Search results for "PHOSPHATE"

Aryl azides formation under mild conditions: a kinetic study in some ionic liquid solutions.

2009

The kinetics of nucleophilic aromatic substitution of three nitrothiophene derivatives in different [1-butyl-3-methylimidazolium][N(3)]/ionic liquid binary mixtures was studied spectrophotometrically at 298 K. Ionic liquids differing for cation structure (imidazolium or pyrrolidinium) and for size, shape, and coordination ability of the anion ([BF(4)(-)], [PF(6)(-)], [SbF(6)(-)], and [NTf(2)(-)]) were used. Furthermore, in order to have a comparison with conventional organic solvents, the target reaction was also carried out in DMF solution at increasing concentration of NaN(3) or [bmim][N(3)]. Data collected show that the reaction occurs faster in DMF than in ionic liquid solution. Further…

Mixing relationships and the effects of secondary alteration in the Wishstone and Watchtower Classes of Husband Hill, Gusev Crater, Mars

2006

[1] The Wishstone and Watchtower Class rocks on Husband Hill preserve evidence for a geochemical relationship consistent with two-component mixing between a high Al 2 O 3 , TiO 2 , CaO, Na 2 O, P 2 O 5 end-member and a second end-member enriched in the elements MgO, Zn, S, Br, and Cl. The first end-member appears to be reasonably well represented by rocks of the Wishstone Class, while the second end-member is consistent with a chemical component, not represented by any lithology encountered by Spirit. The Watchtower Class appears to be an intermediate in the mixture. The concentration of the redox sensitive elements Fe and Mn display no systematic variation between rock classes, and the Fe-…

Delivering Inorganic and Organic Reagents and Enzymes from Zein and Developing Optical Sensors.

2018

Nowadays, interest in using environmentally friendly materials is increasing in many fields. However, the rational design of sensors with biodegradable materials is a challenge. The main aim of this work is to show the possibility of using zein, a protein from corn, as a biodegradable and low-cost material for immobilizing, stabilizing, and delivering different kind of reagents for developing optical sensors. Enzymes, metallic salts, and aromatic and small organic compounds were tested. In addition, different techniques of immobilization, entrapment and adsorption, were used, and different formats, such as solid devices and also multiwell platforms, were proposed. The capacity of zein for i…

Receptor phosphorylation does not mediate cross talk between muscarinic M(3) and bradykinin B(2) receptors.

1999

This study examined cross talk between phospholipase C-coupled muscarinic M3and bradykinin B2receptors coexpressed in Chinese hamster ovary (CHO) cells. Agonists of either receptor enhanced phosphoinositide signaling (which rapidly desensitized) and caused protein kinase C (PKC)-independent, homologous receptor phosphorylation. Muscarinic M3but not bradykinin B2receptors were also phosphorylated after phorbol ester activation of PKC. Consistent with this, muscarinic M3receptors were phosphorylated in a PKC-dependent fashion after bradykinin B2receptor activation, but muscarinic M3receptor activation did not influence bradykinin B2receptor phosphorylation. Despite heterologous phosphorylatio…

The inhibition of Ca2+-ATPases of human erythrocyte membranes by covalent binding of ATP derivatives.

1982

UV-induced cross-linking of Tet repressor to DNA containing tet operator sequences and 8-azidoadenines.

1990

The synthesis of 8-azido-2'-deoxyadenosine-5'-triphosphate is described. The photoreactive dATP analog was characterized by thin layer chromatography, proton resonance spectroscopy, infrared spectroscopy and UV spectroscopy. Its photolysis upon UV irradiation was studied. After incorporation of this dATP analog into DNA containing the tet operator sequence the investigation of the interactions between tet operator DNA and Tet repressor protein by UV photocross-linking becomes possible. Photocross-linking of protein to DNA was demonstrated by the reduced migration of the DNA in SDS polyacrylamide gel electrophoresis. Addition of the inducer tetracycline prior to UV irradiation significantly …

The Low-Affinity ATP Binding Site of the Escherichia coli SecA Dimer Is Localized at the Subunit Interface

1997

The homodimeric SecA protein is the ATP-dependent force generator in the Escherichia coli precursor protein translocation cascade. SecA contains two essential nucleotide binding sites (NBSs), i.e., NBS1 and NBS2 that hind ATP with high and low affinity, respectively. The photoactivatable bifunctional cross-linking agent 3'-arylazido-8-azidoadenosine 5'-triphosphate (diN(3)ATP) was used to investigate the spatial arrangement of the nucleotide binding sites of SecA, DiN(3)ATP is an authentic ATP analogue as it supports SecA-dependent precursor protein translocation and translocation ATPase, UV-induced photo-cross-linking of the diN(3)ATP-bound SecA results in the formation of stable dimeric s…

A comparative biochemical, pharmacological and immunological study of Clostridium novyi alpha-toxin, C. difficile toxin B and C. sordellii lethal tox…

1991

The three clostridial cytotoxins, i.e. alpha-toxin of C. novyi (Tox alpha-nov), toxin B of C. difficile (ToxB-dif) and lethal toxin of C. sordellii (LT-sor) consist of single peptide chains of about 200,000 (Tox alpha-nov), 250,000 (LT-sor) and 275,000 (ToxB-dif) mol. wts. ToxB-dif and LT-sor but not Tox alpha-nov cross-reacted with rabbit polyclonal antibodies. Toxicity upon i.v. injection in mice was similar (LD50, 100 hr, 50-200 ng/kg) and was characterized by a slowly developing fluid loss into the interstitial space. When injected into the rat paw the toxins caused a delayed local edema lasting for days. In vitro the three toxins provoked a persistent retraction of endothelial cells cu…

Dynamics of particulate major and trace elements in the lower reaches of the Daugava River and adjacent area of the Gulf of Riga (Baltic Sea).

2004

Suspended particulate matter (SPM) was collected in the freshwater-seawater mixing zone in the lower reaches of the Daugava River (Latvia) and adjacent marine area, during five cruises in 1998-2001. The study focused on biogeochemical phase exchange processes. SPM in the freshwater was found to be mainly allochthonous with a high content of organic matter, Mn and sorbed phosphate. Property-salinity plots suggested flocculation of humic-Fe complexes across the salinity gradient. The variability of sorbed phosphate was related to particulate Fe, although no dependence on pH and ionic strength was observed. The Mn contents of SPM mainly follow conservative mixing, but there are also indication…

Improved composite materials for rechargeable lithium metal polymer batteries

1999

Abstract The performance of several polymer electrolytes for lithium metal batteries for electric vehicle applications are reported. The best performing electrolyte is the composite PEO 20 LiCF 3 SO 3 –γLiAlO 2 , which was prepared by a solvent-free procedure. It showed coulombic efficiency values of the lithium deposition–stripping process of 94%–96%. Electrochemical tests of lithium polymer battery (LPB) prototypes based on a 3 V LiMn 2 O 4 composite cathode material laminated together with the PEO 20 LiCF 3 SO 3 –γLiAlO 2 electrolyte gave promising results for electric vehicle applications. Even under non-optimized battery design, the prototypes delivered, at the C/3 rate and at 94°C, 40…