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18967984 | Spectrofluorimetric determination of diclofenac in the presence of alpha-cyclodextrin. | This study focuses on the complex formed between alpha-cyclodextrin (CD) and the anti-inflammatory drug diclofenac in aqueous solution and also on its potential analytical applications. It was corroborated that the fluorescence emission band of diclofenac is significantly intensified in the presence of alpha-CD. From t... |
10940980 | Gemini Surfactants. | How easy it is to dismiss the humdrum surfactant! After all, its structure is unglamorous by present-day norms. And the surfactant has been entrenched in so many areas of commerce for so many decades that its chemistry might seem old and tired. The purpose of this review is to persuade the reader otherwise, all the whi... |
10926235 | A molecular dynamics study of the structure and evolution of the 4,4'-bis(diphenylhydroxymethyl)biphenyl/acetone host-guest system | The 4,4'-bis(diphenylhydroxymethyl)biphenyl/acetone (DHMB-Ac) system was studied by NPT molecular dynamics (MD) calculations; the study was prompted by the availability of X-ray single-crystal diffraction and calorimetric data (L. Johnson, L. Nassimbeni, E. Weber and K. Skobridis, J. Chem. Soc. Perkin Trans. 2, 1992, 2... |
10926234 | The influence of macrocyclic polyether constitution upon ammonium ion/crown ether recognition processes | Secondary dialkylammonium (R2NH2+) ions are bound readily by dibenzo[24]crown-8 (DB24C8) to form threaded complexes, namely [2]pseudo-rotaxanes. The effect of replacing one or both of the catechol rings in DB24C8 with resorcinol rings upon the crown ether's ability to bind R2NH2+ ions has now been investigated. When on... |
10926233 | Self-complementary | Three [3]catenanes with cavities large enough to accommodate aromatic guests have been designed and synthesized (yields = 5-20 %) by means of kinetically controlled self-assembly processes. The X-ray structural analysis of one of three [3]catenanes confirmed the presence of a rectangular cavity (dimensions = 7 x 11 A) ... |
10926223 | Crystalline self-assembly into monolayers of folded oligomers at the air-water interface | Insertion of the 1,3-bis(ethynylene)benzene unit as a rigid spacer into a linear alkyl chain, thus separating the two resulting stems by 9 A. induces chain folding at the air-water interface. These folded molecules self-assemble into crystalline monolayers at this interface, with the plane of the folding unit almost pe... |
10926218 | Rigidified calixarenes bearing four carbamoylmethylphosphineoxide or carbamoylmethylphosphoryl functions at the wide rim | Conformationally rigidified tetraCMPO derivatives have been prepared from calix[4]arene bis(crown ether) 4a in which adjacent oxygens are bridged at the narrow rim by two diethylene glycol links. Acylation of the tetraamine 4c with the CMPO-active ester 5b gave the tetraphosphine oxide 6a, while the tetraphosphinate 6b... |
10926215 | Hydrogen-bonding clusters leading to formation of supramolecular dimers of metalloporphyrin receptors: modulation of Lewis acidity by pi-pi interactions | Two remarkable crystal structures are reported of a cyclic receptor 1, containing two metalloporphyrin units. The overall crystal structure of 1 provides the first direct evidence that pi-stacking between two metalloporphyrins reduces the Lewis acidity of the metal ion and thereby dramatically reduces the affinity of z... |
10926214 | Multiple expression of molecular information: enforced generation of different supramolecular inorganic architectures by processing of the same ligand information through specific coordination algorithms | The multisubunit ligand 2 combines two complexation substructures known to undergo, with specific metal ions, distinct self-assembly processes to form a double-helical and a grid-type structure, respectively. The binding information contained in this molecular strand may be expected to generate, in a strictly predeterm... |
10926213 | Programmed chemical systems: multiple subprograms and multiple processing/expression of molecular information | Programmed chemical systems rest on the structural information stored in a molecular framework and on its reading and processing through non-covalent interactional algorithms to yield specific supramolecular entities. Beyond single-code self-assembly, which generates exclusively a single, specific superstructure, sever... |
10894404 | Synthesis of expanded graphdiyne substructures | Graphdiyne (1) is a member of a novel family of interesting and potentially important allotropes of carbon. Reported herein are the synthesis and spectroscopic characterization of model substructures 2-6. The macrocycles were prepared by the intramolecular cyclization of suitable alpha,omega-polyynes. Key to the succes... |
10894401 | Synthesis and characterization of tris-methacrylated 3,4,5-tris | The synthesis of liquid crystalline 3,4,5-tris(11-methacryloylundecyl-1-oxybenzyloxy)benzoic acid, 2-methyl-(1,4,7,10,13-pentaoxacyclopentadecane)-3,4,5-tris[4-(11-methacryloylundecyl-1-oxy)benzyloxy] benzoate and its 1:1 complex with sodium triflate is described. The observed mesophases were identified, by polarized o... |
10894394 | A flexible cyclophane: design, synthesis, and structure of a multibridged tris-tetrathiafulvalene (TTF) macrocycle | The tris-tetrathiafulvalene (TTF) macrocycles 3 with a large end-cavity were effectively synthesized from the readily available tetrakis(cyanoethylthio)TTF by means of a selective deprotection/realkylation sequence followed by an intramolecular coupling reaction. Crystar structure analyses revealed that the neutral mol... |
10894393 | Template-induced and molecular recognition directed hierarchical generation of supramolecular assemblies from molecular strands | The linear oligo-isophthalamide strand 1 undergoes a conformational reorganization upon binding of a cyanuric acid template as effector to afford a helical disklike object possessing radially disposed alkyl residues. Solvophobic and stacking interactions, in turn, drive a "second level" self-assembly of the templated s... |
10866612 | UV-vis and IR spectral characterization of persistent carbenium ions, generated upon incorporation of cinnamyl alcohols in the acid zeolites HZSM-5 and HMor | Cinnamyl alcohol (1) and two derivatives 2 and 3 have been incorporated in dehydrated HMor and HZSM-5 zeolites with the aim to characterize spectroscopically the corresponding carbocations generated within the solids. Product studies of the supernatant liquid phase combined with diffuse reflectance UV-vis and IR spectr... |
10864755 | Synthesis of macrocyclic cage compounds by diamine-dihalide one-step coupling reaction | Macropolycyclic cage compounds were synthesized by a direct reaction between diamines and bis(bromomethyl) compounds. The procedure for constructing the polycyclic cage structure is simple and straightforward. The macropolycyclic compounds obtainable from this cyclization procedure are three-dimensional cage compounds,... |
10857618 | Evaluation of binding selectivities of caged crown ligands toward heavy metals by electrospray ionization/quadrupole ion trap mass spectrometry | Electrospray ionization (ESI)/quadrupole ion trap mass spectrometry is used to evaluate the heavy metal binding selectivities of five caged crown ethers and two polyether reference compounds in methanol solution. The binding preferences for Hg2+, Pb2+, Cd2+, and Cu2+ were analyzed by comparison of ESI mass spectral int... |
10857608 | Ion-selective electrode for dodecyldimethylamine oxide: a "twice-Nernstian" slope for the determination of a neutral component | An electrode originally sensitive to dodecyltrimethylammonium (DTA+) was proven to be sensitive to dodecyldimethylamine oxide (DDAO), a surfactant with acidobasic properties. The response of the electrode was tested from pH 2 to 9.3. Its slope is Nernstian when the surfactant is entirely protonated. At a pH where the m... |
10846159 | A nanoplotter with both parallel and serial writing capabilities | The development of an eight-pen nanoplotter capable of doing parallel dip-pen nanolithography (DPN) is reported. Because line width and patterning speed in DPN are independent of contact force, only one of the tips in the parallel writing mode (the "imaging" tip) has a feedback system to monitor tip position and to wri... |
10846157 | Forming supramolecular networks from nanoscale rods in binary, phase-separating mixtures | Simulations show that when low-volume fractions of nanoscale rods are immersed in a binary, phase-separating blend, the rods self-assemble into needle-like, percolating networks. The interconnected network arises through the dynamic interplay of phase-separation between the fluids, through preferential adsorption of th... |
10843641 | Toward chiral polyhydroxylated dendrimers. Preparation and chiroptical properties | Four dendrimers (1b-4b) containing chiral vicinal diol-based subunits were prepared from their acetonide-protected precursors (1a-4a). The optical activity of these chiral dendritic structures was successfully modeled using structurally similar, low molecular weight model compounds. Using the [Phi](d) values of the low... |
10841500 | A facile synthetic route to a third-generation dendrimer with generation-specific functional aryl bromides | The synthesis of three third-generation dendrimers that selectively carry one aryl bromide functional group in the first, second, or third generation, respectively, is described. These functions, regardless of their location, can be chemically modified by Suzuki cross-coupling chemistry with p-tert-butylbenzene boronic... |
10841494 | Synthesis of periphery-functionalized dendritic molecules using polylithiated dendrimers as starting material | A general method for the functionalization of Si-Cl terminated carbosilane dendritic molecules via organolithium or organomagnesium reagents is described. Quantitative exchange of the bromine atoms of 4-bromophenyl-functionalized dendrimers affords polylithiated species that are valuable starting materials for further ... |
10841480 | Supramolecular chirogenesis in bis(zinc porphyrin): An absolute configuration probe highly sensitive to guest structure | The role of the ligand's structure and absolute configuration in the supramolecular chirality induction in achiral bis(zinc porphyrin) has been studied. The amines with bulkier substituents resulted in stronger CD signals due to increased helical displacement in the anti conformer. All the amines with an R absolute con... |
10841476 | Modular construction of dendritic carbosilanes. Organization Of dendrimer connectivity around bifunctional precursors that are adapted for sequential convergent and divergent propagative steps | Regiospecific hydrosilylation of 1-bromo-4-(prop-2-enyl)benzene offers an efficient route to molecular building block precursors that can accommodate sequential divergent and convergent steps for dendritic extension, establishing a modular methodology for assembly and organization of connectivity used for synthesis of ... |
11038226 | The Actinorhizal Symbiosis. | The term "actinorhiza" refers both to the filamentous bacteria Frankia, an actinomycete, and to the root location of nitrogen-fixing nodules. Actinorhizal plants are classified into four subclasses, eight families, and 25 genera comprising more than 220 species. Although ontogenically related to lateral roots, actinorh... |
15263113 | Hexaaquacobalt(II) bis(4-toluenesulfonate). | The title compound, [Co(H(2)O)(6)](CH(3)C(6)H(4)SO(3))(2), has a structure where the metal atom is surrounded by six molecules of water forming the cation and the anion is deprotonated 4-toluenesulfonic acid. The Co atom is in a nearly regular octahedral coordination geometry, with Co-O distances between 2.0529 (14) an... |
12958975 | [Study on the photoinduced-color changing about novel azobenzocrown ether derivatives 16ABC-OH and 16ABC-NH2 in water solution and Langmuir-Blodgett film]. | Two kinds of azobenzocrown ether derivation 16ABC-OH and 16ABC-NH2 have been synthesized, and their photoinduced color changing phenomena has been investigated in water solution, the reaction of 16ABC-OH is the photochemical Cis-trans-isomerization, and it is a first-order reaction, but the reaction of 16ABC-NH2 photoc... |
11429015 | The use of itraconazole as prophylaxis against invasive fungal infection in blood and marrow transplant recipients. | Invasive fungal infections play a key role in contributing to morbidity and mortality in patients undergoing treatment for haematological malignancies and related diseases. Risk factors for development of invasive fungal infections after blood or bone marrow transplantation include the use of broad-spectrum antibiotics... |
11207581 | Proteolytic activation of receptor-bound anthrax protective antigen on macrophages promotes its internalization. | Immunofluorescence and other methods have been used to probe the self-assembly and internalization of the binary toxin, anthrax lethal toxin (LeTx), in primary murine macrophages. Proteolytic activation of protective antigen (PA; 83 kDa, the B moiety of the toxin) by furin was the rate-limiting step in internalization ... |
11232830 | Effect of conformational constraints on gated electron-transfer kinetics. 3. Copper(II/I) complexes with cis- and trans-cyclopentanediyl-1,4,8,11-tetrathiacyclotetradecane. | Previous kinetic and electrochemical studies of copper complexes with macrocyclic tetrathiaethers-such as 1,4,8,11-tetrathiacyclotetradecane ([14]aneS4)-have indicated that electron transfer and the accompanying conformational change occur sequentially to give rise to a dual-pathway mechanism. Under appropriate conditi... |
11232823 | Electrochemical studies of corrphycenes and metallocorrphycenes. | Corrphycene 3 (Cn) is a structural isomer of porphyrin 1 that was synthesized for the first time 5 years ago. This paper reports on the redox properties of free-base octaethylcorrphycene H2OECn and 16 metal complexes derived therefrom. In CH2Cl2 solution, the free base and the metallo(II) octaethylcorrphycenes, M(II)OE... |
11225864 | Voltammetric determination of copper at chemically modified electrodes based on crown ethers. | The feasibility of fabricating copper-sensitive chemically modified electrodes (CMEs) for trace analysis in aqueous and in 40% (v/v) ethanol-water media was investigated. Carbon paste electrodes modified with crown ethers were constructed by mixing the crown ethers into a graphite powder-paraffin oil matrix. The electr... |
11197026 | Self-assembling molecular wires of halogen-bridged platinum complexes in organic media. Mesoscopic supramolecular assemblies consisting of a mixed valent Pt(II)/Pt(IV) complex and anionic amphiphiles. | A novel class of supramolecular assemblies in organic media consisting of a molecular wire of a halogen-bridged platinum complex [Pt(en)2][PtCl2(en)2]4+ (en = 1,2-diaminoethane) and anionic amphiphiles is developed. When double-chained phosphates or sulfonates are employed, the resultant [Pt(en)2][PtCl2(en)2](4+)-lipid... |
11197021 | M+(12-crown-4) supramolecular cations (M+ = Na+, K+, Rb+, and NH4+) within Ni(2-thioxo-1,3-dithiole-4,5-dithiolate)2 molecular conductor. | Monovalent cations (M+ = Na+, K+, Rb+, and NH4+) and 12-crown-4 were assembled to new supramolecular cation (SC+) structures of the M+(12-crown-4)n (n = 1 and 2), which were incorporated into the electrically conducting Ni(dmit)2 salts (dmit = 2-thioxo-1,3-dithiole-4,5-dithiolate). The Na+, K+, and Rb+ salts are isostr... |
11196997 | Ligand binding inside the cavities of lacunar and saddle-shaped cyclidene complexes: molecular mechanics and molecular dynamics studies. | Cobalt(II) complexes with tetradentate macrocyclic cyclidene ligands are known to coordinate one additional axial base molecule, leaving the sixth vacant coordination site at the metal ion available for small ligand (e.g., O2) binding. Molecular mechanics and molecular dynamics simulations provide a microscopic view of... |
11196996 | Synthesis, characterization, and structure of macrocyclic mono- and C2-symmetric, binuclear nickel calixsalen complexes. | Mono- (3a,b) and binuclear (4a,b) tetradentate NiII complexes of a series of 26-membered macrocyclic salen dimers, [salen(CH2)]2, are prepared in good yield by solvent-controlled reaction with Ni(OAc)2. The mononuclear complex 3b crystallizes in the trigonal space group 3P1(#144), a = 18.2566(2) A, c = 15.9244(2) A, V ... |
11073319 | Effect of modification of light-harvesting complex II on fluorescence properties of thylakoid membranes of Arabidopsis thaliana. | The 77 K chlorophyll fluorescence spectra of Arabidopsis thaliana mutants deficient in lipid fatty acid desaturation have been used in order to further explore the influence of the modification of LHC II after mutation and proteolitic treatment on the energy transfer between the chlorophyll-protein complexes, as well a... |
11059240 | [Septic shock caused by perforation of sigmoid diverticulum into the Retzius space. A case report]. | An uncommon complication of the sigmoid diverticulitis personally observed is described. A woman, 59 years old, presented a septic shock caused by perforated sigmoid diverticulum into the space of Retzius. The diagnosis was carried out by an X-ray of the abdomen that suspected the presence of air in the retroperitoneum... |
10980662 | Effect of vehicle upon in vitro transcorneal permeability and intracorneal content of Delta9-tetrahydrocannabinol. | <h4>Purpose</h4>To determine the transcorneal flux, and intracorneal penetration, of Delta9-tetrahydrocannabinol when presented to the isolated rabbit cornea in different vehicles.<h4>Methods</h4>Corneas were mounted in specular microscope chambers, with ( 3)H-Delta9-tetrahydrocannabinol on the epithelial surface in on... |
10980658 | Amyloid-like protein structure in mammalian ocular lenses. | <h4>Purpose</h4>Over the past 30 years, extensive Raman and infrared spectroscopy studies determined that the major proteins in normal mammalian lenses exist predominantly as beta-pleated sheets in vivo. The present study examines the presence of amyloid protein supramolecular order of lens protein beta-pleated sheet a... |
10960875 | Effects of cyclic polylactate (CPL) on the growth of cloned leukemic cells in vitro. | A novel supramolecular oligomer, cyclic polylactate (CPL), was first discovered in the culture medium of HeLa-S tumour cells, and was reported to inhibit the growth of FM3A ascites tumour cells by inhibiting the activities of pyruvate kinase (PK) and lactic dehydrogenase (LDH). We have now synthesized CPL-containing ol... |
10955910 | Interfacial self-assembly of fungal hydrophobins of the lichen-forming ascomycetes Xanthoria parietina and X. ectaneoides. | In the symbiotic phenotype of the lichen-forming ascomycetes Xanthoria parietina and X. ectaneoides, a conglutinate, hydrophilic cortex surrounds a system of aerial hyphae with hydrophobic wall surfaces. In X. parietina freeze-fracture electron microscopy showed that a rodlet layer covers the fungal and algal wall surf... |
10950307 | DNA repeat expansions and human disease. | The repeat expansion diseases are genetic disorders caused by intergenerational expansions of a specific tandem DNA repeat. These disorders range from mildly to severely debilitating or fatal, and all have limited treatment options. How expansion occurs and causes disease is only now beginning to be understood. Efforts... |
10950306 | Structure and function of small heat shock/alpha-crystallin proteins: established concepts and emerging ideas. | Small heat shock/alpha-crystallin proteins are defined by conserved sequence of approximately 90 amino acid residues, termed the alpha-crystallin domain, which is bounded by variable amino- and carboxy-terminal extensions. These proteins form oligomers, most of uncertain quaternary structure, and oligomerization is pre... |
10950304 | Adducin: structure, function and regulation. | Adducin is a ubiquitously expressed membrane-skeletal protein localized at spectrin-actin junctions that binds calmodulin and is an in vivo substrate for protein kinase C (PKC) and Rho-associated kinase. Adducin is a tetramer comprised of either alpha/beta or alpha/gamma heterodimers. Adducin subunits are related in se... |
10940228 | Self-assembly of beta-amyloid 42 is retarded by small molecular ligands at the stage of structural intermediates. | Assemblyof the amyloid-beta peptide (Abeta) into fibrils and its deposition in distinct brain areas is considered responsible for the pathogenesis of Alzheimer's disease (AD). Thus, inhibition of fibril assembly is a potential strategy for therapeutic intervention. Electron cryomicroscopy was used to monitor the initia... |
10940223 | Review: model peptides and the physicochemical approach to beta-amyloids. | beta-Amyloid peptides are the main protein components of neuritic plaques and may be important in the pathogenesis of Alzheimer's Disease. The determination of the structure of beta-amyloid fibrils poses a challenge because of the limited solubility of beta-amyloid peptides and the noncrystalline nature of fibrils form... |
10940221 | The Alzheimer's peptide a beta adopts a collapsed coil structure in water. | The self-assembly of the soluble peptide Abeta into Alzheimer's disease amyloid is believed to involve a conformational change. Hence the solution conformation of Abeta is of significant interest. In contrast to studies in other solvents, in water Abeta is collapsed into a compact series of loops, strands, and turns an... |
10923197 | [Halogenation in a series of metallocomplexes of porphyrin]. | We found that thionyl chloride can chlorinate porphyrin complexes with transient metals (Pd, Ni, or Cu) at the free beta- and meso-positions of the porphyrin macrocycle. A more prolonged or rigorous treatment also causes the chlorination of side alkyl substituents, mainly, methyl groups. |
10923794 | Synthesis of novel heterobranched beta-cyclodextrins from 4(2)-O-beta-D-galactosyl-maltose and beta-cyclodextrin by the reverse action of pullulanase, and isolation and characterization of the products. | From the mixture of 4(2)-O-beta-D-galactosyl-maltose (Gal-G2) and beta-cyclodextrin (betaCD), novel heterobranched betaCDs, (Gal-G2)-betaCD and (Gal-G2)2-betaCDs, were synthesized by the reverse action of debranching enzyme. The optimum conditions for the production of (Gal-G2)2-betaCDs were examined. A mixture of (Gal... |
10910218 | Fast development of separation methods for the chiral analysis of amino acid derivatives using capillary electrophoresis and experimental designs. | The use of experimental design in method development was studied for the chiral separation of several amino acid derivatives with capillary electrophoresis. The aim of this study was to define rapidly experimental conditions under which the enantiomers can be sufficiently separated for quantification and to derive a me... |
10910208 | Insoluble beta-cyclodextrin polymer for capillary gas chromatographic separation of enantiomers and isomers. | An insoluble beta-cyclodextrin polymer cross-linked with identified epichiorohydrin has been prepared; its structure was identified by means of infrared and 13C NMR spectra. Three capillary columns have been coated with the polymer treated by ultrasonication by three coating methods. Chromatographic characteristics suc... |
10910206 | Chromatographic characterization of molecularly imprinted polymers binding the herbicide 2,4,5-trichlorophenoxyacetic acid. | Two polymers binding the herbicide 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) were prepared by utilising the technique of the non-covalent molecular imprinting polymerisation in an aqueous medium. The polymers obtained were packed in HPLC columns and the effects of the mobile phase composition on the retention of the ... |
10910167 | Electrocatalytic oxidation of NADH at the self-assembled monolayer of nickel(II) macrocycle on gold electrode. | Electroactive self-assembled monolayers (SAMs) of macrocyclic Ni(II) complex (1) were fabricated on gold electrode and its electrochemistry has been studied in different supporting electrolytes. Substantial stabilization of tervalent nickel and a significant negative shift of formal potential of the Ni(3+/2+) couple ha... |
10907236 | Effect of beta-cyclodextrin on pasting properties of wheat starch. | Changes of viscosity characteristics of genetically diverse hexaploid wheat starches during pasting in water, 1% NaCl solution, or at pH 4 or pH 10 were studied using a Rapid Visco-Analyzer. Peak viscosity (PV), hot paste viscosity (HPV) and cool paste viscosity (CPV) of all the wheat starches was little affected in pH... |
10903031 | Molecular dynamics simulations of cyclohenicosakis-[(1-->2)-beta-D-gluco-henicosapyranosyl], a cyclic (1-->2)-beta-D-glucan (a 'cyclosophoraose') of DP 21. | We report molecular dynamics simulations of cyclohenicosakis-[(1-->2)-beta-D-gluco-henicosapyranosyl], termed 'cyclosophohenicosamer', a member of a class of cyclic (1-->2)-beta-D-glucans ('cyclosophoraoses'). Our goals were to provide insights into the conformational preferences of these cyclosophoraoses. Simulated an... |
10903030 | Computational studies on carbohydrates: solvation studies on maltose and cyclomaltooligosaccharides (cyclodextrins) using a DFT/ab initio-derived empirical force field, AMB99C. | An empirical force field, denoted AMB99C, has been used to study molecular properties of alpha-(1-->4)-linked carbohydrates in solution. AMB99C was parameterized using structural and energetic parameters from density functional ab initio methodology. In this work we examine the solution behavior of the beta anomer of m... |
10903029 | Computational studies on carbohydrates: in vacuo studies using a revised AMBER force field, AMB99C, designed for alpha-(1-->4) linkages. | Modifications to the AMBER force field [W.D. Cornell, P. Cieplak, C.I. Bayly, I.R. Gould, K. Merz, D.M. Ferguson, D.C. Spellmeyer, T. Fox, J.W. Caldwell, P.A. Kollman, J. Am. Chem. Soc., 117 (1995) 5179-5197] have been made to improve our ability to reproduce observed molecular properties of alpha-linked carbohydrates ... |
10896106 | Tyrosine analogues as alternative substrates for protein tyrosine kinase Csk: insights into substrate selectivity and catalytic mechanism. | Protein tyrosine kinases are critical enzymes in cell signal transduction but relatively little is known about the molecular recognition of the tyrosine substrate by these enzymes. Details of tyrosine substrate specificity within the context of a short peptide were investigated for protein tyrosine kinase Csk. It was f... |
10892816 | Molecular simulation study of cooperativity in hydrophobic association. | To investigate the cooperativity of hydrophobic interactions, the potential of mean force of two- and three-molecule methane clusters in water was determined by molecular dynamics simulations using two methods: umbrella-sampling with the weighted histogram analysis method and thermodynamic integration. Two water models... |
10892803 | Conformational behavior of ionic self-complementary peptides. | Several de novo designed ionic peptides that are able to undergo conformational change under the influence of temperature and pH were studied. These peptides have two distinct surfaces with regular repeats of alternating hydrophilic and hydrophobic side chains. This permits extensive ionic and hydrophobic interactions ... |
10770943 | Syntenin-syndecan binding requires syndecan-synteny and the co-operation of both PDZ domains of syntenin. | Syntenin is an adaptor-like molecule that binds to the cytoplasmic domains of all four vertebrate syndecans. Syntenin-syndecan binding involves the C-terminal part of syntenin that contains a tandem of PDZ domains. Here we provide evidence that each PDZ domain of syntenin can interact with a syndecan. Isolated or combi... |
10770947 | Channel formation by the glycosylphosphatidylinositol-anchored protein binding toxin aerolysin is not promoted by lipid rafts. | Glycosylphosphatidylinositol-anchored proteins may be concentrated in membrane microdomains (lipid rafts) that are also enriched in cholesterol and sphingolipids. The glycosyl anchor of these proteins is a specific, high affinity receptor for the channel-forming protein aerolysin. We wished to determine if the presence... |
10888552 | Study of interaction phenomena between aroma compounds and carbohydrate matrixes by inverse gas chromatography. | Besides the conventional techniques used for the investigation of food-flavor interactions, inverse gas chromatography (IGC) may provide a useful tool for the direct assessment of the retention of aroma compounds in a matrix. IGC consists of single reference compound injections at a fixed temperature onto a column whic... |
10886390 | Anti-anti-idiotypic (Ab3) antibodies that bind progesterone-11alpha-bovine serum albumin differ in their combining sites from antibodies raised directly against the antigen. | Polyclonal rabbit anti-idiotypic (Ab2) antibodies raised against the antiprogesterone mAb DB3 (Ab1) were used to induce an Ab3 antiprogesterone response in BALB/c mice. While the affinity of Ab3 sera for progesterone was 10-50-times lower than that of DB3, their steroid-binding specificity showed considerable similarit... |
10880224 | A new approach to macrocyclization via alkene formation in catalytic diazo decomposition. Synthesis of patulolides A and B. | [reaction: see text] Effective synthetic uses of bisdiazocarbonyl compounds for the selective construction of diverse macrocycles, including the synthesis of patulolides A and B, by catalytic "carbene dimer" formation are reported. Control of stereochemistry and efficient methods for product isomerization or kinetic is... |
10880216 | A survey of acid catalysts for use in two-step, one-flask syntheses of meso-substituted porphyrinic macrocycles. | [reaction: see text] Diverse Lewis acids and Bronsted acids were examined in the two-step, one-flask synthesis of meso-tetraphenylporphyrin, N-confused tetraphenylporphyrin, and tetraphenylsapphyrin. The scope of acid catalysis was found to be very broad, with 35 of 45 acids providing TPP in yields ranging from 5% to 5... |
10880215 | Phosphatase-triggered guest release from a cyclodextrin complex. | [reaction: see text] A synthetic supramolecular system is described that models the effect of phosphoryl transfer in molecular recognition. beta-Cyclodextrin-6A-phosphate (pCD), which is shown to be a substrate of alkaline phosphatase, binds cationic aromatic guests, including anticancer agents, up to 100-fold better t... |
10881193 | The structure of the transcriptional antiterminator NusB from Escherichia coli. | We have determined the solution structure of NusB, a transcription antitermination protein from Escherichia coli. The structure reveals a novel, all alpha-helical protein fold. NusB mutations that cause a loss of function (NusB5) or alter specificity for RNA targets (NusB101) are localized to surface residues and likel... |
10879965 | An enantiomeric assay for the flavonoids medicarpin and vestitone using capillary electrophoresis. | An enantiomeric assay for the flavonoids vestitone and medicarpin from transgenic plant extracts was developed using capillary electrophoresis. It was found that no single cyclodextrin proved capable of resolving the enantiomers of both medicarpin and vestitone. Instead, hydroxypropyl-beta-cyclodextrin provided the bes... |
10879962 | Capillary electrophoretic separation of binaphthyl enantiomers with two polymeric chiral surfactants: 1H-nuclear magnetic resonance and fluorescence spectroscopy study. | The use of the water-soluble polymeric chiral surfactants (PCS), sodium N-undecanoyl-L-valinate (poly-L-SUV) and sodium undecanoyl-L-isoleucinate (poly-L-SUI) as buffer additives in electrokinetic chromatography (EKC) afforded the separation of racemic mixtures of 2,2'-dihydroxy-1,1'-binaphthyl (BOH) and 1,1'-binaphthy... |
10879961 | Experimental verification of a predicted, hitherto unseen separation selectivity pattern in the nonaqueous capillary electrophoretic separation of weak base enantiomers by octakis (2,3-diacetyl-6-sulfato)-gamma-cyclodextrin. | The capillary electrophoretic separation of cationic enantiomers with single-isomer multivalent anionic resolving agents was reexamined with the help of the charged resolving agent migration model. Three general model parameters were identified that influence the shape of the separation selectivity and enantiomer mobil... |
10879960 | Use of single-isomer, multiply charge chiral resolving agents for the continuous, preparative-scale electrophoretic separation of enantiomers based on the principle of equal-but-opposite analyte mobilities. | A novel approach to continuous, preparative-scale electrophoretic enantiomer separations has been developed based on the observation that stable, equal-but-opposite effective mobilities can be created for the enantiomers of a single-charged analyte by complexing them with a single-isomer, multiply charged resolving age... |
10871369 | Regulation of the RNA-dependent protein kinase by triple helix formation. | The RNA-dependent protein kinase (PKR) is an interferon-induced, RNA-activated enzyme that phos-phorylates the alpha-subunit of the translation initiation factor eIF-2, inhibiting its function. PKR is activated in vitro by binding to double-stranded RNA (dsRNA) molecules of approximately 30 bp or longer. Here we show t... |
10871367 | Bacterial cryptochrome and photolyase: characterization of two photolyase-like genes of Synechocystis sp. PCC6803. | Photolyase is a DNA repair enzyme that reverses UV-induced photoproducts in DNA in a light-dependent manner. Recently, photolyase homologs were identified in higher eukaryotes. These homologs, termed crypto-chromes, function as blue light photoreceptors or regulators of circadian rhythm. In contrast, most bacteria have... |
10871286 | Apical membrane targeting of Nedd4 is mediated by an association of its C2 domain with annexin XIIIb. | Nedd4 is a ubiquitin protein ligase (E3) containing a C2 domain, three or four WW domains, and a ubiquitin ligase HECT domain. We have shown previously that the C2 domain of Nedd4 is responsible for its Ca(2+)-dependent targeting to the plasma membrane, particularly the apical region of epithelial MDCK cells. To invest... |
10871285 | GAP43, MARCKS, and CAP23 modulate PI(4,5)P(2) at plasmalemmal rafts, and regulate cell cortex actin dynamics through a common mechanism. | The dynamic properties of the cell cortex and its actin cytoskeleton determine important aspects of cell behavior and are a major target of cell regulation. GAP43, myristoylated alanine-rich C kinase substrate (MARCKS), and CAP23 (GMC) are locally abundant, plasmalemma-associated PKC substrates that affect actin cytosk... |
10872655 | Collagen and elastin degradation by matrix metalloproteinases and tissue inhibitors of matrix metalloproteinase in aortic dissection. | The degradation of collagen fibrils and elastic fibers in 21 cases of acute aortic dissection (AD) was ultrastructurally and immunohistochemically investigated; and the expression of the catabolic matrix metalloproteinases (MMPs)-1, -2, -3, and -9 and their inhibitors, the tissue inhibitors of matrix metalloproteinase ... |
10871049 | Interaction of the peptide antibiotic alamethicin with bilayer- and non-bilayer-forming lipids: influence of increasing alamethicin concentration on the lipids supramolecular structures. | Incorporation of the helical antimicrobial peptide alamethicin from aqueous phase into hydrated phases of dioleoylphosphatidylethanolamine (DOPE) and dioleoylphosphatidylcholine (DOPC) was investigated within a range of peptide concentrations and temperatures by time-resolved synchrotron X-ray diffraction. It was found... |
10864754 | NH tautomerism in the natural chlorin derivatives. | The NH tautomerism of five Mg-free chlorophyll a and b derivatives 2-6 was studied utilizing NMR spectroscopy and molecular modeling. The results from the dynamic NMR measurements of the chlorins revealed that substituent effects contribute crucially to the free energy of activation (DeltaG(double dagger)) in the NH ta... |
10864747 | Synthesis and fluorescence properties of new fluorescent, polymerizable, metal-chelating lipids. | Liposomes incorporating fluorescent, metal-chelating lipids find applications in molecular recognition of peptides, 2D protein recrystallization, protein targeting, and biological sensing. It would be advantageous to combine the usefulness of polymerizable, metal-chelating lipids and fluorescent lipids. Herein, we repo... |
10864509 | Global folds of proteins with low densities of NOEs using residual dipolar couplings: application to the 370-residue maltodextrin-binding protein. | The global fold of maltose-binding protein in complex with the substrate beta-cyclodextrin was determined by solution NMR methods. The two-domain protein is comprised of a single polypeptide chain of 370 residues, with a molecular mass of 42 kDa. Distance information in the form of H(N)-H(N), H(N)-CH(3) and CH(3)-CH(3)... |
10866155 | The '2+1' construction of homooxacalix[3]arenes possessing different substituents on their upper rims. | Several homooxacalix[3]arenes possessing different substituents on their upper rims were synthesized in yields of 7-20% by a condensation reaction between the p-substituted-phenol dimer and monomer under acidic high-dilution conditions. |
10866138 | Study of tolbutamide-hydroxypropyl-gamma-cyclodextrin interaction in solution and solid state. | Tolbutamide-hydroxypropyl-gamma-cyclodextrin (TBM-HPGCD) interaction has been investigated in an aqueous environment and in the solid state. The solubility of TBM was increased in accord with the amount of HPGCD added to the aqueous medium forming a soluble inclusion compound. The phase solubility diagram obtained was ... |
10861735 | Enantioselective determination of bromoisovalerylurea by liquid chromatography on chiral stationary phase in reversed- or normal-phase partition mode. | Bromoisovalerylurea (bromvalerylurea) is a sedative-hypnotic given orally as a racemate. Enantiomers of this drug could be separated by high-performance liquid chromatography on the three chiral stationary phases (a vancomycin-bonded, beta-cyclodextrin derivative-bonded, or urea derivative-bonded phase). Biological flu... |
10864207 | Enhancement of chemotherapy and radiotherapy of murine tumours by AQ4N, a bioreductively activated anti-tumour agent. | AQ4 (1,4-Bis-[[2-(dimethylamino-N-oxide)ethyl]amino]5,8-dihydroxyanthrace ne-9, 10-dione) is a prodrug designed to be excluded from cell nuclei until bioreduced in hypoxic cells to AQ4, a DNA intercalator and topoisomerase II poison. Thus, AQ4N is a highly selective bioreductive drug that is activated in, and is prefer... |
10852965 | A substance P-opioid chimeric peptide as a unique nontolerance-forming analgesic. | To elucidate mechanisms of acute and chronic pain, it is important to understand how spinal excitatory systems influence opioid analgesia. The tachykinin substance P (SP) represents the prototypic spinal excitatory peptide neurotransmitter/neuromodulator, acting in concert with endogenous opioid systems to regulate ana... |
10852962 | Unarmed, tumor-specific monoclonal antibody effectively treats brain tumors. | The epidermal growth factor receptor (EGFR) is often amplified and rearranged structurally in tumors of the brain, breast, lung, and ovary. The most common mutation, EGFRvIII, is characterized by an in-frame deletion of 801 base pairs, resulting in the generation of a novel tumor-specific epitope at the fusion junction... |
10861010 | T cell immunity to copolymer 1 confers neuroprotection on the damaged optic nerve: possible therapy for optic neuropathies. | We recently reported that the posttraumatic spread of degeneration in the damaged optic nerve can be attenuated by the adoptive transfer of autoimmune T cells specific to myelin basic protein. However, it would be desirable to obtain immune neuroprotection free of any possible autoimmune disease. In an attempt to obtai... |
10852954 | Regulation of protein kinase CbetaI by two protein-tyrosine kinases, Btk and Syk. | Two protein-tyrosine kinases, Bruton's tyrosine kinase (Btk) and Syk, and members of the protein kinase C (PKC) subfamily of serine/threonine kinases play crucial roles in signal transduction through antigen receptors in B lymphocytes and high-affinity IgE receptors (FcepsilonRI) in mast cells. The present study provid... |
10860995 | Inhibition of sonic hedgehog autoprocessing in cultured mammalian cells by sterol deprivation. | Sonic hedgehog (Shh) is a signaling molecule that is important for defining patterning in the developing vertebrate central nervous system. After translation, Shh autoproteolyzes and covalently attaches cholesterol to the newly formed carboxyl terminus, a modification crucial for normal Shh signaling. Presented here is... |
10860984 | The histone deacetylase-3 complex contains nuclear receptor corepressors. | Acetylation and deacetylation of nucleosomal histones have profound effects on gene transcription in all eukaryotes. In humans, three highly homologous class I and four class II histone deacetylase (HDAC) enzymes have been identified to date. The class I deacetylases HDAC1 and HDAC2 are components of multisubunit compl... |
10860979 | Structure-based discovery of an organic compound that binds Bcl-2 protein and induces apoptosis of tumor cells. | Bcl-2 and related proteins are key regulators of apoptosis or programmed cell death implicated in human disease including cancer. We recently showed that cell-permeable Bcl-2 binding peptides could induce apoptosis of human myeloid leukemia in vitro and suppress its growth in severe combined immunodeficient mice. Here ... |
10860508 | Affinity biosensor for avidin using a double functionalized dendrimer monolayer on a gold electrode. | We have developed an affinity biosensor system based on avidin-biotin interaction on a gold electrode. As the building block of an affinity-sensing monolayer, a fourth-generation (G4) poly(amidoamine) dendrimer having partial ferrocenyl-tethered surface groups was prepared and used. The unmodified surface amine groups ... |
10856215 | Hierarchical self-assembly of F-actin and cationic lipid complexes: stacked three-layer tubule networks. | We describe a distinct type of spontaneous hierarchical self-assembly of cytoskeletal filamentous actin (F-actin), a highly charged polyelectrolyte, and cationic lipid membranes. On the mesoscopic length scale, confocal microscopy reveals ribbonlike tubule structures that connect to form a network of tubules on the mac... |
10856231 | Peptide antagonists of the plasmodesmal macromolecular trafficking pathway. | In plants, cell-to-cell transport of endogenous and viral proteins and ribonucleoprotein complexes (RNPCs) occurs via plasmodesmata. Specificity of this transport pathway appears to involve interaction between such proteins/RNPCs and plasmodesmal chaperones/receptors. Here, KN1 and the cucumber mosaic virus movement pr... |
10856020 | Endocrine disruptors and human health--is there a problem? An update. | It has been hypothesized that environmental exposure to synthetic estrogenic chemicals and related endocrine-active compounds may be responsible for a global decrease in sperm counts, decreased male reproductive capacity, and breast cancer in women. Results of recent studies show that there are large demographic variat... |
10854228 | Asebia-2J (Scd1(ab2J)): a new allele and a model for scarring alopecia. | A spontaneous, autosomal, recessive mouse mutation exhibiting mild scaly skin, progressive scarring alopecia, slightly runted growth, and photophobia arose at The Jackson Laboratory in 1993 in the inbred mouse strain DBA/1LacJ. Because this mutant mouse showed genetic, anatomical, and laboratory similarities to the ase... |
10854213 | Glomerular expression of type IV collagen chains in normal and X-linked Alport syndrome kidneys. | Alport syndrome is an inherited nephropathy characterized by alterations of the glomerular basement membrane because of mutations in type IV collagen genes. COL4A5 mutations, causing X-linked Alport syndrome, frequently result in the loss of the alpha5 chains of type IV collagen in basement membranes. This is associate... |
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