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  • 1
    ISSN: 0006-3592
    Keywords: metabolic engineering ; carbon metabolism ; Escherichia coli mutants ; microbial growth ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Escherichia coli strains devoid of one or both of the two pyruvate kinase isoenzymes (PKA and PKF), were grown on minimal media in batch fermentations. The strain lacking both PKs showed a 28% decrease on its specific growth rate when compared to the wild type. However, protein and CO2 yields did not change. Using radioactive 1-C14 glucose and collecting the CO2 produced by the cultures, it was found that the mutant lacking both pyruvate kinases, metabolized glucose mainly through the pentose pathway (PP). The increased participation of the PP in glucose metabolism in this strain, was also reflected on the levels of the glucose-6-phosphate and 6-phosphogluconate dehydrogenases.© 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 58:292-295, 1998.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 56 (1997), S. 62-70 
    ISSN: 0006-3592
    Keywords: osmotic shock ; water permeability ; mixing time constant ; mathematical model ; yeast ; leukemia K562 cells ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Water permeability (Lp), calculated from the volume variations of cells subjected to an osmotic shock, is classically used to characterize cell membrane properties. In this work, we have shown the importance of the kind of mixing reactor used to measure the Lp parameter. A mathematical model including the mixing time constant has been proposed allowing an accurate Lp estimation even though the mixing time constant is higher than the cell time constant obtained in response to a perfect shock. The estimated Lp values of human leukemia K562 cells were found to be the same whatever the mixing time constant. The Lp value of Saccharomyces cerevisiae could not be exactly estimated. However, S. cerevisiae has unexpectedly high water permeability, implying that this yeast may contain water channels in the membrane. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 56: 62-70, 1997.
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  • 3
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Linear polyacrylamide ; Inverse emulsion polymerization ; DNA sequencing by capillary electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: In a previous paper, a 2% w/w replaceable high molecular mass linear polyacrylamide solution (high molecular mass LPA) was used to achieve long readlengths for DNA sequencing by capillary electrophoresis (E. Carrilho et al. Anal. Chem. 1996, 68, 3305-3313). In that work, the polymer was prepared by polymerization in water at 6% w/w, followed by dilution to 2% w/w. In this study, an improved method for preparation of high molecular mass LPA was developed, based on inverse emulsion polymerization. With this polymerization procedure, the LPA results in a molecular mass of approximately 9 MDa with characteristics of a fine powder of high purity and practically unlimited shelf life. Using size exclusion chromatography (SEC) and viscosity measure ments to characterize the polymer, good batch-to-batch reproducibility was found. It was observed that the viscous polymer solutions made from these high molecular mass polymers require careful preparation and handling because the method of dissolution could affect the molecular mass distribution and the resultant separation of DNA components. Solution containing 2% w/w of LPA made by emulsion polymerization were simple to prepare resulting in excellent performance as a replaceable matrix for DNA sequencing by capillary electrophoresis. The viscosity of the polymer decreased exponentially when pressure was applied. allowing easy replacement from a capillary using a syringe. With a properly prepared matrix, a read-length on morethan 1000 bases in 80 min with an accuracy better than 97%, and better than 99% for the first 800 bases, could be achieved.
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  • 4
    ISSN: 0173-0835
    Keywords: Two-dimensional polyacrylamide gel electrophoresis ; Silver staining ; Mass spectrometry ; Proteome ; Mitochondria ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Owing to the complexity of higher eukaryotic cells, characterization of a complete proteome is likely to be difficult to achieve. However, advantage can be taken of the cell compartmentalization to build organelle proteomes, which can moreover be viewed as specialized tools to study specifically the biology and “physiology” of the target organelle. Within this frame, we report here the construction of the human mitochondrial proteome, using placenta as the source tissue. Protein identification was carried out mainly by peptide mass fingerprinting, but other methods were also used (N-terminal microsequencing, blotting). The optimization steps in two-dimensional (2-D) electrophoresis needed for proteome research are discussed. However, the relative paucity of data concerning mitochondrial proteins is still the major limiting factor in building the corresponding proteome, which should be a useful tool for researchers working on human mitochondria and their deficienciesThis work can be found on the Internet at the following address: http://www-dsv.cea.fr/MitoPick/Default.html.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Cell Biochemistry and Function 13 (1995), S. 217-225 
    ISSN: 0263-6484
    Keywords: 5637 tumour bladder cell ; tumoural invasion ; taxol ; estramustrine-phosphate ; microtubules ; proteinase secretion ; u-plasminogen activator ; gelatinase ; conditioned media ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The secretion of proteinases into the extracellular matrix is one of the main features of tumour cells, as related to their invasive behaviour. Considering the role of the microtubule cytoskeleton, and particularly the action of microtubule-associated protein (MAPs) in mediating protein secretion, the effects of the anti-microtubule drugs estramustine and taxol, on the secretion of urokinase-type plasminogen activator (u-PA) and the 72 kDa gelatinase were investigated. Treatment of 5637 bladder carcinoma cells with estramustine and taxol inhibited u-PA secretion into the conditioned medium in a drug concentration-dependent fashion. This inhibition was confirmed by determinations of u-PA enzymatic activities and by measurements of the levels of immunoreactive activator. Studies using gelatin zymograms also showed an inhibition of another tumoural proteinase namely the 72 kDa gelatinase. Time-course uptake experiments showed that estramustine was incorporated into the cells, a process which depended on temperature. On the other hand, immunofluorescence studies indicated that the microtubule network was affected by taxol with the formation of bundles of microtubules at different cell domains. Minor effects were visualized after treatment of the cells with estramustine-phosphate, a drug that blocks primarily the action of microtubule-associated proteins. The studies provide a way to analyse the relationships between u-PA secretion and the integrity of the cytoskeletal network.
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  • 6
    ISSN: 0173-0835
    Keywords: Alu repeats ; Population genetics ; Paternity testing ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Alu sequences represent the largest family of short interspersed repetitive elements (SINEs) in humans with 500 000 copies per genome. Recently, one Alu subfamily was found to be human specific (HS). We originally described the use of polymorphic HS Alu insertions as a tool in population studies and recently as tools in DNA fingerprinting and forensic analysis. In this report, we will use this simple polymerase chain reaction (PCR) base technique for the detection of HS Alu insertion polymorphisms. We will test the resolving power of this DNA profiling approach in both population genetics and paternity assessment. At the population level, we will describe the genotypic distribution of five polymorphic Alu insertions among 3 populations from the American continent, one of African origin, the other two Amerindians. Insight into their relationships will be provided. At the family level, we will examine one European American family of seven individuals and the same pedigree will also be characterized by way of the two systems currently and widely used to ascertain paternity: PCR-sequence specific oligonucleotide probe hybridization (PCR-SSO) and PCR-restriction fragment length polymorphism (PCR-RFLP) of human leucocyte antigen (HLA) class II molecules, and a standard RFLP protocol used in forensic casework and paternity studies. The importance and strengths of the method as well as its perspectives for future use in filiation studies will be evaluated.
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  • 7
    ISSN: 1075-2617
    Keywords: β-amino-alcohol ; statine ; UNCAs ; vicinal tricarbonyl compounds ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: N-Urethane-protected N-carboxyanhydrides (UNCAs) are very reactives. They have been successfully used in peptide synthesis, in both solution and solid phase. We have demonstrated that UNCAs are interesting starting materials for the synthesis of various amino acid derivatives. Chemoselective reduction of UNCAs with sodium borohydride led the corresponding N-protected β amino alcohols. Reaction of UNCAs with Meldrum's acid, followed by cyclisation, yielded enantiomerially pure tetramic acid derivatives. Diastereoselective reduction of tetramic acid derivatives produced (4S,5S)-N-alkoxycarbonyl-4-hydroxy-5-alkylpyrrolidin-2-ones derived from amino acids, which after hydrolysis yielded statine and statine analogues. Tetramic acid derivatives could also be obtained by reaction of UNCAs with benzyl ethyl followed by hydrogenolytic deprotection and decarboxylation. UNCAs also reacted with phosphoranes to produce the ketophosphorane in excellent yields. Subsequent oxidation with oxone or with [bis(acetoxy)-iodol]-benzene produced vicinal tricarbonyl derivatives. These reactions usually proceeded smoothly and with high yields.
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  • 8
    ISSN: 1075-2617
    Keywords: β-bend ; 310-helix ; peptide conformational analysis ; spin-labelled amino acid ; TOAC peptides ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A variety of host L-alanine homo-peptides (to the pentamer) containing one or two spin-labelled TOAC (2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid) residues were synthesized by solution methods and fully characterized. The conformational features of the terminally blocked, doubly spin-labelled-TOAC-(Ala)2-TOAC-Ala- pentapeptide were examined in the crystal state by X-ray diffraction and in solution using a combination of techniques (Fourier transform infrared, circular dichroism, cyclic voltammetry and electron spin resonance) in comparison with singly labelled shorter peptides. The 310-helical structure of the pentapeptide, promoted by the two Cα,α-disubstituted glycines under favourable experimental conditions, allows an interaction to take place between the two nitroxide TOAC side chains spaced by one turn of the helix. Taken together, these results suggest that TOAC is an excellent probe for exploring bends and helices in doubly labelled peptides.
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  • 9
    ISSN: 0884-3996
    Keywords: chemiluminescence ; flow injection ; isoniazid ; solid-phase reactors ; pharmaceutical analysis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A flow injection procedure for the indirect chemiluminescent determination of isoniazid is proposed. The method is performed in a flow-injection manifold provided with a solid-phase reactor. The reactor was made from manganese dioxide physically entrapped by polymerization; the redox reaction isoniazid-manganese dioxide released Mn(II) which was monitored through its inhibitory effect on the reaction between luminol and hydrogen peroxide in presence of potassium hexacyanoferrate(III). The procedure resulted in a linear calibration graph over the range 5-15 mg/L of isoniazid with a sample throughput of 43 samples/h. The influence of foreign compounds was studied and the method was applied to determination of the drug in a pharmaceutical formulation. © 1998 John Wiley & Sons, Ltd.
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  • 10
    ISSN: 0173-0835
    Keywords: Electrophoresis ; RNA ; Low molecular weight RNA ; Microbial taxonomy ; Microbial ecology ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Stable low molecular weight (LMW) RNA comprises molecules used in the taxonomy of microorganisms and in studies on the microbial diversity of populations. However, the use of electrophoretic techniques has been hampered due to the low resolution obtained with techniques used for the separation of this kind of molecule. In this work we develop an electrophoretic method (staircase electrophoresis) that increases the resolution of the technique. This improvement in the resolution adequately resolves the three zones that integrate the profiles of LMW RNA: ribosomic 5S RNA (5S rRNA), class 2 transfer RNA (tRNA), and class 1 transfer RNA, allowing the technique to be applied to taxonomic studies (diagnostic, the identification of the individuals), phylogenetic studies and studies on naturally occurring microbial populations.
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