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12589045 | Visualizing lipid raft dynamics and early signaling events during antigen receptor-mediated B-lymphocyte activation. | Recent biochemical evidence indicates that an early event in signal transduction by the B-cell antigen receptor (BCR) is its translocation to specialized membrane subdomains known as lipid rafts. We have taken a microscopic approach to image lipid rafts and early events associated with BCR signal transduction. Lipid ra... |
12588177 | Redox active macrocyclic receptors for neutral guests. | A novel series of triazine-appended macrocyclic complexes has been investigated as potential hydrogen bonding receptors for complementarily disposed heterocycles. Cocrystallization of a melamine-appended azacyclam complex of Cu(II) has been achieved with barbitone, the barbiturate anion and thymine. In each case, a com... |
12588151 | Nickel(II) macrocyclic complexes with long alkyl pendant chain: synthesis, x-ray structure, and anion exchange property in the solid state. | A nickel(II) pentaaza macrocyclic complex containing a 1-hexadecyl pendant chain, [Ni(C(25)H(55)N(5))](ClO(4))(2).H(2)O (1), was synthesized by a one-pot metal-template condensation reaction. Crystal data for 1: triclinic, Ponemacr;, a = 8.333(4) A, b = 8.356(3) A, c = 28.374(9) A, alpha = 81.865(19) degrees, beta = 86... |
12588141 | Reduction pathway of end-on coordinated dinitrogen. 3. Electronic structure and spectroscopic properties of molybdenum/tungsten hydrazidium complexes. | The spectroscopic properties and electronic structure of the hydrazidium complexes [MF(NNH(3))(depe)(2)](BF(4))(2), M = Mo and W, are investigated (depe = 1,2-bis(diethylphosphino)ethane). Vibrational spectroscopic data for both compounds are evaluated with a quantum-chemistry-assisted normal coordinate analysis, givin... |
12585899 | Computational studies on pseudorotaxanes by molecular dynamics and free energy perturbation simulations. | A computational scheme that comprises the utilization of the AMBER force field with RESP charges and an explicit solvent model for acetonitrile proved to be useful for studying the structures and energetics of pseudorotaxanes of benzidine and 4,4'-biphenol with cyclobis(paraquat-p-phenylene). The scheme can be further ... |
12585880 | Enantioselective synthesis of spirocyclic aminochroman derivatives according to the CN(R,S) strategy. | Enantiomerically pure (3'R)- and (3'S)-3',4'-dihydrospiro[piperidine-2,3'(2'H)-benzopyran]s (R)-10 and (S)-10 were successfully synthesized according to the CN(R,S) methodology with the aim of serving as a pattern for the generation of related spirocyclic compounds. Two different synthetic pathways were studied startin... |
12586510 | Hydrophilic and hydrophobic cyclodextrins in a new sustained release oral formulation of nicardipine: in vitro evaluation and bioavailability studies in rabbits. | The feasibility of using complexes with cyclodextrins (CDs) in nicardipine (NC) controlled delivery has been examined, with a view to extending the pharmaceutical applications spectrum of these carriers. For a fast release fraction, a hydrophilic beta-cyclodextrin derivative (hydroxypropyl-beta-cyclodextrin) was employ... |
12586498 | Dendrimers conjugates for colonic delivery of 5-aminosalicylic acid. | The water-soluble polyamidoamine (PAMAM) dendrimer conjugates for colonic delivery of 5-aminosalicylic acid (5-ASA) were designed. The drug was bound to the dendrimer using two different spacers containing azo-bond, p-aminobenzoic acid (PABA) and p-aminohippuric acid (PAH). Incubation of PAMAM dendrimer conjugates cont... |
12586461 | ESI-mass spectrometry analysis of unsubstituted and disubstituted beta-cyclodextrins: fragmentation mode and identification of the AB, AC, AD regioisomers. | The study of unsubstituted and disubstituted beta-cyclodextrins (beta-CDs) by ESI-mass spectrometry is reported, applying a cone-induced fragmentation in the presence of a twofold excess of sodium chloride, in order to gain information about the fragmentation of the different regioisomers. On the basis of the fragmenta... |
12586368 | Involvement of cholesterol in the inhibitory effect of dimethyl-beta-cyclodextrin on P-glycoprotein and MRP2 function in Caco-2 cells. | We compared the inhibitory effect of various cyclodextrins (CyDs) on P-glycoprotein (P-gp) and multidrug resistance-associated protein 2 (MRP2) function and examined the contribution of cholesterol to the inhibitory effect of 2,6-di-O-methyl-beta-cyclodextrin (DM-beta-CyD) on the efflux activity of the function in Caco... |
12585492 | Porphyrin assembly on beta-cyclodextrin for selective sensing and detection of a zinc ion based on the dual emission fluorescence ratio. | In the present paper, a new cyclodextrin/porphyrin supramolecular sensitizer for zinc ion has been proposed based on the porphyrin dual fluorescence emission ratio. In aqueous solution, meso-tetraphenylporphyrin shows weak fluorescence, while in the presence of alkylated beta-cyclodextrin, it exhibits significant fluor... |
12585464 | Synergistic pseudo-hydroxide extraction: synergism and anion selectivity in sodium extraction using a crown ether and a series of weak lipophilic acids. | The nature of the weak lipophilic acid used in synergistic combination with a model crown ether cation host was shown to have a strong effect on the strength and selectivity of sodium hydroxide separation from alkaline aqueous salt solutions. Sodium ion-pair extraction employing only cis-syn-cis-dicyclohexano-18-crown-... |
12584714 | Combinatorial library of low molecular-weight organo- and hydrogelators based on glycosylated amino acid derivatives by solid-phase synthesis. | A combinatorial approach for the synthesis of supramolecular gelators as new organic materials is described herein. In the course of the development of a convenient and flexible solid-phase synthesis of the artificial glycolipids, some of these compounds were accidentally found to act as low molecular-weight gelators t... |
12584711 | A computational study of regioselectivity in a cyclodextrin-mediated Diels-Alder reaction: revelation of site selectivity and the importance of shallow binding and multiple binding modes. | The use of a cyclodextrin.Diels-Alder transition structure complex (CD.TS) as a model in molecular dynamics simulations has enabled us to gain insight into the controlling factors in the cyclodextrin-mediated Diels-Alder reaction of methyl-p-benzoquinone with isoprene. MD simulations were carried out with multiple bind... |
12584708 | Hierarchical self-assembly, coassembly, and self-organization of novel liquid crystalline lattices and superlattices from a twin-tapered dendritic benzamide and its four-cylinder-bundle supramolecular polymer. | The synthesis and structural analysis of the twin-dendritic benzamide 10, based on the first-generation, self-assembling, tapered dendrons 3,4,5-tris(4'-dodecyloxybenzyloxy)benzoic acid and 3,4,5-tris(4'-dodecyloxybenzyloxy)-1-aminobenzene, and the polymethacrylate, 20, which contains 10 as side groups, are presented. ... |
12584699 | Rapid screening of binding constants by calibrated competitive 1H NMR spectroscopy. | A calibrated competitive NMR method has been developed that is appropriate for the rapid screening of binding constants. This method involves the initial characterisation of a receptor-substrate binding event for which the (1)H NMR spectrum of a given receptor (calibrant) is modified by the substrate of interest at a r... |
12582248 | Inhibition of human papilloma virus E2 DNA binding protein by covalently linked polyamides. | Polyamides are a class of heterocyclic small molecules with the potential of controlling gene expression by binding to the minor groove of DNA in a sequence-specific manner. To evaluate the feasibility of this class of compounds as antiviral therapeutics, molecules were designed to essential sequence elements occurring... |
12582246 | Mutations in the histone fold domain of the TAF12 gene show synthetic lethality with the TAF1 gene lacking the TAF N-terminal domain (TAND) by different mechanisms from those in the SPT15 gene encoding the TATA box-binding protein (TBP). | The general transcription factor TFIID, composed of the TATA box-binding protein (TBP) and 14 TBP-associated factors (TAFs), is important for both basal and regulated transcription by RNA polymerase II. Although it is well known that the TAF N-terminal domain (TAND) at the amino-terminus of the TAF1 protein binds to TB... |
12582241 | A single-nucleotide natural variation (U4 to C4) in an influenza A virus promoter exhibits a large structural change: implications for differential viral RNA synthesis by RNA-dependent RNA polymerase. | The influenza A virus promoter is recognized by the influenza A virus RNA-dependent RNA polymerase, and directs both transcription and replication of the viral RNA genome. Within the sequence of this promoter, flu strains exhibit a natural, unique variation, either a U or a C, at the fourth position from the 3' end. Pr... |
12582240 | DNA crosslinking and biological activity of a hairpin polyamide-chlorambucil conjugate. | A prototype of a novel class of DNA alkylating agents, which combines the DNA crosslinking moiety chlorambucil (Chl) with a sequence-selective hairpin pyrrole-imidazole polyamide ImPy-beta-ImPy-gamma-ImPy-beta-Dp (polyamide 1), was evaluated for its ability to damage DNA and induce biological responses. Polyamide 1-Chl... |
12582234 | Structural transition from antiparallel to parallel G-quadruplex of d(G4T4G4) induced by Ca2+. | Guanine quadruplex (G-quadruplex) structures are formed by guanine-rich oligonucleotides. Because of their in vivo and in vitro importance, numerous studies have been demonstrated that the structure and stability of the G-quadruplex are dependent on the sequence of oligonucleotide and environmental conditions such as e... |
12580604 | Preparation and characterization of polypseudorotaxanes based on block-selected inclusion complexation between poly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide) triblock copolymers and alpha-cyclodextrin. | A series of new polypseudorotaxanes were synthesized in high yields when the middle poly(ethylene oxide) (PEO) block of poly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide) (PPO-PEO-PPO) triblock copolymers was selectively recognized and included by alpha-cyclodextrin (alpha-CD) to form crystalline inclusio... |
12580581 | Determination of the enantiomeric composition of guest molecules by chemometric analysis of the UV-visible spectra of cyclodextrin guest-host complexes. | Multivariate statistical techniques were applied to the UV spectra of a series of solutions at pH 12 containing a fixed concentration (30 mM) of beta-cyclodextrin (beta-CD) and a fixed concentration (15 mM) of 2-phenylglycine (phi-Gly) with various known enantiomeric compositions. Multivariate correlation of the spectr... |
12581203 | Relation between domain evolution, specificity, and taxonomy of the alpha-amylase family members containing a C-terminal starch-binding domain. | The alpha-amylase family (glycoside hydrolase family 13; GH 13) contains enzymes with approximately 30 specificities. Six types of enzyme from the family can possess a C-terminal starch-binding domain (SBD): alpha-amylase, maltotetraohydrolase, maltopentaohydrolase, maltogenic alpha-amylase, acarviose transferase, and ... |
12582125 | Targeting the variable surface of African trypanosomes with variant surface glycoprotein-specific, serum-stable RNA aptamers. | African trypanosomes cause sleeping sickness in humans and Nagana in cattle. The parasites multiply in the blood and escape the immune response of the infected host by antigenic variation. Antigenic variation is characterized by a periodic change of the parasite protein surface, which consists of a variant glycoprotein... |
12580945 | Verotoxin 1 binding to intestinal crypt epithelial cells results in localization to lysosomes and abrogation of toxicity. | Verotoxins (VTs) are important virulence factors of enterohaemorrhagic Escherichia coli (EHEC), a group of bacteria associated with severe disease sequelae in humans. The potent cytotoxic activity of VTs is important in pathogenicity, resulting in the death of cells expressing receptor Gb3 (globotriaosylceramide). EHEC... |
12578122 | Burn injury-mediated alterations in cell cycle progression in lymphoid organs of mice. | A key event in the cellular and molecular pathogenesis of multiple organ failure (MOF) after burn injury may be the change in profiles of the cell cycle progression in affected organs. We investigated the effects of burn injury on cell cycle progression in immune organs. Cell cycle analysis in the lymphoid tissues of m... |
12576665 | Novel channel structure of bile acid-guest inclusion complex formed between ursodeoxycholic acid and phenanthrene. | The crystal structure of inclusion complex between ursodeoxycholic acid (UDCA), and phenanthrene has been determined. UDCA molecules formed hydrogen bond network to provide the channel structure along b axis, and phenanthrene molecules were accommodated in the cavity with a stoichiometry of 1 : 1 molar ratio. The chann... |
12576065 | Simultaneous resolution of underivatized regioisomers and stereoisomers of arachidonate epoxides by capillary electrophoresis. | cis-Epoxyeicosatrienoic acids (EETs) and their hydrolysis products (threo-DHETs) have been proposed to be endothelial-dependent hyperpolarizing factors (EDHFs) which upregulate blood flow when tissue perfusion is impaired. Various EET regioisomers and enantiomers are formed from arachidonate by inducible cytochrome P45... |
12574813 | A critical role of lipid rafts in the organization of a key FcgammaRIIa-mediated signaling pathway in human platelets. | The involvement of platelet FcgammaRIIa in heparin-associated thrombocytopenia (HIT) is now well established. However, the precise sequence of molecular events initiated by FcgammaRIIa cross-linking in platelets remains partly characterized. We investigated here the role of lipid rafts in the spatio-temporal organizati... |
12574260 | Characterization of some actinomyces-like isolates from human clinical sources: description of Varibaculum cambriensis gen nov, sp nov. | Fifteen strains of an anaerobic, catalase-negative, gram-positive diphtheroid-shaped bacterium recovered from human sources were characterized by phenotypic and molecular chemical and molecular genetic methods. The unidentified bacterium showed some resemblance to Actinomyces species and related taxa, but biochemical t... |
12573895 | Mechanisms of phthalate ester toxicity in the female reproductive system. | Phthalates are high-production-volume synthetic chemicals with ubiquitous human exposures because of their use in plastics and other common consumer products. Recent epidemiologic evidence suggests that women have a unique exposure profile to phthalates, which raises concern about the potential health hazards posed by ... |
12574120 | Glycoprotein G isoforms from some alphaherpesviruses function as broad-spectrum chemokine binding proteins. | Mimicry of host chemokines and chemokine receptors to modulate chemokine activity is a strategy encoded by beta- and gammaherpesviruses, but very limited information is available on the anti-chemokine strategies encoded by alphaherpesviruses. The secretion of chemokine binding proteins (vCKBPs) has hitherto been consid... |
12574114 | Homo- and heterotetrameric architecture of the epithelial Ca2+ channels TRPV5 and TRPV6. | The molecular assembly of the epithelial Ca(2+) channels (TRPV5 and TRPV6) was investigated to determine the subunit stoichiometry and composition. Immunoblot analysis of Xenopus laevis oocytes expressing TRPV5 and TRPV6 revealed two specific bands of 75 and 85-100 kDa, corresponding to the core and glycosylated protei... |
12569363 | Selective PDZ protein-dependent stimulation of phosphatidylinositol 3-kinase by the adenovirus E4-ORF1 oncoprotein. | While PDZ domain-containing proteins represent cellular targets for several different viral oncoproteins, including human papillomavirus E6, human T-cell leukemia virus type 1 Tax, and human adenovirus E4-ORF1, the functional consequences for such interactions have not been elucidated. Here we report that, at the plasm... |
12568614 | Self-assembly mechanism of a bimetallic europium triple-stranded helicate. | We report the self-assembly process of a supramolecular edifice based on the coordination of europium(III) by a ditopic strand L bearing tridentate bis(benzimidazolyl)pyridine subunits. Varying the metal/ligand ratio and using a fruitful combination of electrospray mass spectrometry and absorption spectrophotometry, we... |
12569473 | Unidirectional threading of triphenylureidocalix[6]arene-based wheels: oriented pseudorotaxane synthesis. | Triphenylureidocalix[6]arenes 5 a,b are heteroditopic receptors having a pinched cone structure able to interact with both the cation and the anion of ion pairs. They are able to act as wheels and form complexes of the pseudorotaxane type with axles derived from dialkylviologen salts. An investigation into the possibil... |
12569472 | Recognition of caffeine in aqueous solutions. | Binding of caffeine in aqueous solutions has been achieved for the first time by using water-soluble, tetracationic peptide-porphyrin conjugates Zn-1 as the receptor molecules. The association constant for caffeine with receptor Zn-1 is in some cases as high as 6000 M(-1), only 5-6 times lower than the highest binding ... |
12569455 | Halide anion capture and recognition by a tetrahedral tetraammonium receptor in water: a molecular dynamics investigation. | We report molecular dynamics potential of mean force (PMF) simulations on the capture of halide anions X(-) (F(-), Cl(-), Br(-)) by a tetrahedral receptor L(4+) built from four quaternary ammonium sites connected by six (CH(2))(n) chains, leading to the formation of inclusion complexes X(-) subset L(4+). Simulations pe... |
12565736 | Disulfide bridges and blockage of Shaker B K(+)-channels by another butantoxin peptide purified from the Argentinean scorpion Tityus trivittatus. | A peptide was isolated from the venom of the scorpion Tityus trivittatus. It is an isoform of the toxin TsTX-IV earlier described [Toxicon 37 (1999) 651] and identical to butantoxin [Arch. Biochem. Biophys. 379 (2000) 18], both isolated from the Brazilian scorpion Tityus serrulatus. This newly characterized peptide con... |
12566431 | Mechanism of filopodia initiation by reorganization of a dendritic network. | Afilopodium protrudes by elongation of bundled actin filaments in its core. However, the mechanism of filopodia initiation remains unknown. Using live-cell imaging with GFP-tagged proteins and correlative electron microscopy, we performed a kinetic-structural analysis of filopodial initiation in B16F1 melanoma cells. F... |
12566430 | EPLIN regulates actin dynamics by cross-linking and stabilizing filaments. | Epithelial protein lost in neoplasm (EPLIN) is a cytoskeleton-associated protein encoded by a gene that is down-regulated in transformed cells. EPLIN increases the number and size of actin stress fibers and inhibits membrane ruffling induced by Rac. EPLIN has at least two actin binding sites. Purified recombinant EPLIN... |
12566426 | The intramitochondrial dynamin-related GTPase, Mgm1p, is a component of a protein complex that mediates mitochondrial fusion. | A balance between fission and fusion events determines the morphology of mitochondria. In yeast, mitochondrial fission is regulated by the outer membrane-associated dynamin-related GTPase, Dnm1p. Mitochondrial fusion requires two integral outer membrane components, Fzo1p and Ugo1p. Interestingly, mutations in a second ... |
12566425 | Anthrax toxin rafts into cells. | Anthrax toxin binds to a plasma membrane receptor and after endocytosis exerts its deadly effects on the cell. Until now, however, the mechanism of initial toxin uptake was unknown. In this issue, Abrami et al. (2003) demonstrate that toxin oligomerization clusters the anthrax receptor into lipid rafts and this complex... |
12565820 | The role of alpha3beta1 integrin in determining the supramolecular organization of laminin-5 in the extracellular matrix of keratinocytes. | Analyses of mice with targeted deletions in the genes for alpha3 and beta1 integrin suggest that the alpha3beta1 integrin heterodimer likely determines the organization of the extracellular matrix within the basement membrane of skin. Here we tested this hypothesis using keratinocytes derived from alpha3 integrin-null ... |
12566079 | Differential allosteric modulation by amiloride analogues of agonist and antagonist binding at A(1) and A(3) adenosine receptors. | The diuretic drug amiloride and its analogues were found previously to be allosteric modulators of antagonist binding to A(2A) adenosine receptors. In this study, the possibility of the allosteric modulation by amiloride analogues of antagonist binding at A(1) and A(3) receptors, as well as agonist binding at A(1), A(2... |
12563291 | Transglutaminases: crosslinking enzymes with pleiotropic functions. | Blood coagulation, skin-barrier formation, hardening of the fertilization envelope, extracellular-matrix assembly and other important biological processes are dependent on the rapid generation of covalent crosslinks between proteins. These reactions--which are catalysed by transglutaminases--endow the resulting supramo... |
12562531 | Methyl-beta-cyclodextrin but not retinoic acid reduces EAAT3-mediated glutamate uptake and increases GTRAP3-18 expression. | The Na+-dependent glutamate transporter EAAT3 facilitates glutamate uptake into neurons as well as many other cell types. GTRAP3-18 (JWA, Arl6ip5) is a novel protein that interacts with EAAT3 and negatively modulates EAAT3-mediated glutamate uptake. Previous studies suggest that retinoic acid (RA) decreases Na+-depende... |
12562510 | Palmitic and stearic fatty acids induce caspase-dependent and -independent cell death in nerve growth factor differentiated PC12 cells. | Apoptotic cell death has been proposed to play a role in the neuronal loss observed following traumatic injury in the CNS and PNS. The present study uses an in vitro tissue culture model to investigate whether free fatty acids (FFAs), at concentrations comparable to those found following traumatic brain injury, trigger... |
12562208 | Synthesis, crystal structures, and third-order nonlinear optical properties of a series of ferrocenyl organometallics. | Three novel ferrocenyl complexes [Zn(4-PFA)(2)(NO(3))(2)](H(2)O) (1), [Hg(2)(OAc)(4)(4-BPFA)(2)](CH(3)OH) (2), and [Cd(2)(OAc)(4)(4-BPFA)(2)] (3) (4-PFA = [(4-pyridylamino)carbonyl]ferrocene, 4-BPFA = 1,1'-bis[(4-pyridylamino)carbonyl]ferrocene) were prepared, and complexes 1 and 2 were structurally characterized by me... |
12562198 | Subtle role of polyatomic anions in molecular construction: structures and properties of AgX bearing 2,4'-thiobis(pyridine) (X(-) = NO(3)(-), BF(4)(-), ClO(4)(-), PF(6)(-), CF(3)CO(2)(-), and CF(3)SO(3)(-)). | Studies on the subtle effects and roles of polyatomic anions in the self-assembly of a series of AgX complexes with 2,4'-Py(2)S (X(-) = NO(3)(-), BF(4)(-), ClO(4)(-), PF(6)(-), CF(3)CO(2)(-), and CF(3)SO(3)(-); 2,4'-Py(2)S = 2,4'-thiobis(pyridine)) have been carried out. The formation of products appears to be primaril... |
12562194 | Peripheral metal-ion binding to tris(thia-oxo crown) porphyrazines. | We report the preparation and solution properties of metal-free [1b(H(2))] and cobalt [1c(Co)] porphyrazines (pz's), where three pyrroles are functionalized with a S(2)O(3) crown ether for metal-ion binding and the fourth pyrrole is appended with two long-chain alcohols (bis((11-hydroxyundecyl)thio)) for potential use ... |
12562190 | Synthesis, crystal structure, and magnetic properties of ([Cu(oxbe)]Mn(H(2)O)[Cu(oxbe)(DMF)])(n).nDMF.nH(2)O: From dissymmetrical mononuclear entities to a 3D heterometallic supramolecular coordination polymer. | Self-assembly of the building block [Cu(oxbe)](-) with Mn(II) led to a novel coordination polymer ([Cu(oxbe)]Mn(H(2)O)[Cu(oxbe)(DMF)])n).nDMF.nH(2)O, where H(3)oxbe is a new dissymmetrical ligand N-benzoato-N'-(2-aminoethyl)oxamido and DMF = dimethylformamide. The crystal forms in the triclinic system, space group Pone... |
12560512 | Single primer amplification (SPA) of cDNA for microarray expression analysis. | The potential of expression analysis using cDNA microarrays to address complex problems in a wide variety of biological contexts is now being realised. A limiting factor in such analyses is often the amount of RNA required, usually tens of micrograms. To address this problem researchers have turned to methods of improv... |
12560501 | Synapsis and strand exchange in the resolution and DNA inversion reactions catalysed by the beta recombinase. | In the presence of a sequence-independent chromatin-associated protein, such as Hbsu or HMGB, the beta recombinase catalyses resolution between two directly oriented recombination sites (six sites) and both resolution and DNA inversion between two inversely oriented six sites. Assembly of the synaptic complex requires ... |
12560051 | Determination of hydroxyanthraquinoids in Rhubarb by cyclodextrin-modified micellar electrokinetic chromatography using a mixed micellar system of sodium dodecyl sulfate and sodium cholate. | A cyclodextrin-modified micellar electrokinetic chromatographic (CD-MEKC) method was established to determine five hydroxyanthraquinoids in Rhubarb. The five components were successfully separated by using the mixed micellar system consisting of 20 mmol/l sodium dodecyl sulfate (SDS) and 20 mmol/l sodium cholate (SC) w... |
12558448 | A mild deprotection strategy for allyl-protecting groups and its implications in sequence specific dendrimer synthesis. | A mild deprotection strategy for allyl ethers under basic conditions in the presence of a palladium catalyst is described. Under these conditions, aryl allyl ethers can be cleaved selectively in the presence of alkyl allyl ethers. These conditions are also effective in the deprotection of allyloxycarbonyl groups. The u... |
12558440 | A novel type of hydrogen-bonded assemblies based on the melamine.cyanuric acid motif. | This paper reports the formation of novel hydrogen-bonded assemblies 1(3).CA obtained upon mixing cyanuric acid (CA) with melamine derivatives 1, in which two of the three possible H-bonding arrays have been blocked. The four components are held together by 9 hydrogen bonds and form a rigid planar structure in which a ... |
12558439 | Contracted and expanded meso-alkynyl porphyrinoids: from triphyrin to hexaphyrin. | The boron trifluoride-catalyzed Rothemund condensation of triisopropylsilyl (TIPS) propynal 1 with 3,4-diethylpyrrole in dichloromethane, followed by oxidation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) generates a mixture of products, including [15]triphyrin(1.1.3) H3, corrole H(3)4, porphyrin H(2)2, [24]pen... |
12558408 | Catalytic specificity exhibited by p-sulfonatocalix[n]arenes in the methanolysis of N-acetyl-l-amino acids. | Specific acid catalysis of p-sulfonatocalix[n]arenes (n = 4, Calix-S4; n = 6, Calix-S6; n = 8, Calix-S8) was observed in the alcoholysis of N-acetyl-l-amino acids in methanol. The methanolysis rates of basic amino acid substrates (His, Lys, and Arg) were markedly enhanced in the presence of Calix-Sn, as compared with r... |
12558405 | Synthesis of novel cross-conjugated dendritic fluorophores containing both phenylenevinylene and phenyleneethynylene moieties. | New dendrons and dendrimers with dendritic arms composed of alternate phenyleneethynylene and phenylenevinylene moieties have been efficiently synthesized using orthogonal and convergent syntheses that combine Sonogashira and Horner-Wadsworth-Emmons reactions. Two different iterative routes have been developed that all... |
12558397 | Rhodium-catalyzed addition of arylboronic acids to alkynyl aza-heteroaromatic compounds in water. | Alkynyl heteroaromatic compounds reacted with arylboronic acids to give addition products in the presence of a rhodium catalyst. The best results were obtained when a novel pyridine-substituted water-soluble phosphine ligand was used. The reactions proceed to give trisubstituted alkenes from various arylboronic acids a... |
12558385 | Shape-persistent nanosize organometallic complexes: synthesis and application in a nanofiltration membrane reactor. | Shape-persistent multi(NCN-palladium and/or -platinum) complexes having one- (5 and 6), two- (1 and 2), and three-dimensional (3 and 4) geometries were prepared in moderate to good yields. Two different approaches were used to construct the multimetallic materials: (i) the construction of the multisite ligands followed... |
12559927 | Utilising structural knowledge in drug design strategies: applications using Relibase. | The concept of structure-based drug design is based upon an in-depth understanding of the principles of molecular recognition. Despite our lack of a thorough comprehension of these principles, the wealth of protein structures available opens up unprecedented possibilities for new insights from the analysis of these dat... |
12559748 | Regioselective sulfonylation at O-2 of cyclomaltoheptaose with 1-(p-tolylsulfonyl)-(1H)-1,2,4-triazole. | 2(I)-O-p-Tolylsulfonylcyclomaltoheptaose was obtained in 42% yield by reaction of 1-(p-tolylsulfonyl)-(1H)-1,2,4-triazole on NaH-deprotonated cyclomaltoheptaose in DMF and further converted into the corresponding mono-2(I),3(I)-manno-epoxide. |
12559746 | Crystal structure of beta-cyclodextrin-benzoic acid inclusion complex. | The inclusion complex of beta-cyclodextrin (beta-CD) with benzoic acid (BA) has been characterized crystallographically. Two beta-CDs cocrystallize with two BAs, 0.7 ethanol and 20.65 water molecules [2(C(6)H(10)O(5))(7).2(C(7)H(6)O(2)).0.7(C(2)H(6)O).20.65H(2)O] in the triclinic space group P1 with unit cell constants... |
12559733 | Crystallographic analysis of the thermal motion of the inclusion complex of cyclomaltoheptaose (beta-cyclodextrin) with hexamethylenetetramine. | The crystal structure of the inclusion complex of cyclomaltoheptaose (beta-cyclodextrin) with hexamethylenetetramine was determined at temperatures of 123, 173, 223, and 293 K. The rigid-body motion of the host and guest molecules was evaluated by means of the TLS method that represents the molecular motion in terms of... |
12556194 | Synthesis and structure of a polyphenylene macrocycle related to "cubic graphite". | [structure: see text] Palladium-catalyzed coupling of 1,2-bis(4-bromophenyl)-3,4,5,6-tetraphenylbenzene and the corresponding hexaphenylbenzene bis(boronic acid) gave a mixture of linear and cyclic oligomers of hexaphenylbenzene. An X-ray crystal structure of the tetrameric oligomer showed it to be the polyphenylene ma... |
12556188 | The first electroresponsive phenylazomethine macrocycles: highly preferential formation and regular molecular packing. | [structure: see text] Highly preferential formation of novel polyphenylazomethine macrocycles was achieved by further addition of TiCl(4) and/or the monomer during the course of the polycondensation. These macrocycles have unique structures based on the (E)/(Z)-conformation of the azomethine bonds, the extremely regula... |
12556164 | Binding ability and self-assembly behavior of linear polymeric supramolecules formed by modified beta-cyclodextrin. | [structure: see text] The binding ability and self-assembly behavior of molecular interpenetration by newly synthesized mono[6-O-(4-formyl-phenyl)-beta-cyclodextrin has been investigated, revealing the formation mechanism of modified cyclodextrin from solution aggregation to solid linear polymeric supramolecules. |
12556481 | SKIP negatively regulates insulin-induced GLUT4 translocation and membrane ruffle formation. | Skeletal muscle and kidney enriched inositol phosphatase (SKIP) is an inositol polyphosphate 5-phosphatase that hydrolyzes phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P3] to downregulate intracellular levels. In this study, we show that SKIP inhibits phosphoinositide 3-kinase signaling in insulin-stimulated CHO ... |
12556401 | Activation of scleral cold thermoreceptors by temperature and blood flow changes. | <h4>Purpose</h4>To study the response of scleral cold receptors located in areas of the eye unexposed to temperature and blood flow changes.<h4>Methods</h4>In anesthetized cats, the neural activity was recorded from single, cold-sensory fibers of the ciliary nerves innervating the sclera and limbus. Controlled temperat... |
12554868 | Selection of RRE RNA binding peptides using a kanamycin antitermination assay. | The arginine-rich domains of several RNA-binding proteins have been shown to bind their cognate RNAs with high affinities and specificities as isolated peptides, adopting different conformations within different complexes. The sequence simplicity and structural diversity of the arginine-rich motif has made it a good fr... |
12554801 | Differential recruitment of alpha2beta1 and alpha4beta1 integrins to lipid rafts in Jurkat T lymphocytes exposed to collagen type IV and fibronectin. | Collagen type IV (CnIV) and fibronectin (Fn) were used as ligands to study the distribution of alpha(2)beta(1) and alpha(4)beta(1) integrins in low-density, detergent-resistant microdomains (DRM) of Jurkat lymphocytes. CnIV-coated microspheres induced (optical trapping) the redistribution of GM(1)-associated fluorescen... |
12553839 | Crown-annelated oligothiophenes as model compounds for molecular actuation. | Crown-annelated quater- (4T) and sexithiophenes (6T) with oligooxyethylene chains of various lengths attached at the 3-positions of the terminal thiophene rings have been synthesized. Analysis of the cation-binding properties of the macrocycles by (1)H NMR and UV-vis spectroscopy reveals the formation of a 1:1 complex ... |
12553838 | Entropic barriers in nanoscale adhesion studied by variable temperature chemical force microscopy. | Intermolecular interactions drive the vast majority of condensed phase phenomena from molecular recognition to protein folding to particle adhesion. Complex energy barriers encountered in these interactions include contributions from van der Waals forces, hydrogen bonding, and solvent medium. With the spectacular excep... |
12553829 | Detection and amplification of a small enantiomeric imbalance in alpha-amino acids by a helical poly(phenylacetylene) with crown ether pendants. | We have designed a novel stereoregular poly(phenylacetylene) bearing the bulky crown ether as the pendant (poly-1) for the amino acid binding site. The polymer forms a one-handed helix upon complexation with l-amino acid perchlorates, and the complexes exhibit an induced circular dichroism (ICD) with the same Cotton ef... |
12553828 | Functional nanocomposites prepared by self-assembly and polymerization of diacetylene surfactants and silicic acid. | Conjugated polymer/silica nanocomposites with hexagonal, cubic, or lamellar mesoscopic order were synthesized by self-assembly using polymerizable amphiphilic diacetylene molecules as both structure-directing agents and monomers. The self-assembly procedure is rapid and incorporates the organic monomers uniformly withi... |
12553827 | Origin of the red shifts in the optical absorption bands of nonplanar tetraalkylporphyrins. | The view that the large red shifts seen in the UV-visible absorption bands of peripherally crowded nonplanar porphyrins are the result of nonplanar deformations of the macrocycle has recently been challenged by the suggestion that the red shifts arise from substituent-induced changes in the macrocycle bond lengths and ... |
12553800 | Supramolecular H-bonded assemblies of redox-active metallodendrimers and positive and unusual dendritic effects on the recognition of H2PO4-. | The DSM polyamine dendrimers dend-DAB-(NH2)x of generations 1 (x = 4) to 4 (x = 32) form H-bonded dendritic assemblies with the phenol AB3 units p-HOC6H4C(CH2CHCH2)3 and p-HOC6H4C{(CH2)3SiCH2NHCOFc}3 (Fc = ferrocenyl), as shown by the shifts of the NH2 and OH signals giving a concentration-dependent common signal betwe... |
12553785 | To fold or to assemble? | We introduce a new class of foldable oligomers consisting of alternating rigid and flexible regions. The rigid segments overlap to give pi-stacked folded conformers whose formation is driven mostly by pi-pi molecular orbital overlaps. As the oligomer concentration increases, the folded molecular structures further self... |
12554651 | Structural basis of adhesion-molecule recognition by ERM proteins revealed by the crystal structure of the radixin-ICAM-2 complex. | ERM (ezrin/radixin/moesin) proteins recognize the cytoplasmic domains of adhesion molecules in the formation of the membrane-associated cytoskeleton. Here we report the crystal structure of the radixin FERM (4.1 and ERM) domain complexed with the ICAM-2 cytoplasmic peptide. The non-polar region of the ICAM-2 peptide co... |
12554637 | From Alzheimer to Huntington: why is a structural understanding so difficult? | An increasing family of neurodegenerative disorders such as Alzheimer's, Parkinson's and Huntington's diseases, prion encephalopathies and cystic fibrosis is associated with aggregation of misfolded polypeptide chains which are toxic to the cell. Knowledge of the three-dimensional structure of the proteins implicated i... |
12552012 | Structure and mechanism of a coreceptor for infection by a pathogenic feline retrovirus. | Infection of T lymphocytes by the cytopathic retrovirus feline leukemia virus subgroup T (FeLV-T) requires FeLIX, a cellular coreceptor that is encoded by an endogenous provirus and closely resembles the receptor-binding domain (RBD) of feline leukemia virus subgroup B (FeLV-B). We determined the structure of FeLV-B RB... |
12552001 | Molluscum contagiosum virus interleukin-18 (IL-18) binding protein is secreted as a full-length form that binds cell surface glycosaminoglycans through the C-terminal tail and a furin-cleaved form with only the IL-18 binding domain. | Some poxviruses and their mammalian hosts encode homologous proteins that bind interleukin-18 (IL-18) with high affinity and inhibit IL-18-mediated immune responses. MC54L, the IL-18 binding protein of the human poxvirus that causes molluscum contagiosum, is unique in having a C-terminal tail of nearly 100 amino acids ... |
12552000 | Cell penetration and trafficking of polyomavirus. | The murine polyomavirus (Py) enters mouse fibroblasts and kidney epithelial cells via an endocytic pathway that is caveola-independent (as well as clathrin-independent). In contrast, uptake of simian virus 40 into the same cells is dependent on caveola. Following the initial uptake of Py, both microtubules and microfil... |
12551994 | The coxsackie B virus and adenovirus receptor resides in a distinct membrane microdomain. | The coxsackie B virus and adenovirus receptor (CAR) is a member of the immunoglobulin superfamily. In addition to activity as a viral receptor, it may play a role in cellular adhesion. We asked what determines the cell membrane microdomain of CAR. We found that CAR is localized to a novel lipid-rich microdomain similar... |
12551981 | Baculovirus alkaline nuclease possesses a 5'-->3' exonuclease activity and associates with the DNA-binding protein LEF-3. | Alkaline nuclease (AN) of the Autographa californica multiple-capsid nucleopolyhedrovirus (AcMNPV) (open reading frame 133) was expressed in recombinant baculovirus as a His(6)-tagged fusion and purified by sequential chromatography on Ni-NTA-agarose, DEAE-Toyopearl, and heparin-Sepharose. At all stages of purification... |
12550802 | The influence of surface modification on the cytotoxicity of PAMAM dendrimers. | The influence of surface modification on the cytotoxicity of PAMAM dendrimers was examined using Caco-2 cells. Dendrimers were modified by conjugating either lauroyl chains or polyethylene glycol (PEG) 2000 onto the surface of cationic PAMAM dendrimers (G2, G3, G4). The cytotoxicity of unmodified dendrimers towards Cac... |
12550791 | New approach to stability assessment of protein solution formulations by differential scanning calorimetry. | A central composite rotate second order design was used to evaluate chicken egg-white lysozyme (lysozyme) thermal stability at different pH, and lysozyme, sucrose and 2-hydroxypropyl-beta-cyclodextrin (HPbetaCD) concentrations, by means of differential scanning calorimetry (DSC). Four measurements were used to characte... |
12549909 | Molecular recognition of the human coactivator CBP by the HIV-1 transcriptional activator Tat. | HIV-1 Tat is required for the expression of the viral genome. Tat binds to an RNA stem-loop and mediates the recruitment of human coactivators to facilitate HIV-1 transcription. The coactivator and acetyltransferase CREB binding protein (CBP), and the paralog p300, are recruited to the HIV-1 promoter by Tat. Here we id... |
12547435 | Computational bioinorganic chemistry. Part III. The tools of the trade: from high-level ab initio calculations to structural bioinformatics. | Having long focused on the electronic-structural aspects of metalloenzymes and their synthetic models, Abhik is currently exploring a number of synthetic problems related to self-assembly processes, dynamic combinatorial libraries, and fluorine chemistry. |
12547741 | Incidence of injury in semi-professional rugby league players. | <h4>Objectives</h4>To investigate the site, nature, cause, and severity of injuries in semi-professional rugby league players.<h4>Methods</h4>The incidence of injury was prospectively studied in one hundred and fifty six semi-professional rugby league players over two competitive seasons. All injuries sustained during ... |
12547812 | Real-time imaging of nuclear permeation by EGFP in single intact cells. | The NPC is the portal for the exchange of proteins, mRNA, and ions between nucleus and cytoplasm. Many small molecules (<10 kDa) permeate the nucleus by simple diffusion through the pore, but molecules larger than 70 kDa require ATP and a nuclear localization sequence for their transport. In isolated Xenopus oocyte nuc... |
12547807 | Assembly of collagen matrices as a phase transition revealed by structural and rheologic studies. | We have studied the structural and viscoelastic properties of assembling networks of the extracellular matrix protein type-I collagen by means of phase contrast microscopy and rotating disk rheometry. The initial stage of the assembly is a nucleation process of collagen monomers associating to randomly distributed bran... |
12547796 | Excitation energy transfer dynamics and excited-state structure in chlorosomes of Chlorobium phaeobacteroides. | The excited-state relaxation within bacteriochlorophyll (BChl) e and a in chlorosomes of Chlorobium phaeobacteroides has been studied by femtosecond transient absorption spectroscopy at room temperature. Singlet-singlet annihilation was observed to strongly influence both the isotropic and anisotropic decays. Pump inte... |
12547794 | Fluorescence resonance energy transfer over approximately 130 basepairs in hyperstable lac repressor-DNA loops. | Lac repressor (LacI) binds two operator DNA sites, looping the intervening DNA. DNA molecules containing two lac operators bracketing a sequence-directed bend were previously shown to form hyperstable LacI-looped complexes. Biochemical studies suggested that orienting the operators outward relative to the bend directio... |
12547792 | The structure of DNA within cationic lipid/DNA complexes. | The structure of DNA within CLDCs used for gene delivery is controversial. Previous studies using CD have been interpreted to indicate that the DNA is converted from normal B to C form in complexes. This investigation reexamines this interpretation using CD of model complexes, FTIR as well as Raman spectroscopy and mol... |
12547778 | Highly accurate classification of Watson-Crick basepairs on termini of single DNA molecules. | We introduce a computational method for classification of individual DNA molecules measured by an alpha-hemolysin channel detector. We show classification with better than 99% accuracy for DNA hairpin molecules that differ only in their terminal Watson-Crick basepairs. Signal classification was done in silico to establ... |
12547757 | Relating single-molecule measurements to thermodynamics. | Measurements made on large ensembles of molecules are routinely interpreted using thermodynamics, but the normal rules of thermodynamics may not apply to measurements made on single molecules. Using a polymer stretching experiment as an example, it is shown that in the limit of a single, short molecule the outcome of e... |
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