id stringlengths 4 8 | title stringlengths 1 642 | abstract stringlengths 50 17.9k |
|---|---|---|
11950928 | Reconstitution and characterization of budding yeast gamma-tubulin complex. | Nucleation of microtubules is central to assembly of the mitotic spindle, which is required for each cell division. gamma-Tubulin is a universal component essential for microtubule nucleation from centrosomes. To elucidate the mechanism of microtubule nucleation in budding yeast we reconstituted and characterized the y... |
11950330 | A high-throughput screening protocol for fast evaluation of enantioselective catalysts. | A new high-throughput screening protocol that allows fast evaluation of enantioselective catalysts has been developed. The usefulness of norephedrine-derived beta-amino alcohols as catalysts for the enantioselective alkylation of prochiral aldehydes has been determined by simultaneous screening of three representative ... |
11950310 | Complexation in pseudorotaxanes based on alpha-cyclodextrin and different alpha,omega-diaminoalkanes by NMR diffusion measurements. | The interactions of 1,4-diaminobutane (1), 1,6-diaminohexane (2), 1,8-diaminooctane (3), 1,10-diaminodecane (4), and 1,12-diaminododecane (5) with alpha-cyclodextrin (alpha-CD) were studied in aqueous solutions by NMR diffusion measurements before and after protonation. The correlation between the association constant ... |
11950307 | EPR investigation of persistent radicals produced from the photolysis of dibenzyl ketones adsorbed on ZSM-5 zeolites. | Photolysis of ketones (1, 1-oMe, 2, 2-oMe, 3, and 4) adsorbed on ZSM-5 zeolites produces persistent carbon-centered radicals that can be readily observed by conventional steady-state EPR spectroscopy. The radicals are persistent for time periods of seconds to many hours depending on the supramolecular structure of the ... |
11950284 | Photoinduced electron transfer in a supramolecular species building of mono-6-p-nitrobenzoyl-beta-cyclodextrin with naphthalene derivatives. | Photoinduced electron transfer was observed in the supramolecular complexes of p-nitrobenzoyl-beta-cyclodextrin (NBCD) with a number of naphthalene derivatives, which were stabilized clearly via hydrophobic interactions in aqueous solution. Both steady-state and time-resolved fluorescence measurements were conducted, w... |
11950470 | Structural and physicochemical characterization of the inclusion complexes of cyclomaltooligosaccharides (cyclodextrins) with melatonin. | The stoichiometry, geometry, stability, and solubility of the inclusion complexes of melatonin (MLT) with native cyclomaltooligosaccharides (alpha-, beta- or gamma-cyclodextrins, CDs) are determined experimentally by high-resolution NMR spectroscopy, calorimetric and solubility measurements, and mass spectrometry. The ... |
11948582 | Hydrophobic similarity between molecules: a MST-based hydrophobic similarity index. | A similarity index based on the hydrophilic/hydrophobic properties of molecules is presented. Such an index is defined based on the fractional partition of the free energy of solvation developed within the framework of the self-consistent reaction field MST model, which divides the free energy of solvation or the free ... |
11943400 | Multivalent interactions between biotin-polyrotaxane conjugates and streptavidin as a model of new targeting for transporters. | Kinetic analysis of interactions between biotin-polyrotaxane or biotin-alpha-cyclodextrin (biotin-alpha-CD) conjugates and streptavidin was carried out as a model of new targeting to transporters using the surface plasmon resonance (SPR) technique. The biotin-polyrotaxane conjugates, in which biotin-introduced alpha-CD... |
11942837 | CdS nanoparticles modified to chalcogen sites: new supramolecular complexes, butterfly bridging, and related optical effects. | All present approaches to surface modification of nanoparticles (NPs) with organic ligands exploit metal (cadmium) sites as anchor points. To obtain efficient interaction of NP surface with p-orbitals of organic chromophores, we utilize the chalcogen (sulfur) sites on the NP surface. These sites present several advanta... |
11942834 | Gold(I) macrocycles and topologically chiral [2]catenanes. | The design and synthesis of a new type of topologically chiral [2]catenane is reported. The compounds are formed easily by self-assembly on reaction of the oligomeric digold(I) diacetylide precursor complex [[4-BrC(6)H(4)CH(4-C(6)H(4)OCH(2)CCAu)(2)](n)] with diphosphine ligands. Reactions with the diphosphines PP = bis... |
11942830 | The effect of macromolecular architecture in nanomaterials: a comparison of site isolation in porphyrin core dendrimers and their isomeric linear analogues. | The influence of macromolecular architecture on the physical properties of polymeric materials has been studied by comparing poly(benzyl ether) dendrons with their exact linear analogues. The results clearly confirm the anticipation that dendrimers are unique when compared to other architectures. Physical properties, f... |
11942828 | Cooperative binding interactions of glycopeptide antibiotics. | Glycopeptide antibiotics of the vancomycin group bind to bacterial cell wall analogue precursors, and typically also form dimers. We have studied the interplay between these two sets of noncovalent bonds formed at separate interfaces. Indole-2-carboxylic acid (L) forms a set of hydrogen bonds to the glycopeptide antibi... |
11937626 | A general approach for the use of oligonucleotide effectors to regulate the catalysis of RNA-cleaving ribozymes and DNAzymes. | A general approach is described for controlling the RNA-cleaving activity of nucleic acid enzymes (ribozymes and DNAzymes) via the use of oligonucleotide effectors (regulators). In contrast to the previously developed approaches of allosteric and facilitator-mediated regulation of such enzymes, this approach, called 'e... |
11937625 | Nuclear actin is associated with a specific subset of hnRNP A/B-type proteins. | Pre-mRNP complexes were isolated from rat liver nuclei as 40S hnRNP particles, and actin-binding proteins were collected by DNase I affinity chromatography. The bound proteins were analyzed by 2D gel electrophoresis, and the following five hnRNP A/B-type proteins were identified by tandem mass spectrometry: DBP40/CBF-A... |
11937572 | CXCR4 function requires membrane cholesterol: implications for HIV infection. | HIV requires cholesterol and lipid rafts on target cell membranes for infection. To elucidate a possible mechanism, we determined that cholesterol extraction by hydroxypropyl-beta-cyclodextrin (BCD) inhibits stromal cell-derived factor 1alpha (SDF-1alpha) binding to CXCR4 on T cell lines and PBMCs. Intracellular calciu... |
11934609 | Molecular recognition of bacterial phosphorelay proteins. | The transfer of the phosphoryl group from a histidine kinase to a response regulator forms the basis of bacterial signal transduction. The critical question of how a component of a signal transduction system specifically associates with its partner to produce the ideal environment for phosphotransfer is addressed in th... |
11934839 | PPAR activators as antiinflammatory mediators in human T lymphocytes: implications for atherosclerosis and transplantation-associated arteriosclerosis. | Activation of T lymphocytes and their ensuing elaboration of proinflammatory cytokines, such as interferon (IFN)-gamma, represent a critical step in atherogenesis and arteriosclerosis. IFNgamma pathways also appear integral to the development of transplantation-associated arteriosclerosis (Tx-AA), limiting long-term ca... |
11934809 | 17-beta-oestradiol-induced vasorelaxation in vitro is mediated by eNOS through hsp90 and akt/pkb dependent mechanism. | 1. The L-arginine-NO pathway has been implicated in the vasorelaxant effect of 17-beta-oestradiol. Here we have addressed the involvement of two distinct activation steps of endothelial nitric oxide synthase (eNOS) in the 17-beta-oestradiol-induced vasorelaxant effect on rat aortic rings. 2. Rat aortic rings contracted... |
11932232 | Genotypic testing for human immunodeficiency virus type 1 drug resistance. | There are 16 approved human immunodeficiency virus type 1 (HIV-1) drugs belonging to three mechanistic classes: protease inhibitors, nucleoside and nucleotide reverse transcriptase (RT) inhibitors, and nonnucleoside RT inhibitors. HIV-1 resistance to these drugs is caused by mutations in the protease and RT enzymes, th... |
11933087 | Cyclopentadienylrhodium coordination to alkenylarenes. | Photochemical reaction of [Rh(eta-C(5)H(5))(C(2)H(4))(2)] (5) with alkenyl benzene derivatives PhC(R(1))=CHR(2) results in the formation of four types of cyclopentadienylrhodium complexes: the mononuclear ethylene eta(2)-alkenylbenzene complexes [Rh(eta-C(5)H(5))(eta-C(2)H(4))(eta(2)-PhC(R(1))=CHR(2))] 9 a (R(1)=H, R(2... |
11933237 | A novel cyclodextrin-derived tellurium compound with glutathione peroxidase activity. | A novel dicyclodextrinyl ditelluride (2-TeCD) compound was devised as a functional mimic of the glutathione peroxidase (GPX) enzymes that normally remove hydroperoxides from the cell. The GPX activity of the mimic was found to be 46.7 U microM(-1), which is 46 times as active as Ebselen, a well-known GPX mimic. A detai... |
11931663 | Thermodynamics of the ligandin function of human class Alpha glutathione transferase A1-1: energetics of organic anion ligand binding. | In addition to their catalytic functions, cytosolic glutathioneS-transferases (GSTs) are a major reserve of high-capacity binding proteins for a large variety of physiological and exogenous non-substrate compounds. This ligandin function has implicated GSTs in numerous ligand-uptake, -transport and -storage processes. ... |
11931647 | The role of syndecan-2 in regulation of actin-cytoskeletal organization of Lewis lung carcinoma-derived metastatic clones. | Syndecans, a family of transmembrane heparan sulphate proteoglycans, contribute to various biological processes, including adhesion, motility, proliferation, differentiation and morphogenesis. We document here the involvement of syndecan-2 acting alone or co-operatively with integrin alpha5beta1, for regulation of acti... |
11929706 | Supercritical CO2 fluid radiochromatography system used to purify [11C]toluene for PET. | Abuse of inhalants in today's society has become such a widespread problem among today's adolescents that in many parts of the world their use exceeds that of many other illicit drugs or alcohol. Even so, little is known how such inhalants affect brain function to an extent that can lead to an abuse liability. While me... |
11929672 | A chromatographic method for the quantification of prostaglandin E(1) and prostaglandin A(1) encapsulated in an intravenous lipid formulation. | Peripheral vascular disease is a common ailment of the aged and diabetic communities. As the numbers of these individuals increase, the need for therapeutic interventions will continue to grow. One of the possible therapies is the use of prostaglandins (PGE(1), prostacyclin and Iloprost) to decrease the vascular tone a... |
11929664 | Voltammetric studies of the interaction of lumazine with cyclodextrins and DNA. | The interaction of lumazine, an antibacterial drug, with alpha-, beta-cyclodextrins and DNA in aqueous solution was studied by differential pulse stripping voltammetry and cyclic voltammetry as well as UV-vis spectroscopy. The electrochemical and absorption spectral data indicated a 1:1 complex formation of lumazine wi... |
11929242 | Thermodynamic correlation analysis: hydration and perturbation sensitivity of RNA secondary structures. | The thermodynamic parameters DeltaH, DeltaS, T(m), and DeltaG of a total of 36 RNA strands, 22 tetralooped 22mers, and 14 heptalooped 25mers (same stem sequence) were analyzed with respect to enthalpy-entropy compensation (EEC). The EEC plots [DeltaH, DeltaS] were compared with collected literature data from protein an... |
11929240 | Kinetics of disassembly of a DNA-bound porphyrin supramolecular array. | trans-Bis(N-methylpyridinium-4-yl)diphenylporphine forms extended, organized assemblies on DNA templates under appropriate conditions of concentration, ionic strength, and temperature. Addition of beta-cyclodextrin to these arrays leads to their disassembly as evidenced by changes in extinction, circular dichroism, and... |
11929229 | Photoinduced supramolecular chirality in amorphous azobenzene polymer films. | Supramolecular chirality was optically induced in amorphous and achiral azobenzene polymer films by irradiation of a laser beam with elliptical polarization. The chirality resulted from helical orientation of azobenzene chromophores by a combined process of circular and linear polarization. The helix-handedness could b... |
11926990 | PU.1 is dominant and HAF-1 supplementary for activation of the gp91(phox) promoter in human monocytic PLB-985 cells. | Gp91(phox) is a key component of the phagocyte NADPH oxidase. Mutations of its promoter found in patients with chronic granulomatous disease cause deficient binding of PU.1 and HAF-1. Because the two factors bind to the same site (Pu box) of the promoter, we attempted to clarify their relative in vivo contributions to ... |
11927561 | GAGA can mediate enhancer function in trans by linking two separate DNA molecules. | Enhancers have been defined as cis-acting DNA sequences that stimulate transcription from a linked promoter in a distance- and orientation-independent manner. How enhancers activate gene transcription over vast chromosomal distances within metazoan genomes remains poorly understood. Here, we show that the transcription... |
11926833 | Cooperation between lateral ligand mobility and accessibility for receptor recognition in selectin-induced cell rolling. | Selectin-induced leukocyte rolling along the endothelial surface is an essential step in the immune response. Several in vitro studies showed that this cell rolling is a highly regulated adhesion phenomenon, controlled by the kinetics and forces of selectin-ligand interactions. In the flow chamber study presented here,... |
11926832 | Islet amyloid: phase partitioning and secondary nucleation are central to the mechanism of fibrillogenesis. | Islet amyloid polypeptide (IAPP) contributes to the pathogenesis of type II diabetes by depositing as cytotoxic amyloid fibers in the endocrine pancreas. Fiber formation occurs with a marked conformational change from an unstructured precursor. Using real-time quantitative kinetic methods, fibrillogenesis was character... |
11925622 | Nuclear factor kB activity in patients with acute severe cholangitis. | <h4>Aim</h4>To determine the NF-kB activity in peripheral blood mononuclear cells (PBMC) in patients with acute cholangitis of severe type (ACST) and correlate the degree of NF-kB activation with severity of biliary tract infection and clinical outcome.<h4>Methods</h4>Twenty patients with ACST were divided into survivo... |
11925621 | Liver sinusoidal endothelial cell injury by neutrophils in rats with acute obstructive cholangitis. | <h4>Aim</h4>The objective of this study is to elucidate the potential role of poly-morphonuclear neutrophils (PMN) in the development of such a sinusoidal endothelial cell (SEC) injury during early acute obstructive cholangitis (AOC) in rats.<h4>Methods</h4>Twenty one Wistar rats were divided into three groups: the AOC... |
11925606 | Specific CEA-producing colorectal carcinoma cell killing with recombinant adenoviral vector containing cytosine deaminase gene. | <h4>Aim</h4>To kill CEA positive colorectal carcinoma cells specifically using the E coli cytosine deaminase (CD) suicide gene, a new replication-deficient recombinant adenoviral vector was constructed in which CD gene was controlled under CEA promoter and its in vitro cytotoxic effects were evaluated.<h4>Methods</h4>S... |
11925252 | Pyrene-armed calix[4]azacrowns as new fluorescent ionophores: "molecular taekowndo" process via fluorescence change. | A series of new calixarene-based fluoroionophores were synthesized. With our new calixarene derivative bearing a crown ether and an azacrown ether as two binding sites, the metal ion was found to selectively choose its better binding pocket between these two ligands. Interesting "molecular taekowndo" processes between ... |
11925232 | Synthesis and photochromism of spirobenzopyrans and spirobenzothiapyran derivatives bearing monoazathiacrown ethers and noncyclic analogues in the presence of metal ions. | Spirobenzopyrans bearing monoazathiacrown ethers and noncyclic analogues were synthesized, and their ion-responsive photochromism depending on the dual metal ion interaction with the crown ether and the phenolate anion moieties was examined using alkali and alkaline-earth metal ions, Ag(+), Tl(+), Pb(2+), Hg(2+), and Z... |
11925222 | Synthesis of new transglycosidically tethered 5'-nucleotides constrained to a highly biologically relevant profile. | A new motif for restricting 5'-nucleotides to highly biologically relevant conformations has been developed. The 5',6-oxomethylene transglycosidically tethered versions of uridine 5'-monophosphate and 2'-deoxyuridine 5'-monophosphate (1 and 2, respectively) were synthesized in 10-11 steps from their respective natural ... |
11925210 | A novel crown ether generation containing different heteroaromatic cations: synthesis, characterization, solid-phase (13)C NMR, X-ray crystal structure, and selective amino acid recognition. | The synthesis and structural characterization of a novel generation of crown ethers, 3, 5 and 6 containing pyrilium, thiopyrilium, and pyridinium subunits, respectively, are reported. The crown ether unit is potentially capable of forming host-guest complexes with inorganic and organic cations, while the heteroaromatic... |
11925197 | Five-coordinate iron(III) porphycenes: (1)H NMR, magnetic, and structural studies. | Five-coordinate iron(III) 2,7,12,17-tetrapropylporphycene (TPrPc)Fe(III)X (X = C(6)H(5)O(-), Cl(-), Br(-), I(-), ClO(4)(-)) complexes have been investigated. The (1)H NMR spectra demonstrate downfield shifts for pyrrole resonances [(TPrPc)Fe(III)(C(6)H(5)O), 65.3 ppm; (TPrPc)Fe(III)Cl, 28.5 ppm] but large upfield ones ... |
11925186 | Synthesis and resolution of (R,R)-(+/-)-1,1,4,7,10,10-hexaphenyl-1,10-diarsa-4,7-diphosphadecane: new ligand for the stereoselective self-assembly of dicopper(I), disilver(I), and digold(I) helicates. | Diphenylvinylarsine oxide reacts with 1,2-bis(phenylphosphino)ethane in the presence of potassium tert-butoxide to give the anti-Markovnikov product (R,R)-(+/-)/(R,S)-1,1,4,7,10,10-hexaphenyl-1,10-diarsa-4,7-diphosphadecane dioxide-1AsO,10AsO, which, upon reduction with HSiCl(3)/NEt(3) in boiling acetonitrile, affords ... |
11925181 | Self-assembly of transition-metal-based macrocycles linked by photoisomerizable ligands: examples of photoinduced conversion of tetranuclear-dinuclear squares. | A series of hetero- and homometallic square complexes bridged by a photoactive 4,4'-azopyridine (AZP) or 1,2-bis(4-pyridyl)ethylene (BPE) ligand, cyclobis[[cis-(dppf)M](mu-L)(2)(fac-Re(CO)(3)Br)](OTf)(4) (M = Pd, L = trans-AZP (5); M = Pt, L = trans-AZP (7); M = Pd, L = trans-BPE (8); M = Pt, L = trans-BPE (10)), cyclo... |
11925173 | Carboxyester hydrolysis catalyzed by a novel dicopper(II) complex with an alcohol-pendant macrocycle. | A novel hexaaza macrocycle bearing two hydroxyethyl pendants (L), 3,6,9,16,19,22-hexaaza-6,19-bis(2-hydroxyethyl)tricyclo[22,2,2,2(11,14)]triaconta-1,11,13,24,27,29-hexaene, was synthesized as a potential binucleating ligand. The corresponding Cu(II) complex [Cu(2)LCl(2)]Cl(2) small middle dot5.5H(2)O was isolated as a... |
11925105 | Eukaryotic cell locomotion depends on the propagation of self-organized reaction-diffusion waves and oscillations of actin filament assembly. | Actin filament (F-actin) assembly kinetics determines the locomotion and shape of crawling eukaryotic cells, but the nature of these kinetics and their determining reactions are unclear. Live BHK21 fibroblasts, mouse melanoma cells, and Dictyostelium amoebae, locomoting on glass and expressing Green Fluorescent Protein... |
11922812 | Self-assembly and characterization of supramolecular [60]fullerene-containing 2,6-diacylamidopyridine with uracil derivative by hydrogen-bonding interaction. | [structure: see text] Novel self-assembly systems of uracil derivatives with organofullerene by a three-point hydrogen-bonding interaction were designed and established. The formation of hydrogen bonding was established by 1H NMR studies in CDCl3. |
11923444 | NG2 is a major chondroitin sulfate proteoglycan produced after spinal cord injury and is expressed by macrophages and oligodendrocyte progenitors. | Several extracellular matrix (ECM) molecules have been identified as potent inhibitors of neurite outgrowth in vitro and are believed to limit axonal growth after CNS injury. Recent studies have shown that different members of the chondroitin sulfate proteoglycan (CSPG) class of putatively inhibitory ECM molecules are ... |
11923428 | Spontaneous retinal activity is tonic and does not drive tectal activity during activity-dependent refinement in regeneration. | During development, waves of activity periodically spread across retina to produce correlated activity that is thought to drive activity-dependent ordering in optic fibers. We asked whether similar waves of activity are produced in the retina of adult goldfish during activity-dependent refinement by regenerating optic ... |
11923642 | Biodistribution of a 153 Gd-folate dendrimer, generation = 4, in mice with folate-receptor positive and negative ovarian tumor xenografts. | <h4>Rationale and objectives</h4>An important characteristic of targeted contrast agents is how they are tolerated in a biologic environment and their localization in the surrounding tissues in addition to target tissue. We evaluate the biodistribution of a gadolinium Gd 153-folate-dendrimer in high affinity folate-rec... |
11923640 | Identifying tumor vascular permeability heterogeneity with magnetic resonance imaging contrast agents. | <h4>Rationale and objectives</h4>Dynamic contrast enhanced (DCE) MR mammography (MRM) uses tumor capillary density differences for prognosis. The heterogeneous response of permeability-surface area products (PS = Kp<-->t) was examined in mammary tumors, as a function of contrast agent size, to determine what effect ROI... |
11918702 | Cholesterol-rich plasma membrane domains (lipid rafts) in keratinocytes: importance in the baseline and UVA-induced generation of reactive oxygen species. | The biologic effects of ultraviolet radiation such as DNA damage, mutagenesis, cellular aging, and carcinogenesis are in part mediated by reactive oxygen species. In unirradiated cells the major known sources of reactive oxygen species are the mitochondrial respiratory chain and the membrane oxidases functionally coupl... |
11917022 | Immunostimulatory properties of phosphorothioate CpG DNA containing both 3'-5'- and 2'-5'-internucleotide linkages. | Synthetic oligodeoxyribonucleotides containing CpG-dinucleotides (CpG DNA) in specific sequence contexts activate the vertebrate immune system. We have examined the effect of 3'-deoxy-2'-5'-ribonucleoside (3'-deoxynucleoside) incorporation into CpG DNA on the immunostimulatory activity. Incorporation of 3'-deoxynucleos... |
11916430 | Investigation on the nature of the adsorption sites of pyrrole in alkali-exchanged zeolite y by nuclear magnetic resonance in combination with infrared spectroscopy. | Multinuclear solid-state NMR and infrared spectroscopy have been applied to investigate the host-guest interactions and the nature of the adsorption sites of pyrrole on alkali-exchanged zeolites Y (LiNaY, NaY, KNaY, and CsNaY). The presence of pyrrole provokes changes in the MAS NMR spectra of (23)Na, (7)Li, and (133)C... |
11916425 | Detecting the adsorption of dye molecules in homogeneous poly(propylene imine) dendrimer monolayers by surface plasmon resonance sensor. | In this work, we studied guest-host interactions between various dye molecules and the fifth-generation poly(propylene imine) (PPI-5) dendrimers in aqueous solutions using a surface plasmon resonance (SPR) sensor. The effect of the properties of guest and host molecules (e.g., charge and shape) and media (e.g., pH and ... |
11916424 | Heme distortions in sperm-whale carbonmonoxy myoglobin: correlations between rotational strengths and heme distortions in MD-generated structures. | We have investigated the effects of heme rotational isomerism in sperm-whale carbonmonoxymyoglobin using computational techniques. Several molecular dynamics simulations have been performed for the two rotational isomers A and B, which are related by a 180 degrees rotation around the alpha-gamma axis of the heme, of sp... |
11916403 | Ring expansion via olefin metathesis. | Various macrocycles were prepared in one step by a novel ring-expansion method using olefin metathesis. |
11916402 | Built to order: molecular tinkertoys from the [Re(6)(mu(3)-Se)(8)](2+) clusters. | Ligand substitution of [Re(6)(mu(3)-Se)(8)(PEt(3))(5)(CH(3)CN)](SbF(6))(2) (1) with pyridyl-based ligands, 2,4,6-tri-4-pyridyl-1,3,5-triazine (L1) and 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphine (L2), produced respectively the star-shaped tricluster (T1) and tetracluster (T2) arrays, wherein three (T1) and four (T2) u... |
11916881 | A new deformation model of hard alpha-keratin fibers at the nanometer scale: implications for hard alpha-keratin intermediate filament mechanical properties. | The mechanical behavior of human hair fibers is determined by the interactions between keratin proteins structured into microfibrils (hard alpha-keratin intermediate filaments), a protein sulfur-rich matrix (intermediate filaments associated proteins), and water molecules. The structure of the microfibril-matrix assemb... |
11916874 | Absorption and CD spectroscopy and modeling of various LH2 complexes from purple bacteria. | The absorption (OD) and circular dichroism (CD) spectra of LH2 complexes from various purple bacteria have been measured and modeled. Based on the lineshapes of the spectra we can sort the LH2 complexes into two distinguishable groups: "acidophila"-like (type 1) and "molischianum"-like (type 2). Starting from the known... |
11916872 | Interaction of proteins in solution from small-angle scattering: a perturbative approach. | In this work an improved methodology for studying interactions of proteins in solution by small-angle scattering is presented. Unlike the most common approach, where the protein-protein correlation functions g(ij)(r) are approximated by their zero-density limit (i.e., the Boltzmann factor), we propose a more accurate r... |
11916863 | Conformational characterization of ceramides by nuclear magnetic resonance spectroscopy. | Ceramide (Cer) has been identified as an active lipid second messenger in the regulation of cell growth, differentiation, and apoptosis. Its analog, dihydroceramide, without the 4 to 5 trans double bond in the sphingoid backbone lacks these biological effects. To establish the conformational features that distinguish c... |
11916844 | Initial stages of cell-matrix adhesion can be mediated and modulated by cell-surface hyaluronan. | A conceptual temporal and spatial gap exists between the first encounter of a cell with an adhesive substrate and the advanced stages of focal adhesion formation. Although ample information is available on focal adhesions structure and function, the mechanism of the first interaction events and the nature of the molecu... |
11916840 | Binding and diffusion of CheR molecules within a cluster of membrane receptors. | Adaptation of the attractant response in Escherichia coli is attributable to the methylation of its transmembrane chemotactic receptors by the methyltransferase CheR. This protein contains two binding domains, one for the sites of methylation themselves and the other for a flexible tether at the C terminus of the recep... |
11916662 | Role of Bacillus thuringiensis Cry1 delta endotoxin binding in determining potency during lepidopteran larval development. | Five economically important crop pests, Manduca sexta, Pieris brassicae, Mamestra brassicae, Spodoptera exigua, and Agrotis ipsilon, were tested at two stages of larval development for susceptibility to Bacillus thuringiensis toxins Cry1Ac, Cry1Ca, Cry1J, and Cry1Ba. Bioassay results for M. sexta showed that resistance... |
11914353 | Role for vitamin B(12) in light induction of gene expression in the bacterium Myxococcus xanthus. | A light-inducible promoter (P(B)) drives the carB operon (carotenoid genes) of the bacterium Myxococcus xanthus. A gene encoding a regulator of carotenoid biosynthesis was identified by studying mutant strains carrying a transcriptional fusion to P(B) and deletions in three candidate genes. Our results prove that the i... |
11914351 | Expression, autoregulation, and DNA binding properties of the Mycobacterium tuberculosis TrcR response regulator. | The TrcRS two-component system of Mycobacterium tuberculosis is comprised of the TrcS histidine kinase and the TrcR response regulator, which is homologous to the OmpR class of DNA binding response regulators. Reverse transcription-PCRs with total RNA showed that the trcR and trcS two-component system genes are transcr... |
11910031 | Improved affinity of engineered streptavidin for the Strep-tag II peptide is due to a fixed open conformation of the lid-like loop at the binding site. | The Strep-tag II is a nine-amino acid peptide that was developed as an affinity tool for the purification of corresponding fusion proteins on streptavidin columns. The peptide recognizes the same pocket of streptavidin where the natural ligand is normally bound so that biotin or its chemical derivatives can be used for... |
11910019 | Natively unfolded proteins: a point where biology waits for physics. | The experimental material accumulated in the literature on the conformational behavior of intrinsically unstructured (natively unfolded) proteins was analyzed. Results of this analysis showed that these proteins do not possess uniform structural properties, as expected for members of a single thermodynamic entity. Rath... |
11906739 | Gene expression profiling diagnosis through DNA molecular computation. | Gene expression profiling is the characterization of cells based on the level of gene activity represented by concentrations of complementary DNA reverse transcribed from messenger RNA. The spectrum of cDNA concentrations, the expression profile, is determined using a DNA microarray. Although this approach is valuable ... |
11907246 | Hepatitis C virus-like particle morphogenesis. | Although much is known about the hepatitis C virus (HCV) genome, first cloned in 1989, little is known about HCV structure and assembly due to the lack of an efficient in vitro culture system for HCV. Using a recombinant Semliki forest virus replicon expressing genes encoding HCV structural proteins, we observed for th... |
11907243 | Structural requirements for the assembly of Norwalk virus-like particles. | Norwalk virus (NV) is the prototype strain of a group of human caliciviruses responsible for epidemic outbreaks of acute gastroenteritis. While these viruses do not grow in tissue culture cells or animal models, expression of the capsid protein in insect cells results in the self-assembly of recombinant NV virus-like p... |
11907212 | Human cytomegalovirus major immediate-early proteins and simian virus 40 large T antigen can inhibit apoptosis through activation of the phosphatidylinositide 3'-OH kinase pathway and the cellular kinase Akt. | The temperature-sensitive cell line ts13 is mutated in CCG1, the gene encoding TAF(II)250, the largest of the TATA-binding protein-associated factors (TAFs) in TFIID. At the nonpermissive temperature, the temperature-sensitive phenotypes are (i) transcription defects, (ii) cell cycle arrest in G(1), and (iii) apoptosis... |
11907208 | Selection of RNA aptamers that are specific and high-affinity ligands of the hepatitis C virus RNA-dependent RNA polymerase. | In order to find small RNA molecules that are specific and high-affinity ligands of nonstructural 5B (NS5B) polymerase, we screened by SELEX (systematic evolution of ligands by exponential amplification) a structurally constrained RNA library with an NS5BDeltaC55 enzyme carrying a C-terminal biotinylation sequence. Amo... |
11907096 | Segregation of Bad from lipid rafts is implicated in the induction of apoptosis. | Many molecules relocate subcellularly in cells undergoing apoptosis. Using coimmunoprecipitation experiments we demonstrate that Bad is not associated to 14-3-3 protein, suggesting a new mechanism for the control of the proapoptotic role of Bad. Here we show, by confocal microscopy and cellular fractionation, that Bad ... |
11903058 | Nuclear receptor corepressor-dependent repression of peroxisome-proliferator-activated receptor delta-mediated transactivation. | The nuclear receptor corepressor (NCoR) was isolated as a peroxisome-proliferator-activated receptor (PPAR) delta interacting protein using the yeast two-hybrid system. NCoR interacted strongly with the ligand-binding domain of PPAR delta, whereas interactions with the ligand-binding domains of PPAR gamma and PPAR alph... |
11897974 | Role of chiral chromatography in therapeutic drug monitoring and in clinical and forensic toxicology. | Advances in chiral chromatographic separations have given pharmacologists and toxicologists the tools to examine unexpected clinical results involving chiral drugs. The ability to unravel complex phenomena associated with drug transport and drug metabolism is presented in this manuscript. The relation between the chira... |
11897549 | Postsynaptic calcium signaling microdomains in neurons. | Calcium ions are crucial messengers in the regulation of synaptic efficacy. In the postsynaptic neuron, this is exemplified by the tight temporal and spatial co-segregation of calcium ions with calcium-dependent signal transduction protein complexes in dendritic spines. Over the last several years optical imaging, phys... |
11896197 | GIT1 functions in a motile, multi-molecular signaling complex that regulates protrusive activity and cell migration. | GIT1 is a multidomain protein that is thought to function as an integrator of signaling pathways controlling vesicle trafficking, adhesion and cytoskeletal organization. It regulates ARF GTPases and has binding domains for paxillin and PIX, which is a PAK-binding protein and an exchange factor for Rac. We show that GIT... |
11895962 | Helicobacter pylori uses motility for initial colonization and to attain robust infection. | Helicobacter pylori has been shown to require flagella for infection of the stomach. To analyze whether flagella themselves or motility is needed by these pathogens, we constructed flagellated nonmotile mutants. This was accomplished by using both an insertion mutant and an in-frame deletion of the motB gene. In vitro,... |
11895933 | Carcinoembryonic antigen family receptor recognition by gonococcal Opa proteins requires distinct combinations of hypervariable Opa protein domains. | Neisserial Opa proteins function as a family of adhesins that bind heparan sulfate proteoglycan (HSPG) or carcinoembryonic antigen family (CEACAM) receptors on human host cells. In order to define the CEACAM binding domain on Opa proteins, we tested the binding properties of a series of gonococcal (strain MS11) recombi... |
11895931 | The major structural subunits of Dr and F1845 fimbriae are adhesins. | Fimbrial adhesins mediate the attachment of pathogenic Escherichia coli to various host tissues leading to the development of disease. The Dr hemagglutinin and F1845 fimbriae belong to the Dr family of adhesins, which is associated with urinary tract infections and diarrheal disease. These adhesins bind to the Dr(a) bl... |
11893587 | Long-chain fatty acids increase basal metabolism and depolarize mitochondria in cardiac muscle cells. | The effects of long-chain (LC) fatty acids on rate of heat production (heat rate) and mitochondrial membrane potential (DeltaPsi) of intact guinea pig cardiac muscle were investigated at 37 degrees C. Heat rate of ventricular trabeculae was measured with microcalorimetry, and DeltaPsi was monitored in isolated ventricu... |
11884585 | The PHD type zinc finger is an integral part of the CBP acetyltransferase domain. | Histone acetyltransferases (HATs) such as CBP and p300 are regarded as key regulators of RNA polymerase II-mediated transcription, but the critical structural features of their HAT modules remain ill defined. The HAT domains of CBP and p300 are characterized by the presence of a highly conserved putative plant homeodom... |
11884568 | E1 protein of bovine papillomavirus type 1 interferes with E2 protein-mediated tethering of the viral DNA to mitotic chromosomes. | Eukaryotic viruses can maintain latency in dividing cells as extrachromosomal plasmids. It is therefore of vital importance for viruses to ensure nuclear retention and proper segregation of their viral DNA. The bovine papillomavirus (BPV) E2 enhancer protein plays a key role in these processes by tethering the viral DN... |
11884555 | The RNA binding domain of the hantaan virus N protein maps to a central, conserved region. | The nucleocapsid (N) protein of hantaviruses encapsidates both viral genomic and antigenomic RNAs, although only the genomic viral RNA (vRNA) is packaged into virions. To define the domain within the Hantaan virus (HTNV) N protein that mediates these interactions, 14 N- and C-terminal deletion constructs were cloned in... |
11884551 | The fusion peptide of Semliki Forest virus associates with sterol-rich membrane domains. | Semliki Forest virus (SFV) is an enveloped alphavirus whose membrane fusion is triggered by low pH and promoted by cholesterol and sphingolipid in the target membrane. Fusion is mediated by E1, a viral membrane protein containing the putative fusion peptide. Virus mutant studies indicate that SFV's cholesterol dependen... |
11884548 | Ty5 gag mutations increase retrotransposition and suggest a role for hydrogen bonding in the function of the nucleocapsid zinc finger. | The Ty5 retrotransposon of Saccharomyces paradoxus transposes in Saccharomyces cerevisiae at frequencies 1,000-fold lower than do the native Ty1 elements. The low transposition activity of Ty5 could be due to differences in cellular environments between these yeast species or to naturally occurring mutations in Ty5. By... |
11880318 | Podocyte slit-diaphragm protein nephrin is linked to the actin cytoskeleton. | Nephrin is an Ig-like transmembrane protein. It is a major component of the podocyte slit diaphragm and is essential for maintaining normal glomerular permeability. CD2-associated protein (CD2AP) is also necessary for normal glomerular permeability and is a putative nephrin adapter molecule. Here, we document that neph... |
11880282 | Heterologous desensitization of EGF receptors and PDGF receptors by sequestration in caveolae. | Epidermal growth factor (EGF) and platelet-derived growth factor (PDGF) receptors have been reported to signal via caveolin-containing membranes called caveolae. In contrast, others report that EGF and PDGF receptors are exclusively associated with caveolin-devoid membranes called rafts. Our subcellular fractionation a... |
11870868 | Noncovalent interaction energies in covalent complexes: TEM-1 beta-lactamase and beta-lactams. | The class A beta-lactamase TEM-1 is a key bacterial resistance enzyme against beta-lactam antibiotics, but little is known about the energetic bases for complementarity between TEM-1 and its inhibitors. Most inhibitors form a covalent adduct with the catalytic Ser70, making the measurement of equilibrium constants, and... |
11861114 | Chiral CE separation of warfarin in albumin containing samples. | A capillary zone electrophoresis method with ultraviolet (UV) absorbance detection for the chiral separation of warfarin enantiomers using highly sulfated beta-cyclodextrin (beta-CD) was developed and optimized. Enantiomeric separation of warfarin was characterized by high resolution and efficiency. The optimized elect... |
11861113 | Direct determination of pindolol enantiomers in human serum by column-switching LC-MS/MS using a phenylcarbamate-beta-cyclodextrin chiral column. | A direct analytical method of pindolol enantiomers in body fluids was developed by means of column-switching semi-microcolumn liquid chromatography/tandem mass spectrometry (LC-MS/MS). A pre-column packed with a silica-based cation-exchanger was used for on-line sample cleanup. Subsequent enantioseparation was conducte... |
11857281 | Enzyme activation in organic solvents: co-lyophilization of subtilisin Carlsberg with methyl-beta-cyclodextrin renders an enzyme catalyst more active than the cross-linked enzyme crystals. | In this study we explored the efficiency of the additive methyl-beta-cyclodextrin (M beta CD) to enhance the activity and enantioselectivity of the serine protease subtilisin Carlsberg in organic solvents. These two parameters, measured for different transesterification reactions and in several solvents, are compared w... |
11836119 | Synthesis and capillary electrophoretic analysis of enantiomerically enriched reference standards of MDMA and its main metabolites. | Enantiomerically-enriched (S)-3,4-methylenedioxymethamphetamine (MDMA) and its main metabolites (S)-4-hydroxy-3-methoxymethamphetamine (HMMA) and (S)-3,4-dihydroxymethamphetamine (HHMA) were prepared for unequivocal identification of the differential enantioselective metabolism of these compounds as well as for its app... |
11836090 | DNA analogues: from supramolecular principles to biological properties. | Mainly driven by the needs of antisense research, a large number of oligonucleotide analogues have been prepared and evaluated over the last 15 years. Besides minor structural modifications of the building blocks of DNA and RNA itself, a considerable effort has been devoted to the de novo design of nucleoside analogues... |
11836089 | Chemical approaches to the investigation of cellular systems. | Biochemistry in the context of a living cell or organism is complicated by many variables such as supramolecular organization, cytoplasmic viscosity, and substrate heterogeneity. While these variables are easily excluded or avoided in reconstituted systems, they must be dealt with in cellular environments. New developm... |
11835174 | Anticoagulant activity of sulfonated polyrotaxanes as blood-compatible materials. | Polyrotaxanes, in which alpha-cyclodextrins (alpha-CDs) are threaded onto poly(ethylene glycol)-b-poly(propylene glycol)-b-poly(ethylene glycol) triblock copolymers (Pluronic) capped with benzyloxycarbonyl(Z)-L-phenylalanine (Z-L-Phe), were prepared, and sulfopropyl groups were introduced to hydroxyl groups of alpha-CD... |
16578866 | All-optical processing with molecular switches. | A gradual transition from electrical to optical networks is accompanying the rapid progress of telecommunication technology. The urge for enhanced transmission capacity and speed is dictating this trend. In fact, large volumes of data encoded on optical signals can be transported rapidly over long distances. Their prop... |
11917139 | Helicogenicity of solvents in the conformational equilibrium of oligo(m-phenylene ethynylene)s: implications for foldamer research. | A (R)-binaphthol tethered bis-hexameric oligo(m-phenylene ethynylene) foldamer was examined in 30 solvents to correlate the unfolded-folded conformational equilibrium to bulk solvent properties and specific solvent-chain interactions. The oligomer is soluble in a variety of solvents of intermediate polarity, with the m... |
11917115 | Inclusion of methylviologen in cucurbit[7]uril. | The inclusion behavior of methylviologen (N,N'-dimethyl-4,4'-bipyridinium, MV) dication in cucurbit[7]uril (CB[7]) has been studied by using various spectroscopic and electrochemical methods. The inclusion complex of MV dication in CB[7] is stable thermodynamically and kinetically. The electrochemical study reveals tha... |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.