Página 1 dos resultados de 24 itens digitais encontrados em 0.004 segundos

Methyl jasmonate does not induce changes in Eucalyptus grandis leaves that alter the effect of constitutive defences on larvae of a specialist herbivore

Henery, Martin; Wallis, Ian; Stone, C; Foley, William
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
515.17375%
The up-regulation of secondary metabolic pathways following herbivore attack and the subsequent reduction in herbivore performance have been identified in numerous woody plant species. Eucalypts constitutively express many secondary metabolites in the lea

Synthesis of the chelator lipid nitrilotriacetic acid ditetradecylamine (NTA-DTDA) and its use with the IAsys biosensor to study receptor-ligand interactions on model membranes

Altin, Joseph; White, Felix; Easton, Christopher
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
721.6214%
This work describes the synthesis and use of the chelator lipid, nitrilotriacetic acid ditetradecylamine (NTA-DTDA). This lipid is readily dispersed in aqueous media, both alone and when mixed with carrier lipids like dimyristoylphosphatidylcholine (DMPC)

Processing of sting pheromone and its components in the antennal lobe of the worker honeybee

Wang, Shunpeng; Sato, Katsushige; Giurfa, Martin; Zhang, Shao Wu
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
509.11684%
In the honeybee Apis mellifera, a sting pheromone produced by sting glands plays an important role in coordinating defensive behavior. This pheromone is a blend constituted by several components. Little is known about the neural substrates underlying stin

Effect of introduced charge in cellulose gels on surface interactions and the adsorption of highly charged cationic polyelectrolytes

Notley, Shannon
Fonte: Royal Society of Chemistry Publicador: Royal Society of Chemistry
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
517.5346%
The interaction between cellulose surfaces in aqueous solution has been measured using colloidal probe microscopy. Cellulose thin films with varying charge through carboxyl group substitution were used in this study with the surface forces fit to DLVO the

Characterization of novel vanadium(III)/acetate clusters formed in aqueous solution

Fry, Fiona; Dougan, Brenda; McCann, Nichola; Zeigler, Christopher; Brasch, Nicola
Fonte: American Chemical Society Publicador: American Chemical Society
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
499.4432%
We report the first structures of simple acetate complexes of vanadium(III) formed in aqueous solution. Paramagnetic 1H NMR spectroscopy titration experiments indicate the formation of two major V(III)/acetate complexes in acidic aqueous solution for acetate/V(III) ≤4, pD 3.50. A novel tetranuclear cluster and a trinuclear cluster have been characterized by X-ray diffraction studies. Mass spectrometry measurements show these clusters retain their integrity in solution.

Targeting dendritic cells with antigen-containing liposomes: A highly effective procedure for induction of antitumor immunity and for tumor immunotherapy

Van Broekhoven, Christina; Parish, Christopher; Demangel, Caroline; Britton, Warwick; Altin, Joseph
Fonte: American Association for Cancer Research Publicador: American Association for Cancer Research
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
518.3464%
Dendritic cells (DCs) are potent stimulators of immunity, and DCs pulsed with tumor antigen ex vivo have applications in tumor immunotherapy. However, DCs are a small population of cells, and their isolation and pulsing with antigen can be impractical. Here we show that a crude preparation of plasma membrane vesicles (PMV) from the highly metastatic murine melanoma (B16-OVA) and a surrogate tumor antigen (OVA) can be targeted directly to DCs in vivo to elicit functional effects. A novel metal-chelating lipid, 3(nitrilotriacetic acid)-ditetradecylamine, was incorporated into B16-OVA-derived PMV, allowing recombinant hexahistidine-tagged forms of single chain antibody fragments to the DC surface molecules CD11c and DEC-205, to be conveniently " engrafted" onto the vesicle surface by metal-chelating linkage. The modified PMV, or similarly engrafted synthetic stealth liposomes containing OVA or OVA peptide antigen, were found to target DCs in vitro and in vivo, in experiments using flow cytometry and fluorescence confocal microscopy. When used as vaccines in syngeneic mice, the preparations stimulated strong B16-OVA-specific CTL responses in splenic T cells and a marked protection against tumor growth. Protection was dependent on the simultaneous delivery of both antigen and a DC maturation or "danger signal" signal (IFN-γ or lipopolysaccharide). Administration of the DC-targeting vaccine to mice challenged with B16-OVA cells induced a dramatic immunotherapeutic effect and prolonged disease-free survival. The results show that the targeting of antigen to DCs in this way is highly effective at inducing immunity and protection against the tumor...

Rapid and convergent assembly of the polycyclic framework assigned to the cytotoxic marine alkaloid halitulin

Banwell, Martin; Bray, Andrew; Edwards, Alison; Wong, David
Fonte: Royal Society of Chemistry Publicador: Royal Society of Chemistry
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
499.4432%
Compound 3, representing the tetra-O-methyl ether derivative of structure, 1, assigned to the cytotoxic marine alkaloid halitulin, has been assembled in a convergent manner from the readily available building blocks 5, 6 and 11.

Methodology for the synthesis of 11,13-dihydroxy gibberellins

Liu, Jin; Mander, Lewis; Koshioka, Masaji
Fonte: ARKAT Foundation Publicador: ARKAT Foundation
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
526.53176%
A general procedure has been established for the synthesis of 11,13-dihydroxy gibberellins. The key steps involve the isomerization of the 19,10 lactone functionality to the 19,2-isomer, bromination at C-1 and C-11, then selective nucleophilic displacement of the 11-bromo substituent by acetate with silver(1) acetate. Reconstitution of the 19,10 lactone functionality was effected by bromolactonization of a Δ9-ene 19-carboxylic acid to give a 9β-bromo 19,10-lactone followed by stereoselective hydrogenolysis of the bromo substituent.

Gas chromatography-mass spectrometry analysis of indoleacetic acid and tryptophan following aqueous chloroformate derivatisation of Rhizobium exudates

Perrine, Francine; Rolfe, Barry; Hynes, Michael F; Hocart, Charles
Fonte: Gauthier-Villars Publicador: Gauthier-Villars
Tipo: Artigo de Revista Científica
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612.90297%
A new method for preparing alkyl esters of indole-3-acetic acid (IAA) in aqueous solution is adapted from the chloroformate method originally described by Hǔek for the analysis of amino acids. This method has the significant advantage of avoiding the gen

Expression profiling of metabolic genes in response to methyl jasmonate reveals regulation of genes of primary and secondary sulfur-related pathways in Arabidopsis thaliana

Jost, Ricarda; Altschmied, Lothar; Bloem, Elke; Bogs, Jochen; Gershenzon, Jonathan; Hahnel, Urs; Hansch, Robert; Hartmann, Tanja; Kopriva, Stanislav; Kruse, Cordula; Mendel, Ralf R; Papenbrock, Jutta; Reichelt, Michael; Rennenberg, Heinz; Schnug, Ewald; S
Fonte: Kluwer Academic Publishers Publicador: Kluwer Academic Publishers
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
515.17375%
The treatment of Arabidopsis thaliana with methyl jasmonate was used to investigate the reaction of 2467 selected genes of primary and secondary metabolism by macroarray hybridization. Hierarchical cluster analysis allowed distinctions to be made between

Divergent mechanisms of suicide inactivation for ethanolamine ammonia-lyase

Sandala, Gregory; Smith, David M; Radom, Leo
Fonte: American Chemical Society Publicador: American Chemical Society
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
627.01105%
Ab initio molecular orbital calculations have been used to study the mechanism of suicide inactivation of ethanolamine ammonia-lyase induced by three different substrate analogues. Analysis of the normal catalytic mechanism with 2-aminoethanol (ethanolamine) as substrate predicts that both the hydrogen-abstraction and hydrogen-reabstraction steps involving the B 12-cofactor are likely to be exothermic. On the other hand, the proposed inactivation mechanism for the first substrate analogue, glycolaldehyde, leads to a highly stabilized radical that results in a very endothermic (by ca. 90 kJ mol-1) hydrogen-reabstraction step, which is thought to halt the normal function of the enzyme. Curiously, the energy requirements for a catalytically imposed mechanism in the case of the second substrate analogue, 2-hydroxyethylhydrazine (HEH), parallel those for the catalytic substrate, despite the fact that HEH is found to inactivate EAL experimentally. However, further analysis reveals the presence of a lower energy pathway for HEH that leads to the formation of the highly stabilized hydrazinium radical cation. In a manner similar to when glycolaldehyde is the substrate analogue, this results in an endothermicity for the hydrogen-reabstraction step that is prohibitively large. In contrast to these related inactivation mechanisms...

Total synthesis of herboxidiene, a complex polyketide from Streptomyces species A7847

Banwell, Martin; McLeod, Malcolm; Premraj, Rajaratnam; Simpson, Gregory Wayne
Fonte: International Union of Pure and Applied Chemistry Publicador: International Union of Pure and Applied Chemistry
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
832.2754%
A formal total synthesis of the polyketide herboxidiene (1) has been achieved by Homer-Wittig coupling of the side-chain fragment 12-epi-(2) with the tetrahydropyran-2-acetic acid derivative (3) followed by desilylation of the resulting triene (19) and hydroxyl-directed mono-epoxidation of the ensuing bis-homoallylic alcohol (20).

Oxidation of oxa and thia fatty acids and related compounds catalyzed by 5- and 15-lipoxygenase

Easton, Christopher; Robertson, Thomas; Pitt, Michael; Rathjen, Deborah A; Ferrante, Antonio; Poulos, Alf
Fonte: Pergamon-Elsevier Ltd Publicador: Pergamon-Elsevier Ltd
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
768.6057%
The modified fatty acids, (Z,Z,Z)-(octadeca-6,9,12-trienyloxy)acetic acid, (Z,Z,Z)-(octadeca-9,12,15-trienyloxy)acetic acid, (all-Z)-(eicosa-5,8,11,14-tetraenyloxy)acetic acid, (all-Z)-(eicosa-5,8,11,14-tetraenylthio)acetic acid, 3-[(all-Z)-(eicosa-5,8,11,14-tetraenylthio)]propionic acid, (all-Z)-(eicosa-5,8,11,14-tetraenylthio)succinic acid, N-[(all-Z)-(eicosa-5,8,11,14-tetraenoyl)]glycine and N-[(all-Z)-(eicosa-5,8,11,14-tetraenoyl)]aspartic acid, all react with soybean 15-lipoxygenase. The products were treated with triphenylphosphine to give alcohols, which were isolated using HPLC. Analysis of the alcohols using negative ion tandem electrospray mass spectrometry, and by comparison with compounds obtained by autoxidation of arachidonic acid, shows that each enzyme-catalysed oxidation occurs at the ω-6 position of the substrate. In a similar fashion, it has been found that (Z,Z,Z)-(octadeca-6,9,12-trienyloxy)acetic acid, (Z,Z,Z)-(octadeca-9,12,15-trienyloxy)acetic acid, (all-Z)-(eicosa-5,8,11,14-tetraenylthio)acetic acid and 3-[(all-Z)-(eicosa-5,8,11,14-tetraenylthio)]propionic acid each undergoes regioselective oxidation at the carboxyl end of the polyene moiety on treatment with potato 5-lipoxygenase. Neither (all-Z)-(eicosa-5...

Kinetics of the Biotransformation of Maleylacetone and Chlorofluoroacetic Acid by Polymorphic Variants of Human Glutathione Transferase Zeta (hGSTZ1-1)

Lantum, Hoffman; Board, Philip; Anders, Michael
Fonte: American Chemical Society Publicador: American Chemical Society
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
610.62516%
Glutathione transferase zeta (GSTZ1-1) catalyzes the cis-trans isomerization of maleylacetoacetate and the biotransformation of a range of α-haloacids. The objective of this study was to determine the kinetics of the biotransformation of maleylacetone (M

Glutathione transferase zeta-catalyzed biotransformation of deuterated dihaloacetic acids

Werkmeister, Jerome A; Anderson, Warwick P; Tzeng, Huey-Fen; Board, Philip; Anders, Michael
Fonte: Academic Press Publicador: Academic Press
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
622.65965%
Glutathione transferase zeta (GSTZ) catalyzes the biotransformation of α-haloalkanoic acids. Treatment of rats or humans with dichloroacetic acid prolongs its elimination half-life, and preliminary studies in this laboratory show that fluorine-lacking, b

IMMUNOHISTOCHEMICAL LOCALIZATION AND ACTIVITY OF GLUTATHIONE TRANSFERASE ZETA (GSTZ1-1) IN RAT TISSUES

Lantum, Hoffman; Baggs, Raymond; Krenitsky, Daria; Board, Philip; Anders, Michael
Fonte: American Society for Pharmacology and Experimental Therapeutics Publicador: American Society for Pharmacology and Experimental Therapeutics
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
510.62516%
Glutathione transferase zeta (GSTZ1-1) catalyzes the biotransformation of a range of α-haloacids, including dichloroacetic acid (DCA), and the penultimate step in the tyrosine degradation pathway. DCA is a rodent carcinogen and a common drinking water co

Polymorphism- and Species-Dependent Inactivation of Glutathione Transferase Zeta by Dichloroacetate

Tzeng, Huey-Fen; Blackburn, Anneke; Board, Philip; Anders, Michael
Fonte: American Chemical Society Publicador: American Chemical Society
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
505.50008%
Glutathione transferase zeta catalyzes the glutathione-dependent oxidation or conjugation of a range of α-haloacids. Repeated administration of dichloroacetate to human subjects increases its plasma elimination half- life, and the activity of glutathione

Guaiacol transprotection: replacement of the phenoxy isopropyl protecting function by acetyl

Williams, Craig; Mander, Lewis
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
632.52227%
A one-step method for the conversion of isopropyl protected guaiacols to the corresponding acetates is reported. Treating 6-substituted isopropyl protected guaiacols with trimethylsilyl trifluoromethanesulfonate in a mixture of acetic anhydride and acetonitrile affords 6-substituted guaiacol acetates in yields ranging from 35% to 99%.

IDENTIFICATION AND CHARACTERIZATION OF THE ZETA CLASS OF GLUTATHIONE TRANSFERASES

Board, Philip; Chelvanayagam, Gareth; Jermiin, Lars; Blackburn, Anneke
Fonte: Gordon and Breach Publicador: Gordon and Breach
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
628.36594%
A new class of glutathione transferase isoenzymes has been identified by sequence data base analysis. The Zeta class isoenzymes occur in a wide range of species including plants, insects and mammals. The human enzyme has been shown to catalyse the glutathione dependent transformation of dichloroacetic acid to glyoxylic acid and the isomerization of maleylacetoacetate to fumarylacetoacetate. The latter reaction is an essential step in the catabolism of tyrosine. The GSTZ1 gene is composed of 9 exons that extend over 10.9 kb and has been localized to chromosome 14q24.3.

Non-linear Optical Properties of Transition Metal Acetylides and Their Derivatives

Powell, Clem; Humphrey, Mark
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
509.11684%
The nonlinear optical (NLO) properties of metal acetylide and vinylidene complexes are summarized, and molecular structure-NLO property trends are developed. The origin of NLO effects in molecules is presented, and the advantages and shortcomings of experimental procedures that have been used to measure optical nonlinearities for these complexes are discussed. Attempts to "switch" optical nonlinearities of acetylide or vinylidene complexes are summarized.