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1Author    Akira TaketoRequires cookie*
 Title    Sensitivity of Escherichia coli to Viral Nucleic Acid. XVI. Temperature Conditions for Ca2+-Dependent DNA Uptake in Escherichia coli  
 Abstract    Properties of C a2+-or Ba2+-dependent transfection and transform ation in Escherichia coli were examined, using (PX174 replicative-form (R F) D NA and plasm id DNA. F or the transfection and transformation, a heat pulse step was dispensable and the yield o f transfectants was, in most E. coli strains, rather reduced by the heat treatment. The heat pulse step was also detrim ental for the transformation o f certain strains such as lipopolysaccharide mutants. The first stage o f the DNA uptake process (formation of DNA • recipient cell complex) was dependent on low tem perature and Ca2+ ion. A substantial am ount o f the complexed R F-D N A was released from the bacteria, by washing with a chilled Tris buffer. Although a R F-D N A • cell complex was formed even at 37 °C or in chilled 0.05 m MgCl2, the complex did not yield transfectants. 
  Reference    Z. Naturforsch. 37c, 87—92 (1982); received October 141981 
  Published    1982 
  Keywords    DNA, Transfection, Transformation, Escherichia coli 
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 TEI-XML for    default:Reihe_C/37/ZNC-1982-37c-0087.pdf 
 Identifier    ZNC-1982-37c-0087 
 Volume    37 
2Author    Akira TaketoRequires cookie*
 Title    Ba2+-Induced Competence for Transfecting D NA  
 Abstract    Effect of alkaline earth metal ions on induction of the competence for DNA transfection was investigated. Unlike spheroplasts, the bulk of the bacteria treated with these ions retains colony-forming ability. The order of effectiveness for transfection of replicative-form DNA has been found to be Ba2+> C a 2+> S r 2+> M g 2+. The competence of Ba2+-treated cells is 3 to 5 times higher than that of Ca^-treated bacteria and about 40 times higher than that of lysozyme-EDTA sphero­ plasts. The Ba^-dependent transfection is cryophilic and formation of the infective complex occurs very rapidly at 0 °C, but not at 37 °C. 
  Reference    (Z. Naturforsch. 30c, 520—522 [1975]; received March 11 1975) 
  Published    1975 
  Keywords    Ba2+, Competence, DNA, Escherichia coli, Transfection 
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 TEI-XML for    default:Reihe_C/30/ZNC-1975-30c-0520.pdf 
 Identifier    ZNC-1975-30c-0520 
 Volume    30 
3Author    E. Šimaga, KosRequires cookie*
 Title    Š  
 Abstract    Experiments designed to elucidate the mechanism of uracil degradation by E. coli K12S showed that in contrast to uracil, dihydrouracil — the postulated intermediate of a reductive mechanism — did not stimulate the growth of bacteria as additional source of nitrogen, nor it was cata-bolized to ureido carbon dioxide. However, the chromato­ graphic analysis of dihydrouracil metabolic products, re­ vealed the presence of an enzyme converting dihydrouracil to /?-ureidopropionic acid. Results of growth and biochemi­ cal studies indicated that barbituric acid — the postulated intermediate of an oxidative pathway — is not involved in uracil degradation. 
  Reference    Z. Naturforsch. 33c, 1006 (1978); received August 4 1978 
  Published    1978 
  Keywords    Escherichia coli, Catabolism, Uracil, Dihydrouracil, Barbituric Acid 
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 TEI-XML for    default:Reihe_C/33/ZNC-1978-33c-1006_n.pdf 
 Identifier    ZNC-1978-33c-1006_n 
 Volume    33 
4Author    Arie Rosner, Marian Gorecki, Haim AvivRequires cookie*
 Title    Screening for Highly Active Plasmid Promoters via Fusion to /?-Galactosidase Gene  
 Abstract    A plasmid containing promoter-deleted inactive /?-galactosidase gene [1] was used to select promoters of the pEP121 plasmid [2]. Colonies o f cells harboring reactivated /?-galactosidase gene were identified by their red color on McConkey plates. The quantitative amounts o f /?-galactosidase produced in each clone were estimated by assaying enzyme activity and by measuring the specific /?-galactosidase protein following fractionation o f total cells' proteins on polyacrylamide gel. A wide range o f enzyme activities was observed. The most active promoter isolated was shown to promote /?-galactosidase production more efficiently, compared with the original /?-galactosidase promoter, amounting to 20% o f all cell proteins. Such highly active promoters may be utilized in the future, to promote expression o f cloned genes in bacteria. 
  Reference    Z. Naturforsch. 37c, 441—444 (1982); received January 13 1982 
  Published    1982 
  Keywords    Plasmid Promoter, /?-Galactosidase Gene, Escherichia coli 
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 TEI-XML for    default:Reihe_C/37/ZNC-1982-37c-0441.pdf 
 Identifier    ZNC-1982-37c-0441 
 Volume    37 
5Author    Agnieszka Bzowska3, Lucyna Magnowska3, Zygmunt KazimierczukbRequires cookie*
 Title    Synthesis of 6-Aryloxy-and 6-Arylalkoxy-2-chloropurines and Their Interactions with Purine Nucleoside Phosphorylase from Escherichia coli  
 Abstract    The phase transfer method was applied to perform the nucleophilic substitution of 2,6-dichloropurines by modified arylalkyl alcohol or phenols. Since under these conditions only the 6-halogen is exchanged, this method gives 2-chloro-6-aryloxy-and 2-chloro-6-arylalkoxy-purines. 2-Chloro-6-benzylthiopurine was synthesized by alkylation of 2-chloro-6-thiopurine with benzyl bromide. The stereoisom ers of 2-chloro-6-(l-phenyl-l-ethoxy)purine were ob­ tained from R-and 5-enantiomers of sec.-phenylethylalcohol and 2,6-dichloropurine. A ll derivatives were tested for inhibition with purified hexameric E. coli purine nucleoside phosphorylase (PNP). For analogues showing IC50 < 10 ^.m, the type o f inhibition and inhibi­ tion constants were determined. In all cases the experimental data were best described by the mixed-type inhibition model and the uncompetitive inhibition constant, Kiu, was found to be several-fold lower than the competitive inhibition constant, Kic. This effect seems to be due to the 6-aryloxy-or 6-arylalkoxy substituent, because a natural PNP substrate adenine, as well as 2-chloroadenine, show mixed type inhibition with almost the same inhibition con­ stants Kiu and K1C . The most potent inhibition was observed for 6-benzylthio-2-chloro-, 6-benzyloxy-2-chloro-, 2-chloro-6-(2-phenyl-l-ethoxy), 2-chloro-6-(3-phenyl-l-propoxy)-and 2-chloro-6-ethoxypur-ines (Kiu = 0.4, 0.6, 1.4, 1.4 and 2.2 [im, respectively). The i?-stereoisomer o f 2-chloro-6-(l-pheny-l-ethoxy)purine has Kiu = 2.0 ^im, whereas inhibition o f its S counterpart is rather weak (IC50> 12 jim). More rigid (e.g. phenoxy-), non-planar (cyclohexyloxy-), or more bulky (2,4,6-trimethylphenoxy-) substituents at position 6 of the purine base gave less potent inhibi­ tors (IC50 = 26, 56 and >100 [im, respectively). The derivatives are selective inhibitors of hexameric "high-molecular mass" PNPs because no inhibitory activity vs. trimeric Cellulomo-nas sp. PNP was detected. By establishing the ligand-dependent stabilization pattern of the E. coli PNP it was shown that the new derivatives, similarly as the natural purine bases, are able to form a dead-end ternary complex with the enzyme and orthophosphate. It was also shown that the derivatives are substrates in the reverse synthetic direction catalyzed by E. coli PNP 
  Reference    Z. Naturforsch. 54c, 1055—1067 (1999); received May 31/August 2 1999 
  Published    1999 
  Keywords    2-Chloropurines, Purine Nucleoside Phosphorylase, Inhibition, Escherichia coli, Phase Transfer Reactions 
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 TEI-XML for    default:Reihe_C/54/ZNC-1999-54c-1055.pdf 
 Identifier    ZNC-1999-54c-1055 
 Volume    54 
6Author    Pavel Balgavý, Robert TurekRequires cookie*
 Title    Inhibition of Excision Repair without Influence upon UV-Sensitivity and UV-Mutability in Escherichia coli B/r Hcr +  
 Abstract    Pre-irradiation starvation of exponentially growing Escherichia coli B/r Hcr+ thy~trp~ strain for thymine and tryptophan causes inhibition of pyrimidine dimer excision from ultraviolet damaged cells DNA. This inhibition of excision repair has not resulted in increasing ultraviolet sensitivity nor in increasing frequency of ultraviolet induced tryptophan revertants. The possible mechanisms of the non-excision repair in the prestarved cells, which is at least as accurate and effective as the whole dark repair in exponentially growing cells, are discussed. 
  Reference    (Z. Naturforsch. 30c, 406 [1975]; received August 1/November 22 1974) 
  Published    1975 
  Keywords    DNA-Repair, UV-Sensitivity, UV-Mutagenesis, Escherichia coli, UV-Radiation 
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 TEI-XML for    default:Reihe_C/30/ZNC-1975-30c-0406.pdf 
 Identifier    ZNC-1975-30c-0406 
 Volume    30 
7Author    AnnaM M Ata, Juan López-BareaRequires cookie*
 Title    Purification by Affinity Chromatography of Glutathione Reductase (EC from Escherichia coli and Characterization of such Enzyme  
 Abstract    The glutathione reductase from Escherichia coli strain S33 was purified to homogeneity by a simple and fast procedure consisting of two affinity chromatography steps. After 40-80% ammonium sulfate fractionation, the enzyme was adsorbed to an N 6-2'.5'-ADP-Sepharose affinity column from which it was specifically eluted by a 0 -10 m M N ADP+ linear gradient. The enzyme was finally purified to homogeneity after a second affinity chromatography step in a C8-ATPR-Sepharose column, from which it was eluted by means of the same N AD P+ gradient. 
  Reference    Z. Naturforsch. 39c, 908—915 (1984); received December 16 1983/April 26 1984 
  Published    1984 
  Keywords    Escherichia coli, Glutathione Reductase, Purification by Affinity Chromatography, Molecular and Kinetic Characterization, Redox Inactivation under Reducing Conditions 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0908.pdf 
 Identifier    ZNC-1984-39c-0908 
 Volume    39