- Urea-Based Imprinted Polymer Hosts with Switchable Anion Preference
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The design of artificial oxyanion receptors with switchable ion preference is a challenging goal in host-guest chemistry. We here report on molecularly imprinted polymers (MIPs) with an external phospho-sulpho switch driven by small molecule modifiers. The polymers were prepared by hydrogen bond-mediated imprinting of the mono-or dianions of phenyl phosphonic acid (PPA), phenyl sulfonic acid (PSA), and benzoic acid (BA) using N-3,5-bis-(trifluoromethyl)-phenyl-?-4-vinylphenyl urea (1) as the functional host monomer. The interaction mode between the functional monomer and the monoanions was elucidated by 1H NMR titrations and 1H-1H NMR NOESY supported by molecular dynamic simulation, which confirmed the presence of high-order complexes. PPA imprinted polymers bound PPA with an equilibrium constant Keq = 1.8 × 105 M-1 in acetonitrile (0.1percent 1,2,2,6,6-pentamethylpiperidine) and inorganic HPO42- and SO42- with Keq = 2.9 × 103 M-1 and 4.5 × 103 M-1, respectively, in aqueous buffer. Moreover, the chromatographic retentivity of phosphonate versus sulfonate was shown to be completely switched on this polymer when changing from a basic to an acidic modifier. Mechanistic insights into this system were obtained from kinetic investigations and DSC-, MALDI-TOF-MS-, 1H NMR-studies of linear polymers prepared in the presence of template. The results suggest the formation of template induced 1-1 diad repeats in the polymer main chain shedding unique light on the relative contributions of configurational and conformational imprinting.
- Esen, Cem,Incel, Anil,Mansour, Mona,Nicholls, Ian A.,Olsson, Gustaf D.,Sellergren, B?rje,Shinde, Sudhirkumar,Urraca, Javier
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- Organophosphorous phenyl phosphates: Synthesis, dye/protein interactions and antimicrobial evaluation
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A series of Phenyl Phosphates (PPs) has been synthesized and characterized with FTIR spectroscopy. PPs, the product of the reaction of phenol and phosphoryl chloride followed by hydrolysis having larger number of hydrophilic hydroxyl groups, used for the dye interaction and antimicrobial activities. Interaction of PPs with 1,2-diphenyldiazene and 4-(phenyldiazene)phenol were studied through UV/ Vis method where observed hypochromic effect has revealed the dye adsorption property of PPs. Similarly PPs have shown the interaction with bovine serum and human serum albumins where the weaker interaction observed with later. Antimicrobial in vitro evaluation has been assessed on the basis of zone of inhibition with six bacterial (gram +ve and –ve) strains. Since PPs were found very active so minimal inhibitory concentration (MIC) analysis was done where all PPs have shown MIC less than 5 μg/mL. Due to high number of hydroxyl groups PPs have shown good interactions with biomolecules and cell wall of bacteria therefore this impression has predicted their future in medicinal field.
- Ameta, Rakesh Kumar,Duan, Yongtao,Koshti, Rohit R.,Muddassir, Mohd.,Patel, Amee S.,Trivedi, Nidhi S.,Vyas, Akshay
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- MATERIALS FOR ORGANIC ELECTROLUMINESCENT DEVICES
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The present invention relates to compounds of the formula (1) which are suitable for use in electronic devices, in particular organic electroluminescent devices, and to electronic devices, which comprise these compounds.
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Page/Page column 59
(2018/06/06)
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- Transition States and Control of Substrate Preference in the Promiscuous Phosphatase PP1
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Catalytically promiscuous enzymes are an attractive frontier for biochemistry, because enzyme promiscuities not only plausibly explain enzyme evolution through the mechanism of gene duplication but also could provide an efficient route to changing the catalytic function of proteins by mimicking this evolutionary process. PP1γ is an effectively promiscuous phosphatase for the hydrolysis of both monoanionic and dianionic phosphate ester-based substrates. In addition to its native phosphate monoester substrate, PP1γ catalyzes the hydrolysis of aryl methylphosphonates, fluorophosphate esters, phosphorothioate esters, and phosphodiesters, with second-order rate accelerations that fall within the narrow range of 1011-1013. In contrast to the different transition states in the uncatalyzed hydrolysis reactions of these substrates, PP1γ catalyzes their hydrolysis through similar transition states. PP1γ does not catalyze the hydrolysis of a sulfate ester, which is unexpected. The PP1γ active site is tolerant of variations in the geometry of bound ligands, which permit the effective catalysis even of substrates whose steric requirements may result in perturbations to the positioning of the transferring group, both in the initial enzyme-substrate complex and in the transition state. The conservative mutation of arginine 221 to lysine results in a mutant that is a more effective catalyst toward monoanionic substrates. The surprising conversion of substrate preference lends support to the notion that mutations following gene duplication can result in an altered enzyme with different catalytic capabilities and preferences and may provide a pathway for the evolution of new enzymes.
- Chu, Yuan,Williams, Nicholas H.,Hengge, Alvan C.
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p. 3923 - 3933
(2017/08/07)
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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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- Small ligands interacting with the phosphotyrosine binding pocket of the Src SH2 protein
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Various small fragments bearing phosphate, phosphonate or phosphonic acid moieties have been prepared through parallel synthesis and their binding potencies evaluated on the Src SH2 protein using a BIAcore assay. This provided us insight into the requirement of the Src SH2 pTyr binding pocket and some promising small ligands have been characterised.
- Deprez, Pierre,Mandine, Eliane,Gofflo, Dominique,Meunier, Stephane,Lesuisse, Dominique
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p. 1295 - 1298
(2007/10/03)
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- A kinetic study of competing fragmentation and hydrolyses of phenyl hydrogen α-hydroxyiminobenzylphosphonate - A case of acid mediated inhibition of acid catalysis
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The behavior of phenyl hydrogen α-hydroxyiminobenzylphosphonate (E)-2 in aqueous hydrochloric acid solution was examined by 31P NMR spectroscopy and by HPLC. Compound (E)-2 was found to undergo two competing acid-catalyzed reactions. 1) Fragmentation to phenyl phosphate (6) and benzonitrile, similar to the fragmentation of other hydroxyiminophosphonates to metaphosphate examined previously. The fragmentation of (E)-2 was found to be slower by a factor of 4 than that of hydrogen methyl α-hydroxyiminobenzylphosphonate ((E)-1). This phenomenon is interpreted in terms of inductive effects on the suggested metaphosphate intermediate. 2) Compound (E)-2 was found to undergo hydrolytic cleavage of the oxime group giving NH2OH and hydrogen phenyl benzoylphosphonate (4), which was found to hydrolyze to phenol and benzoylphosphonic acid (5). The latter reacted with the NH2OH liberated in the previous step to give α-hydroxyiminobenzylphosphonic acid ((E)-3), which fragmented to benzonitrile and phosphoric acid. The rate of a possible hydrolysis of the phenol group in oxime (E)-2 was shown to be slower by two orders of magnitude than that from ketone 4. This phenomenon is interpreted in terms of acid mediated retardation of acid catalyzed hydrolysis of phenol due to initial protonation of the oxime nitrogen in (E)-2.
- Ta-Shma, Rachel,Schneider, Hava,Mahajna, Mahmoud,Katzhendler, Jehoshua,Breuer, Eli
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p. 1404 - 1407
(2007/10/03)
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- Role of peroxophosphate intermediates in reactions of tris(4-nitrophenyl) phosphate and phenyl phosphorochloridate with alkaline hydrogen peroxide
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Reaction of alkaline hydrogen peroxide with tris(4-nitrophenyl) phosphate generates ca 1.5 equiv. of 4-nitrophenol per mole of substrate with no evidence of build-up of an intermediate, and reaction of bis(4-nitrophenyl) phosphate anion is too slow to give a product. The initially formed bis(4-nitrophenyl) peroxophosphate is assumed to decompose to the phosphate ester by reaction with H2O2 or to eliminate 4-nitrophenoxide ion with the formation of a transient cyclic peroxophosphate. Reaction of phenyl phosphorochloridate anion with HO2- does not give phenoxide ion by this intramolecular reaction. Semi-empirical and ab initio simulations indicate that elimination of aryloxide ion from an aryl peroxophosphate should generate a cyclic rather than an open-chain peroxophosphate. Copyright
- Foroudian, Houshang J.,Gillitt, Nicholas D.,Bunton, Clifford A.,Yatsimirsky, Anatoly K.
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p. 310 - 314
(2007/10/03)
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- Inhibition of serine β-lactamases by acyl phosph(on)ates: A new source of inert acyl [and phosphyl] enzymes
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Acyl phosph(on)ates are shown to inhibit serine β-lactamases and provide a new source of relatively stable complexes. Thus, benzoyl phenyl phosphate, benzoyl phenylphosphonate, and dibenzoyl phosphate react with the class C β-lactamase of Enterobacter cloacae P99 at micromolar concentrations to form an acyl enzyme of half-life about 40 s. The phosphonate reacts further more slowly to produce a much more inert complex. Dibenzoyl phosphate reacts with the class A TEM β-lactamase to from an acyl enzyme of half-life about 8 s and, more slowly, reaching completion after an average of about 80 turnovers, a more inert complex, of half-life about 2 h. The acyl phosphonates thus represent a new starting point for the design of β- lactamase inhibitors and perhaps of antibacterial agents.
- Li, Naixin,Pratt
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p. 4264 - 4268
(2007/10/03)
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- Mg2+-Promoted P-O vs. S-O Bond Cleavage in the Alcoholyses of Phenyl Phosphatosulfate
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In order to obtain insight into the selectivity of Mg2+ at the site of bond cleavage of P-O and S-O of the P-O-S linkage, metal ion-promoted alcoholyses of phenyl phosphatosulfate were studied.Mg2+ quantitatively promoted P-O bond cleavage in the methanolysis, but mixed cleavage of the P-O bond, which occurred partly due to hydrolysis by trace water and the S-O bond in the reaction of ethanol, 1- or 2-propanol.The ratio of the S-O bond cleavage against the mixed cleavage increased in a order EtOH (11.5percent) 2+ and Zn2+ promoted selective P-O and S-O bond cleavage, respectively, in the reaction of 2-propanol as well as methanolysis.The medium-dependent change in the selectivity of Mg2+ at the site of bond cleavage was discussed.
- Eiki, Toshio,Negishi, Shin-ichi,Izumi, Mitsunori,Ishida, Naoko,Hada, Hiroshi
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p. 2931 - 2935
(2007/10/02)
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- The Selective Dealkylation of Mixed Esters of Phosphoric Acid and Phenylphosphonic Acid Using Cation Exchange Resin
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Cation exchange resin (SO3H) is a highly selective dealkylation reagent for mixed esters of phosphorus oxyacids bearing primary and secondary alkyl groups.The desired products which were produced by dealkylation of the secondary alkyl group were obtained in high yields under anhydrous and mild conditions.Keywords - dealkylation; cation exchange resin; carbonium ion; phosphorus oxyacid ester; trialkyl phosphate; dialkyl phenylphosphonate; p-toluenesulfonic acid
- Nitta, Yoshihiro,Arakawa, Yasushi
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p. 3121 - 3129
(2007/10/02)
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- Enhanced Base Hydrolysis of Coordinated Phosphate Esters: The Reactivity of an Unusual Cobalt(III) Amine Dimer
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The hydrolysis of the dimeric cation bis(μ-4-nitrophenyl phosphato)bis(2+) has been studied at pH 10 and over the hydroxide concentration range 0.05-1.0 M.Product distribution, kinetics (involving 4-nitrophenol release), and 31P NMR and 18O tracer studies were carried out to establish the course of the reaction.In a rapid first step, the eight-membered ring of the dimer is opened by rupture of one of the Co-O bonds (SN1cB) to give a cis hydroxo complex.The ring-opened species reacts further via two competing pathways: (a) intramolecular attack of the coordinated hydroxide upon the bridging phosphate ester moiety and (b) further cleavage of the dimer by base-catalyzed (SN1cB) rupture of some Co-O bonds.Route a results in ester hydrolysis with the concomitant formation of a chelated bridging phosphate species whereas route b yields cis- and trans-hydroxy(p-nitrophenyl phosphate)bis(1,2-ethanediamine)cobalt(III).The phosphate chelate ring in the initial product of path a is subsequently opened by Co-O bond rupture and the resultant dimeric bridging phosphato species slowly decomposes to cis- and trans-hydroxo(phosphato)bis(1,2-ethanediamine)cobalt(III).Comparison of the rate data for hydrolysis of the dimer and the cis-hydroxo(4-nitrophenyl phosphato)bis(1,2-ethanediamine)cobalt(III) ion indicates that the attack by the intramolecular nucleophile is largely responsible for the enhanced rate of ester hydrolysis (ca 1E5) with a smaller contribution from charge neutralization at the P center by the metal ion (ca 10-100).Parallel kinetic studies on the analogous dimer bis(μ-4-nitrophenyl phosphato)bis(2+), previously incorrectly formulated as a monomeric species containing chelated phosphate ester, indicate that ester hydrolysis in this complex proceeds by a similar mechanism to that for the 1,2-ethanediamine complex.In total, the results are rationalized in relation to a possible mechanism for the Zn2+ containing enzyme E. coli alkaline phosphatase.
- Jones, David R.,Lindoy, Leonard F.,Sargeson, Alan M.
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p. 7807 - 7819
(2007/10/02)
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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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- ETUDE D'UN SCHEMA DE SYNTHESE PEPTIDIQUE INTRAMOLECULAIRE A L'AIDE DE DERIVES DU PHOSPHORE TETRAEDRIQUE
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A new scheme of repetitive and controlled peptide synthesis offers two advantages compared to the usual methods of synthesis: two steps only are used for the prolongation of a peptide chain with an amino-acid residue and the risk of racemisation is minimized.The two postulated steps are verified particularly by the rearrangement, in an alkaline alcoholic medium, of phosphordiamides 1 incorporating one amino-acid residue, leading to the formation of the peptide derivatives 6 and 8.The severe limitations of this method are discussed.
- Mulliez, M.
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p. 2027 - 2041
(2007/10/02)
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- The Dealkylation of Phosphate and Phosphonate Esters by Iodotrimethylsilane: A Mild and Selective Procedure
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Iodotrimethylsilane transforms alkyl esters of phosphorus oxyacids into their corresponding trimethylsilyl esters and alkyl iodide.The reaction is rapid and quantitative at room temperature.The reagent has no effect on aryl phosphate ester functions or upon alkyl carboxylate, ether, bromoalkane, vinyl, and ethynyl functions under the conditions employed for transesterification.The trimethylsilyl esters can be isolated by distillation or solvolysed without purification using methanol or water to afford dealkylated phosphate and phosphonate species.Selective monodealkylation of dialkyl phosphonates cannot be achieved using only one equivalent of the reagent, wich leads to the formation of mixed products.
- Blackburn, G. Michael,Ingleson, David
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p. 1150 - 1153
(2007/10/02)
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