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10338017 | The calorimetric criterion for a two-state process revisited. | The "calorimetric criterion" is one of the important experimental approaches for determining whether protein folding is an "all-or-none" two-state transition (i.e., whether intermediates are present at equilibrium). The calorimetric criterion states that the equivalence of the "measured" calorimetric enthalpy change an... |
10332075 | Solid lipid nanoparticles as carriers of hydrocortisone and progesterone complexes with beta-cyclodextrins. | Inclusion complexes of hydrocortisone and progesterone were formed with beta-cyclodextrin or 2-hydroxypropyl-beta-cyclodextrin. The formation of the complexes was confirmed by differential scanning calorimetry (DSC). The inclusion complexes were incorporated in two types of solid lipid nanoparticles (SLN). In the prese... |
10334518 | Comparative efficacy of adjuvant chemotherapy in patients with Dukes' B versus Dukes' C colon cancer: results from four National Surgical Adjuvant Breast and Bowel Project adjuvant studies (C-01, C-02, C-03, and C-04) | <h4>Purpose</h4>Although the benefit from adjuvant chemotherapy has been clearly established in patients with Dukes' C colon cancer, such benefit has been questioned in patients with Dukes' B disease. To determine whether patients with Dukes' B disease benefit from adjuvant chemotherapy and to evaluate the magnitude of... |
10330413 | Critical role for cholesterol in Lyn-mediated tyrosine phosphorylation of FcepsilonRI and their association with detergent-resistant membranes. | Tyrosine phosphorylation of the high affinity immunoglobulin (Ig)E receptor (FcepsilonRI) by the Src family kinase Lyn is the first known biochemical step that occurs during activation of mast cells and basophils after cross-linking of FcepsilonRI by antigen. The hypothesis that specialized regions in the plasma membra... |
10330396 | A role for RanBP1 in the release of CRM1 from the nuclear pore complex in a terminal step of nuclear export. | We recently developed an assay in which nuclear export of the shuttling transcription factor NFAT (nuclear factor of activated T cells) can be reconstituted in permeabilized cells with the GTPase Ran and the nuclear export receptor CRM1. We have now used this assay to identify another export factor. After preincubation... |
10325219 | Polymersomes: tough vesicles made from diblock copolymers. | Vesicles were made from amphiphilic diblock copolymers and characterized by micromanipulation. The average molecular weight of the specific polymer studied, polyethyleneoxide-polyethylethylene (EO40-EE37), is several times greater than that of typical phospholipids in natural membranes. Both the membrane bending and ar... |
10329695 | A model for dynamin self-assembly based on binding between three different protein domains. | Dynamin is a 100-kDa GTPase that assembles into multimeric spirals at the necks of budding clathrin-coated vesicles. We describe three different intramolecular binding interactions that may account for the process of dynamin self-assembly. The first binding interaction is the dimerization of a 100-amino acid segment in... |
10329657 | The role of amino acids in extracellular loops of the human P2Y1 receptor in surface expression and activation processes. | The P2Y1 receptor is a membrane-bound G protein-coupled receptor stimulated by adenine nucleotides. Using alanine scanning mutagenesis, the role in receptor activation of charged amino acids (Asp, Glu, Lys, and Arg) and cysteines in the extracellular loops (EL) of the human P2Y1 receptor has been investigated. The muta... |
10329614 | Structure and selectivity in post-translational modification: attaching the biotinyl-lysine and lipoyl-lysine swinging arms in multifunctional enzymes. | The post-translational attachment of biotin and lipoic acid to specific lysine residues displayed in protruding beta-turns in homologous biotinyl and lipoyl domains of their parent enzymes is catalysed by two different ligases. We have expressed in Escherichia coli a sub-gene encoding the biotinyl domain of E.coli acet... |
10331869 | X-ray structures along the reaction pathway of cyclodextrin glycosyltransferase elucidate catalysis in the alpha-amylase family. | Cyclodextrin glycosyltransferase (CGTase) is an enzyme of the alpha-amylase family, which uses a double displacement mechanism to process alpha-linked glucose polymers. We have determined two X-ray structures of CGTase complexes, one with an intact substrate at 2.1 A resolution, and the other with a covalently bound re... |
10331823 | Itraconazole in cyclodextrin solution. | Itraconazole, a water-insoluble oral triazole antifungal, has been formulated in cyclodextrin as a solution. Cyclodextrin is a ring of glucose molecules that can accept a lipophilic guest molecule within the ring. This enables solubilization and delivery to the lipid interface of the gut lumen, resulting in absorption ... |
10331507 | Plasma sFas and sFas ligand levels in patients with thrombotic thrombocytopenic purpura and in those with disseminated intravascular coagulation. | Fas, a member of the tumor necrosis receptor superfamily, is 36 kD surface protein containing a single transmembrane region and induces apoptosis by Fas-Fas ligand binding. Soluble Fas (sFas) is produced as the form lacking 21 amino acid residues containing the transmembrane domain by alternative splicing. We found tha... |
10322029 | In vitro selection of integration host factor binding sites. | Integration host factor (IHF) is a bacterial protein that binds and severely bends a specific DNA target. IHF binding sites are approximately 30 to 35 bp long and are apparently divided into two domains. While the 3' domain is conserved, the 5' domain is degenerate but is typically AT rich. As a result of physical cons... |
10320360 | Thermodynamics of reversible and irreversible unfolding and domain interactions of glucoamylase from Aspergillus niger studied by differential scanning and isothermal titration calorimetry. | The stability of three forms of glucoamylase from Aspergillus niger has been investigated by differential scanning and isothermal titration calorimetry: Glucoamylase 1 (GA1), which consists of a catalytic domain and a starch-binding domain (SBD) connected by a heavily O-glycosylated linker region; glucoamylase 2 (GA2),... |
10318957 | A conotoxin from Conus textile with unusual posttranslational modifications reduces presynaptic Ca2+ influx. | Cone snails are gastropod mollusks of the genus Conus that live in tropical marine habitats. They are predators that paralyze their prey by injection of venom containing a plethora of small, conformationally constrained peptides (conotoxins). We report the identification, characterization, and structure of a gamma-carb... |
10318932 | A cell surface mucin specifically expressed in the midgut of the malaria mosquito Anopheles gambiae. | An invertebrate intestinal mucin gene, AgMuc1, was isolated from the malaria vector mosquito Anopheles gambiae. The predicted 122-residue protein consists of a central core of seven repeating TTTTVAP motifs flanked by hydrophobic N- and C-terminal domains. This structure is similar to that of mucins that coat the proto... |
10318910 | Solution structure and dynamics of a de novo designed three-helix bundle protein. | Although de novo protein design is an important endeavor with implications for understanding protein folding, until now, structures have been determined for only a few 25- to 30-residue designed miniproteins. Here, the NMR solution structure of a complex 73-residue three-helix bundle protein, alpha3D, is reported. The ... |
10318898 | Bivalency as a principle for proteasome inhibition. | The proteasome, a multicatalytic protease, is known to degrade unfolded polypeptides with low specificity in substrate selection and cleavage pattern. This lack of well-defined substrate specificities makes the design of peptide-based highly selective inhibitors extremely difficult. However, the x-ray structure of the ... |
10234020 | DSD-1-proteoglycan is the mouse homolog of phosphacan and displays opposing effects on neurite outgrowth dependent on neuronal lineage. | DSD-1-PG is a chondroitin sulfate proteoglycan (CSPG) expressed by glial cells that can promote neurite outgrowth from rat embryonic mesencephalic (E14) and hippocampal (E18) neurons, an activity that is associated with the CS glycosaminoglycans (GAGs). Further characterization of DSD-1-PG has included sequencing of pe... |
10234018 | Different contributions of microtubule dynamics and transport to the growth of axons and collateral sprouts. | Axonal growth is believed to depend on microtubule transport and microtubule dynamic instability. We now report that the growth of axon collateral branches can occur independent of microtubule dynamic instability and can rely mostly on the transport of preassembled polymer. Raising embryonic sensory neurons in concentr... |
10233095 | Urease and hexadecylamine-urease films at the air-water interface: an x-ray reflection and grazing incidence x-ray diffraction study. | We report the results of surface x-ray scattering measurements performed on urease and hexadecylamine-urease films at the air-aqueous solution interface. It is demonstrated that although hexadecylamine does not form a stable monolayer on the pure aqueous surface, it does self-assemble into a stable, well-organized stru... |
10233094 | Viscoelastic properties of f-actin, microtubules, f-actin/alpha-actinin, and f-actin/hexokinase determined in microliter volumes with a novel nondestructive method. | A nondestructive method to determine viscoelastic properties of gels and fluids involves an oscillating glass fiber serving as a sensor for the viscosity of the surrounding fluid. Extremely small displacements (typically 1-100 nm) are caused by the glass rod oscillating at its resonance frequency. These displacements a... |
10235554 | Retinal ischemic preconditioning in the rat: requirement for adenosine and repetitive induction. | <h4>Purpose</h4>A brief period of ischemia can induce a remarkably complete state of ischemic tolerance in the retina, a phenomenon known as ischemic preconditioning (IPC). The mechanisms of IPC were studied in the rat retina by examining the role of adenosine as a possible mediator and determining whether IPC protecti... |
10229652 | Encapsulation and release of rhodium(II) citrate and its association complex with hydroxypropyl-beta-cyclodextrin from biodegradable polymer microspheres. | Rhodium(II) carboxylates and their derivatives constitute a promising class of second-generation transition metal compounds with anticancer properties. While most transition metal anticancer compounds chelate DNA and cause extensive chromosomal damage, rhodium(II) carboxylates act on the enzyme DNA polymerase alpha and... |
10229631 | Structure-activity relationships of bisphosphate nucleotide derivatives as P2Y1 receptor antagonists and partial agonists. | The P2Y1 receptor is present in the heart, in skeletal and various smooth muscles, and in platelets, where its activation is linked to aggregation. Adenosine 3',5'- and 2',5'-bisphosphates have been identified as selective antagonists at the P2Y1 receptor (Boyer et al. Mol. Pharmacol. 1996, 50, 1323-1329) and have been... |
10229684 | Inhibition of fibril formation in beta-amyloid peptide by a novel series of benzofurans. | A series of benzofuran derivatives have been identified as inhibitors of fibril formation in the beta-amyloid peptide. The activity of these compounds has been assessed by a novel fibril-formation-specific immunoassay and for their effects on the production of a biologically active fibril product. The inhibition afford... |
10228153 | PDZ-mediated interactions retain the epithelial GABA transporter on the basolateral surface of polarized epithelial cells. | The PDZ target motifs located in the C-terminal end of many receptors and ion channels mediate protein-protein interactions by binding to specific PDZ-containing proteins. These interactions are involved in the localization of surface proteins on specialized membrane domains of neuronal and epithelial cells. However, t... |
10228152 | ZipA is a MAP-Tau homolog and is essential for structural integrity of the cytokinetic FtsZ ring during bacterial cell division. | The first visible event in prokaryotic cell division is the assembly of the soluble, tubulin-like FtsZ GTPase into a membrane-associated cytokinetic ring that defines the division plane in bacterial and archaeal cells. In the temperature-sensitive ftsZ84 mutant of Escherichia coli, this ring assembly is impaired at the... |
10228150 | The specificity of polygalacturonase-inhibiting protein (PGIP): a single amino acid substitution in the solvent-exposed beta-strand/beta-turn region of the leucine-rich repeats (LRRs) confers a new recognition capability. | Two members of the pgip gene family (pgip-1 and pgip-2) of Phaseolus vulgaris L. were expressed separately in Nicotiana benthamiana and the ligand specificity of their products was analysed by surface plasmon resonance (SPR). Polygalacturonase-inhibiting protein-1 (PGIP-1) was unable to interact with PG from Fusarium m... |
10230821 | Effect of methyl-beta-cyclodextrin on the acrosomal responsiveness of human sperm. | Human sperm incubated in vitro gradually become capable of acrosome-reacting in response to the agonist, progesterone (P4). Loss of unesterified cholesterol is an obligatory step in the development of acrosomal responsiveness. These experiments tested the ability of methyl-beta-cyclodextrin (MbetaCD) to accelerate sper... |
10225916 | Towards a Taenia solium cysticercosis vaccine: an epitope shared by Taenia crassiceps and Taenia solium protects mice against experimental cysticercosis. | The Taenia crassiceps recombinant antigen KETc7 has been shown to be effective as a vaccine against experimental murine cysticercosis, a laboratory model used to test potentially promising molecules against porcine Taenia solium cysticercosis. Based on the deduced amino acid sequence of this proline-rich polypeptide, t... |
10225901 | Molecular interactions of Porphyromonas gingivalis fimbriae with host proteins: kinetic analyses based on surface plasmon resonance. | Fimbriae of Porphyromonas gingivalis are thought to play an important role in the colonization and invasion of periodontal tissues. In this study, we analyzed the interactions of P. gingivalis fimbriae with human hemoglobin, fibrinogen, and salivary components (i.e., proline-rich protein [PRP], proline-rich glycoprotei... |
10225900 | Enterohemorrhagic Escherichia coli O157:H7 produces Tir, which is translocated to the host cell membrane but is not tyrosine phosphorylated. | Intimate attachment to the host cell leading to the formation of attaching and effacing (A/E) lesions is an essential feature of enterohemorrhagic Escherichia coli (EHEC) O157:H7 pathogenesis. In a related pathogen, enteropathogenic E. coli (EPEC), this activity is dependent upon translocation of the intimin receptor, ... |
10225890 | Activation of neutrophil collagenase in periodontitis. | Neutrophil collagenase (matrix metalloproteinase 8 [MMP-8]) is an important mediator of tissue destruction in inflammatory diseases. Studies of anaerobic periodontal infections have shown that active MMP-8 in gingival crevicular fluid is associated with the degradation of periodontal tissues in progressive periodontiti... |
10225860 | Down regulation of Entamoeba histolytica virulence by monoxenic cultivation with Escherichia coli O55 is related to a decrease in expression of the light (35-kilodalton) subunit of the Gal/GalNAc lectin. | Entamoeba histolytica virulence is related to a number of amebic components (lectins, cysteine proteinases, and amebapore) and host factors, such as intestinal bacterial flora. Trophozoites are selective in their interactions with bacteria, and the parasite recognition of glycoconjugates plays an important role in ameb... |
10225961 | Laminin polymerization induces a receptor-cytoskeleton network. | The transition of laminin from a monomeric to a polymerized state is thought to be a crucial step in the development of basement membranes and in the case of skeletal muscle, mutations in laminin can result in severe muscular dystrophies with basement membrane defects. We have evaluated laminin polymer and receptor int... |
10225960 | Characterization and expression of the laminin gamma3 chain: a novel, non-basement membrane-associated, laminin chain. | Laminins are heterotrimeric molecules composed of an alpha, a beta, and a gamma chain; they have broad functional roles in development and in stabilizing epithelial structures. Here, we identified a novel laminin, composed of known alpha and beta chains but containing a novel gamma chain, gamma3. We have cloned gene en... |
10225956 | p120(ctn) acts as an inhibitory regulator of cadherin function in colon carcinoma cells. | p120(ctn) binds to the cytoplasmic domain of cadherins but its role is poorly understood. Colo 205 cells grow as dispersed cells despite their normal expression of E-cadherin and catenins. However, in these cells we can induce typical E-cadherin-dependent aggregation by treatment with staurosporine or trypsin. These tr... |
10225948 | Trafficking of an acylated cytosolic protein: newly synthesized p56(lck) travels to the plasma membrane via the exocytic pathway. | The Src-related tyrosine kinase p56(lck) (Lck) is primarily expressed in T lymphocytes where it localizes to the cytosolic side of the plasma membrane and associates with the T cell coreceptors CD4 and CD8. As a model for acylated proteins, we studied how this localization of Lck is achieved. We followed newly synthesi... |
10224258 | Role of the male specific lethal (msl) genes in modifying the effects of sex chromosomal dosage in Drosophila. | Immunostaining of chromosomes shows that the male-specific lethal (MSL) proteins are associated with all female chromosomes at a low level but are sequestered to the X chromosome in males. Histone-4 Lys-16 acetylation follows a similar pattern in normal males and females, being higher on the X and lower on the autosome... |
10224250 | Genetic and biochemical interactions involving tricarboxylic acid cycle (TCA) function using a collection of mutants defective in all TCA cycle genes. | The eight enzymes of the tricarboxylic acid (TCA) cycle are encoded by at least 15 different nuclear genes in Saccharomyces cerevisiae. We have constructed a set of yeast strains defective in these genes as part of a comprehensive analysis of the interactions among the TCA cycle proteins. The 15 major TCA cycle genes c... |
10224152 | Cellular cholesterol regulates expression of the macrophage type B scavenger receptor, CD36. | CD36, the macrophage type B scavenger receptor, binds and internalizes oxidized low density lipoprotein (OxLDL), and may potentially play a role in the development of atherosclerosis. We reported that the native and modified low density lipoproteins increased CD36 mRNA and protein ( J. Biol. Chem. 272: 21654-21659). In... |
10224147 | Cell cholesterol efflux: integration of old and new observations provides new insights. | Numerous studies using a variety of cell/acceptor combinations have demonstrated differences in cholesterol efflux among cells. These studies also show that different acceptors, ranging from simple molecules like cyclodextrins to serum, stimulate efflux through a variety of mechanisms. By combining early observations w... |
10224139 | Structural characterization of Saccharomyces cerevisiae prion-like protein Ure2. | Sacchromyces cerevisiae prion-like protein Ure2 was expressed in Escherichia coli and was purified to homogeneity. We show here that Ure2p is a soluble protein that can assemble into fibers that are similar to the fibers observed in the case of PrP in its scrapie prion filaments form or that form on Sup35 self-assembly... |
10224030 | A sandwiched-culture technique for evaluation of heterologous protein production in a filamentous fungus. | Aspergillus niger is known for its efficient excretion machinery. However, problems have often arisen in obtaining high amounts of heterologous proteins in the culture medium. Here we present a quick method using sandwiched colonies to evaluate transgenic strains for secretion of heterologous proteins. Expressing the A... |
10224006 | Rhodococcus erythropolis DCL14 contains a novel degradation pathway for limonene. | Strain DCL14, which is able to grow on limonene as a sole source of carbon and energy, was isolated from a freshwater sediment sample. This organism was identified as a strain of Rhodococcus erythropolis by chemotaxonomic and genetic studies. R. erythropolis DCL14 also assimilated the terpenes limonene-1,2-epoxide, lim... |
10224005 | Pullulanase type I from Fervidobacterium pennavorans Ven5: cloning, sequencing, and expression of the gene and biochemical characterization of the recombinant enzyme. | The gene encoding the type I pullulanase from the extremely thermophilic anaerobic bacterium Fervidobacterium pennavorans Ven5 was cloned and sequenced in Escherichia coli. The pulA gene from F. pennavorans Ven5 had 50.1% pairwise amino acid identity with pulA from the anaerobic hyperthermophile Thermotoga maritima and... |
10223995 | Study of the response of a biofilm bacterial community to UV radiation. | We have developed a bioluminescent whole-cell biosensor that can be incorporated into biofilm ecosystems. RM4440 is a Pseudomonas aeruginosa FRD1 derivative that carries a plasmid-based recA-luxCDABE fusion. We immobilized RM4440 in an alginate matrix to simulate a biofilm, and we studied its response to UV radiation d... |
10223990 | Purification and characterization of an extremely thermostable cyclomaltodextrin glucanotransferase from a newly isolated hyperthermophilic archaeon, a Thermococcus sp. | The extremely thermophilic anaerobic archaeon strain B1001 was isolated from a hot-spring environment in Japan. The cells were irregular cocci, 0.5 to 1.0 micrometers in diameter. The new isolate grew at temperatures between 60 and 95 degrees C (optimum, 85 degrees C), from pH 5.0 to 9.0 (optimum, pH 7.0), and from 1.0... |
10222595 | Surface-induced dissociation of singly and multiply protonated polypropylenamine dendrimers. | The ease of fragmentation of various charge states of protonated polypropylenamine (POPAM) dendrimers is investigated by surface-induced dissociation. Investigated are the protonated diaminobutane propylenamines [DAB(PA)n] DAB(PA)8 (1+ and 2+), DAB(PA)16 (2+ and 3+), and DAB(PA)32 (3+ and 4+). These ions have been prop... |
10217784 | Ferric enterobactin binding and utilization by Neisseria gonorrhoeae. | FetA, formerly designated FrpB, an iron-regulated, 76-kDa neisserial outer membrane protein, shows sequence homology to the TonB-dependent family of receptors that transport iron into gram-negative bacteria. Although FetA is commonly expressed by most neisserial strains and is a potential vaccine candidate for both Nei... |
10217754 | DnaA boxes are important elements in setting the initiation mass of Escherichia coli. | The binding of DnaA protein to its DNA binding sites-DnaA boxes-in the chromosomal oriC region is essential for initiation of chromosome replication. In this report, we show that additional DnaA boxes affect chromosome initiation control, i.e., increase the initiation mass. The cellular DnaA box concentration was incre... |
10210736 | Determination of stability constant of beta-cyclodextrin complexes using the membrane permeation technique and the permeation behavior of drug-competing agent-beta-cyclodextrin ternary systems. | The stability constants (Kc) of beta-cyclodextrin (beta-CyD) complexes with phenacetin and various benzoic acids were determined using the membrane permeation technique using a cellophane membrane permeable for guest molecules which was impermeable for beta-CyD molecules. The permeation rate equations of guests in the ... |
10210727 | Cyclodextrins as permeation enhancers: some theoretical evaluations and in vitro testing. | It is well known that cyclodextrins can enhance the permeation of poorly soluble drugs through biological membranes. However, the permeability will decrease if cyclodextrin is added in excess of the concentration needed to solvate the drug. The mechanism of cyclodextrin effect on drug permeability has not been fully ex... |
10207064 | Corepressor required for adenovirus E1B 55,000-molecular-weight protein repression of basal transcription. | Adenovirus E1B 55,000-molecular-weight protein (55K) binds to host cell p53, stabilizing it, greatly increasing its affinity for its cognate DNA-binding site, and converting it from a regulated activator to a constitutive repressor. Here we analyzed the mechanism of repression by the p53-E1B 55K complex. E1B 55K repres... |
10198432 | Theoretical calculations, synthesis and base pairing properties of oligonucleotides containing 8-amino-2'-deoxyadenosine. | Theoretical calculations on double and triple helices containing 8-amino-2'-deoxyadenosine were made to analyze the possible differences in base pairing properties between 8-aminoadenine and adenine. These calculations indicate a strong preferential stabilization of the triplex over the duplex when adenine is replaced ... |
10196345 | Immunization with potato plants expressing VP60 protein protects against rabbit hemorrhagic disease virus. | The major structural protein VP60 of rabbit hemorrhagic disease virus (RHDV) has been produced in transgenic potato plants under the control of a cauliflower mosaic virus 35S promoter or a modified 35S promoter that included two copies of a strong transcriptional enhancer. Both types of promoters allowed the production... |
10196338 | Long-term episomal maintenance of bovine papillomavirus type 1 plasmids is determined by attachment to host chromosomes, which Is mediated by the viral E2 protein and its binding sites. | Papillomavirus genomes are stably maintained as extrachromosomal nuclear plasmids in dividing host cells. To address the mechanisms responsible for stable maintenance of virus, we examined nuclear compartmentalization of plasmids containing the full-length upstream regulatory region (URR) from the bovine papillomavirus... |
10196318 | CCAAT displacement protein binds to and negatively regulates human papillomavirus type 6 E6, E7, and E1 promoters. | Expression of human papillomavirus genes increases as the target cell, the keratinocyte, differentiates. CCAAT displacement protein (CDP) is a cellular protein which has been shown in other cell types to negatively regulate gene expression in undifferentiated cells but not in differentiated cells. We have previously sh... |
10196270 | Identification of a receptor-binding pocket on the envelope protein of friend murine leukemia virus. | Based on previous structural and functional studies, a potential receptor-binding site composed of residues that form a pocket at one end of the two long antiparallel helices in the receptor-binding domain of Friend 57 murine leukemia virus envelope protein (RBD) has been proposed. To test this hypothesis, directed sub... |
10193196 | Stereochemical specificity of Alzheimer's disease beta-peptide assembly. | The formation and growth of insoluble amyloid deposits composed primarily of the human beta-amyloid peptide (A beta) in brain is an essentially invariant feature of Alzheimer's disease (AD) and is widely believed to contribute to the progressive neurodegeneration of the disorder. To probe the specificity of amyloid for... |
29711879 | A Potassium Complex of a Fluorine-Containing Macrocyclic Cage Compound: Interactions between Fluorine Atoms and Metal Ions. | A new donor, the C-F unit, can be added to the field of host-guest chemistry. The interaction between fluorine atoms and a potassium ion was proven with the fluorine-containing cage compound 1 as a host. The six fluorine atoms of K<sup>+</sup> ⊂1 are coordinated to K<sup>+</sup> in a distorted octahedral fashion. |
29711872 | Noncovalent Assembly of a Fifteen-Component Hydrogen-Bonded Nanostructure. | A total of 72 hydrogen bonds are formed in the spontaneous association of calix[4]arene tetramelamine and barbituric acid derivatives to give nanosized assemblies of the type represented in the picture. These consist of 15 components that assemble in a completely diastereoselective sense: of the eight possible diastere... |
29711862 | Dynamic Light Scattering Evidence for a Ligand-Induced Motion between the Two Domains of Glucoamylase G1 of Aspergillus niger with Heterobivalent Substrate Analogues. | Heterobifunctional ligands that bind at the same time to the catalytic domain and to the starch-binding domain of glucoamylase induce a conformational change of the protein, as shown by dynamic light scattering. The ligands consist of acarbose and β-cyclodextrin linked together by oligoethylene glycols of variable leng... |
29711863 | Electron Tunneling in DNA. | The reorganization energy that accompanies interfacial or through-strand electron tunneling in DNA is remarkably similar to that of a protein, and the attenuation factor for electron transfer between intercalated reagents also remains protein-like. These factors ensure rapid, but short-range electron tunneling through ... |
29711856 | Decreased Electron Transfer Rates of Manganese Porphyrins with Conformational Distortion of the Macrocycle. | Slow electron transfer to manganese(iii) porphyrins results when the macrocycle deviates from planarity. This was demonstrated by measuring the kinetics of homogeneous electron transfer from a series of semiquinone radical anions to synthetic manganese porphyrins (shown schematically; R<sup>1</sup> =H, Cl, F; R<sup>2</... |
29711853 | A New Anion-Trapping Radical Host, [(Cu-dppe)<sub>3</sub> {hat-(CN)<sub>6</sub> }]<sup>2+</sup> . | Anions PF<sub>6</sub><sup>-</sup> and CF<sub>3</sub> SO<sub>3</sub><sup>-</sup> are trapped by the new radical host [(Cu-dppe)<sub>3</sub> {hat-(CN)<sub>6</sub> }]<sup>2+</sup> , which was synthesized in a one-pot reaction from a copper(I) source, hat-(CN)<sub>6</sub> , and dppe in acetone. The trapped salts have been ... |
29711851 | Dendrimers: From Design to Application-A Progress Report. | A unique combination of a clearly defined particle structure and a very highly functionalized surface is offered by the topical dendrimers. Many groups work on this unusual molecular architecture to develop new applications. The most advanced progress in this respect is an MRI contrast agent based on dendrimers (see sc... |
29711848 | Novel Aluminum-Containing Ring Systems: An Octanuclear Structural Analogue of a Calix[4]pyrrole. | Depending on the hydrazine reagent, Me<sub>3</sub> Al reacts to afford novel aluminum-containing macrocyclic ring structures. The reaction of Me<sub>3</sub> Al with Me<sub>2</sub> NNH<sub>2</sub> provides the octanuclear calix[4]pyrrole-like 1, while under analogous conditions the reaction with MePhNNH<sub>2</sub> give... |
21662960 | Molecularly imprinted electrosynthesized polymers: new materials for biomimetic sensors. | The preparation and characterization of electrosynthesized poly(o-phenylenediamine) (PPD) imprinted by glucose (iPPD) is reported as the first case of an electrosynthesized polymer molecularly imprinted by a neutral template. The material is employed as the recognition element of a QCM biomimetic sensor for glucose. Sc... |
21662955 | Detection of volatile compounds with mass-sensitive sensor arrays in the presence of variable ambient humidity. | Mass-sensitive sensor arrays were established for the detection of isomeric or highly analogue analyte mixtures, which show similar physical and morphological properties. Supramolecular host-guest chemistry and arrays of four mass-sensitive quartz crystal microbalances have been successfully combined with multivariate ... |
21662949 | Enhanced Microdialysis Extraction Efficiency of Ibuprofen in Vitro by Facilitated Transport with β-Cyclodextrin. | A novel approach to increase microdialysis recovery (extraction efficiency, E(d)) by facilitated transport through the microdialysis membrane is described. This new approach facilitates mass transport into the microdialysis probe by inclusion of a complexation agent in the microdialysis perfusion fluid. In these studie... |
21649059 | Peer Reviewed: MIPs as Chromatographic Stationary Phases for Molecular Recognition. | Molecular imprint polymers recognize specific compounds and show promise as separation media, especially for chiral molecules. |
20700821 | Automated detection of problem restraints in NMR data sets using the FINGAR genetic algorithm method. | The recently described FINGAR genetic algorithm method for NMR refinement [D.A. Pearlman (1996) J. Biomol. NMR, 8, 67-76] has been extended so that it can be used to detect problem restraints in an NMR-derived set of data. A problem restraint is defined as a restraint in a generally well-behaved set where the associate... |
10927358 | Experimental evidence for the amino-group non-planarity in nitroanilines: neutron diffraction study of 2-methyl-5-nitroaniline at 100 K. | An appreciable degree of pyramidalization of the amine N atom is observed in the title compound. The existence of polar chains, induced by N-H.O synthons, is confirmed. C-H.O interactions, not noted in a previous X-ray study, were found to stabilize further the known head-to-tail assembling of the chains. The structure... |
10221906 | Self-assembly of disk-shaped molecules to coiled-coil aggregates with tunable helicity | A disk-shaped molecule with chiral tails is shown to form long fibers of molecular diameter and micrometer length by self-assembly in chloroform. The molecules are derived from crown ethers and contain a phthalocyanine ring. In the fibers, they have a clockwise, staggered orientation that leads to an overall right-hand... |
10092356 | Drug-Cyclodextrin Association Constants Determined by Surface Tension and Surface Pressure Measurements. | The compression of water-insoluble drug monolayers spread on the aqueous subphase containing cyclodextrins (CD) led to a shift of surface pressure (pi)-area (A) isotherms toward smaller molecular areas with respect to the pi-A isotherms on the pure water subphase. The displacement of the compression isotherm obtained f... |
10092355 | Drug-Cyclodextrin Association Constants Determined by Surface Tension and Surface Pressure Measurements. | The complexation reaction between the amphiphilic peptide antibiotic polymyxin B and naturally occurring cyclodextrins, used as potential drug carriers, was quantitatively evaluated from surface tension measurements at various drug concentrations. The association constant, Ka, of polymyxin B:beta-cyclodextrin inclusion... |
10079151 | Laser-Desorption Supersonic Jet Spectroscopy of Phthalocyanines. | The laser-induced fluorescence excitation spectra of zinc phthalocyanine, chloroaluminum phthalocyanine, magnesium phthalocyanine, and free-base phthalocyanine have been investigated under jet-cooled conditions, by using pulsed infrared laser desorption as the means of vaporization. Assignment of the observed vibronic ... |
11674416 | New Tetraazacrown Ethers Containing Two Pyridine, Quinoline, 8-Hydroxyquinoline, or 8-Aminoquinoline Sidearms. | A series of macrocyclic tetraazacrown ethers containing two pyridine, quinoline, 8-hydroxyquinoline, or 8-aminoquinoline sidearms has been prepared. Crab-like cyclization of bis(alpha-chloroacetamide)s and diamines followed by reduction of the cyclic diamides was used to synthesize the selected crown ethers containing ... |
11674414 | Effects on Metal Binding of Circular NH- - -O=C Intramolecular Hydrogen Bonding in Hydrophilic Pseudocavities of p-tert-Butylcalix[4]arenes Carrying Amino Acid Moieties. | Calix[4]arenes bearing amino acid moieties were prepared by the reaction of carboxyl-protected amino acids with the acid chlorides of O-carboxymethylcalix[4]arenes. The binding ability toward metal ions was estimated by solvent extraction. These calixarenes showed selective extraction capability toward Na(+) and Ag(+) ... |
11674338 | Enantioselective Photochemical Reactions of N-Phenyl Enaminones in Inclusion Complex Crystals Using a Chiral Host Compound. | Enantioselective reaction of N-methyl-N-phenyl-3-amino-2-cyclohexen-1-one derivatives to the corresponding N-methylhexahydro-4-carbazolones has been accomplished by photolysis in a water suspension of 1:1 inclusion compounds of the starting material with optically active host compounds derived from tartaric acid. 3-(N-... |
11674337 | Synthesis of Lipophilic Paramagnetic Contrast Agents. | The facile, high-yielding synthesis of a series of macrocycles 7a-k in 75-100% yield is reported. The transformation of these compounds to their carboxymethylated analogues 8a-k in 75-90% yield and subsequent gadolinium complexes 9a-k provides a series of homologous neutral paramagnetic contrast agents (PCAs) with tuna... |
11674334 | Chemistry of Zerumbone. 1. Simplified Isolation, Conjugate Addition Reactions, and a Unique Ring Contracting Transannular Reaction of Its Dibromide. | Zerumbone (1) was isolated from fresh rhizomes of Zingiber zerumbet Smith in yields of 0.3-0.4% by simple steam distillation and recrystallization. 1 accepted 2 equiv of hydrogen cyanide at the C6 and C9 double bonds of the cross-conjugated dienone system to give a mixture of diastereomers 3a-d. In the presence of pota... |
11670946 | Nickel(II) and Zinc(II) meso-Tetracyclohexylporphyrins. Structural and Electronic Effects Induced by meso-Cyclohexyl Substitution in Metalloporphyrins. | The synthesis and X-ray structures of the zinc(II) and nickel(II) complexes of meso-tetracyclohexylporphyrin H(2)(TCHP) are described. The nonplanarity of the meso substituents results in steric crowding at the porphyrin periphery. In the solid state, the nickel(II) complex Ni(TCHP) has a ruffled porphyrin conformation... |
11670935 | Synthesis and Physicochemical Characterization of Protonated and Deprotonated Forms in Heteroleptic Lanthanide(III) Porphyrinate Double-Deckers. X-ray Structure of Gd(III)H(oep)(tpp) at 298 and 21 K. | The synthesis, spectroscopic characterization, and electrochemical study of eleven heteroleptic and their corresponding homoleptic lanthanide sandwiches are reported. Studies in solution have been carried out in solvents of different basicity, in order to elucidate the equilibrium between the protonated and deprotonate... |
11670934 | The Reduction Pathway of End-on Coordinated Dinitrogen. II. Electronic Structure and Reactivity of Mo/W-N(2), -NNH, and -NNH(2) Complexes. | DFT calculations (B3LYP/LanL2DZ) of simplified models of [Mo(N(2))(2)(dppe)(2)] and the two protonated derivatives [MoF(NNH)(dppe)(2)] and [MoF(NNH(2))(dppe)(2)](+) (dppe = 1,2-bis(diphenylphosphino)ethane) provide quantitative insight into the reduction and protonation of dinitrogen bound end-on terminally to transiti... |
11670932 | Structural Analysis of All the Nickel 14-Membered Tetraaza Macrocycles in the Cambridge Structural Database. | One hundred and thirty-nine nickel complexes containing the 1,4,8,11-tetraazacyclotetradecane backbone were found in the Cambridge Structural Database. Cluster analysis was used to separate the structures according to their macrocyclic configurations, using their conformations as a separation criteria. The most commonl... |
10074542 | Facklamia languida sp. nov., isolated from human clinical specimens. | Three strains of a gram-positive catalase-negative, facultatively anaerobic coccus-shaped organism originating from human clinical samples were characterized by phenotypic and molecular taxonomic methods. Sequencing of genes encoding 16S rRNA showed that the strains are phylogenetically closely related (99.9 to 100% se... |
10074524 | Helicobacter pylori can be induced to assume the morphology of Helicobacter heilmannii. | Cultures of Helicobacter pylori obtained from the American Type Culture Collection (strain 43504) were grown as isolated colonies or lawns on blood agar plates and in broth culture with constant shaking. Examination of bacterial growth with Gram-stained fixed preparation and differential interference contrast microscop... |
10074186 | Long-term follow-up of chimpanzees inoculated with the first infectious clone for hepatitis C virus. | Two chimpanzees (Ch1535 and Ch1536) became infected with hepatitis C virus (HCV) following intrahepatic inoculation with RNA transcribed from a full-length cDNA clone of the virus. Both animals were persistently infected and have been followed for 60 weeks. They showed similar responses to infection, with transient liv... |
10074170 | Dissecting the role of the N-terminal domain of human immunodeficiency virus integrase by trans-complementation analysis. | The human immunodeficiency virus (HIV) integrase protein (IN) catalyzes two reactions required to integrate HIV DNA into the human genome: 3' processing of the viral DNA ends and integration. IN has three domains, the N-terminal zinc-binding domain, the catalytic core, and the C-terminal SH3 domain. Previously, it was ... |
10074159 | Substitutions in the receptor-binding domain of the avian sarcoma and leukosis virus envelope uncouple receptor-triggered structural rearrangements in the surface and transmembrane subunits. | The retrovirus avian sarcoma and leukosis virus (ASLV) enters cells via pH-independent membrane fusion. This reaction is catalyzed by the viral glycoprotein Env, composed of a membrane-distal subunit, SU, and a membrane-anchored subunit, TM. Previous mutational analysis of a variable region, central within the SU subun... |
10074155 | Production and characterization of a soluble, active form of Tva, the subgroup A avian sarcoma and leukosis virus receptor. | The receptor for the subgroup A avian sarcoma and leukosis viruses [ASLV(A)] is the cellular glycoprotein Tva. A soluble form of Tva, sTva, was produced and purified with a baculovirus expression system. Using this system, 7 to 10 mg of purified sTva per liter of cultured Sf9 cells was obtained. Characterization of the... |
10074153 | Bamboo mosaic potexvirus satellite RNA (satBaMV RNA)-encoded P20 protein preferentially binds to satBaMV RNA. | A satellite RNA of 836 nucleotides [excluding the poly(A) tail] depends on the bamboo mosaic potexvirus (BaMV) for its replication and encapsidation. The BaMV satellite RNA (satBaMV) contains a single open reading frame encoding a 20-kDa nonstructural protein (P20). The P20 protein with eight histidine residues at the ... |
10074149 | HMG protein family members stimulate human immunodeficiency virus type 1 and avian sarcoma virus concerted DNA integration in vitro. | We have reconstituted concerted human immunodeficiency virus type 1 (HIV-1) integration in vitro with specially designed mini-donor HIV-1 DNA, a supercoiled plasmid acceptor, purified bacterium-derived HIV-1 integrase (IN), and host HMG protein family members. This system is comparable to one previously described for a... |
12575108 | [Study on the inclusion of oridonin-beta-cyclodextrin]. | The inclusion compound of Oridonin-beta-cyclodextrin was prepared by the liquid-phase method in aqueous solution. And it was confirmed by thin layer chromatography, differential thermal analysis and specific rotation. The change (A) of ultraviolet spectrum was determined. The composition ratio of inclusion compound bet... |
11550305 | Characterization of paclitaxel (Taxol) sensitivity in human glioma- and medulloblastoma-derived cell lines. | Paclitaxel (Taxol), a cytotoxic natural product that disrupts microtubule integrity, is being clinically evaluated for use against gliomas. We examined paclitaxel-induced killing in seven cell lines derived from human malignant astrocytic gliomas and medulloblastomas with the goal of characterizing range of sensitivity... |
10935930 | Tolerance and specificity of recombinant 6-methylsalicyclic acid synthase. | <h4>Background</h4>6-Methylsalicylic acid synthase (MSAS), a fungal polyketide synthase from Penicillium patulum, is perhaps the simplest polyketide synthase that embodies several hallmarks of this family of multifunctional enzymes--a large multidomain protein, a high degree of specificity toward acetyl-CoA and malonyl... |
10698533 | Systematic screening approach for chiral separations of basic compounds by capillary electrophoresis with modified cyclodextrins. | A simple, systematic method was developed for rapidly screening potential capillary electrophoresis (CE) separation conditions for small, amine-containing enantiomers. During method development, 39 pairs of enantiomers were investigated and partial or complete separation was achieved in every case. Baseline resolution ... |
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