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11934272 | The effect of spermine on plasmid condensation and dye release observed by fluorescence correlation spectroscopy. | We demonstrate that fluorescence correlation spectroscopy (FCS) can be employed to follow the conformational changes of DNA molecules induced by the addition of a cationic condensing compound (spermine). In our experiments the plasmid pHbetaAPr-1-neo (10 kbp; contour length 3.4 microm) was labeled with propidium iodide... |
11924605 | Axonal transport of neurofilaments in normal and disease states. | Neurofilaments are among the most abundant organelles in neurones. They are synthesised in cell bodies and then transported into and through axons by a process termed 'slow axonal transport' at a rate that is distinct from that driven by conventional fast motors. Several recent studies have now demonstrated that this s... |
11911775 | Elastin as a self-organizing biomaterial: use of recombinantly expressed human elastin polypeptides as a model for investigations of structure and self-assembly of elastin. | Elastin is the major extracellular matrix protein of large arteries such as the aorta, imparting characteristics of extensibility and elastic recoil. Once laid down in tissues, polymeric elastin is not subject to turnover, but is able to sustain its mechanical resilience through thousands of millions of cycles of exten... |
11911773 | Silk: molecular organization and control of assembly. | The interface between the science and engineering of biology and materials is an area of growing interest. One of the goals of this field is to utilize biological synthesis and processing of polymers as a route to gain insight into topics such as molecular recognition, self-assembly and the formation of materials with ... |
11911772 | Biological liquid crystal elastomers. | Liquid crystal elastomers (LCEs) have recently been described as a new class of matter. Here we review the evidence for the novel conclusion that the fibrillar collagens and the dragline silks of orb web spiders belong to this remarkable class of materials. Unlike conventional rubbers, LCEs are ordered, rather than dis... |
11911771 | Elastomeric gradients: a hedge against stress concentration in marine holdfasts? | The byssal threads of marine mussels are elastomeric fibres with a great capacity for absorbing and dissipating energy. Up to 70% of the total absorbed energy can be dissipated in the byssus. Because byssal threads attach the mussel to hard inert surfaces in its habitat, they must combine the need to be good shock abso... |
11908912 | Cyclodextrins: a potential tool for studying the role of glycerolipids in photosynthetic membranes. | A novel cyclodextrin derivative, i.e., permethylated-alpha-cyclodextrin (PM-alpha-CD), was used for removing glycerolipids from spinach thylakoid membranes and investigating their role in photosynthetic activities. A three-step selective removal of each lipid class was observed in treated membranes. Up to a concentrati... |
11905535 | Resonance Rayleigh scattering technology as a new method for the determination of the inclusion constant of beta-cyclodextrin. | The interaction of procaine hydrochloride and beta-cyclodextrin in aqueous solution was studied using resonance Rayleigh scattering technology. The molar ratio of the inclusion complex was 1:1 established by spectrophotometry. The resonance Rayleigh scattering technology was first applied in the determination of the be... |
11905534 | Spectral and photophysical studies of inclusion complexes of 2-amino-4,6-dimethyl pyrimidine with beta-cyclodextrin. | The interaction of 2-amino-4,6-dimethyl pyrimidine (ADMP) with beta-cyclodextrin (beta-CD) has been studied by means of UV absorption, steady state and time resolved fluorescence techniques. Spectral characteristics, bandwidths and photophysical parameters indicating that ADMP experience two different environments in a... |
11902439 | Insights on the conformational stability of collagen. | This review describes work on the conformational stability of the collagen triple helix. In 1994, the structure of collagen was determined at high resolution. Since then, much work has been done on synthetic mimics of collagen that contain host-guest peptides, tethers, peptoid residues, or analogs of the prevalent 4(R)... |
11897344 | Aluminum corrolin, a novel chlorophyll analogue. | A corrole-based chlorophyll analogue has been prepared, based on the notation that the major differences between the prosthetic groups of chlorophylls and hemes are the presence of a non-transition metal (Mg vs. Fe) and one reduced double bond in the porphyrin ligand. As corroles act as tri- rather than dianionic ligan... |
11897343 | A supramolecular enzyme model catalyzing the central cleavage of carotenoids. | Several bis-beta-cyclodextrin porphyrins have been prepared as supramolecular receptors of carotenoids. The binding constants of carotenoids to receptors were determined by quenching the fluorescence of the porphyrins on hydrophobic binding of carotenoids within the cavities of cyclodextrins. K(a)=8.3 x 10(6) M(-1) was... |
11897420 | rhEGF/HP-beta-CD complex in poloxamer gel for ophthalmic delivery. | The purpose of the present study is to prepare chemically and physically stable rhEGF/poloxamer gel and to investigate its possibility of ophthalmic delivery. The rhEGF/HP-beta-CD complex markedly increased rhEGF stability compared with rhEGF solution at 4 degrees C. The poloxamer gel was composed of poloxamer 407 (16%... |
11883663 | Enantioselective separation of racemic secondary amines on a chiral crown ether-based liquid chromatography stationary phase. | The first general enantioselective separation of racemic secondary amines on a crown ether-based liquid chromatography chiral stationary phase (CSP) is presented. The CSP is based on (+)- or (-)-(18-crown-6)-2,3,11,12-tetracarboxylic acid covalently bonded to silica gel. A mobile phase containing methanol, acetonitrile... |
11883643 | Permeability profiles of M-alkoxysubstituted pyrrolidinoethylesters of phenylcarbamic acid across caco-2 monolayers and human skin. | <h4>Purpose</h4>The purpose of the present research was to study 10 m-alkoxysubstituted pyrrolidinoethylesters of phenylcarbamic acid-potential local anesthetics. The relationships between the structure of the molecule, its physicochemical parameters (log D(oct), log k, R(M), solubility) were correlated to the permeabi... |
11883608 | Inhibiting effect of beta-cyclodextrin on thymine dimerization photosensitized by para-aminobenzoic acid. | Beta-cyclodextrin can act as an efficient inhibitor of the photosensitized dimerization of thymine by para-aminobenzoic acid (PABA) in aqueous solution. This can be explained by considering the formation of an inclusion complex between PABA and beta-cyclodextrin. |
11878189 | Effect of 2-hydroxypropyl-beta-cyclodextrin on the solubility, stability, and pharmacological activity of the chemical delivery system of TRH analogs. | To improve the aqueous solubility and stability of the chemical delivery system (CDS) of the thyrotropin-releasing hormone (TRH) analogs, 2-hydroxypropyl-beta-cyclodextrin (HPBCD) has been attempted. TRH analogs were [Leu2]-TRH, [Nva2]-TRH and [Nva2, Pip3]-TRH. Excess amount of CDS was added in various HPBCD in water s... |
11878196 | The use of chemically modified cyclodextrins in the development of formulations for chemical delivery systems. | Retrometabolic drug design provides a highly useful and directed approach for identifying new drug candidates with improved therapeutic indices based on predictable/controlled metabolism and/or site-targeted delivery. In the process, formulation becomes an important and integral concern especially for brain-targeting c... |
11874110 | Guest-responsive fluorescence variations of gamma-cyclodextrins labeled with hetero-functionalized pyrene and tosyl moieties. | Regioselectively hetero-labeled hosts, 6A-pyrenebutylate-6X-tosyl-modified gamma-cyclodextrins (X = B or H, C or G, D or F, and E for gamma-1, gamma-2, gamma-3, and gamma-4, respectively), were synthesized in order to investigate their chemo-sensor properties for applications to organic compounds, such as bile acids an... |
11873994 | Impurity profiling of ephedrines in methamphetamine by high-performance liquid chromatography. | Separation of the enantiomers and diastereomers of ephedrines was investigated for impurity profiling of methamphetamine. We describe a method for the analysis of (1S,2R)-(+)-ephedrine, (1R,2S)-(-)-ephedrine, (1S,2S)-(+)-pseudoephedrine and racemic methylephedrine in bulk methamphetamine by HPLC using two different col... |
11873969 | Separation of racemic sulfoxides and sulfinate esters on four derivatized cyclodextrin chiral stationary phases using capillary gas chromatography. | The separation of 17 chiral sulfoxides and eight chiral sulfinate esters by gas chromatography (GC) on four derivatized cyclodextrin chiral stationary phases (CSPs) (Chiraldex G-TA, G-BP, G-PN, B-DM) is presented. Many of these compounds are structural isomers or part of a homologous series. Differences in enantioselec... |
11870761 | Separation of DNA fragments in hydroxylated poly(dimethylacrylamide) copolymers. | The novel polymer matrices reported here are low-viscosity sieving media for DNA capillary electrophoresis. This new family of matrices comprises copolymers of N,N-dimethylacrylamide with different monomers which increase polymer hydrophilicity. All these new copolymers self-coat on fused-silica capillaries. Resolution... |
11870748 | Nonaqueous capillary electrophoretic separation of basic enantiomers using octakis(2,3-O-dimethyl-6-O-sulfo)-gamma-cyclodextrin, a new, single-isomer chiral resolving agent. | The enantiomers of 34 pharmaceutical weak-base analytes were separated by nonaqueous capillary electrophoresis in acidic methanol background electrolytes using the sodium salt of the new, single-isomer chiral resolving agent, octakis(2,3-O-dimethyl-6-O-sulfo)-gamma-cyclodextrin (ODMS). The effective mobilities, separat... |
11870744 | Nonaqueous affinity capillary electrophoresis investigation of small molecule molecular recognition. | The conditional binding constants for a bis-guanidinium-like receptor and a series of dicarboxylate ligands have been determined in two buffer/solvent systems, namely 25 mM ammonium acetate/1% acetic acid in acetonitrile/methanol (7:3 v:v) and 30 mM N-methyl morpholine/15 mM methanesulfonic acid in acetonitrile/methano... |
11866065 | Conjugation of luminescent quantum dots with antibodies using an engineered adaptor protein to provide new reagents for fluoroimmunoassays. | We describe the preparation and characterization of bioinorganic conjugates made with highly luminescent semiconductor CdSe-ZnS core-shell quantum dots (QDs) and antibodies for use in fluoroimmunoassays. The conjugation strategy employs an engineered molecular adaptor protein, attached to the QDs via electrostatic/hydr... |
11866063 | Sequential injection 90Sr determination in environmental samples using a wetting-film extraction method. | A sequential injection procedure involving a flow-reversal wetting-film extraction method for the determination of the radionuclide 90Sr has been developed. The methodology is based on the coating of the inner walls of an open tubular reactor with a film prepared from a 0.14 M 4,4'(5')-bis(tert-butylcyclohexano)-18-cro... |
11865027 | Vimentin affects localization and activity of sodium-glucose cotransporter SGLT1 in membrane rafts. | It has been reported that vimentin, a cytoskeleton filament that is expressed only in mesenchymal cells after birth, is re-expressed in epithelial cells in vivo under pathological conditions and in vitro in primary culture. Whether vimentin re-expression is only a marker of cellular dedifferentiation or is instrumental... |
11861661 | Dynamics of lysosomal cholesterol in Niemann-Pick type C and normal human fibroblasts. | The dynamics of endolysosomal cholesterol were investigated in Niemann-Pick type C (NPC) cells and in human fibroblasts treated with class 2 amphiphiles to mimic NPC cells. We showed through new approaches that the massive pools of endolysosomal cholesterol in these cells are not trapped but, rather, circulate to the c... |
11860713 | Self-assembly of a virus-mimicking nanostructure system for efficient tumor-targeted gene delivery. | Molecular therapy, including gene therapy, is a promising strategy for the treatment of human disease. However, delivery of molecular therapeutics efficiently and specifically to the target tissue remains a significant challenge. A human transferrin (Tf)-targeted cationic liposome-DNA complex, Tf-lipoplex, has shown hi... |
11861472 | Low density detergent-insoluble membrane of Xenopus eggs: subcellular microdomain for tyrosine kinase signaling in fertilization. | Protein-tyrosine phosphorylation plays an important role in egg activation signaling at fertilization. We show that in Xenopus, fertilization stimulates a rapid and transient tyrosine phosphorylation of egg proteins, as revealed by immunoblotting with anti-phosphotyrosine antibody. Immunofluorescent microscopic analysi... |
11860361 | DNA-binding of drugs used in medicinal therapies. | The interactions of various low-molecular weight substances with DNA are naturally relevant mechanisms in the cellular cycle and so also used in medicinal treatment. Depending on the particular drug structure, DNA-binding modes like groove-binding, intercalating and/or stacking, give rise to supramolecular assemblies o... |
11859364 | Chiral recognition in dimerization of adsorbed cysteine observed by scanning tunnelling microscopy. | Stereochemistry plays a central role in controlling molecular recognition and interaction: the chemical and biological properties of molecules depend not only on the nature of their constituent atoms but also on how these atoms are positioned in space. Chiral specificity is consequently fundamental in chemical biology ... |
11858480 | The tissue factor and plasminogen activator inhibitor type-1 response in pediatric sepsis-induced multiple organ failure. | <h4>Study objective</h4>Cytokines increase endothelial tissue factor (TF) and tissue plasminogen activator inhibitor type-1 (PAI-1) expression in vitro. Tissue factor interacts with factor VII to facilitate thrombosis and PAI-1 inhibits fibrinolysis by endogenous plasminogen activators. Because cytokine release is incr... |
11856021 | Protonation studies of modified adenine and adenine nucleotides by theoretical calculations and (15)N NMR. | The acid/base character of nucleobases affects phenomena such as self-association, interaction with metal ions, molecular recognition by proteins, and nucleic acid base-pairing. Therefore, the investigation of proton-transfer equilibria of natural and synthetic nucleos(t)ides is of great importance to obtain a deeper u... |
11856011 | Heterodimerization of dye-modified cyclodextrins with native cyclodextrins. | The heterodimerization behavior of dye-modified beta-cyclodextrins (1-6) with native cyclodextrins (CDs) was investigated by means of absorption and induced circular dichroism spectroscopy in an aqueous solution. Three types of azo dye-modified beta-CDs (1-3) show different association behaviors, depending on the posit... |
11856007 | Shape recognition of alkylammonium ions by 1,3-bridged calix[5]arene crown-6 ethers: endo- vs exo-cavity complexation. | A series of tri-O-substituted 1,3-bridged calix[5]arene crown-6 ethers bearing alkyl, arylalkyl, alkoxyalkyl, and alkoxycarbonylmethyl residues at the lower rim and either (t)()Bu or H substituents at the upper rim have been synthesized. (1)H NMR studies have shown that p-tert-butylcalix[5]crowns, irrespective of the s... |
11855997 | Alkylating capacity and reaction products of antimalarial trioxanes after activation by a heme model. | The reactivity of 1,2,4-trioxane molecules 2-5, structurally related to the antimalarial drug artemisinin, with a heme model, manganese(II) tetraphenylporphyrin, is reported. With the pharmacologically active drugs 2-4, covalent adducts were obtained by addition of a drug-derived radical onto the porphyrin macrocycle, ... |
11856346 | GPI-microdomains (membrane rafts) and signaling of the multi-chain interleukin-2 receptor in human lymphoma/leukemia T cell lines. | Subunits (alpha, beta and gamma) of the interleukin-2 receptor complex (IL-2R) are involved in both proliferative and activation-induced cell death (AICD) signaling of T cells. In addition, the signaling beta and gamma chains are shared by other cytokines (e.g. IL-7, IL-9, IL-15). However, the molecular mechanisms resp... |
11857709 | Supramolecular assemblies of a bis(terpyridine) ligand and of its [2x2] grid-type Zn(II) and Co(II) complexes on highly ordered pyrolytic graphite. | The synthesis and characterisation of bis(terpyridine)-derived ligands which are capable of forming [2x2] grid-like complexes is presented. Additional pyridine substituents on these ligands do not interfere with the complexation process. Adsorbing one of the pure ligands on highly ordered pyrolytic graphite (HOPG) show... |
11857707 | A cuboctahedral supramolecular capsule by 4:4 self-assembly of Tris(Zn(II)-cyclen) and trianionic trithiocyanurate in aqueous solution at neutral pH (cyclen=1,4,7,10-tetraazacyclododecane). | A 1:1 mixture of a tris(Zn(II)-cyclen) (1: [Zn(3)L(1)], L(1)=1,3,5-tris(1,4,7,10-tetraazacyclododecan-1-ylmethyl)benzene) and trithiocyanuric acid (TCA) yielded a 4:4 self-assembly complex [(Zn(3)L(1))(4)-(TCA(3-))(4)] (6) through the formation of Zn(II)-S(-) coordination bonds and hydrogen bonds between 1,3,5-triazine... |
11857702 | Self-assembly of molecular dumbbells into organized bundles with tunable size. | Dumbbell-shaped molecules consisting of three biphenyls connected through vinyl linkages as a conjugated rod segment and aliphatic polyether dendritic wedges with different cross-sections (i.e., dibranch (1), tetrabranch (2) and hexabranch (3)) were synthesized and characterized. The molecular dumbbells self-assemble i... |
11857696 | Dendritic galactosides based on a beta-cyclodextrin core for the construction of site-specific molecular delivery systems: synthesis and molecular recognition studies. | In order to evaluate the ability of multivalent glycosides based on a beta-cyclodextrin core as site-specific molecular carriers, a study on both the inclusion complexation behaviour and lectin binding affinity of branched and hyperbranched beta-cyclodextrins is presented. A series of cluster galactosides constructed o... |
11857693 | How to synthesize macrocycles efficiently by using virtual combinatorial libraries. | The selection of different diimines 4 a-c by alkaline earth ions from a virtual combinatorial library (VCL) is described. The products were stabilized by reduction to the diamines 6 a-c; this allowed easy analysis. The library can be directed toward different target molecules 6 a-c upon addition of alkaline earth ions ... |
11855720 | Self-assembly of gold(I) rings and reversible formation of organometallic [2]catenanes. | The reaction of the digold(I) diacetylide [(AuCCCH2OC6H4)2CMe2] with diphosphane ligands can lead to formation of either macrocyclic ring complexes or [2]catenanes by self-assembly. This gives an easy route to rare organometallic [2]catenanes, and the effect of the diphosphane ligand on the selectivity of self-assembly... |
11855715 | Ferrocene-containing carbohydrate dendrimers. | Aliphatic amines, incorporating one or three (branched) acylated beta-D-glucopyranosyl residues, were coupled with the acid chloride of ferrocenecarboxylic acid and with the diacid chloride of 1,1'-ferrocenedicarboxylic acid to afford four dendrimer-type, carbohydrate-coated ferrocene derivatives in good yields (54-92%... |
11855713 | 1,1'-Binaphthyl-substituted macrocycles as receptors for saccharide recognition. | The preparation of receptors for saccharide recognition in a natural environment has been an unmet goal for a long time. We present herein the synthesis and binding properties of (R,S)-1,1'-binaphthyl-substituted macrocycles as receptors for saccharide recognition in water/acetonitrile (1:1) and in DMSO. Porphyrin and ... |
11855709 | Facile preparation of [4.4]metacyclophane- and [5.5]paracyclophane-type macrocycles from arylboronic acids and salicylideneaminoaryl alcohols. | Four different salicylideneaminoaryl alcohols have been treated with arylboronic acids in order to prepare air-stable cyclophane-type macrocyclic systems. In two cases, this objective could be realized with the high-yield formation of [4.4]metacyclophane and [5.5]paracyclophane derivatives. The skeleton in these macroc... |
11855706 | Supramolecular self-assembling properties of membrane-spanning archaeal tetraether glycolipid analogues. | The self-assembling properties of a new series of archaeal tetraether glycolipid analogues 1-6 that are characterized by a bipolar architecture with two similar or different glycosidic and/or phosphate polar heads and a lipid core possessing a cyclopentane unit and/or branched chains were studied by means of differenti... |
11854532 | Expression of bitter taste receptors of the T2R family in the gastrointestinal tract and enteroendocrine STC-1 cells. | Although a role for the gastric and intestinal mucosa in molecular sensing has been known for decades, the initial molecular recognition events that sense the chemical composition of the luminal contents has remained elusive. Here we identified putative taste receptor gene transcripts in the gastrointestinal tract. Our... |
11854530 | Attenuation of thermal nociception and hyperalgesia by VR1 blockers. | Vanilloid receptor subunit 1 (VR1) appears to play a critical role in the transduction of noxious chemical and thermal stimuli by sensory nerve endings in peripheral tissues. Thus, VR1 antagonists are useful compounds to unravel the contribution of this receptor to pain perception, as well as to induce analgesia. We ha... |
11854499 | p56Lck anchors CD4 to distinct microdomains on microvilli. | Cell-surface microvilli play a central role in adhesion, fusion, and signaling processes. Some adhesion and signaling receptors segregate on microvilli but the determinants of this localization remain mostly unknown. In this study, we considered CD4, a receptor involved in immune response and HIV infection, and p56(Lck... |
11854413 | Macromolecular uptake is a spontaneous event during mitosis in cultured fibroblasts: implications for vector-dependent plasmid transfection. | The process through which macromolecules penetrate the plasma membrane of mammalian cells remains poorly defined. We have examined whether natural cellular events modulate the capacity of cells to take up agents applied extraneously. Herein, we report that during mitosis and in a cell type-independent manner, cells exh... |
11854721 | Early abdominal closure with mesh reduces multiple organ failure after ruptured abdominal aortic aneurysm repair: guidelines from a 10-year case-control study. | <h4>Objective</h4>The objectives of this study were the comparison of patients who needed mesh closure of the abdomen with patients who underwent standard abdominal closure after ruptured abdominal aortic aneurysm repair and the determination of the impact of timing of mesh closure on multiple organ failure (MOF) and m... |
11853922 | Colon-specific delivery of prednisolone-appended alpha-cyclodextrin conjugate: alleviation of systemic side effect after oral administration. | Prednisolone (PD), a typical glucocorticoid, has been widely used for the treatment of inflammatory bowel disease (IBD). However, when PD is administered orally, a large amount of the drug is absorbed from the upper gastrointestinal (GI) tract and causes systemic side effects. In this study, the anti-inflammatory effec... |
11853457 | Supramolecular gold nanoparticles for the redox recognition of oxoanions: syntheses, titrations, stereoelectronic effects, and selectivity. | Stable, CH(2)Cl(2)-soluble mixed dodecanethiol/(amidoferrocenyl)alkanethiol (AFAT) gold colloids were synthesized by ligand substitution reactions from Brust's dodecanethiol gold colloids and the AFAT ligands to study the recognition and titration of oxoanions. Gold colloids were obtained with various chain lengths (C(... |
11853451 | Coherent effects in energy transport in model dendritic structures investigated by ultrafast fluorescence anisotropy spectroscopy. | Measurements of ultrafast fluorescence anisotropy decay in model branched dendritic molecules of different symmetry are reported. These molecules contain the fundamental branching center units of larger dendrimer macromolecules with either three (C(3))- or four (T(d), tetrahedral)-fold symmetry. The anisotropy for a te... |
11853449 | A supramolecular microfluidic optical chemosensor. | A supramolecular microfluidic optical chemosensor (muFOC) has been fabricated. A serpentine channel has been patterned with a sol-gel film that incorporates a cyclodextrin supramolecule modified with a Tb(3+) macrocycle. Bright emission from the Tb(3+) ion is observed upon exposure of the (mu)FOC to biphenyl in aqueous... |
11853441 | Stereocontrolled synthesis of (-)-macrolactin A. | The total synthesis of (-)-macrolactin A, a 24-membered macrolide, has been achieved using a newly developed 1,3-diol synthon for the introduction of two key stereogenic centers. The synthon was derived from sequential use of the Noyori asymmetric reduction followed by chiral sulfoxide methodology. Tellurium-derived cu... |
11853433 | Ketopremithramycins and ketomithramycins, four new aureolic acid-type compounds obtained upon inactivation of two genes involved in the biosynthesis of the deoxysugar moieties of the antitumor drug mithramycin by Streptomyces argillaceus, reveal novel insights into post-PKS tailoring steps of the mithramycin biosynthet... | Mithramycin is an aureolic acid-type antimicrobial and antitumor agent produced by Streptomyces argillaceus. Modifying post-polyketide synthase (PKS) tailoring enzymes involved in the production of mithramycin is an effective way of gaining further information regarding the late steps of its biosynthetic pathway. In ad... |
11853523 | Enantioseparation of vinclozolin by gamma-cyclodextrin-modified micellar electrokinetic chromatography. | Cyclodextrin-modified micellar electrokinetic chromatography was applied to the enantioseparation of vinclozolin, which has been used as a fungicide and has an anti-androgenic activity, using gamma-cyclodextrin together with sodium dodecyl sulfate. Factors affecting the chiral resolution and migration time of vinclozol... |
11853470 | Improved amperometric method for the rapid and quantitative measurement of lipoxygenase activity in vegetable tissue crude homogenates. | An improved amperometric method for rapid (2 min) quantitative determination of lipoxygenase (LOX) activity in vegetable tissue crude homogenates is presented. Measured LOX activity was linear (R(2) > 0.99) throughout the entire activity range for green bean and for corn below 70% activity. The resolution was 0.4% or 1... |
11851346 | Peptide investigations of pairwise interactions in the collagen triple-helix. | Pairwise interactions have been studied for the major secondary structures in proteins. The present work extends the characterization of interactions between side-chains to the context of a collagen triple-helix. In this study, the most frequent Gly-X-Y tripeptide sequences in collagen are characterized in terms of int... |
11851345 | Convergence of experimental, computational and evolutionary approaches predicts the presence of a tetrameric form for CD3-zeta. | Experimental results using multiple site-specific infrared dichroism have shown that, when reconstituted into lipid bilayers, the orientation of the transmembrane domain of CD3-zeta is not compatible with a dimeric right-handed model reported previously. This model, obtained using a computational approach that uses evo... |
11851344 | Multiple site-specific infrared dichroism of CD3-zeta, a transmembrane helix bundle. | The structure of the transmembrane domain of CD3-zeta a component of the T-cell receptor involved in signal transduction, has been studied in its native state (a lipid bilayer) by multiple site-specific infrared dichroism. For the first time, the transmembrane domain has been labelled at multiple positions along the se... |
11851419 | Stereochemistry of catalysis by the ketoreductase activity in the first extension module of the erythromycin polyketide synthase. | Multiple ketoreductase activities play a crucial role in establishing the stereochemistry of the products of modular polyketide synthases (PKSs), but there has been little systematic scrutiny of catalysis by individual ketoreductases. To allow this, a diketide synthase, consisting of the loading module, first extension... |
11851407 | Dissection of the pathway of molecular recognition by calmodulin. | Amide hydrogen exchange has been used to examine the structural dynamics and energetics of the interaction of a peptide corresponding to the calmodulin-binding domain of smooth muscle myosin light chain kinase (smMLCKp) with calcium-saturated calmodulin. Heteronuclear NMR (15)N-(1)H correlation spectroscopy was used to... |
11849087 | Formation of molecular ladder elements with macrocyclic platforms via linear bifunctional ligands. | Reaction between 4-aminopyridine and a dinuclear zinc(II) component of a Robson macrocyclic ligand has resulted in the formation of a molecular ladder element motif. X-ray single crystal structural analysis indicates that two pyridine rings are assembled at the same direction of the macrocycle, which are placed in a ne... |
11849064 | Unprecedented eta(1)-P(basal) coordination of P(4)X(3) molecules (X = S, Se). An experimental and theoretical study of the apical vs basal complexation dichotomy. | Reaction of [(triphos)Re(CO)(2)(OTf)] (1) [triphos = MeC(CH(2)PPh(2))(3); OTf = OSO(2)CF(3)] with P(4)S(3) and P(4)Se(3) yields pairs of coordination isomers, namely, [(triphos)Re(CO)(2)[eta(1)-P(apical)-P(4)X(3)]](+) (X = S, 2; Se, 5) and [(triphos)Re(CO)(2)[eta(1)-P(basal)-P(4)X(3)]](+) (X = S, 3; Se, 6). The latter ... |
11849059 | 1,3,5-Triazine templated self-assembly of a hexameric copper(I) chloride triphenyl phosphite core. | The reaction of CuCl, P(OPh)(3), and 1,3,5-triazine (Trz) in CHCl(3) produces [(CuCl)(6)(P(OPh)(3))(6)(Trz)(2)] via molecular self-assembly. An X-ray structural study has revealed a D(3d) symmetry hexamer containing an oblate spheroid core. The core consists of a Cu(6)Cl(6) macrocycle, which is capped by two mu(3)-Trz ... |
11846675 | Effects of host-guest recognition on kinetics of Diels-alder reaction of quinocrown ethers with cyclopentadiene. | Diels-Alder reactions of 15-21-membered quinocrown ethers 1a-c and 18-membered quinobenzocrown ether 1d with cyclopentadiene were catalyzed by the addition of alkali, alkaline earth metal and ammonium perchlorates, and scandium trifluoromethane-sulfonate. The alkali metal and ammonium ions brought about a fairly select... |
11846660 | Synthesis and interaction with copper(II) cations of cyano- and aminoresorcin[4]arenes. | Following our studies on resorcin[4]arenes, we synthesized new macrocycles containing cyanomethyl and aminomethyl side chains. Three stereoisomers (2a-c) of the former were obtained by BF3*Et2O tetramerization of the corresponding trans-cinnamic acid derivative and were shown to be in the 1,2-alternate, cone, and 1,3-a... |
11846654 | Functionalized macrocyclic ligands for use in supramolecular chemistry. | The synthesis of three cross-conjugated macrocycles bearing pyridine functionality is described. The ability of two of these molecules, 5a and 5c, to behave as 4,4'-bipyridine mimics in self-assembly reactions is demonstrated by axial coordination to a metalloporphyrin. The directed coordinative ability of the pyridine... |
11846794 | Antimicrobial dendrimeric peptides. | Dendrimeric peptides selective for microbial surfaces have been developed to achieve broad antimicrobial activity and low hemolytic activity to human erythrocytes. The dendrimeric core is an asymmetric lysine branching tethered with two to eight copies of a tetrapeptide (R4) or an octapeptide (R8). The R4 tetrapeptide ... |
11847131 | SR proteins and hnRNP H regulate the splicing of the HIV-1 tev-specific exon 6D. | A naturally arising point mutation in the env gene of HIV-1 activates the aberrant inclusion of the cryptic exon 6D into most viral messages, leading to inefficient viral replication. We set out to understand how a single nucleotide substitution could cause such a dramatic change in splicing. We have determined that th... |
11847120 | Recruitment of the priming protein pTP and DNA binding occur by overlapping Oct-1 POU homeodomain surfaces. | The human transcription factor Oct-1 can stimulate transcription from a variety of promoters by interacting with the coactivators OBF-1/OCA-B/BOB-1, SNAP190 and VP16. These proteins contact Oct-1 regions different from the DNA binding surface. Oct-1 also stimulates the DNA replication of adenovirus through its DNA bind... |
11843608 | Generation of ketenes from acid chlorides using NaH/crown ether shuttle-deprotonation for use in asymmetric catalysis. | [reaction: see text] We describe methodology for the in situ generation of reactive monosubstituted ketenes from acid chlorides through a shuttle deprotonation process using NaH as an inexpensive stoichiometric base and a crown ether cocatalyst. We have successfully applied this new procedure to the catalytic, asymmetr... |
11843590 | Poised on the brink between a bistable complex and a compound. | [reaction: see text] An enmeshed supramolecular complex, based on a semi-dumbbell-shaped component containing an asymmetrically substituted tetrathiafulvalene site and a 1,5-dioxynaphthalene site for encirclement by a cyclobis(paraquat-p-phenylene) ring component and with a "speed bump" in the form of an thiomethyl gro... |
11843578 | Inclusion behavior of thiacalix[4]arenetetrasulfonate toward water-miscible organic molecules studied by salting-out and X-ray crystallography. | [reaction: see text] Inclusion ability of thiacalix[4]arenetetrasulfonate (TCAS) toward water-miscible organic molecules such as alcohols, ketones, cyclic ethers, and so on was studied by salting-out of the inclusion complex. NMR spectra of the recovered precipitates showed size selectivity to include the guest molecul... |
11844499 | Thermodynamic insight into the origin of the inclusion of monosulfonated isomers of triphenylphosphine into the beta-cyclodextrin cavity. | Formation of inclusion complexes between the beta-cyclodextrin and the potassium salt of o-, m-, and p-substituted monosulfonated triphenylphosphine derivatives was investigated in aqueous solution by NMR spectroscopy. Titration and continuous variation plots obtained from 31P and 1H NMR data indicate the formation of ... |
11844491 | Improved preparation of perallylated cyclodextrins: facile synthesis of cyclodextrin-based polycationic and polyanionic compounds. | An improved procedure for the perallylation of cyclodextrins allowed the preparation of O-perallylated alpha-, beta-, and gamma-cyclodextrins in 89, 91, and 88% yields, respectively. These were converted into two cyclodextrin-based functionalized compounds, the polycationic heptakis[2,3,6-tri-O-(6-amino-3-thiahexyl)]-b... |
11841325 | Hierarchical self-assembly of amphiphilic metallohosts to give discrete nanostructures. | The synthesis and aggregation behavior of a new class of rigid metallohosts is described. The molecules consist of a ruthenium-bipyridine complex functionalized with a glycoluril-based receptor cavity. By specific molecular recognition processes in water, the metallohosts self-assemble to form large arrays of molecules... |
11841309 | Artificial lamellar mesostructures to WS(2) nanotubes. | A direct pyrolysis method from artificial lamellar mesostructures to nanotubes was developed for the synthesis of tungsten disulfide (WS(2)) nanotubes. In this process, a tungsten sulfide artificial lamellar mesostructure composite with intercalated cetyltrimethylammonium cations (WS-L) was prepared on the basis of the... |
11841306 | A new class of functionalized terpyridyl ligands as building blocks for photosensitized supramolecular architectures. Synthesis, structural, and electronic characterizations. | A new class of triarylpyridinio-derivatized [4'-(p-phenyl)(n)]terpyridyl ligands, R(1)(2)R(2)TP(+)-(p)(n)tpy, was designed as a novel category of electron-acceptor (A)-substituted proto-photosensitizing molecules. The first elements of this versatile family of ligands (i.e., n = 0, 1 and R(1) = R(2) = H), H(3)TP(+)-tpy... |
11841304 | Calix[4]tubes: a new class of potassium-selective ionophore. | A new class of cryptand-like ionophore based on a bis calix[4]arene structure has been developed. These molecules proved highly selective for complexation of potassium over all group I metal cations and barium. A range of symmetric and asymmetric calix[4]tubes featuring either alkyl or phenyl substituents at the upper ... |
11841303 | Calix[6]arene-based cuprous "funnel complexes": a mimic for the substrate access channel to metalloenzyme active sites. | Two calixarene-based model systems (a and b) for monocopper enzymes are compared. Both present a tris(pyridine) coordination site for Cu that mimics the imidazole-rich neutral binding site in enzymes. Upon reaction with 1 equiv of copper(I), the tridentate ligands gave rise to ill-defined unsymmetrical complexes. Howev... |
11841296 | Supramolecular organization of alpha,alpha'-disubstituted sexithiophenes. | The self-assembly of alpha,alpha'-linked sexithiophenes with chiral and achiral penta(ethylene glycol) chains attached at the alpha-positions of the terminal rings, that is, 2,2':5',2'':5'',2''':5''',2'''':5'''',2'''''-sexithiophene-5,5'''''-dicarboxylic acid-2S)-2-methyl-3,6,9,12,15-pentaoxahexadecyl ester (1) and 2,2... |
11841217 | Conjugation of a magainin analogue with lipophilic acids controls hydrophobicity, solution assembly, and cell selectivity. | Our basic understanding of how to combat fungal infections has not kept pace with the recent sharp rise in life-threatening cases found particularly among immuno-compromised individuals. Current investigations for new potential antifungal agents have focused on antimicrobial peptides, which are used as a cell-free defe... |
11839302 | Insight into Schmid metaphyseal chondrodysplasia from the crystal structure of the collagen X NC1 domain trimer. | Collagen X is expressed specifically in the growth plate of long bones. Its C1q-like C-terminal NC1 domain forms a stable homotrimer and is crucial for collagen X assembly. Mutations in the NC1 domain cause Schmid metaphyseal chondrodysplasia (SMCD). The crystal structure at 2.0 A resolution of the human collagen X NC1... |
11839490 | Coupling of folding and binding for unstructured proteins. | There are now numerous examples of proteins that are unstructured or only partially structured under physiological conditions and yet are nevertheless functional. Such proteins are especially prevalent in eukaryotes. In many cases, intrinsically disordered proteins adopt folded structures upon binding to their biologic... |
11839484 | Unraveling hot spots in binding interfaces: progress and challenges. | Protein interface hot spots, as revealed by alanine scanning mutagenesis, continue to stimulate interest in the biophysical basis of molecular recognition. Although these regions apparently constitute fertile grounds for intermolecular interactions, no general algorithm has yet been developed that can predict hot spots... |
11838699 | Imprinting of nucleotide and monosaccharide recognition sites in acrylamidephenylboronic acid-acrylamide copolymer membranes associated with electronic transducers. | Molecular recognition sites for the nucleotides adenosine 5'-monophosphate (1), guanosine 5'-monophosphate (2), cytosine 5'-monophosphate (3), and uridine 5'-monophosphate (4) are imprinted in an acrylamide-acrylamidephenylboronic acid copolymer (5) membrane. The imprinted membranes are assembled on piezoelectric Au qu... |
11838675 | Electrogenerated chemiluminescence. 68. Detection of sodium ion with a ruthenium(II) complex with crown ether moiety at the 3,3'-positions on the 2,2'-bipyridine ligand. | We show here how a Ru(bpy)2(CE-bpy) complex can be used for the ECL detection of sodium ion in both aqueous and nonaqueous media. Recognition of Na+ by the crown ether moiety in CE-bpy results in a significant increase in the ECL emission intensity of the complex. |
11838674 | Electrochemiluminescent detection of metal cations using a ruthenium(II) bipyridyl complex containing a crown ether moiety. | The effects of metal ions on the electrochemiluminescence (ECL) properties of (bpy)2Ru(AZA-bpy) (bpy = 2,2'-bipyridine; AZA-bpy = 4-(N-aza-18-crown-6-methyl-2,2'-bipyridine) have been investigated. The electrochemistry, photophysics and ECL of Ru(bpy)3(2+) in the presence of Pb2+, Hg2+, Cu2+, and K+ are reported. The a... |
11836518 | Emerging structure of the nicotinic acetylcholine receptors. | The conversion of acetylcholine binding into ion conduction across the membrane is becoming more clearly understood in terms of the structure of the receptor and its transitions. A high-resolution structure of a protein that is homologous to the extracellular domain of the receptor has revealed the binding sites and su... |
11835562 | Computational and experimental studies of di- and tetrasubstituted calix[4]arenes. | Calixarenes are molecular bowls or baskets that have been demonstrated to serve as hosts for cations, anions, and neutral molecules. The central cavity and scaffolding of various functionalities on the upper and lower rims establishes this class of compounds as extremely important in supramolecular chemistry studies. I... |
11835556 | Asymmetric induction under confinement. | Confinement may efficiently condition the stereochemical outcome of a reaction through space constriction and molecular close contact. This article briefly reviews recent approaches of supramolecular chemistry to achieve chiral confinement. Crystallization is not always possible and the use of chiral crystals or clathr... |
11835553 | Role of the heteroatom on stereoselectivity in the complex metal hydride reduction of six-membered cyclic ketones. | The role of the heteroatom on the stereochemistry and the relative rate for the complex metal hydride reduction of heteracyclohexanones and methoxy substituted cyclohexanones is explained by the difference in the nonbonding two electron stabilization between the incipient sigma* bond and the anti periplanar allylic sig... |
11834127 | Catalytic activities of intracellular dimeric neopullulanase on cyclodextrin, acarbose and maltose. | Multi-substrate specificity of neopullulanase towards cyclodextrin, acarbose and maltose was investigated using a clone originating from Bacillus stearothermophilus IMA6503. The enzyme purified from Escherichia coli harbouring the corresponding nplA gene hydrolysed beta-cyclodextrin (beta-CD) to maltose and glucose. It... |
11833092 | Early diagnosis and treatment of severe acute cholangitis. | <h4>Aim</h4>To investigate the diagnostic standard for early identification of severe acute cholangitis in order to lower the incidence of morbidity and mortality rate.<h4>Methods</h4>A diagnostic standard was proposed in this study as follows:documented biliary duct obstruction by ultrasound or computerized tomography... |
11832501 | Analysis of a C-methyltransferase gene (aviG1) involved in avilamycin biosynthesis in Streptomyces viridochromogenes Tü57 and complementation of a Saccharopolyspora erythraea eryBIII mutant by aviG1. | Streptomyces viridochromogenes Tü57 is the principal producer of avilamycin A. aviG1, a putative methyltransferase gene, was detected in the avilamycin biosynthetic gene cluster. To determine the function of aviG1, a targeted gene inactivation experiment was performed. The resulting chromosomal mutant, carrying an in-f... |
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