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14990478 | Evidence for the lack of a specific interaction between cholesterol and sphingomyelin. | The putative specific interaction and complex formation by sphingomyelin and cholesterol was investigated. Accordingly, low contents (1 mol % each) of fluorescently labeled derivatives of these lipids, namely 1-palmitoyl-2[10-(pyren-1-yl)]decanoyl-sn-glycero-3-phosphocholine (PyrPC), n-[10-(1-pyrenyl)decanoyl]sphingomy... |
14990470 | Equilibrium thermodynamics of cell-cell adhesion mediated by multiple ligand-receptor pairs. | In many situations, cell-cell adhesion is mediated by multiple ligand-receptor pairs. For example, the interaction between T cells and antigen-presenting cells of the immune system is mediated not only by T cell receptors and their ligands (peptide-major histocompatibility complex) but also by binding of intracellular ... |
14989486 | Application of tetraoxadiaza-crown ether derivatives as chiral selector modifiers in capillary electrophoresis. | Two new diaza-crown ether derivatives (R-1, RS-1) have been synthesized from 1,4,10,13-tetraoxa-7,16-diazacyclooctadecane and tested as potential chiral selectors in capillary electrophoresis (CE) for the chiral separation of five amino acid derivatives. The individual use of the selectors did not lead to chiral differ... |
14986976 | Selective binding of aromatic amines by self-assembled monolayers of a calix[6]crown-4 derivative. | A p-tert-butylcalix[6]crown-4 derivative immobilized on gold surfaces via self-assembly, endowed with a rigid cavity, can serve as a remarkably efficient sensor for aniline compared to alkylamines. The stability of the inclusion complex is attributed to the size fit and to the multipoint recognition motifs between the ... |
14986946 | Calix[4]pyrrole-capped metalloporphyrins as ditopic receptor models for anions. | Strapped calix[4]pyrrole-metalloporphyrin conjugates, potential hosts for anionic guests, have been synthesized and characterized. The condensation unexpectedly resulted in the formation of the two conformational isomers of calix[4]pyrrole-capped porphyrins 6 and 7. The anion binding studies revealed that only isomer 6... |
14986945 | Synthesis of aryl/alkyl building blocks for dendrimer and hyperbranched polymer synthesis. | Several useful aryl/alkyl building blocks for dendrimer and hyperbranched polymer synthesis were prepared by Suzuki-Miyaura cross-coupling reactions and iododesilylation reactions. The iododesilylations were carried out with iodine monochloride (ICl) in methylene chloride and diethyl ether (10:1). This solvent combinat... |
14986942 | Unusual solid-state behavior in a neutral [2]catenane bearing a hydrolyzable component. | A template-directed strategy to forming a bis(diimide) macrocycle through an intermediate asymmetric [2]catenane is reported. Saponification of the ester linkages within the crown ether component is much slower in the mechanically interlocked structure when compared to the free crown. The predominance of a single trans... |
14986941 | A self-assembled supramolecular optical sensor for NiII, CdII, and CrIII. | A new chromogenic supramolecular sensor for transition metals is reported. It is based on a newly designed phenanthroline-containing molecule that self-assembles via an organometallic "clip" into a supramolecular optical sensor for metals. [reaction: see text] |
14987012 | An investigation of the reaction of 2-aminobenzaldehyde derivatives with conjugated nitro-olefins: an easy and efficient synthesis of 3-nitro-1,2-dihydroquinolines and 3-nitroquinolines. | 2-Aryl-3-nitro-1,2-dihydroquinolines 3 were prepared from the reaction of beta-nitrostyrenes 2 and 2-aminobenzaldehyde 1 in the presence of DABCO. Not only beta-nitrostyrenes but other alkyl nitro olefins also can be used in this reaction as well. When DDQ or silica gel was added to a solution of 3-nitro-1,2-dihydroqui... |
14987844 | Protonated nucleobase ligands: synthesis, structure and characterization of 9-methyladeninium hexachloroplatinate and pentachloro(9-methyladeninium)platinum(IV). | Na(2)[PtCl(6)] was found to react with (9-MeAH)Cl(.)H(2)O (2) (9-MeA=9-methyladenine) in aqueous solution yielding (9-MeAH)(2)[PtCl(6)](.)2H(2)O (3). The same compound was obtained from hexachloroplatinic acid and 9-methyladenine. Performing this reaction at 60 degrees C, complex formation took place yielding the 9-met... |
14987109 | Real-time quantification of methanol in plants using a hybrid alcohol oxidase-peroxidase biosensor. | An amperometric biosensor immobilizing two enzymes and an electron mediator in an identical plane has been fabricated by the self-assembly technique for determination of methanol in crude plant samples. A self-assembled mixed monolayer of 4,4'-dithiodibutyric acid covalently attached two enzymes (Hansenula sp. alcohol ... |
14987106 | Potentiometric response characteristics of polycation-sensitive membrane electrodes toward poly(amidoamine) and poly(propylenimine) dendrimers. | The potentiometric response characteristics of polycation-sensitive membrane electrodes toward two classes of polycationic dendrimers are examined. Using appropriately formulated polymer membrane electrodes composed of a dinonylnaphthalenesulfonate (DNNS) salt in a plasticized polyurethane matrix, it is shown that poly... |
14987103 | Molecularly imprinted TiO2-matrix-assisted laser desorption/ionization mass spectrometry for selectively detecting alpha-cyclodextrin. | This study describes a new means to conduct molecular recognition-based analysis using mass spectrometry. Taking advantage of the unique characteristic of the absorption capacity of the TiO(2) sol-gel material in the UV region, a TiO(2) sol-gel-deposited thin film was employed as the sample substrate to assist in UV la... |
14987098 | Real-time detection of bacterial contamination in dynamic aqueous environments using optical sensors. | Here we describe on-line, real-time detection of waterborne bacteria using an optical sensor based on a starburst dendrimer film containing a lipophilic fluorophore. The sensor is constructed via covalent coupling between amine-terminated polyamidoamine dendrimer and silanized glass through an amide bond. The reporter ... |
14982455 | Design, synthesis, and crystallographic studies of neutral platinum-based macrocycles formed via self-assembly. | A series of neutral, platinum-based macrocycles was synthesized from rigid oxygen donor building blocks via self-assembly. The combination of a platinum-based 60 degrees acceptor unit 1 with several linear and angular dicarboxylate bridging ligands afforded hitherto unknown neutral platinum-based supramolecular triangl... |
14982454 | Molecular recognition and fluorescence sensing of monophosphorylated peptides in aqueous solution by bis(zinc(II)-dipicolylamine)-based artificial receptors. | The phosphorylation of proteins represents a ubiquitous mechanism for the cellular signal control of many different processes, and thus selective recognition and sensing of phosphorylated peptides and proteins in aqueous solution should be regarded as important targets in the research field of molecular recognition. We... |
14982440 | Pyridinedicarboxamide strands form double helices via an activated slippage mechanism. | The intertwining process of two strands of oligo-pyridinecarboxamides to form a double helix (Nature 2000, 407, 720) is found to consist of a series of discrete steps, where the tail of one of the strands proceeds inside the other single helix in an eddy-like process. While a plethora of minima can be located along the... |
14982435 | Modulation of radical ion pair lifetimes by the presence of a third spin in rodlike donor-acceptor triads. | It is well known that the molecular structure of an electron donor-acceptor system can be changed to optimize the electronic coupling between photogenerated radical ion pairs (PRPs), resulting in favorable charge separation (CS) and charge recombination (CR) rates. It would be far more convenient to avoid extensive syn... |
14982424 | Nanometric sponges made of water-soluble hydrophobic dendrimers. | The behavior of a fifth generation phosphorus dendrimer having a hydrophobic interior and hydrophilic end groups is studied in solution in water using the pulsed-field gradient spin-echo NMR technique. Addition of THF to this solution induces dramatic changes concerning the size of the dendrimer (+150% in volume), T1 r... |
14982416 | Can multivalency be expressed kinetically? The answer is yes. | Inspired by the concept of multivalency and in pursuit of ever more intricate artificial molecular machines, we investigated the strict self-assembly of a triply threaded two-component superbundle, starting from a tritopic receptor in which three benzo[24]crown-8 macrorings are fused onto a triphenylene core and a trif... |
14982808 | Relative bioavailability of three newly developed albendazole formulations: a randomized crossover study with healthy volunteers. | This study of healthy volunteers shows that the relative bioavailability of albendazole formulations that use arachis oil-polysorbate 80 or hydroxypropyl-beta-cyclodextrin as an excipient was enhanced 4.3- and 9.7-fold compared to the results seen with commercial tablets. Administration of macrogol suppositories did no... |
14982798 | Quantitative analysis of a parasitic antiviral strategy. | We extended a computer simulation of viral intracellular growth to study a parasitic antiviral strategy that diverts the viral replicase toward parasite growth. This strategy inhibited virus growth over a wide range of conditions, while minimizing host cell perturbations. Such parasitic strategies may inhibit the devel... |
14982779 | Plasmodium falciparum isolates in India exhibit a progressive increase in mutations associated with sulfadoxine-pyrimethamine resistance. | The combination of sulfadoxine-pyrimethamine (SP) is used as a second line of therapy for the treatment of uncomplicated chloroquine-resistant Plasmodium falciparum malaria. Resistance to SP arises due to certain point mutations in the genes for the dihydrofolate reductase (DHFR) and dihydropteroate synthetase (DHPS) e... |
14981139 | Protons block BK channels by competitive inhibition with K+ and contribute to the limits of unitary currents at high voltages. | Proton block of unitary currents through BK channels was investigated with single-channel recording. Increasing intracellular proton concentration decreased unitary current amplitudes with an apparent pKa of 5.1 without discrete blocking events, indicating fast proton block. Unitary currents recorded at pH(i) 8.0 and 9... |
14980541 | Molecular recognition: the fragment approach in lead generation. | The successful practice of medicinal chemistry is crucially dependent on the principles of molecular recognition: the first and "fundamental" requirement for a drug is to bind to its target; specificity, or at least selectivity, of binding is also a must. Subsequent optimization steps to develop a lead compound into a ... |
14980819 | 1H NMR spectra of branched-chain cyclomaltohexaoses (alpha-cyclodextrins). | The 1H NMR spectra of seven branched alpha-cyclodextrins (alpha-CDs) were observed and analyzed in detail. They were compared with spectra of alpha-CD and amylose. Although these branched alpha-CDs consist only of alpha-D-glucose with the same alpha-(1-->4) O-glucosyl binding, aside from one exception, differences in c... |
14980636 | Synthesis and biological evaluation of novel macrocyclic bis-7-azaindolylmaleimides as potent and highly selective glycogen synthase kinase-3 beta (GSK-3 beta) inhibitors. | Palladium catalyzed cross-coupling reactions were used to synthesize two key intermediates 3 and 5 that resulted in the synthesis of novel series of macrocyclic bis-7-azaindolylmaleimides. Among the three series of macrocycles, the oxygen atom and thiophene containing linkers yielded molecules with higher inhibitory po... |
14979721 | Calorimetric measurement of phospholipid interaction with methyl-beta-cyclodextrin. | Cyclodextrins are able to bind hydrophobic molecules in their interior cavity and as such have received a great deal of attention as carriers of cholesterol, lipophilic drugs, and other sparingly soluble compounds. Despite the importance of these biochemical applications, relatively little is known about the interactio... |
14978312 | Oligomerization of hydrophobin SC3 in solution: from soluble state to self-assembly. | Hydrophobin SC3 is a protein with special self-association properties that differ depending on whether it is in solution, on an air/water interface or on a solid surface. Its self-association on an air/water interface and solid surface have been extensively characterized. The current study focuses on its self-associati... |
14978228 | Functional role of lipid raft microdomains in cyclic nucleotide-gated channel activation. | Cyclic nucleotide-gated (CNG) channels are the primary targets of light- and odorant-induced signaling in photoreceptors and olfactory sensory neurons. Compartmentalized cyclic nucleotide signaling is necessary to ensure rapid and efficient activation of these nonselective cation channels. However, relatively little is... |
14977987 | Determination of surface-exposed, functional domains of gonococcal transferrin-binding protein A. | The gonococcal transferrin receptor is composed of two distinct proteins, TbpA and TbpB. TbpA is a member of the TonB-dependent family of integral outer membrane transporters, while TbpB is lipid modified and thought to be peripherally surface exposed. We previously proposed a hypothetical topology model for gonococcal... |
14977958 | Helicobacter pylori and complex gangliosides. | Recognition of sialic acid-containing glycoconjugates by the human gastric pathogen Helicobacter pylori has been repeatedly demonstrated. To investigate the structural requirements for H. pylori binding to complex gangliosides, a large number of gangliosides were isolated and characterized by mass spectrometry and prot... |
14973045 | Identification and mapping of self-assembling protein domains encoded by the Escherichia coli K-12 genome by use of lambda repressor fusions. | Self-assembling proteins and protein fragments encoded by the Escherichia coli genome were identified from E. coli K-12 strain MG1655. Libraries of random DNA fragments cloned into a series of lambda repressor fusion vectors were subjected to selection for immunity to infection by phage lambda. Survivors were identifie... |
14973030 | In silico and transcriptional analysis of carbohydrate uptake systems of Streptomyces coelicolor A3(2). | Streptomyces coelicolor is the prototype for the investigation of antibiotic-producing and differentiating actinomycetes. As soil bacteria, streptomycetes can metabolize a wide variety of carbon sources and are hence vested with various specific permeases. Their activity and regulation substantially determine the nutri... |
14970397 | Eukaryotic protein synthesis inhibitors identified by comparison of cytotoxicity profiles. | The National Cancer Institute (NCI) Human Tumor Cell Line Anti-Cancer Drug Screen has evaluated the cytotoxicity profiles of a large number of synthetic compounds, natural products, and plant extracts on 60 different cell lines. The data for each compound/extract can be assessed for similarity of cytotoxicity pattern, ... |
14970389 | Intracellular expression of engineered RNase P ribozymes effectively blocks gene expression and replication of human cytomegalovirus. | A ribozyme (M1GS RNA) constructed from the catalytic RNA subunit of RNase P from Escherichia coli was used to target the overlapping region of two human cytomegalovirus (HCMV) mRNAs, which encode for the viral essential protease (PR) and capsid assembly proteins (AP), respectively. The results show a reduction of >80% ... |
14662007 | Lipid rafts: heterogeneity on the high seas. | Lipid rafts are membrane microdomains that are enriched in cholesterol and glycosphingolipids. They have been implicated in processes as diverse as signal transduction, endocytosis and cholesterol trafficking. Recent evidence suggests that this diversity of function is accompanied by a diversity in the composition of l... |
14616090 | Methyl-beta-cyclodextrin stimulates glucose uptake in Clone 9 cells: a possible role for lipid rafts. | An acute increase in the Vmax for glucose uptake occurs in many mammalian cell types after exposure to osmotic or metabolic stress. In the rat epithelial Clone 9 cell line, the glucose transporter isoform GLUT1 is responsible for this enhanced uptake. Although stimulation of transport in these cells is known to result ... |
14616089 | Anthrax lethal factor-cleavage products of MAPK (mitogen-activated protein kinase) kinases exhibit reduced binding to their cognate MAPKs. | Anthrax lethal toxin is the major cause of death in systemic anthrax. Lethal toxin consists of two proteins: protective antigen and LF (lethal factor). Protective antigen binds to a cell-surface receptor and transports LF into the cytosol. LF is a metalloprotease that targets MKKs [MAPK (mitogen-activated protein kinas... |
14963172 | Identification of peptides that inhibit the DNA binding, trans-activator, and DNA replication functions of the human papillomavirus type 11 E2 protein. | Peptide antagonists of the human papillomavirus type 11 (HPV-11) E2-DNA association were identified using a filamentous bacteriophage random peptide library. Synthetic peptides antagonized the E2-DNA interaction, effectively blocked E2-mediated transcriptional activation of a reporter gene in cell culture, and inhibite... |
14963169 | Roles of the E6 and E7 proteins in the life cycle of low-risk human papillomavirus type 11. | Many important functions have been attributed to the high-risk human papillomavirus (HPV) E6 and E7 proteins, including binding and degradation of p53 as well as interacting with Rb proteins. In contrast, the physiological roles of the low-risk E6 and E7 proteins remain unclear. Previous studies demonstrated that the h... |
14963159 | Immunization strategies to block the herpes simplex virus type 1 immunoglobulin G Fc receptor. | Herpes simplex virus type 1 (HSV-1) glycoprotein gE functions as an immunoglobulin G (IgG) Fc receptor (FcgammaR) that promotes immune evasion. When an IgG antibody binds by the F(ab')(2) domain to an HSV antigen, the Fc domain of some of the same antibody molecules binds to the FcgammaR, which blocks Fc-mediated funct... |
14963133 | Alterations of pr-M cleavage and virus export in pr-M junction chimeric dengue viruses. | During the export of flavivirus particles through the secretory pathway, a viral envelope glycoprotein, prM, is cleaved by the proprotein convertase furin; this cleavage is required for the subsequent rearrangement of receptor-binding E glycoprotein and for virus infectivity. Similar to many furin substrates, prM in ve... |
14963127 | Characterization of rotavirus cell entry. | While recently we have learned much about the viral and cellular proteins involved in the initial attachment of rotaviruses to MA104 cells, the mechanism by which these viruses reach the interior of the cell is poorly understood. For this study, we observed the effects of drugs and of dominant-negative mutants, known t... |
14764109 | Helicobacter pylori gamma-glutamyltranspeptidase upregulates COX-2 and EGF-related peptide expression in human gastric cells. | Gastric mucosa responds to Helicobacter pylori-induced cell damage by increasing the expression of COX-2 and EGF-related peptides. We sought to investigate the bacterial virulence factor/s and the host cellular pathways involved in the upregulation of COX-2, HB-EGF and amphiregulin in MKN 28 and AGS gastric mucosal cel... |
14762892 | Degradation of NSC-281612 (4-[bis[2-[(methylsulfonyl)oxy]ethyl]amino]-2-methyl-benzaldehyde), an experimental antineoplastic agent: effects of pH, solvent composition, (SBE)7m-beta-CD, and HP-beta-CD on stability. | NSC-281612 (4-[bis[2-[(methylsulfonyl)oxy]ethyl]amino]-2-methyl-benzaldehyde, 1), is a chemically unstable, poorly water soluble, experimental antineoplastic agent. The saturated solubility in water at 25 degrees C was determined as approximately 30 microg/mL. In the pH range 2-11, 1 displayed pH-independent stability ... |
14757086 | Dendrimer-templated Ag-Pd bimetallic nanoparticles. | Ultrafine dendrimer-templated Ag-Pd bimetallic nanoparticles with various metal compositions have been prepared successfully using silver(I)-bis(oxalato)palladate(II) complex. The use of an oxalate complex, in which two metal ions exist in one complex, is found to be effective in preventing unfavorable silver halide fo... |
14757080 | Nanoscale organization of adsorbed collagen: influence of substrate hydrophobicity and adsorption time. | The adsorption of collagen on polystyrene (PS) and polystyrene oxidized by oxygen plasma discharge (PSox) was studied as a function of time using radiolabeling, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). Radiolabeling and XPS indicated that the initial step of adsorption was faster on PS... |
18007418 | Lipid-lowering effects of ethyl 2-phenacyl-3-aryl-1H-pyrrole- 4-carboxylates in rodents. | A series of substituted 2-phenacyl-3-phenyl-1H-pyrrole-4-carboxylates were prepared from substituted acetophenones in 6 steps. The final condensations between a chloroenal and an aminoketone were carried out under neutral conditions in parallel to yield the series listed below. Selected pyrrole derivatives proved to be... |
18007410 | Noncovalent labeling of biomolecules with red and near- infrared dyes. | Biopolymers such as proteins and nucleic acids can be labeled with a fluorescent marker to allow for their detection. Covalent labeling is achieved by the reaction of an appropriately functionalized dye marker with a reactive group on a biomolecule. The recent trend, however, is the use of noncovalent labeling that res... |
15045097 | Destruction of perfluoroalkyl surfactant aggregates by beta-cyclodextrin. | A water 1H NMRD and 19F NMR spectroscopy study has proved, for the first time, that perfluoroalkyl surfactant micelles can be completely destroyed upon addition of beta-cyclodextrin to form successively 1:1 and 2:1 (beta-CD:R(F)) inclusion complexes. |
15113423 | COMe: the ontology of bioinorganic proteins. | <h4>Background</h4>Many characterised proteins contain metal ions, small organic molecules or modified residues. In contrast, the huge amount of data generated by genome projects consists exclusively of sequences with almost no annotation. One of the goals of the structural genomics initiative is to provide representat... |
14990571 | Expression and supramolecular assembly of recombinant alpha1(viii) and alpha2(viii) collagen homotrimers. | Collagen VIII is an extracellular matrix macromolecule comprising two polypeptide chains, alpha1(VIII) and alpha2(VIII), that can form homotrimers in vitro and in vivo. Here, recombinant collagen VIII was expressed to study its supramolecular assembly following secretion. Cells transfected with alpha1(VIII) or alpha2(V... |
14990801 | Asymmetric catalysis: an enabling science. | Chirality of organic molecules plays an enormous role in areas ranging from medicine to material science, yet the synthesis of such entities in one enantiomeric form is one of the most difficult challenges. The advances being made stem from the convergence of a broader understanding of theory and how structure begets f... |
14990752 | Quantitative high-throughput analysis of transcription factor binding specificities. | We present a general high-throughput approach to accurately quantify DNA-protein interactions, which can facilitate the identification of functional genetic polymorphisms. The method tested here on two structurally distinct transcription factors (TFs), NF-kappaB and OCT-1, comprises three steps: (i) optimized selection... |
14990747 | Conformational change of pseudouridine 55 synthase upon its association with RNA substrate. | Pseudouridine 55 synthase (Psi55S) catalyzes isomerization of uridine (U) to pseudouridine (Psi) at position 55 in transfer RNA. The crystal structures of Thermotoga maritima Psi55S, and its complex with RNA, have been determined at 2.9 and 3.0 A resolutions, respectively. Structural comparisons with other families of ... |
14988734 | Eucaryotic initiation factor 4B controls eIF3-mediated ribosomal entry of viral reinitiation factor. | The cauliflower mosaic virus reinitiation factor TAV interacts with host translation initiation factor 3 (eIF3) and the 60S ribosomal subunit to accomplish translation of polycistronic mRNAs. Interaction between TAV and eIF3g is critical for the reinitiation process. Here, we show that eIF4B can preclude formation of t... |
15070736 | Exploring amyloid formation by a de novo design. | Protein deposition as amyloid fibrils underlies many debilitating human disorders. The complexity and size of disease-related polypeptides, however, often hinders a detailed rational approach to study effects that contribute to the process of amyloid formation. We report here a simplified peptide sequence successfully ... |
15034615 | Multivalent binding of galactosylated cyclodextrin vesicles to lectin. | Amphiphilic beta-cyclodextrins with alkylthio chains at the primary-hydroxyl side and galactosylthio-oligo-(ethylene glycol) units at the secondary-hydroxyl side, which form nanoparticles and vesicles, show multivalent effects in their binding to lectin. |
14988499 | Water in protein structure prediction. | Proteins have evolved to use water to help guide folding. A physically motivated, nonpairwise-additive model of water-mediated interactions added to a protein structure prediction Hamiltonian yields marked improvement in the quality of structure prediction for larger proteins. Free energy profile analysis suggests that... |
15004697 | Protein NMR in biomedical research. | Nuclear magnetic resonance (NMR) spectroscopy is a versatile biophysical technique with wide applicability in drug discovery research, particularly for the detection and characterization of molecular interactions. This review highlights in a comprehensive manner the aspects of biomolecular NMR which are most beneficial... |
15252478 | Electrochemical anion recognition with ferrocene functionalised macrocycles. | The syntheses and characterization of two new redox active cyclam ligands ferrocenylmethyl-(6-methyl-1,4,8,11-tetraazacyclotetradec-6-yl)-amine (L3) and 1,1'-ferrocenylmethyl-bis(6-methyl-1,4,8,11-tetraazacyclotetradec-6-yl)-amine (L4) are reported. The compounds each possess a ferrocenyl group bearing one (L3) or two ... |
15045058 | Solvent templated synthesis of metal-organic frameworks: structural characterisation and properties of the 3D network isomers [[Mn(dcbp)].1/2DMF]n and [[Mn(dcbp)][middle dot]2H2O](n). | The identity of the metal-organic framework formed by Mn(ii) and 4,4[prime or minute]-dicarboxy-2,2[prime or minute]-bipyridine (H(2)dcbp) depends upon the predominant solvent employed in the synthesis and yields the robust network isomers [[Mn(dcbp)][middle dot]1/2DMF](n), and [[Mn(dcbp)][middle dot]2H(2)O](n), which ... |
15052359 | Preparation of photocyclizable dianthracene derivatives of resorc[4]arenes which are potential photoswitches. | Resorc[4]arenes have been difunctionalized on opposite sides of the macrocycle using two anthracene units, which undergo intramolecular dimerization on irradiation at 350 nm. Syntheses and time-dependent photochemical experiments are reported. |
14993702 | Crystallization and preliminary X-ray study of gamma-type cyclodextrin glycosyltransferase from Bacillus clarkii. | A gamma-cyclodextrin glycosyltransferase (EC 2.4.1.19) from Bacillus clarkii was crystallized using the hanging-drop vapour-diffusion method at 293 K. X-ray diffraction data were collected to 2.2 A. The crystal belongs to space group R3, with unit-cell parameters a = b = 211.6, c = 52.7 A. The asymmetric unit contains ... |
15252680 | Alkene metatheses in transition metal coordination spheres: dimacrocyclizations that join trans positions of square-planar platinum complexes to give topologically novel diphosphine ligands. | The alkene-containing phosphines PPh((CH2)(n)CH=CH2)2)2 are prepared from PPhH(2), n-BuLi, and the corresponding bromoalkenes (1:2:2), and combined with the platinum tetrahydrothiophene complex [Pt(mu-Cl)(C(6)F(5))(S(CH2CH2(-))2)]2 to give the square-planar adducts trans-(Cl)(C(6)F(5))Pt(PPh((CH2)(n)CH=CH2)2)2 (11, 93-... |
14995465 | Antiferroelectric ordering of amphiphilic glycolipids in bent-core liquid crystals. | Lipids are the main constituents of biological cell membranes, and their liquid crystalline properties play a crucial role in cell functions. We have discovered that dodecyl-beta-D-glucopyranoside glycolipid layers can be electrically polarized in supramolecular structures of glycolipid and bent-core ("banana-shape") m... |
15045094 | Growth of poly(pseudorotaxane) on gold using host-stabilized charge-transfer interaction. | A novel supramolecular polymer (poly(pseudorotaxane)) in which the repeating units are linked by host-stabilized charge-transfer interaction between the guest molecules is grown on gold and characterized. |
15007423 | NMR and ESR investigations of the interaction between a carboxylic acid and an amine at the focal point of L-lysine based dendritic branches. | This paper reports the characterisation of supramolecular complexes formed between the carboxylic acid group at the focal point of host dendritic branches based on l-lysine building blocks and an amine group on an appropriate guest molecule. (1)H NMR titration investigations indicate that the interaction is relatively ... |
15198533 | Preparation and physicochemical characterization of 5 niclosamide solvates and 1 hemisolvate. | The purpose of the study was to characterize the physicochemical, structural, and spectral properties of the 1:1 niclosamide and methanol, diethyl ether, dimethyl sulfoxide, N,N' dimethylformamide, and tetrahydrofuran solvates and the 2:1 niclosamide and tetraethylene glycol hemisolvate prepared by recrystallization fr... |
15026818 | Metallosupramolecular squares: from structure to function. | Metallosupramolecular squares have been successfully evolved over the past years as versatile substitutes of the conventional organic macrocycles owing to the development of reliable synthetic protocols and abundant structural variability (metals and ligands). In this review we have presented the fundamental aspects of... |
14981269 | Stereochemistry in self-assembled encapsulation complexes: constellational isomerism. | A previously uncharacterized form of stereochemistry, constellational isomerism, is described. The isomerism arises from different arrangements of small-molecule guests in the space of a self-assembled, cylindrical host. The cylindrical host detains three molecules each of CHCl(3), 1,2-dichloroethane, or isopropyl chlo... |
14981244 | Engineering biological structures of prescribed shape using self-assembling multicellular systems. | Self-assembly is a fundamental process that drives structural organization in both inanimate and living systems. It is in the course of self-assembly of cells and tissues in early development that the organism and its parts eventually acquire their final shape. Even though developmental patterning through self-assembly... |
14981096 | Dynamic redistribution of raft domains as an organizing platform for signaling during cell chemotaxis. | Spatially restricted activation of signaling molecules governs critical aspects of cell migration; the mechanism by which this is achieved nonetheless remains unknown. Using time-lapse confocal microscopy, we analyzed dynamic redistribution of lipid rafts in chemoattractant-stimulated leukocytes expressing glycosyl pho... |
14981095 | Epiblast cells that express MyoD recruit pluripotent cells to the skeletal muscle lineage. | Embryonic stem cells are derived from the epiblast. A subpopulation of epiblast cells expresses MyoD mRNA and the G8 antigen in vivo. G8 positive (G8pos) and G8 negative (G8neg) populations were isolated by magnetic cell sorting. Nearly all G8pos cells switched from E- to N-cadherin and differentiated into skeletal mus... |
14978217 | Human topoisomerase IIalpha: targeting to subchromosomal sites of activity during interphase and mitosis. | Mammalian topoisomerase IIalpha (topo IIalpha) plays a vital role in the removal of topological complexities left on DNA during S phase. Here, we developed a new assay to selectively identify sites of catalytic activity of topo IIalpha with subcellular resolution. We show that topo IIalpha activity concentrates at repl... |
14978215 | The tetraspan protein EMP2 modulates the surface expression of caveolins and glycosylphosphatidyl inositol-linked proteins. | Caveolae are a subset of lipid rafts enriched in glycosphingolipids and cholesterol-rich domains, but selectively lacking glycosylphosphatidyl inositol-anchored proteins (GPI-APs). Caveolin proteins are the organizing component of caveolae, but the corresponding proteins for other classes of lipid rafts are poorly defi... |
15010755 | Diastereospecific synthesis of phosphinidene-capped cyclodextrins leading to "introverted" ligands. | alpha-Cyclodextrins (alpha-CDs) containing "PPh" units which cap the primary face of the CD were obtained in high yield by reaction of Li(2)PPh with A,B- or A,C-dimesylated and A,B,D,E-tetramesylated precursors; the resulting phosphines are diastereomerically pure and constitute valuable precursors for the synthesis of... |
14978287 | Two discriminatory binding sites in the Escherichia coli replication origin are required for DNA strand opening by initiator DnaA-ATP. | Initiation of DNA replication in eukaryotes, archea, and eubacteria requires interaction of structurally conserved ATP-binding initiator proteins and origin DNA to mediate assembly of replisomes. However, the specific requirement for ATP in the early steps of initiation remains unclear. This is true even for the well s... |
14977635 | Changes in membrane cholesterol affect caveolin-1 localization and ICC-pacing in mouse jejunum. | Pacing of mouse is dependent on the spontaneous activity of interstitial cells of Cajal in the myenteric plexus (ICC-MP). These ICC, as well as intestinal smooth muscle, contain small membrane invaginations called caveolae. Caveolae are signaling centers formed by insertions of caveolin proteins in the inner aspect of ... |
14976195 | Expression cloning of a human cDNA restoring sphingomyelin synthesis and cell growth in sphingomyelin synthase-defective lymphoid cells. | Sphingomyelin (SM) synthase has been assumed to be involved in both cell death and survival by regulating pro-apoptotic mediator ceramide and pro-survival mediator diacylglycerol. However, its precise functions are ambiguous due to the lack of molecular cloning of SM synthase gene(s). We isolated WR19L/Fas-SM(-) mouse ... |
15010762 | Novel hybrid hetero-sandwich architectures via stoichiometric control of host-guest self-organization. | Thiocyanate cadmium and methylviologen hybrid host-guest compounds give two novel multiple sandwich architectures with regular or irregular grids of the anionic layer in the structures as effected by the molar ratios of starting ingredients, and show evidence of charge-transfer to the organic dications. |
15007419 | Stereoselective dialkylation of the proximal hydroxy groups of calix- and thiacalix[4]arenes. | Treatment of p-tert-butylcalix[4]arene (C1) and its sulfur-bridged analog T1 with 1,3-dichloro-1,1,3,3-tetraisopropyldisiloxane in the presence of imidazole gives proximally O,O'-disiloxane-1,3-diyl-bridged calixarenes C2 and T2 in excellent yields, respectively. Subsequent base-catalyzed etherification of the remainin... |
15007408 | Studies on the interaction of phosphate anions with N-functionalised polyaza[n]paracyclophanes: the role of N-methylation. | The synthesis and interaction of N,N',N'',N'''-tetramethyl-2,6,9,13-tetraaza[14]paracyclophanes (B323Me(4)) with nucleotides and inorganic phosphates is described. An easy methodology is used to define thermodynamic selectivity. The interaction of B323Me4 and ATP has been monitored by (1)H, (31)P NMR and by molecular m... |
14973329 | Surfection: a new platform for transfected cell arrays. | Efficient high-throughput expression of genes in mammalian cells can facilitate large-scale functional genomic studies. Towards this aim, we developed a simple yet powerful method to deliver genes into cells by cationic polymers on the surface of substrates. Transfection can be achieved by directly contacting nucleic a... |
14973201 | A novel strategy to engineer DNA polymerases for enhanced processivity and improved performance in vitro. | Mechanisms that allow replicative DNA polymerases to attain high processivity are often specific to a given polymerase and cannot be generalized to others. Here we report a protein engineering-based approach to significantly improve the processivity of DNA polymerases by covalently linking the polymerase domain to a se... |
14966533 | Engineered biosynthesis of regioselectively modified aromatic polyketides using bimodular polyketide synthases. | Bacterial aromatic polyketides such as tetracycline and doxorubicin are a medicinally important class of natural products produced as secondary metabolites by actinomyces bacteria. Their backbones are derived from malonyl-CoA units by polyketide synthases (PKSs). The nascent polyketide chain is synthesized by the minim... |
14995478 | Influence of polymer architecture and polymer-wall interaction on the adsorption of polymers into a slit-pore. | The effects of molecular topology and polymer-surface interaction on the properties of isolated polymer chains trapped in a slit were investigated using off-lattice Monte Carlo simulations. Various methods were implemented to allow efficient simulation of molecular structure, confinement force, and free energy for a ch... |
14967816 | Sterol regulation of scavenger receptor class B type I in macrophages. | Scavenger receptor class B type I (SR-BI) is expressed in macrophages, but its role in sterol trafficking in these cells remains controversial. We examined the effect of sterol loading on SR-BI expression in human monocytes/macrophages, mouse peritoneal macrophages, and a cultured mouse macrophage cell line (J774 cells... |
14968132 | Molecular insights into the interaction of PYM with the Mago-Y14 core of the exon junction complex. | The exon junction complex (EJC) is deposited on mRNAs as a consequence of splicing and influences postsplicing mRNA metabolism. The Mago-Y14 heterodimer is a core component of the EJC. Recently, the protein PYM has been identified as an interacting partner of Mago-Y14. Here we show that PYM is a cytoplasmic RNA-binding... |
14966135 | Cholesterol-independent interactions with CD47 enhance alphavbeta3 avidity. | Expression in OV10 cells of either wild-type CD47 or its extracellular IgV domain linked to a glycosylphosphatidylinositol anchor-(IgV-GPI) enhanced ligand-induced alpha(v)beta(3) activation as detected by the binding of LIBS1 and LIBS6 mAbs. The amplitude of LIBS binding was greater with both CD47 and IgV-GPI expressi... |
14966216 | Self assembly of epicuticular waxes on living plant surfaces imaged by atomic force microscopy (AFM). | The cuticle of terrestrial vascular plants and some bryophytes is covered with a complex mixture of lipids, usually called epicuticular waxes. Self-assembly processes of wax molecules lead to crystalline three-dimensional micro- and nanostructures that emerge from an underlying wax film. This paper presents the first A... |
15252475 | Supramolecular triangular and linear arrays of metal-radical solids using pyrazolato-silver(I) motifs. | New chelating radical ligands pzNNH, pzINH, and pzbisINH (3-pyrazolyl nitronyl nitroxide, 3-pyrazolyl imino nitroxide, and pyrazole-3,5-diyl bis(imino nitroxide), respectively) were prepared. Complexation of these ligands with Ag+ gave [Ag(pzNN)]n, [Ag(pzIN)]6, and [Ag(pzbisIN)]n containing the corresponding anionic fo... |
15010796 | Helical supramolecular host with aquapores anchoring alternate molecules of helical water chains. | Unprecedented 1D helical chains of hydrogen bonded water molecules, showing both handedness and anchored onto a helical supramolecular host formed from the self assembly of a dicopper(II) complex (1) containing pentadentate Schiff base (L) and p-hydroxycinnamate in 1.2H(2)O, propagate along the crystallographic 2(1)-sc... |
15010783 | A sequential highly stereoselective hydroboration and Suzuki-Miyaura cross-coupling reaction of fluoroalkylated internal acetylenes: a practical one-pot synthesis of fluoroalkylated trisubstituted alkenes. | The one-pot synthesis of trisubstituted alkenes starting from fluoroalkylated internal alkynes was investigated. Hydroboration of the alkynes proceeded in a highly regio- and stereoselective manner to give the corresponding vinylboranes in excellent yields. Without isolation, treatment of the vinylboranes with various ... |
14963486 | Structure of a flavivirus envelope glycoprotein in its low-pH-induced membrane fusion conformation. | Enveloped viruses enter cells via a membrane fusion reaction driven by conformational changes of specific viral envelope proteins. We report here the structure of the ectodomain of the tick-borne encephalitis virus envelope glycoprotein, E, a prototypical class II fusion protein, in its trimeric low-pH-induced conforma... |
14973570 | Medicinal chemistry in academia: molecular recognition with biological receptors. | Why carry out medicinal chemistry at a university, when it means competing with the billion-dollar research efforts of the pharmaceutical industry? In academic research, the race to get a drug to market is not the prime motivation. Instead, university-based medicinal chemistry is driven by the search for new knowledge ... |
14963033 | Ouabain assembles signaling cascades through the caveolar Na+/K+-ATPase. | Based on the observation that the Na(+)/K(+)-ATPase alpha subunit contains two conserved caveolin-binding motifs, we hypothesized that clustering of the Na(+)/K(+)-ATPase and its partners in caveolae facilitates ouabain-activated signal transduction. Glutathione S-transferase pull-down assay showed that the Na(+)/K(+)-... |
14963261 | Kinetic and thermodynamic characterization of the RNA-cleaving 8-17 deoxyribozyme. | The 8-17 deoxyribozyme is a small DNA catalyst of significant applicative interest. We have analyzed the kinetic features of a well behaved 8-17 construct and determined the influence of several reaction conditions on such features, providing a basis for further exploration of the deoxyribozyme mechanism. The 8-17 boun... |
14960716 | The importance of intrinsic disorder for protein phosphorylation. | Reversible protein phosphorylation provides a major regulatory mechanism in eukaryotic cells. Due to the high variability of amino acid residues flanking a relatively limited number of experimentally identified phosphorylation sites, reliable prediction of such sites still remains an important issue. Here we report the... |
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