| | 1 | Author
| Akira Taketo | Requires 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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| default:Reihe_C/37/ZNC-1982-37c-0087.pdf | | | | Identifier
| ZNC-1982-37c-0087 | | | | Volume
| 37 | |
| 2 | Author
| Akira Taketo | Requires 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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| default:Reihe_C/30/ZNC-1975-30c-0520.pdf | | | | Identifier
| ZNC-1975-30c-0520 | | | | Volume
| 30 | |
| 3 | Author
| E. Šimaga, Kos | Requires 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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| default:Reihe_C/33/ZNC-1978-33c-1006_n.pdf | | | | Identifier
| ZNC-1978-33c-1006_n | | | | Volume
| 33 | |
| 4 | Author
| Arie Rosner, Marian Gorecki, Haim Aviv | Requires 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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| default:Reihe_C/37/ZNC-1982-37c-0441.pdf | | | | Identifier
| ZNC-1982-37c-0441 | | | | Volume
| 37 | |
| 5 | Author
| Agnieszka Bzowska3, Lucyna Magnowska3, Zygmunt Kazimierczukb | Requires 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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| default:Reihe_C/54/ZNC-1999-54c-1055.pdf | | | | Identifier
| ZNC-1999-54c-1055 | | | | Volume
| 54 | |
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