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Potassium Phosphate (potassium + phosphate)

Distribution by Scientific Domains
Chemistry90%

Terms modified by Potassium Phosphate

  • potassium phosphate buffer
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    Selected Abstracts

    Potassium Phosphate or Silica Sulfurc Acid Catalyzed Conjugate Addition of Thiols to ,,,-Unsaturated Ketones at Room Temperature under Solvent-Free Conditions.

    CHEMINFORM, Issue 14 2007
    D. M. Pore
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]

    ChemInform Abstract: Conjugated Addition Reaction of Amine, Carbon Disulfide to Electrophilic Alkenes in the Presence of Anhydrous Potassium Phosphate.

    CHEMINFORM, Issue 51 2001
    Baoguo Guo
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

    Highly Convenient, Clean, Fast, and Reliable Sonogashira Coupling Reactions Promoted by Aminophosphine-Based Pincer Complexes of Palladium Performed under Additive- and Amine-Free Reaction Conditions

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6 2009
    Jeanne
    Abstract Sequential addition of 1,1,,1,,-phosphinetriyltripiperidine and 1,3-diaminobenzene or resorcinol to toluene solutions of (cyclooctadiene)palladium dichloride [Pd(cod)(Cl)2] under nitrogen in "one pot" almost quantitatively yielded the aminophosphine-based pincer complexes {[C6H3 -2,6-(XP{piperidinyl}2)2]Pd(Cl)} (X=NH 1; X=O 2). Complex 1 (and to a minor extent 2) proved to be efficient Sonogashira catalysts, which allow the quantitative coupling of various electronically deactivated and/or sterically hindered and functionalized aryl iodides and aryl bromides with several alkynes as coupling partners within very short reaction times and low catalyst loadings. Importantly, in contrast to most of the Sonogashira catalysts, which either are both air- and moisture-sensitive and/or require the addition of co-catalysts, such as copper(I) iodide [CuI], for example, or a large excess of an amine, the coupling reactions were carried out without the use of amines, co-catalysts or other aditives and without exclusion of air and moisture. Moreover, the desired products were exclusively formed (no side-products were detected) without employing an excess of one of the substrates. Ethylene glycol and potassium phosphate (K3PO4) were found to be the ideal solvent and base for this transformation. Experimental observations strongly indicate that palladium nanoparticles are not the catalytically active form of 1 and 2. On the other hand, their transformation into another homogeneous catalytically active species cannot be excluded. [source]

    Partitioning of chicken egg white proteins in polyelectrolyte/salt aqueous two-phase systems composed of polyethyleneoxide,maleic acid copolymer and potassium phosphate

    JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 4 2002
    Toshio Kajiuchi
    Abstract Aqueous two-phase systems were formed from solutions of a polyelectrolyte, polyethyleneoxide,maleic acid copolymer, and potassium phosphate. The properties of such aqueous two-phase systems were highly dependent on pH. This was reflected in the partition behavior of three chicken egg white proteins: lysozyme, conalbumin and ovalbumin. Separability of these three proteins was improved by the use of the polyelectrolyte, in comparison with when uncharged polyethylene glycol (poly(1,2-dihydroxyethane)) was used as a phase-forming polymer. © 2002 Society of Chemical Industry [source]

    Effects of annealing lyophilized and spray-lyophilized formulations of recombinant human interferon-,

    JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 4 2003
    Serena D. Webb
    Abstract The purpose of this study was to examine the effects of adsorption of recombinant human interferon-, (rhIFN-,) on ice surfaces and subsequent drying during processing by spray-lyophilization and lyophilization. Ice/liquid interfacial areas were manipulated by the freezing method as well as by the addition of an annealing step during lyophilization; that is, rhIFN-, adsorption was modified by the addition of nonionic surfactants. rhIFN-, was lyophilized or spray-lyophilized at a concentration of 1 mg/mL in 5% sucrose, 5% hydroxyethyl starch (HES),±,0.03% polysorbate 20 in 140 mM KCl, and 10 mM potassium phosphate, pH 7.5. After the samples were frozen, half were annealed on the lyophilizer shelf. Recovery of soluble protein was measured at intermediate points during processing. On drying, the secondary structure of rhIFN-, was determined by second-derivative infrared (IR) spectroscopy, specific surface areas (SSAs) were measured, scanning electron micrographs (SEM) were taken, and dissolution times were recorded. Adsorption of rhIFN-, to ice/liquid interfaces alone was not responsible for aggregation. Rather, drying was necessary to cause aggregation in lyophilized sucrose formulations. Addition of an annealing step to the lyophilization cycle resulted in more native-like secondary protein structure in the dried solid, eliminated cracking of the dried cakes, and suppressed both the formation of air/liquid interfaces and rhIFN-, aggregation on reconstitution. © 2003 Wiley-Liss, Inc. and the American pharmaceutical Association J Pharm Sci 92:715,729, 2003 [source]

    Crystal structures and enzymatic properties of three formyltransferases from archaea: Environmental adaptation and evolutionary relationship

    PROTEIN SCIENCE, Issue 9 2002
    Björn Mamat
    Abstract Formyltransferase catalyzes the reversible formation of formylmethanofuran from N5 -formyltetrahydromethanopterin and methanofuran, a reaction involved in the C1 metabolism of methanogenic and sulfate-reducing archaea. The crystal structure of the homotetrameric enzyme from Methanopyrus kandleri (growth temperature optimum 98°C) has recently been solved at 1.65 Å resolution. We report here the crystal structures of the formyltransferase from Methanosarcina barkeri (growth temperature optimum 37°C) and from Archaeoglobus fulgidus (growth temperature optimum 83°C) at 1.9 Å and 2.0 Å resolution, respectively. Comparison of the structures of the three enzymes revealed very similar folds. The most striking difference found was the negative surface charge, which was ,32 for the M. kandleri enzyme, only ,8 for the M. barkeri enzyme, and ,11 for the A. fulgidus enzyme. The hydrophobic surface fraction was 50% for the M. kandleri enzyme, 56% for the M. barkeri enzyme, and 57% for the A. fulgidus enzyme. These differences most likely reflect the adaptation of the enzyme to different cytoplasmic concentrations of potassium cyclic 2,3-diphosphoglycerate, which are very high in M. kandleri (>1 M) and relatively low in M. barkeri and A. fulgidus. Formyltransferase is in a monomer/dimer/tetramer equilibrium that is dependent on the salt concentration. Only the dimers and tetramers are active, and only the tetramers are thermostable. The enzyme from M. kandleri is a tetramer, which is active and thermostable only at high concentrations of potassium phosphate (>1 M) or potassium cyclic 2,3-diphosphoglycerate. Conversely, the enzyme from M. barkeri and A. fulgidus already showed these properties, activity and stability, at much lower concentrations of these strong salting-out salts. [source]

    Determination of carboplatin in canine plasma by high-performance liquid chromatography

    BIOMEDICAL CHROMATOGRAPHY, Issue 8 2010
    Nicolas Villarino
    Abstract Carboplatin is an antineoplastic drug administered to treat different tumoral conditions in canine oncology. The objective of this study was to validate a high-performance chromatographic (HPLC) method which could be applied in canine pharmacokinetic studies. Following ultrafiltration using a Centrifree device, standards, quality controls and plasma samples were separated by isocratic reversed-phase HPLC on an Inertsil ODS-2 (250 × 4.6,mm i.d.) analytical column and quantified using UV detection at 220,nm. The mobile phase was potassium phosphate (pH 4.5), with a flow-rate of 1.0,mL/min. The procedure produced a linear curve (r2 > 0.999) over the concentration range 1,200,,g/mL. The lower limit of quantification was 1,,g/mL. The intra-assay and inter-assay precision was ,90%. The overall recovery was ,90%. The method was illustrated with a preliminary pharmacokinetic analysis on nine dogs treated with carboplatin at our hospital. Carboplatin disposition followed a monocompartmental structure in dogs and was characterized by a short half-life (50,min). Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Partitioning and Characterization of Tyrosine-Tagged Green Fluorescent Proteins in Aqueous Two-Phase Systems

    BIOTECHNOLOGY PROGRESS, Issue 3 2004
    Sara Fexby
    The green fluorescent protein GFPuv has been genetically engineered to investigate the influence of N-terminal tyrosine extensions in aqueous two-phase systems. Fusions in the N-terminus affected the protein expression, and tags containing three tyrosines and prolines influenced the expression favorably. This effect is probably due to changes in mRNA stability, because the amounts of corresponding mRNAs correlated with the amounts of GFPuv proteins. The partitioning was investigated in two different aqueous two-phase systems, a two-polymer system composed of EO30PO70/dextran and a PEG/salt system with potassium phosphate. Partitioning in the PEG/salt system generally was more favorable than in the EO30PO70/dextran system. Tags with three tyrosines resulted in higher partitioning toward the EO30PO70- and PEG-rich phases, respectively. The effect of adding proline residues to the tag was also investigated, and the partitioning effect of the tag was enhanced when prolines were included in the tags with three tyrosines. The best tyrosine tag, Y3P2, increased the partition coefficient 5 times in the PEG/salt system. Thermoseparation of the EO30PO70 phase allowed recovery of 83% Y3P2-GFPuv protein in a water phase. [source]

    Crystallization and preliminary X-ray analysis of the archaeosine tRNA-guanine transglycosylase from Pyrococcus horikoshii

    ACTA CRYSTALLOGRAPHICA SECTION D, Issue 11 2001
    Ryuichiro Ishitani
    The archaeosine tRNA-guanine transglycosylase from the hyperthermophilic archaeon Pyrococcus horikoshii was crystallized and preliminary X-ray characterization was performed. Single crystals were grown by the hanging-drop vapour-diffusion method, using sodium/potassium phosphate and sodium acetate as precipitants. The space group is P41212 or P43212, with unit-cell parameters a = b = 99.28,(14), c = 363.74,(56),Å. The cryocooled crystals diffracted X-rays beyond 2.2,Å resolution using synchrotron ­radiation from station BL44XU at SPring-8 (Harima). Seleno­methionine-substituted protein crystals were prepared in order to solve the structure by the MAD phasing method. [source]