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11514664 | Oligomerization and ligand binding in a homotetrameric hemoglobin: two high-resolution crystal structures of hemoglobin Bart's (gamma(4)), a marker for alpha-thalassemia. | Hemoglobin (Hb) Bart's is present in the red blood cells of millions of people worldwide who suffer from alpha-thalassemia. alpha-Thalassemia is a disease in which there is a deletion of one or more of the four alpha-chain genes, and excess gamma and beta chains spontaneously form homotetramers. The gamma(4) homotetram... |
11514662 | Sequence-structure analysis of FAD-containing proteins. | We have analyzed structure-sequence relationships in 32 families of flavin adenine dinucleotide (FAD)-binding proteins, to prepare for genomic-scale analyses of this family. Four different FAD-family folds were identified, each containing at least two or more protein families. Three of these families, exemplified by gl... |
11513807 | Transduction to self-assembly of molecular geometry and local interactions in mixtures of ceramides and ganglioside GM1. | In mixed monolayers with ganglioside GM1, ceramide induces a non-ideal increase of the monolayer collapse pressure, a reduction of the mean molecular area and a decrease of the surface potential per molecule at all surface pressures. The critical packing parameter and van der Waals interaction energy calculated from mo... |
11513805 | Conformational limitations of glycylsarcosine as a prototypic substrate for peptide transporters. | Peptide transporters are present in all species to absorb the small peptides that occur ubiquitously as products of proteolysis. The broad substrate specificities of these systems allow them to be exploited therapeutically for delivery of peptidomimetic drugs in microbes and man. To this end, glycylsarcosine is current... |
11509375 | The Fe(2+)-His(F8) Raman band shape of deoxymyoglobin reveals taxonomic conformational substates of the proximal linkage. | The band shape of the Raman line attributed to the Fe(2+)-N(epsilon)(His(F8)) stretching mode in deoxymyoglobin contains significant information on the nature of the Fe-His proximal linkage. Raman lines appearing close to it, however, obscure the true line profile. To isolate this from its accompanying lines we use its... |
11509372 | Significance of ligand tails for interaction with the minor groove of B-DNA. | Minor groove binding ligands are of great interest due to their extraordinary importance as transcription controlling drugs. We performed three molecular dynamics simulations of the unbound d(CGCGAATTCGCG)(2) dodecamer and its complexes with Hoechst33258 and Netropsin. The structural behavior of the piperazine tail of ... |
11509363 | Characteristics of pyrene phospholipid/gamma-cyclodextrin complex. | Recently, it was demonstrated that gamma-cyclodextrins (gamma-CDs) greatly accelerates transfer of hydrophobic pyrene-labeled and other fluorescent phospholipid derivatives from vesicles to cells in culture (). To understand better the characteristics of this process, we studied the interaction of gamma-CD with pyrene-... |
11509362 | Characterization of cholesterol-sphingomyelin domains and their dynamics in bilayer membranes. | Lipids segregate with each other into small domains in biological membranes, which can facilitate the associations of particular proteins. The segregation of cholesterol and sphingomyelin (SPM) into domains known as rafts is thought to be especially important. The formation of rafts was studied by using planar bilayer ... |
11509361 | Barrel-stave model or toroidal model? A case study on melittin pores. | Transmembrane pores induced by amphiphilic peptides, including melittin, are often modeled with the barrel-stave model after the alamethicin pore. We examine this assumption on melittin by using two methods, oriented circular dichroism (OCD) for detecting the orientation of melittin helix and neutron scattering for det... |
11509352 | Carbohydrate-protein recognition: molecular dynamics simulations and free energy analysis of oligosaccharide binding to concanavalin A. | Carbohydrate ligands are important mediators of biomolecular recognition. Microcalorimetry has found the complex-type N-linked glycan core pentasaccharide beta-GlcNAc-(1-->2)-alpha-Man-(1-->3)-[beta-GlcNAc-(1-->2)-alpha-Man-(1-->6)]-Man to bind to the lectin, Concanavalin A, with almost the same affinity as the trimann... |
11509346 | Molecular dynamics force probe simulations of antibody/antigen unbinding: entropic control and nonadditivity of unbinding forces. | Unbinding of a spin-labeled dinitrophenyl (DNP) hapten from the monoclonal antibody AN02 F(ab) fragment has been studied by force probe molecular dynamics (FPMD) simulations. In our nanosecond simulations, unbinding was enforced by pulling the hapten molecule out of the binding pocket. Detailed inspection of the FPMD t... |
11507232 | Peptides corresponding to the heptad repeat motifs in the transmembrane protein (gp41) of human immunodeficiency virus type 1 elicit antibodies to receptor-activated conformations of the envelope glycoprotein. | Two heptad repeat regions in the ectodomain of the human immunodeficiency virus type 1 (HIV-1) transmembrane subunit (gp41) self-assemble into a six-helix bundle structure that is critical for virus entry. Immunizations with peptides corresponding to these regions generated antibodies specific to the receptor-activated... |
11507222 | Heparan sulfate glycosaminoglycans are receptors sufficient to mediate the initial binding of adenovirus types 2 and 5. | Cell infection by adenovirus serotypes 2 and 5 (Ad2/5) initiates with the attachment of Ad fiber to the coxsackievirus and Ad receptor (CAR) followed by alpha(v) integrin-mediated entry. We recently demonstrated that heparan sulfate glycosaminoglycans (HS GAGs) expressed on cell surfaces are involved in the binding and... |
11507193 | Role of chimeric murine leukemia virus env beta-turn polyproline spacers in receptor cooperation. | We have previously reported a set of Moloney murine leukemia virus derived envelopes retargeted to the Pit-2 phosphate transporter molecule, by insertion of the Pit-2 binding domain (BD) at the N terminus of the ecotropic retroviral envelope glycoproteins (S. Valsesia-Wittmann et al., J. Virol. 70:2059-2064, 1996). The... |
11502508 | In vitro and in vivo activities of syn2836, syn2869, syn2903, and syn2921: new series of triazole antifungal agents. | The in vitro and in vivo activities of four azole compounds belonging to a new series of 2(2,4-difluorophenyl)-3-(4-substituted piperazin-1-yl)-1-(1,2,4-triazol-1-yl) butanol antifungal agents is described. The compounds were selected from a library of azole compounds synthesized by our group. The in vitro activities o... |
11489860 | Genetic and structural organization of the aminophenol catabolic operon and its implication for evolutionary process. | The aminophenol (AP) catabolic operon in Pseudomonas putida HS12 mineralizing nitrobenzene was found to contain all the enzymes responsible for the conversion of AP to pyruvate and acetyl coenzyme A via extradiol meta cleavage of 2-aminophenol. The sequence and functional analyses of the corresponding genes of the oper... |
11489857 | Extracellular synthesis, specific recognition, and intracellular degradation of cyclomaltodextrins by the hyperthermophilic archaeon Thermococcus sp. strain B1001. | A unique extracellular and thermostable cyclomaltodextrin glucanotransferase (CGTase) from the hyperthermophilic archaeon Thermococcus sp. strain B1001 produces predominantly (>85%) alpha-cyclomaltodextrin (alpha-CD) from starch (Y. Tachibana, et al., Appl. Environ. Microbiol. 65:1991--1997, 1999). Nucleotide sequencin... |
11484226 | Quantum mechanics simulation of protein dynamics on long timescale. | Protein structure and dynamics are the keys to a wide range of problems in biology. In principle, both can be fully understood by using quantum mechanics as the ultimate tool to unveil the molecular interactions involved. Indeed, quantum mechanics of atoms and molecules have come to play a central role in chemistry and... |
11483769 | Nonenveloped nucleocapsids of hepatitis C virus in the serum of infected patients. | One of the characteristics of hepatitis C virus (HCV) is the high incidence of persistent infection. HCV core protein, in addition to forming the viral nucleocapsid, has multiple regulatory functions in host-cell transcription, apoptosis, cell transformation, and lipid metabolism and may play a role in suppressing host... |
11483736 | Multimerization of human immunodeficiency virus type 1 Gag promotes its localization to barges, raft-like membrane microdomains. | The Gag polyprotein of human immunodeficiency virus type 1 (HIV-1) organizes the assembly of nascent virions at the plasma membrane of infected cells. Here we demonstrate that a population of Gag is present in distinct raft-like membrane microdomains that we have termed "barges." Barges have a higher density than stand... |
11483734 | The envelope glycoprotein of friend spleen focus-forming virus covalently interacts with and constitutively activates a truncated form of the receptor tyrosine kinase Stk. | The Friend spleen focus-forming virus (SFFV) encodes a unique envelope glycoprotein, gp55, which allows erythroid cells to proliferate and differentiate in the absence of erythropoietin (Epo). SFFV gp55 has been shown to interact with the Epo receptor complex, causing constitutive activation of various signal-transduci... |
11483730 | Detailed analysis of the requirements of hepatitis A virus internal ribosome entry segment for the eukaryotic initiation factor complex eIF4F. | The hepatitis A virus (HAV) internal ribosome entry segment (IRES) is unique among the picornavirus IRESs in that it is inactive in the presence of either the entero- and rhinovirus 2A or aphthovirus Lb proteinases. Since these proteinases both cleave eukaryotic initiation factor 4G (eIF4G) and HAV IRES activity could ... |
11483723 | Different levels of T-cell receptor triggering induce distinct functions in hepatitis B and hepatitis C virus-specific human CD4(+) T-cell clones. | CD4(+) T cells play a major role in the host defense against viruses and intracellular microbes. During the natural course of such an infection, specific CD4(+) T cells are exposed to a wide range of antigen concentrations depending on the body compartment and the stage of disease. While epitope variants trigger only s... |
11470130 | Cyclodextrin modulation of T lymphocyte signal transduction with aging. | There is an alteration of the immune response in aging that leads to the increased incidence of infections, cancers and autoimmune disorders. The aim of the present study was to investigate whether there exists changes in signal transduction under the IL-2 receptor stimulation and the role of plasma membrane cholestero... |
11470202 | A Plackett-Burnam screening design directs the efficient formulation of multicomponent DRV liposomes. | A computer-based technique was applied for the optimization of recently described multicomponent protective liposomal formulations. These formulations contain riboflavin in either free form or complexed with gamma-cyclodextrin as a model drug, sensitive to photochemical degradation, as well as various light absorbers a... |
11470199 | Molecular recognition in a reconstituted tumor cell membrane. | The design of an immunoliposome system for molecular recognition using reconstituted, hydrogel-supported bilayer lipid membranes (sb-BLMs) is described. By monitoring the electrical properties, two kinds of recognition are feasible: (i) the human bladder tumor cells, Ej and its antibody BDI-1, the lifetime of the recon... |
11470194 | Quantitative determination of piroxicam in a new formulation (piroxicam-beta-cyclodextrin) by derivative UV spectrophotometric method and HPLC. | A derivative ultraviolet (UV) spectrophotometric method for the determination of piroxicam in piroxicam--beta-cyclodextrin tablets was developed. Phosphate buffer (pH 7.8, 0.1 M) and ethanol were used as a solvent system throughout the study. In this study, determination of piroxicam was conducted by using first order ... |
11545679 | Stratum corneum lipids liposomes for the topical delivery of 5-aminolevulinic acid in photodynamic therapy of skin cancer: preparation and in vitro permeation study. | <h4>Background</h4>Photodynamic therapy (PDT) using 5-aminolevulinic acid (5-ALA) is a skin cancer therapy that still has limitations due to the low penetration of this drug into the skin. We have proposed in this work a delivery system for 5-ALA based on liposomes having lipid composition similar to the mammalian stra... |
11519011 | Mutations in the 3beta-hydroxysterol Delta24-reductase gene cause desmosterolosis, an autosomal recessive disorder of cholesterol biosynthesis. | Desmosterolosis is a rare autosomal recessive disorder characterized by multiple congenital anomalies. Patients with desmosterolosis have elevated levels of the cholesterol precursor desmosterol, in plasma, tissue, and cultured cells; this abnormality suggests a deficiency of the enzyme 3beta-hydroxysterol Delta24-redu... |
11517324 | Electrostatics of nanosystems: application to microtubules and the ribosome. | Evaluation of the electrostatic properties of biomolecules has become a standard practice in molecular biophysics. Foremost among the models used to elucidate the electrostatic potential is the Poisson-Boltzmann equation; however, existing methods for solving this equation have limited the scope of accurate electrostat... |
11504715 | Noncovalent interaction between ubiquitin and the human DNA repair protein Mms2 is required for Ubc13-mediated polyubiquitination. | Ubiquitin-conjugating enzyme variants share significant sequence similarity with typical E2 (ubiquitin-conjugating) enzymes of the protein ubiquitination pathway but lack their characteristic active site cysteine residue. The MMS2 gene of Saccharomyces cerevisiae encodes one such ubiquitin-conjugating enzyme variant th... |
11504911 | DNA binding induces dissociation of the multimeric form of HIV-1 integrase: a time-resolved fluorescence anisotropy study. | Self-assembly of HIV-1 integrase (IN) in solution has been studied previously by time-resolved fluorescence, using tryptophan anisotropy decay. This approach provides information on the size of macromolecules via the determination of rotational correlation times (theta). We have shown that, at submicromolar concentrati... |
11502760 | Lipid raft microdomain compartmentalization of TC10 is required for insulin signaling and GLUT4 translocation. | Recent studies indicate that insulin stimulation of glucose transporter (GLUT)4 translocation requires at least two distinct insulin receptor-mediated signals: one leading to the activation of phosphatidylinositol 3 (PI-3) kinase and the other to the activation of the small GTP binding protein TC10. We now demonstrate ... |
11500495 | Effects of the membrane dipole potential on the interaction of saquinavir with phospholipid membranes and plasma membrane receptors of Caco-2 cells. | The combined use of the membrane surface potential fluorescent sensor fluorescein phosphatidylethanolamine (FPE) and the membrane dipole potential fluorescent sensor di-8-ANEPPS to characterize the interaction of molecules with model and cellular membranes and to asses the influence of the dipole potential on the inter... |
11531578 | Mesoscopic correlation of supramolecular chirality in one-dimensional hydrogen-bonded assemblies. | The ordering of 4-[trans-2-(pyrid-4-yl-vinyl)] benzoic acid, a two-dimensional chiral species, was studied by scanning tunneling microscopy at noble metal surfaces. Homochiral molecules self-assemble in supramolecular chiral hydrogen-bonded twin chains, which order in nanogratings where the supramolecular chirality is ... |
11498633 | Methoxy-ether and crown-ether derivatives of tetrahomodioxa- and octahomotetraoxacalix[4]arenes. | Three methoxy-ether and one methoxy-ether/crown-ether derivatives of p-tert-butyltetrahomodioxa- and p-R-octahomotetraoxacalix[4]arenes (R = methyl, tert-butyl, H) have been investigated. The first three compounds, 7,15,21,27-tetra-tert-butyl-29,30,31,32-tetramethoxy-3,11-dioxapentacyclo[23.3.1.1(5,9).1(13,17).1(19,23)... |
11498622 | Hydrogen-bonded chains in N-(2-nitrophenyl)phenylamine. | Molecules of the title compound, C(12)H(10)N(2)O(2), are markedly non-planar. There is an intramolecular N-H...O hydrogen bond, and the molecules are linked into zigzag chains by a single C-H...O hydrogen bond. Comparisons are made with the supramolecular aggregation in isomeric amino-nitro derivatives, and in some N-m... |
11493691 | Mapping the interactions between flavodoxin and its physiological partners flavodoxin reductase and cobalamin-dependent methionine synthase. | Flavodoxins are electron-transfer proteins that contain the prosthetic group flavin mononucleotide. In Escherichia coli, flavodoxin is reduced by the FAD-containing protein NADPH:ferredoxin (flavodoxin) oxidoreductase; flavodoxins serve as electron donors in the reductive activation of anaerobic ribonucleotide reductas... |
11493690 | Segregation of leading-edge and uropod components into specific lipid rafts during T cell polarization. | Redistribution of specialized molecules in migrating cells develops asymmetry between two opposite cell poles, the leading edge and the uropod. We show that acquisition of a motile phenotype in T lymphocytes results in the asymmetric redistribution of ganglioside GM3- and GM1-enriched raft domains to the leading edge a... |
29712005 | Designed Molecules for Self-Assembly: The Controlled Formation of Two Chiral Self-Assembled Polynuclear Species with Predetermined Configuration. | Squaring the cycle: Ligand L<sup>1</sup> has been developed for the fabrication of chiral molecular squares, which can also be considered as circular helicates. By using a chirally modified ligand, one of the two forms of the complex can be generated selectively. bpy=2,2'-bipyridin-6-yl. |
29712001 | Targeting Molecular Recognition: Exploring the Dual Role of Functional Pseudoprolines in the Design of SH3 Ligands. | Pseudoprolines (ΨPro) have been developed as tools for inducing bioactive conformations that allow for optimal spatial complementation in protein-protein interactions. This dual function of ΨPro was explored for tuning proline-rich peptides as potent ligands for SH3 domains. |
29711994 | Ion-Pair Recognition by Nucleoside Self-Assembly: Guanosine Hexadecamers Bind Cations and Anions. | G-Quartets can bind anions as well as cations: Solid-state and solution data indicate that self-assembled ion-pair receptors are formed from 16 guanosine monomers, 2 divalent cations, and 4 picrate anions. Hydrogen-bonding, ion-dipole, and base-stacking interactions combine to give a tubular complex with a cation-loade... |
29711984 | Time- and Space-Resolved Luminescence of a Photonic Dye-Zeolite Antenna. | In a radiationless process, electronic excitation energy can be transported in the photonic antennae presented herein from the borders to the center of cylindrical zeolite L crystals (ca. 2 μm). These antennae are formed by supramolecular organization of a cationic and a neutral dye in the parallel channels of the crys... |
29711982 | Directed Assembly of Periodic Materials from Protein and Oligonucleotide-Modified Nanoparticle Building Blocks. | DNA hybridization enables the three-dimensional assembly of Au nanoparticles and streptavidin. The high-density DNA-modified Au nanoparticles were stable to nonspecific binding of streptavidin. Structural and melting investigations on the assemblies showed their formation was reversible. |
27134334 | Actions of a Series of PPADS Analogs at P2X<sub>1</sub> and P2X<sub>3</sub> Receptors. | [Table: see text] Seven PPADS (<b>P</b>yridoxal-5'-<b>P</b>hosphate 6-<b>A</b>zophenyl 2',4'-<b>D</b>i<b>S</b>ulfonate) analogs were investigated at Group 1 P2X receptors expressed in Xenopus oocytes. All seven analogs potently inhibited P2X<sub>1</sub> (IC<sub>50</sub> range, 5-32 nM) and P2X<sub>3</sub> (IC<sub>50</s... |
18968369 | Role of the water as a surface tension modifier for the retention of a series of dansylaminoacids on a beta-CD stationary phase. | In reversed phase liquid chromatography (RPLC), using a surface tension treatment, the retention and separation of a series of d,l-dansylaminoacids were investigated with native beta-cyclodextrin as a chiral stationary phase. The enantioselectivity thermodynamic parameters were determined from linear van't Hoff plots. ... |
11482957 | Photochromic Inorganic/Organic Self-Assembled Superlattice Films. | Phosphotungstic acid (PW(12)) and 1,10-diaminodecane (1,10-DAD) molecules have been alternatively assembled on 3-aminopropyltriethyoxysilane modified quartz or silicon substrate to form multicomposite mutilayer thin films by the molecular deposition technique. Thus-obtained films were characterized by UV-visible, XRD, ... |
11482950 | Effect of beta-Cyclodextrin on the Photoinduced Charge Transfer in Sodium 1-Anilino-8-naphthalene Sulfate (ANS)/CdS Colloidal System. | The S-center radical (ANS(.)) of sodium 1-anilino-8-naphthalene sulfate (ANS) generated by photoinduced charge transfer in ANS/CdS and ANS/CdS/beta-cyclodextrin(beta-CD) systems has been studied by using spin trapping electron spin resonance techniques, UV-visible spectroscopic methods, and fluorescence spectroscopic m... |
11819828 | Relationship between plasma D(-)-lactate and intestinal damage after severe injuries in rats. | <h4>Aim</h4>To explore the kinetic changes in plasma D(-)-lactate and lipopolysaccharide (LPS) levels, and investigate whether D(-)-lactate could be used as a marker of intestinal injury in rats following gut ischemia/reperfusion, burn, and acute necrotizing pancreatitis (ANP).<h4>Methods</h4>Three models were develope... |
11881862 | Evaluation of efficacy and safety of nimesulide with betacyclodextrin vs nimesulide tablets in osteoarthritis. | Efficacy and safety of nimesulide as well as favourable tolerability have been tested in osteoarthritis in short term study and post-marketing survey. Here is a report which shows the superiority of nimesulide complexed with betacyclodextrin vs ninesulide tablet in osteoarthritis in a long term study. |
11828487 | Photoresponsive dendritic azobenzene peptides. | Two dendritic peptides containing a branched lysine core and up to eight azobenzene moieties in the periphery were synthesized on solid support employing the omega-amino acid 4-(aminomethyl)phenylazobenzoic acid. With an additional peptidic tail consisting of an oligolysine portion, water solubility was achieved for th... |
11716441 | Importance of increased intestinal permeability after multiple injuries. | <h4>Objective</h4>To find out if there was a relationship between increased intestinal permeability and the development of multiple organ failure (MOF) after multiple injuries, we correlated the extent of injury and MOF with intestinal permeability on the second and fourth day after injury.<h4>Design</h4>Prospective op... |
11708096 | Lead-selective membrane potentiometric sensor based on an 18-membered thiacrown derivative. | A PVC-based membrane electrode for lead ions based on hexathia-18-crown-6-tetraone as membrane carrier was prepared. The influence of membrane composition, pH of test solution and foreign ions on the electrode performance were investigated. The electrode showed a Nernstian response over a lead concentration range from ... |
11683511 | Analysis of protein sequences and protein complexes by matrix-assisted laser desorption/ionization mass spectrometry. | In the context of proteome analysis, matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) can fulfil the two tasks of primary structure verification and protein identification. As an illustration of the first of these tasks, the sequence of Eschericha coli isoleucyl-tRNA synthetase, a protein with 1... |
11672683 | Methyl-beta-cyclodextrin: an alternative carrier for intravenous infusion of palmitate during tracer studies in swine (Sus scrofa domestica). | Fatty acid-free albumin has been the standard carrier for intravenous infusion of fatty acids to study in vivo lipid metabolism. However, subjects can have adverse reactions to infusion of albumin. We sought an alternative to albumin as a carrier for intravenous infusion of fatty acids, using the pig as a model. Cyclod... |
11672649 | Amplification of antigen-antibody interactions based on biotin labeled protein-streptavidin network complex using impedance spectroscopy. | Antibody was covalently immobilized by amine coupling method to gold surfaces modified with a self-assembled monolayer of thioctic acid. The electrochemical measurements of cyclic voltammetry and impedance spectroscopy showed that the hexacyanoferrate redox reactions on the gold surface were blocked due to the procedur... |
11587496 | Osmotic properties of sulfobutylether and hydroxypropyl cyclodextrins. | <h4>Purpose</h4>The purpose of this study was to determine the osmolality of sulfobutylether (SBE) and hydroxypropyl (HP) derivatives of cyclodextrins (CDs) via vapor pressure osmometry (VPO) and freezing point depression (FPD). (SBE) and HP-CDs are efficient excipients capable of solubilizing and stabilizing poorly wa... |
11587489 | Inhibitory effects of novel hydrophilic cyclodextrin derivatives on nitric oxide production in macrophages stimulated with lipopolysaccharide. | <h4>Purpose</h4>The objective of this study is to examine the effects of cyclodextrins (CyDs) on nitric oxide (NO) production in macrophages stimulated with lipopolysaccharide (LPS).<h4>Methods</h4>RAW264.7 cells, a mouse macrophage-like cell, were used. Cytotoxicity of CyDs was evaluated by WST-1 method. Nitrite, iNOS... |
11577980 | How do thermophilic proteins deal with heat? | Recent years have witnessed an explosion of sequence and structural information for proteins from hyperthermophilic and thermophilic organisms. Complete genome sequences are available for many hyperthermophilic archaeons. Here, we review some recent studies on protein thermostability along with work from our laboratory... |
11577978 | Tetraspanins. | The first tetraspanins were discovered on surface of human leucocytes, but it was rapidly demonstrated that they had a wider tissue expression. Twenty-six molecules display sufficient homology to belong to the same superfamily. Their function is not precisely known, but data coming from biochemical studies or knockout ... |
11572385 | Simultaneous quantitation of nucleoside HIV-1 reverse transcriptase inhibitors by short-end injection capillary electrochromatography on a beta-cyclodextrin-bonded silica stationary phase. | As part of our on-going study of the analysis and quantitation of anti-HIV nucleosides, a capillary electrochromatography (CEC) method has been developed for the simultaneous quantitation of nucleoside HIV reverse transcriptase inhibitors (NRTIs), i.e. zidovudine (AZT), lamivudine (3TC), didanosine (ddA) and its admini... |
11572381 | Application of the polysilicone fullerene coating for solid-phase microextraction in the determination of semi-volatile compounds. | Solid-phase microextraction using polysilicone fullerene (PF) coating has been applied for the determination of semi-volatile compounds. Detection limits at the 10 ng l(-1) to approximately microg l(-1) level were achieved using flame ionization detection. A wide linear range was obtained with precision below 7% relati... |
11569855 | Molecularly imprinted polymers: new molecular recognition materials for selective solid-phase extraction of organic compounds. | During the last few years molecularly imprinted polymers have appeared as new selective sorbents for solid-phase extraction of organic compounds in different samples. Molecular imprinting technology involves the preparation of a polymer with specific recognition sites for certain molecules. Once the polymer has been ob... |
11565843 | Non-hydrogen bond interactions involving the methionine sulfur atom. | Of all the nonbonded interactions, hydrogen bond, because of its geometry involving polar atoms, is the most easily recognizable. Here we characterize two interactions involving the divalent sulfur of methionine (Met) residues that do not need any participation of proton. In one an oxygen atom of the main-chain carbony... |
11560333 | Scandium(III) coordination polymers containing capsules based on two p-sulfonatocalix[4]arenes. | Reactions of sodium p-sulfonatocalix[4]arene and scandium(III) tristriflate in the presence, and absence, of [18]crown-6 give the crystalline complexes [Sc2(mu-OH)2(H2O)10][Na4(H2O)8-[calix[4]arene(SO3)4]2).13 H2O and [[Sc2(mu-OH)2(H2O)8][Sc(H2O)4]2[calix[4]-arene(SO3)4-H+]2([18]crown-6).16H2O. Both complexes involve n... |
11560332 | Complexation and (templated) synthesis of rhenium complexes with cyclodextrins and cyclodextrin dimers in water. | Several small, lipophilic rhenium complexes form inclusion complexes with native beta-cyclodextrin (beta-CD) and beta-CD dimers. Association constants larger than 10(9)M(-1) were obtained using dimers. The use of beta-CD also enabled the synthesis of these rhenium complexes in water, in excellent yields, through comple... |
11560329 | Self-assembly of rings, catenanes, and a doubly braided catenane containing gold(I): the hinge-group effect in diacetylide ligands. | Reaction of the flexible dialkynyldigold(I) precursors X(4-C6H4OCH2C-CAu)2 with 1,4-bis(diphenylphosphino)butane gave complexes of formula [[[mu-X(4-C6H4OCH2CCAu)2[mu-(Ph2PCH2CH2CH2CH2PPh2)]]n]. The complexes exist as 25-membered ring compounds with n = 1 when X = O or S, as [2]catenanes with n = 2 when X = CH2 or CMe2... |
11560318 | Dual-mode "co-conformational" switching in catenanes incorporating bipyridinium and dialkylammonium recognition sites. | Three [2]catenanes and three [3]catenanes incorporating one or two pi-electron-rich macrocyclic polyethers and one pi-electron-deficient polycationic cyclophane have been synthesized in yields ranging from 4 to 38%. The pi-electron-rich macrocyclic components possess either two 1,4-dioxybenzene or two 1.5-dioxynaphthal... |
11560317 | Novel resorcin[4]arenes as potassium-selective ion-channel and transporter mimics. | A series of novel resorcin-[4]arenes with extended pi systems have been synthesised and developed as potassium-selective transporters. Resorcin[4]arenes that feature crown ether moieties function as efficient carriers of K+ across bulk liquid membranes showing enhanced selectivity over the other alkali metal ions relat... |
11556337 | Application of carboxymethyl-beta-cyclodextrin as a chiral selector in capillary electrophoresis for enantiomer separation of selected neurotransmitters. | The aim of this work was to optimize conditions for capillary electrophoresis separation of different neurotransmitters (serotonin, phenylalanine, dopamine, adrenaline, ephedrine, propranolol and DOPA) in a single run, including separation of existing enantiomers. As chiral selectors added to the borate background, ele... |
11556336 | Amino acid analysis in five pooled single plant cell samples using capillary electrophoresis coupled to laser-induced fluorescence detection. | In this study 21 amino acid standards, samples of pure phloem sap and samples of pooled mesophyll cells were derivatized with fluorescein isothiocyanate, separated by capillary electrophoresis and detected with laser-induced fluorescence at 488 nm. Two different background electrolytes, a sodium borate buffer containin... |
11556335 | Derivatization, stabilization and detection of biogenic amines by cyclodextrin-modified capillary electrophoresis-laser-induced fluorescence detection. | o-Phthalaldehyde (OPA) derivatives of eight biogenic amines were stabilized at 5 degrees C by forming inclusion complexes with methyl-beta-cyclodextrin (MBCD). The derivatives were separated and detected by cyclodextrin-modified capillary electrophoresis (CE) with UV or laser-induced fluorescence (LIF) detection. Using... |
11554417 | Efficient applications of capillary electrophoresis-tandem mass spectrometry to the analysis of adrenoreceptor antagonist enantiomers using a partial filling technique. | Throughout the separation of chiral basic drugs by capillary electrophoresis (CE) with neutral hydroxypropyl-beta-cyclodextrin (HP-beta-CD) as chiral selector, the sensitivity of detection can be improved by using tandem mass spectrometric (MS-MS) detection with a partial filling technique rather than with UV spectrome... |
11545406 | Electrophoretic separation of tryptophan enantiomers in biological samples. | A method for the determination of D- and L-tryptophan (Trp) in biological samples is described. The amino acid enantiomers were precolumn-derivatized with a fluorescence tagging reagent, naphthalene-2,3-dialdehyde (NDA). In the presence of hydroxypropyl-gamma-cyclodextrin (HP-gamma-CD) as the chiral selector, NDA-tagge... |
11545386 | Improved preparative-scale. continuous, free-flow electrophoretic separation of the enantiomers of terbutaline utilizing equal-but-opposite enantiomer mobilities. | The factors that influence yield and product purity in the continuous, preparative-scale electrophoretic separation of the enantiomers of terbutaline when using the principle of equal-but-opposite effective mobilities were studied. The sodium salt of heptakis-6-sulfato-beta-cyclodextrin was used as the resolving agent,... |
11536223 | Multimodal inclusion complexes between barbiturates and 2-hydroxypropyl-beta-cyclodextrin in aqueous solution: isothermal titration microcalorimetry, (13)C NMR spectrometry, and molecular dynamics simulation. | Multiple types (structures) of inclusion complexes between barbiturates and 2-hydroxypropyl-beta-cyclodextrin (HPCD) were evaluated by isothermal titration microcalorimetry and (13)C NMR spectroscopy. The geometries of the inclusion complexes were suggested by molecular dynamics simulation. Barbituric acid (BA), barbit... |
11536213 | Influence of degree of substitution of cyclodextrins on their colligative properties in solution. | The purpose of this study was to investigate the effect of the total degree of substitution (TDS) on the colligative properties of substituted cyclodextrins (CDs; i.e., beta- and gamma-cyclodextrins substituted with sulfobutylether or hydroxypropyl groups) in solution. The osmotic pressure (OP) of aqueous CD solutions ... |
11536210 | Mechanisms and surface chemical prediction of imipramine-induced hemolysis suppressed by modified cyclodextrins. | The suppression of imipramine hydrochloride (IMP)- induced hemolysis by native cyclodextrins (alpha-, beta-, and gamma-CDs) and beta-CD derivatives is measured as a function of CD concentration and is quantitatively correlated with the surface tension of the solution determined at 37.0 degrees C. The modified beta-CDs ... |
11536201 | Cyclodextrin complexes of salts of acidic drugs. Thermodynamic properties, structural features, and pharmaceutical applications. | The objective of this mini-review is to summarize the findings concerning the physicochemical properties and the pharmaceutical applications of acidic drugs whose performances have been modified by simultaneous complexation with cyclodextrins and salt formation. Particular attention is paid to the approaches undertaken... |
11534757 | Chiral separation of beta2-agonists by capillary electrophoresis using hydroxypropyl-alpha-cyclodextrin as a chiral selector. | Enantiomers of five racemic beta2-agonists were investigated by capillary electrophoresis employing a hydroxypropyl-beta-cyclodextrin (HP-beta-CD). The effects of the concentration of HP-beta-CD added to the background electrolyte and of the pH of the buffer on the effective mobility and resolution of the studied compo... |
11534728 | Use of dyes to investigate migration of the chiral selector in CFFE and the impact on the chiral separations. | Continuous free flow electrophoresis was investigated as a tool for the preparative chiral separation of piperoxan enantiomers using sulfated beta-cyclodextrin (sbeta-CD) as the chiral additive. Bulk migration of sbeta-CD was confirmed using LC-MS analysis of the individual fractions collected and visualized with the a... |
11534725 | Self-assembled monolayer of a redox-active calix[4]arene: voltammetric recognition of the Ba2+ ion in aqueous media. | The Redox-active monolayer of a novel calix[4]arene recognizing redox-inactive ionic species by voltammetry is reported. Calix[4]arene-disulfide-diquinone, which is not only redox-active but is also a highly selective ionophore for the Ba2+ ion, spontaneously forms a stable and dense monolayer film on gold. The redox-a... |
11534709 | Moleculary imprinted polymers with metalloporphyrin-based molecular recognition sites coassembled with methacrylic acid. | A diastereoselective molecularly imprinted polymer (MIP) for (-)-cinchonidine, PPM(CD), was prepared by the combined use of methacrylic acid and vinyl-substituted zinc(II) porphyrin as functional monomers. Compared to MIPs using only methacrylic acid or zinc porphyrin as a functional monomer, PM(CD) and PP(CD), respect... |
11532029 | Functional interactions of an archaeal sliding clamp with mammalian clamp loader and DNA polymerase delta. | <h4>Background</h4>By the total genome sequencing of several archaeal organisms, it has been confirmed that many archaeal proteins related to genetic information systems, including DNA replication, transcription and translation, have similar sequences to those of eukaryotes. In eukaryotic DNA replication, proliferating... |
11531123 | Enantiospecific synthesis of the (9S,18R)-diastereomer of the leukocyte adhesion inhibitor cyclamenol A. | Cyclamenol A is one of the very few non-carbohydrate and non-peptide natural products that inhibit leukocyte adhesion to endothelial cells. We report on the first enantioselective total synthesis of the (9S, 18R)-diastereomer of this macrocyclic polyene lactam. Key elements of the synthesis are i) the synthesis of the ... |
11531122 | Calixarene--poly(dithiophene)-based chemically modified electrodes. | The stepwise synthesis of cone and partial cone 1,3-bridged n-propoxy-calix[4]crown ethers ("monomers" 2 and 3) with an electropolymerizable 2,2'-dithiophene-3-yl-hexylene functionality at the lower rim, is described. The potential of 2 and 3 as sensing agents for alkali metal ions was investigated by 1H NMR titration ... |
11531119 | Bis(amino acid) oxalyl amides as ambidextrous gelators of water and organic solvents: supramolecular gels with temperature dependent assembly/dissolution equilibrium. | Bis(LeuOH) (1a), bis-(ValOH) (2a) and bis(PhgOH) (5a) (Phg denotes (R)-phenylglycine) oxalyl amides are efficient low molecular weight organic gelators of various organic solvents and their mixtures as well as water, water/DMSO, and water/DMF mixtures. The organisational motifs in aqueous gels are dominated primarily b... |
11531112 | Highly functionalized dimeric tetraethynylethenes and expanded radialenes: strong evidence for macrocyclic cross-conjugation. | A selection of dimeric tetraethynylethenes (TEEs) and perethynylated expanded radialenes, containing different donor/acceptor substitution patterns, have been prepared and fully characterized. The first X-ray crystal structure of an expanded [6]radialene, with twelve peripheral 3,5-di(tert-butyl)phenyl substituents, is... |
11531106 | Self-assembled organometallic [12]metallacrown-3 complexes. | The reaction of [(arene)RuCl2]2 (arene = C6H6, cymene, C6H3Et3, or C6Me6) or [Cp*RhCl2]2 with 3-hydroxy-2-pyridone in the presence of Cs2CO3 gives trinuclear metallamacrocyclic complexes. The self-assembly process was shown to be completely diastereoselective, and a racemic mixture of complexes with M(R)M(R)M(R) or MsM... |
11531105 | Bioorganic applications of semisynthetic DNA-protein conjugates. | Semisynthetic DNA-protein conjugates are versatile molecular tools useful, for instance, in the self-assembly of high-affinity reagents for immunological detection assays, the fabrication of highly functionalized laterally microstructured biochips, and the biomimetic "bottom-up" synthesis of nanostructured supramolecul... |
11530216 | Molecular properties and involvement of heparanase in cancer progression and normal development. | Heparan sulfate proteoglycans (HSPGs) play a key role in the self-assembly, insolubility and barrier properties of basement membranes and extracellular matrices. Hence, cleavage of heparan sulfate (HS) affects the integrity and functional state of tissues and thereby fundamental normal and pathological phenomena involv... |
11526230 | Symmetrical dimer of the human dopamine transporter revealed by cross-linking Cys-306 at the extracellular end of the sixth transmembrane segment. | There is evidence both for and against Na(+)- and Cl(-)-dependent neurotransmitter transporters forming oligomers. We found that cross-linking the human dopamine transporter (DAT), which is heterologously expressed in human embryonic kidney 293 cells, either with copper phenanthroline (CuP) or the bifunctional reagent ... |
11526228 | Chiral exciton coupling of merocyanine dyes within a well defined hydrogen-bonded assembly. | Multichromophoric hydrogen-bonded assemblies 1(3) small middle dot(BAR)(6) are studied that bear a remarkably close resemblance to commelinin, a naturally occurring assembly responsible for an intense blue color of flowers. The incorporated chromophores exhibit a hypsochromic shift in the UV/visible (Vis) absorption ma... |
11519965 | Enantiomer separation by nonaqueous and aqueous capillary electrochromatography on cyclodextrin stationary phases. | Native beta- and gamma-cyclodextrin bound to silica (ChiraDex-beta and ChiraDex-gamma) were packed into capillaries and used for enantiomer separation by capillary electrochromatography (CEC) under aqueous and nonaqueous conditions. Negatively charged analytes (dansyl-amino acids) were resolved into their enantiomers b... |
11519945 | Influence of the amino acid sequence and nature of the cyclodextrin on the separation of small peptide enantiomers by capillary electrophoresis using randomly substituted and single isomer sulfated and sulfonated cyclodextrins. | The separation of dipeptide and tripeptide enantiomers using negatively charged single isomers as well as randomly sulfated and sulfonated cyclodextrins (CDs) was investigated with respect to the amino acid sequence of the peptides and the nature of the CDs. Standardized conditions concerning buffer pH and molarity, CD... |
11519812 | Chiral separation of six diastereomeric flavanone-7-O-glycosides by capillary electrophoresis and analysis of lemon juice. | The diastereomers of six major flavanone-7-O-glycosides (naringin, prunin, narirutin, hesperidin, neohesperidin and eriocitrin) were completely separated for the first time by chiral capillary electrophoresis (CE) employing various buffers and chiral selectors on the basis of the results achieved in 1998 in our researc... |
11519819 | Analysis of sulfobutyl ether-beta-cyclodextrin mixtures by ion-spray mass spectrometry and liquid chromatography-ion-spray mass spectrometry. | The analysis of two commercial and two home-made sulfobutyl ether beta-cyclodextrin (SBE-beta-CD) samples by ion-spray (IS) mass spectrometry and by liquid chromatography-mass spectrometry coupling (LC-MS) is investigated in a negative ion mode. SBE-beta-CD fragmentation was first investigated by direct infusion. In IS... |
11518526 | Cholesterol, a modulator of membrane-associated Abeta-fibrillogenesis and neurotoxicity. | Recent studies have suggested that cholesterol, an important determinant of the physical state of biological membranes, plays a significant role in the development of Alzheimer's disease. We have employed in situ scanning probe microscopy, fluorescence anisotropy, and electron microscopy to investigate how cholesterol ... |
11516276 | Synthesis and catalytic antibody functionalization of dendrimers. | Antibody 38C2 catalyzed a retro-aldol process upon dendritic modified aliphatic polyesters. This catalytic system was studied in detail and displayed rate enhancements, k(cat)/k(uncat), of greater than 10(6). These antibody-catalyzed reactions took place in a stepwise manner yielding partially modified aldol-dendrimers... |
11516275 | Assembly of metal-organic frameworks from large organic and inorganic secondary building units: new examples and simplifying principles for complex structures. | The secondary building unit (SBU) has been identified as a useful tool in the analysis of complex metal-organic frameworks (MOFs). We illustrate its applicability to rationalizing MOF crystal structures by analysis of nine new MOFs which have been characterized by single-crystal X-ray diffraction. Tetrahedral SBUs in Z... |
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