- Characterization of thermophilic archaeal isopentenyl phosphate kinases
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Archaea synthesize isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP), the essential building blocks of isoprenoid compounds, from mevalonate (MVA). However, an analysis of the genomes of several members of the Archaea failed to identify genes for the enzymes required to convert phosphomevalonate (PM) to IPP in eukaryotes. The recent discovery of an isopentenyl kinase (IPK) in Methanocaldococcus jannaschii (MJ) suggests a new variation of the MVA pathway where PM is decarboxylated to give isopentenyl phosphate (IP), which is phosphorylated to produce IPP. A blast search using the MJ protein as a probe revealed a subfamily of amino acid kinases that include the fosfomycin resistance protein fomA, which deactivates the antibiotic by phosphorylation of its phosphonate residue in a reaction similar to the conversion of IP to IPP. IPK genes were cloned from two organisms identified in the search, Methanothermobacter thermautotrophicus (MTH) and Thermoplasma acidophilum (THA), and the His-tagged recombinant proteins were purified by Ni-NTA chromatography. The enzymes catalyze the reversible phosphorylation of IP by ATP, Keq=6.3 ± 1. The catalytic efficiencies (V/K) of the proteins were ～2 × 106M-1 s-1. In the reverse direction, ADP was a substrate inhibitor for THAIPK, Ki ADP=58 ±6 μM, but not forMTHIPK. Both enzymes were active over a broad range of pH and temperature. Five compounds, dimethylallyl phosphate, isopentenyl thiolophosphate, 1-butyl phosphate, 3-buten-1-yl phosphate, and geranyl phosphate, were evaluated as alternative substrates for the MTH and THA IP kinases. All of the compounds were phosphorylated, although the catalytic efficiency was low for geranyl phosphate. 2009 American Chemical Society.
- Chen, Mo,Poulter, C. Dale
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- α-Radiolysis of the tributyl phosphate–hydrocarbon diluent–nitric acid system
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α-Radiolysis of tributyl phosphate in Sintin n-paraffin diluent in equilibrium with HNO3 solutions at single “internal” irradiation from the extracted 238Pu was studied. The radiation-chemical yields (molecules/100 eV) of butyl hydrogen phosphates (BHP), carboxylic acids, carbonyl compounds, and nitro compounds upon irradiation of 20% TBP in the treated Sintin in equilibrium with 3 M HNO3 were 0.4 (at dibutyl hydrogen phosphate to monobutyl dihydrogen phosphate ratio HDBP: H2MBP = 4.3), 1.4, 0.2–0.3, and 0.2–0.3, respectively. The degradation and oxidation processes occur more deeply than under γ-irradiation. A simple volumetric method for determining carboxylic acids in the extract was developed. In the course of irradiation, the Pu(IV) oxidation state in the extract does not change, and its retention is due to the interaction with BHP at the ratio BHP: Pu = 2 in stripping with 0.02 M HNO3 and BHP: Pu = 4 in stripping with Fe(II). The retention can be eliminated by the displacing action of Np(IV).
- Zilberman, B. Ya.,Chistyakov
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p. 188 - 202
(2016/06/09)
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- Surface properties of butanol phosphate esters in alkali solutions
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Phosphate esters of two butanol isomers were synthesized by esterification of n-butanol and isobutanol with phosphorus pentoxide. The surface activity and penetrability of the esters were analyzed by way of surface chemistry and canvas disc wetting tests in different alkaline solutions. The surface tension of the butanol phosphate esters and their sodium salts was found to decrease with increasing alkaline concentration up to 250 g/L NaOH. Furthermore, the products exhibited a good surface activity with proper penetrability even in highly alkaline solutions. The stable surface activity of the esters in concentrated alkali lye interpreted by the adsorption of the molecule from solution owing to the common ion effect. AOCS 2009.
- Du, Zong-Liang,Zhou, Dong-Liang,Chen, Yong,Chen, Min,Zhu, Pu-Xin
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experimental part
p. 201 - 206
(2011/10/11)
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- Determination of phosphoric acid mono- and diesters in municipal wastewater by solid-phase extraction and ion-pair liquid chromatography-tandem mass spectrometry
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The first analytical method for the determination of 13 phosphoric acid mono- and diesters from aqueous samples is presented. The method consists of solid-phase extraction (SPE) and ion-pair liquid chromatographic separation with tri-n-butylamine coupled to electrospray ionization tandem mass spectrometry in the negative ion mode. Due to a lack of pure standards, only 3 of the 13 esters could be quantified. SPE recoveries ranged from 71 to 112% for di-n-butyl phosphate, diphenyl phosphate, and di-(2-ethylhexyl) phosphate (DEHP) with limits of quantification from 7 to 14 ng/L for 100-mL samples. At analyte concentrations ≥1 μg/L, aqueous samples can be analyzed by direct injection without extraction. In municipal wastewater, six diesters and one monoester were unambiguously identified by comparison with synthesized reference material. DEHP showed highest concentrations of 60 and 5 μg/L in raw and treated wastewater, respectively. The detection of monoethylhexyl phosphate was confirmed by LC-Q-TOF-MS analysis, and it was found at a concentration level comparable to DEHP. Laboratory degradation tests show that phosphoric acid diesters can be formed as intermediates in the microbial degradation of trialkyl phosphates that are being used as flame retardants and plasticizers.
- Quintana, Jose Benito,Rodil, Rosario,Reemtsma, Thorsten
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p. 1644 - 1650
(2008/02/05)
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- Regioselective phosphorylation of carbohydrates and various alcohols by bacterial acid phosphatases; probing the substrate specificity of the enzyme from Shigella flexneri
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Bacterial non-specific acid phosphatases normally catalyze the dephosphorylation of a variety of substrates. As shown previously the enzymes from Shigella flexneri and Salmonella enterica are also able to catalyze the phosphorylation of inosine to inosine monophosphate and D-glucose to D-glucose 6-phosphate (D-G6P) using cheap pyrophosphate as the phosphate donor. After optimization high yields (95%) are achieved in the latter reaction and we show here that it is possible to use these enzymes in a preparative manner. This prompted us to investigate by using 31P NMR and HPLC also the phosphorylation of a broad range of carbohydrates and alcohols. Many cyclic carbohydrates are phosphorylated in a regioselective manner. Non-cyclic carbohydrates are phosphorylated as well. Phosphorylation of linear alcohols, cyclic and aromatic alcohols is also possible. In all cases the acid phosphatase from Shigella prefers a primary alcohol function above a secondary one. We conclude that these enzymes are an attractive alternative to existing chemical and enzymatic methods in the phosphorylation of a broad range of compounds.
- Van Herk, Teunie,Hartog, Aloysius F.,Van Der Burg, Alida M.,Wever, Ron
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p. 1155 - 1162
(2007/10/03)
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- Synthesis of mono-and dialkylphosphates by the reactions of hydroxycompounds with the phosphorus pentaoxide under microwave irradiation
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The reactions of phosphorus pentoxide with two alcohols and one phenol were performed in different conditions under microwave irradiation. The products (alkylphosphates and dialkylphosphates) were identical to those formed by classic heating and were obtained with better yields. The speed of the reaction was increased by a factor from 100 to 4000.
- Elias, Abdelhamid,Didi, M. Amine,Villemin, Didier,Semaoune,Ouattas
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p. 2599 - 2607
(2007/10/03)
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- Fatty alcohol phosphates are subtype-selective agonists and antagonists of lysophosphatidic acid receptors
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A more complete understanding of the physiological and pathological role of lysophosphatidic acid (LPA) requires receptor subtype-specific agonists and antagonists. Here, we report the synthesis and pharmacological characterization of fatty alcohol phosphates (FAP) containing saturated hydrocarbon chains from 4 to 22 carbons in length. Selection of FAP as the lead structure was based on computational modeling as a minimal structure that satisfies the two-point pharmacophore developed earlier for the interaction of LPA with its receptors. Decyl and dodecyl FAPs (FAP-10 and FAP-12) were specific agonists of LPA2 (EC50 = 3.7 ± 0.2 μM and 700 ± 22 nM, respectively), yet selective antagonists of LPA3 (Ki = 90 nM for FAP-12) and FAP-12 was a weak antagonist of LPA1. Neither LPA1 nor LPA3 receptors were activated by FAPs; in contrast, LPA2 was activated by FAPs with carbon chains between 10 and 14. Computational modeling was used to evaluate the interaction between individual FAPs (8 to 18) with LPA2 by docking each compound in the LPA binding site. FAP-12 displayed the lowest docked energy, consistent with its lower observed EC50. The inhibitory effect of FAP showed a strong hydrocarbon chain length dependence with C12 being optimum in the Xenopus laevis oocytes and in LPA3-expressing RH7777 cells. FAP-12 did not activate or interfere with several other G-protein-coupled receptors, including S1P-induced responses through S1P1.2,3.5 receptors. These data suggest that FAPs are ligands of LPA receptors and that FAP-10 and FAP-12 are the first receptor subtype-specific agonists for LPA2.
- Virag, Tamas,Elrod, Don B.,Liliom, Karoly,Sardar, Vineet M.,Parrill, Abby L.,Yokoyama, Kazuaki,Durgam, Gangadhar,Deng, Wenlin,Miller, Duane D.,Tigyi, Gabor
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p. 1032 - 1042
(2007/10/03)
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- LPA receptor agonists and antagonists and methods of use
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The present invention relates to compounds according to formula (I) as disclosed herein as well as pharmaceutical compositions which include those compounds. Also disclosed are methods of using such compounds, which have activity as agonists or as antagonists of LPA receptors; such methods including inhibiting LPA activity on an LPA receptor, modulating LPA receptor activity, treating cancer, enhancing cell proliferation, and treating a wound.
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- LPA receptor agonists and antagonists and methods of use
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The present invention relates to compounds according to formula (I) as disclosed herein as well as pharmaceutical compositions which include those compounds. Also disclosed are methods of using such compounds, which have activity as agonists or as antagonists of LPA receptors; such methods including inhibiting LPA activity on an LPA receptor, modulating LPA receptor activity, treating cancer, enhancing cell proliferation, treating a wound, treating apoptosis or preserving or restoring function in a cell, tissue, or organ, culturing cells, preserving organ or tissue function, and treating a dermatological condition.
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- Oxidative cleavage of o-hydroxyphenyl phosphate by iodobenzene diacetate
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The protecting o-hydroxyphenyl group in the synthesis of mono- or dialkyl phosphates (6 or 8) could be removed by oxidative cleavage of mono- or dialkyl o-hydroxyphenyl phosphates (3 or 7) using iodobenzene diacetate.
- Wu, Pei-Lin,Chen, Jhy-Hong,Huang, Ded-Shih
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p. 967 - 970
(2007/10/03)
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- Synthesis of Trialkyl Phosphates from White Phosphorus
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A new method was proposed for preparing trialkyl phosphates directly from white phosphorus by its electrolysis in a mixture of acetonitrile, alcohol, and water with tetraethylammonium iodide as supporting electrolyte. To increase the amount of the product synthesized in the unit volume of the electrolyte solution and the productivity of the process, phosphorus and water are added to the electrolyte in portions, which allows synthesis of up to 1 mol of trialkyl phosphate in 1 1 of the electrolyte solution.
- Romakhin,Nikitin
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p. 1023 - 1026
(2007/10/03)
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- Phosphorylation with Pyrophosphoric Acid
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Dihydrogenphosphates of primary and secondary aliphatic alcohols as well as phenol were prepared by a very simple procedure with pyrophosphoric acid. t-Butyl and benzyl dihydrogenphosphates could be obtained by a slight modification of the reaction conditions.For the purpose of phosphorylation pyrophosphoric acid was more reactive than orthophosphoric acid.
- Yamaguchi, Hachiro,Ogura, Fumio,Otsubo, Tetsuo,Ikeura, Yasuhiro
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p. 1891 - 1892
(2007/10/02)
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