exploring protein backbone dynamics. A semi-empirical analysis of nitroxide sidechain dynamics in spin-labeled proteins reveals contributions f... |
12069604 | Molecular recognition by the Candida albicans group I intron: tertiary interactions with an imino G.A pair facilitate binding of the 5' exon and lower the KM for guanosine. | A G.A pair at position -5 in the P1 helix of the Candida albicans ribozyme contributes to tertiary binding of the 5' exon substrate [Disney, M. D., Haidaris, C. G., and Turner, D. H. (2001) Biochemistry 40, 6507-6519]. Here, the G in the G.A pair is replaced with inosine (I) in both semisynthetic ribozymes and oligonuc... |
12069577 | Selective uptake from LDL is stimulated by unsaturated fatty acids and modulated by cholesterol content in the plasma membrane: role of plasma membrane composition in regulating non-SR-BI-mediated selective lipid transfer. | We previously reported that unsaturated fatty acids stimulated low-density lipoprotein (LDL) particle uptake in J774 macrophages by increasing LDL receptor activity. Since free fatty acids (FFA) also change plasma membrane properties, a putative cholesteryl ester (CE) acceptor for selective uptake (SU), we questioned t... |
12069628 | Free energy simulations come of age: protein-ligand recognition. | In recent years, molecular dynamics simulations of biomolecular free energy differences have benefited from significant methodological advances and increased computer power. Applications to molecular recognition provide an understanding of the interactions involved that goes beyond, and is an important complement to, e... |
12069242 | Triiodide PVC membrane electrodes based on charge-transfer complexes. | Three new electrodes were prepared by incorporating two different charge-transfer complexes and amino crown ether into plasticized PVC membranes. The electrodes showed Nernstian response to triiodide ion over the activity range from 1.0 x 10(-5) to 1.0 x 10(-1) mol x L(-1) with detection limits at approximately 1.0 x 1... |
12065680 | Glial cell line-derived neurotrophic factor family receptors are abnormally expressed in aganglionic bowel of a subpopulation of patients with Hirschsprung's disease. | Hirschsprung's disease (HSCR), a congenital disease, is characterized by the absence of ganglion cells in the ganglion plexuses of the caudal most gut. In the aganglionic colon, the plexus remnants are replaced by aggregates of glial cells and hypertrophied nerve fibers. Signaling of glial cell line-derived neurotrophi... |
12065611 | Detergent-insoluble glycosphingolipid/cholesterol microdomains of the myelin membrane. | Glycosphingolipids and cholesterol form lateral assemblies, or lipid 'rafts', within biological membranes. Lipid rafts are routinely studied biochemically as low-density, detergent-insoluble complexes (in non-ionic detergents at 4 degrees C; DIGs, detergent-insoluble glycosphingolipid/cholesterol microdomains). Recent ... |
12065420 | A viral protein suppresses RNA silencing and binds silencing-generated, 21- to 25-nucleotide double-stranded RNAs. | Posttranscriptional gene silencing (PTGS) processes double-stranded (ds) RNAs into 21-25 nucleotide (nt) RNA fragments that direct ribonucleases to target cognate mRNAs. In higher plants, PTGS also generates mobile signals conferring sequence-specific silencing in distant organs. Since PTGS acts as an antiviral system ... |
12065416 | Homeodomain protein ATHB6 is a target of the protein phosphatase ABI1 and regulates hormone responses in Arabidopsis. | ABI1, a protein phosphatase 2C, is a key component of signal transduction in Arabidopsis. It regulates diverse responses to the phytohormone abscisic acid (ABA) such as stomatal closure, seed dormancy and inhibition of vegetative growth. By analysing proteins capable of interacting with ABI1, we have identified the hom... |
12065406 | Shigella deliver an effector protein to trigger host microtubule destabilization, which promotes Rac1 activity and efficient bacterial internalization. | Shigella deliver a subset of effectors into the host cell via the type III secretion system, that stimulate host cell signal pathways to modulate the actin dynamics required for invasion of epithelial cells. Here we show that one of the Shigella effectors, called VirA, can interact with tubulin to promote microtubule (... |
12065402 | Crystal structure of vesicular stomatitis virus matrix protein. | The vesicular stomatitis virus (VSV) matrix protein (M) interacts with cellular membranes, self-associates and plays a major role in virus assembly and budding. We present the crystallographic structure, determined at 1.96 A resolution, of a soluble thermolysin resistant core of VSV M. The fold is a new fold shared by ... |
12065398 | Structural basis for the interaction between NTF2 and nucleoporin FxFG repeats. | Interactions with nucleoporins containing FxFG-repeat cores are crucial for the nuclear import of RanGDP mediated by nuclear transport factor 2 (NTF2). We describe here the 1.9 A resolution crystal structure of yeast NTF2-N77Y bound to a FxFG-nucleoporin core, which provides a basis for understanding this interaction a... |
12062664 | Second derivative spectrophotometric determination of trimethoprime and sulfamethoxazole in the presence of hydroxypropyl-beta-cyclodextrin (HP-beta-CD). | An easy and rapid second-derivative spectrophotometric method for the simultaneous analysis of trimethoprime (TMP) and sulfamethoxazole (SM) is described. These drugs have been used as antibacterial against a wide spectrum of organisms and combinations of these drugs are commonly used for the treatment of a variety of ... |
12062528 | Non-covalent associations of cyclomaltooligosaccharides (cyclodextrins) with carotenoids in water. A study on the alpha- and beta-cyclodextrin/psi,psi-carotene (lycopene) systems by light scattering, ionspray ionization and tandem mass spectrometry. | Water-soluble complexes of the dietary carotenoid psi,psi-carotene (lycopene 1) with cyclomaltohexaose (alpha-cyclodextrin, alphaCD) and cyclomaltoheptaose (beta-cyclodextrin, betaCD) have been prepared and characterized via multiangle light scattering (MALS), ionspray/electrospray ionization (IS/ESI) mass spectrometry... |
12060772 | A critical concentration of neutrophils is required for effective bacterial killing in suspension. | We have examined the effect of neutrophil concentration on killing of a clinical isolate of Staphylococcus epidermidis. Human neutrophils at concentrations varying from 10(5) to 10(7) per ml were mixed in suspension with S. epidermidis at concentrations varying from 10(3) to 10(8) colony-forming units/ml, and the conce... |
12060685 | Investigating the structural basis of purine specificity in the structures of MS2 coat protein RNA translational operator hairpins. | We have determined the structures of complexes between the phage MS2 coat protein and variants of the replicase translational operator in order to explore the sequence specificity of the RNA-protein interaction. The 19-nt RNA hairpins studied have substitutions at two positions that have been shown to be important for ... |
12059242 | Magnitudes and chemical consequences of R(3)N(+)-C-H...O[double bond]C hydrogen bonding. | The magnitude of the stabilizing interaction between an aliphatic C[bond]H bond attached to an ammonium nitrogen and a carbonyl oxygen was evaluated by ab initio calculations at the MP2/6-311++G** level of theory. Attractive R(3)N(+)-C-H...O[double bond]C interactions play an important role in supramolecular recognitio... |
12059240 | Heme charge-transfer band III is vibronically coupled to the Soret band. | A complete resonance Raman excitation profile of the heme charge-transfer band known as band III is presented. The data obtained throughout the near-infrared region show preresonance with the Q-band, but the data also clearly show the enhancement of a number of modes in the spectral region of band III. Only nontotally ... |
12059238 | Long-lived charge-separation by retarding reverse flow of charge-balancing cation and zeolite-encapsulated Ru(bpy)(3)(2+) as photosensitized electron pump from zeolite framework to externally placed viologen. | K(+)-exchanged, Ru(bpy)(3)(2+)-encapsulating zeolite-Y [K(+)-Ru(bpy)(3)(2+)Y] and N-[3-(dicyclohexylmethyl)oxypropyl-N'-methyl-4,4'-bipyridinium [DCH-MV(2+)] were prepared, and visible light-induced electron transfer from the zeolite-encapsulated Ru(II) complex to the size-excluded viologen was studied in acetonitrile.... |
12059196 | Chiroptical properties of poly(p-phenyleneethynylene) copolymers in thin films: large g-values. | A series of chirally substituted poly (p-phenyleneethynylene) copolymers was prepared by alkyne metathesis of mixtures of two different 2,5-dialkyl-1,4-dipropynylbenzenes. One of the monomers was the chiral bis-2,5-(S)-3,7-dimethyloctyl-1,4-dipropynylbenzene, and the second one was an achiral dipropynyl monomer. If the... |
12058077 | A polymer model for large-scale chromatin organization in lower eukaryotes. | A quantitative model of large-scale chromatin organization was applied to nuclei of fission yeast Schizosaccharomyces pombe (meiotic prophase and G2 phase), budding yeast Saccharomyces cerevisiae (young and senescent cells), Drosophila (embryonic cycles 10 and 14, and polytene tissues) and Caenorhabditis elegans (G1 ph... |
12058063 | Down-regulation of protease-activated receptor-1 is regulated by sorting nexin 1. | Degradation or "down-regulation" of protease-activated receptor-1 (PAR1), a G protein-coupled receptor for thrombin, is critical for termination of receptor signaling. Toward understanding the molecular mechanisms by which activated PAR1 is internalized, sorted to lysosomes, and degraded, we investigated whether PAR1 i... |
12056901 | Thermodynamics of aminoglycoside-rRNA recognition: the binding of neomycin-class aminoglycosides to the A site of 16S rRNA. | We use spectroscopic and calorimetric techniques to characterize the binding of the aminoglycoside antibiotics neomycin, paromomycin, and ribostamycin to a RNA oligonucleotide that models the A-site of Escherichia coli 16S rRNA. Our results reveal the following significant features: (i) Aminoglycoside binding enhances ... |
12056898 | Mapping the targeted membrane pore formation mechanism by solution NMR: the nisin Z and lipid II interaction in SDS micelles. | Nisin is an example of type-A lantibiotics that contain cyclic lanthionine rings and unusual dehydrated amino acids. Among the numerous pore-forming antimicrobial peptides, type-A lantibiotics form an unique family of post-translationally modified peptides. Via the recognition of cell wall precursor lipid II, nisin has... |
12056833 | Tenascins are associated with lipid rafts isolated from mouse brain. | Lipid rafts are microdomains of the plasma membrane which are enriched in glycosphingolipids and specific proteins. The reported interactions of several raft-associated proteins (such as, e.g., F3) with tenascin C and tenascin R prompted us to consider that these oligomeric multidomain glycoproteins of the extracellula... |
12057907 | Linking hematopoiesis to endochondral skeletogenesis through analysis of mice transgenic for collagen X. | Each skeletal element where marrow develops is first defined by a hypertrophic cartilage blueprint. Through programmed tissue substitution, the cartilaginous skeletal model is replaced by trabecular bone and marrow, with accompanying longitudinal tissue growth. During this process of endochondral ossification, hypertro... |
12054961 | The origins of noncovalent catalysis of intermolecular Diels-Alder reactions by cyclodextrins, self-assembling capsules, antibodies, and RNAses. | The catalysis of Diels-Alder reactions by noncovalent binding by synthetic, protein, and nucleic acid hosts has been surveyed and compared. These catalysts consist of binding cavities that form complexes containing both the diene and the dienophile; the cycloaddition reaction occurs in the cavity. The binding requires ... |
12054934 | Homochiral 4-azalysine building blocks: syntheses and applications in solid-phase chemistry. | Anomalous amino acids not only play central roles as mimics of natural amino acids but also offer opportunities as unique building blocks for combinatorial chemistry. This paper describes the chiral syntheses and solid-phase applications of a versatile atypical amino acid, 4-azalysine (2,6-diamino-4-azahexanoic acid) 1... |
12054858 | Delineating the site of interaction on the pIII protein of filamentous bacteriophage fd with the F-pilus of Escherichia coli. | The minor coat protein pIII at one end of the filamentous bacteriophage fd, mediates the infection of Escherichia coli cells displaying an F-pilus. pIII has three domains (D1, D2 and D3), terminating with a short hydrophobic segment at the C-terminal end. Domain D2 binds to the tip of F-pilus, which is followed by retr... |
12054993 | Linear heterotrinuclear complexes derived from an alkyl platinum(II) twelve-membered macrocycle. | The P,N,P-tridentate ligand 2,6-bis(diphenylphosphino)pyridine, L, was employed to generate a twelve-membered metallomacrocyclic host species cis-Pt(2)Me(4)(mu-L)(2) that encapsulates Tl(I) and Cu(I) guest ions. The ligand was also used to synthesize another two linear heterotrinuclear complexes, [Me(2)Pt(mu-L)(2)Ag(2)... |
12054991 | Enhancing reactivity via structural distortion. | To examine how small structural changes influence the reactivity and magnetic properties of biologically relevant metal complexes, the reactivity and magnetic properties of two structurally related five-coordinate Fe(III) thiolate compounds are compared. (Et,Pr)-ligated [Fe(III)(S(2)(Me2)N(3)(Et,Pr))]PF(6) (3) is synth... |
12054988 | Structural, spectroscopic, and reactivity comparison of xanthene- and dibenzofuran-bridged cofacial bisporphyrins. | A comparison of the structure, spectroscopy, and oxygen atom-transfer reactivity of cofacial bisporphyrins anchored by xanthene (DPX) and dibenzofuran (DPD) pillars is presented. The synthesis and characterization of dicopper(II) and dinickel(II) complexes of DPD completes a homologous series of homobimetallic zinc(II)... |
12052950 | Direct patterning of modified oligonucleotides on metals and insulators by dip-pen nanolithography. | The use of direct-write dip-pen nanolithography (DPN) to generate covalently anchored, nanoscale patterns of oligonucleotides on both metallic and insulating substrates is described. Modification of DNA with hexanethiol groups allowed patterning on gold, and oligonucleotides bearing 5'-terminal acrylamide groups could ... |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.