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  • 1
    ISSN: 1617-4623
    Keywords: Key wordsSaccharomyces cerevisiae ; Gluconeogenesis ; Malate synthase ; Transcriptional regulation ; MLS1
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The malate synthase gene, MLS1, of the yeast Saccharomyces cerevisiae is transcriptionally regulated by the carbon source in the growth medium. A MLS1-lacZ fusion gene, expressed at a basal level in the presence of 2% glucose, is derepressed more than 100-fold under conditions of sugar limitation. No evidence for MLS1 induction by oleic acid was found. By deletion analysis of the MLS1 control region, we identified two sites, UAS1 and UAS2, as important for efficient derepression of the gene. Both sites contain sequences that resemble the previously characterized carbon source-responsive element (CSRE) found in the promoter of the isocitrate lyase gene ICL1. Indeed, UAS1 and UAS2 in the MLS1 upstream region turn out to be functional CSRE sequence variants. This finding allowed us to define a modified version of the CSRE consensus sequence (CCRTYSRNCCG). Protein binding to UAS1MLS1 was observed with extracts from derepressed but not from repressed cells, and could be competed for by an excess of the unlabelled CSRE(ICL1) sequence. No competition was observed with a mutated CSRE variant. Site-directed mutagenesis of both CSREs in the MLS1 promoter reduced gene activation under derepressing conditions to 20% of the wild-type level. The same decrease was observed with the wild-type MLS1 promoter in a cat8 mutant, lacking an activator of CSRE-dependent transcription. The CSRE/Cat8p-independent activation of MLS1 is mediated by constitutive UAS elements. The pleiotropic transcription factor Abf1p, which binds to the MLS1 upstream region, may contribute to constitutive activation. Thus, in order to ensure the severe glucose repression of MLS1 observed, repressor elements that respond to the carbon source must counteract constitutive activation. In summary, ICL1 and MLS1 share common cis-acting elements, although a distinct mechanism of carbon source control also contributes to MLS1 regulation.
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  • 2
    ISSN: 1617-4623
    Keywords: Prolidase ; Metalloprotease ; Lactobacillus delbrueckii subsp. lactis ; Nucleotide sequence analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract From a genomic library of Lactobacillus delbrueckii subsp. lactis (DSM7290) DNA, in the low-copy-number vector pLG339, a recombinant clone was selected, which complemented a mutation in the prolidase gene (pepQ) of Escherichia coli UK173. Nucleotide sequence analysis revealed an open reading frame of 1104 nucleotides corresponding to a protein of 368 amino acids with a calculated pI of 4.64 and a molecular mass of 41087 Da. The start site of pepQ transcription was determined by primer extension analysis with mRNA prepared from L. delbrueckii. Based on homology of the gene product to various peptidases and on the substrate specificity determined, the peptidase was designated PepQ. The influence of various protease inhibitors and cations on peptidase activity indicated that PepQ is a metalloprotease. The absence of a membrane-spanning domain and a signal peptide sequence argues for a cytoplasmic localization of the enzyme.
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  • 3
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Branched and Chain-extended Sugars, XXX.  -  Diastereoselective Synthesis of L-glycero-D-manno-Heptose, a Constituent of the Inner Core Region of LipopolysaccharidesReaction of 2,3;5,6-di-O-isopropylidene-D-mannofuranose (1) with 2-lithio-1,3-dithiane affords diastereoselectively the 3,4;6,7-di-O-isopropylidene-D-glycero-D-galacto-heptose trimethylene dithioacetal (3). Conversion of compound 3 by a sequence of steps gives the tri-O-isopropylidene-D-glycero-D-galacto-heptit 16 which is oxidized with 1,1′-(azodicarbonyl)-dipiperidine to give the tri-O-isopropylidene-L-glycero-D-manno-heptose 17. Finally, compound 17 is transferred via the acetate 19 into the L-glycero-D-manno-heptopyranose 18.
    Notes: 2,3;5,6-Di-O-isopropyliden-D-mannofuranose (1) reagiert diastereoselektiv mit 2-Lithio-1,3-dithian zum 3,4;6,7-Di-O-isopropyliden-D-glycero-D-galacto-heptose-trimethylendithioacetal (3). Nach Umwandlung von 3 über eine Reihe von Zwischenstufen zum Tri-O-isopropyliden-D-glycero-D-galacto-heptit 16 läßt sich dieser mit 1,1′-(Azodicarbonyl)dipiperidin zur Tri-O-isopropyliden-L-glycero-D-manno-heptose 17 oxidieren. Hieraus ist über das Acetat 19 die freie L-glycero-D-manno-heptopyranose 18 zu gewinnen.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1987 (1987), S. 249-258 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Building Units of Oligosaccharides, LXXVIII. - Synthesis of KDO-Containing Lipid A AnaloguesThe non-neighbouring group supported glycosidation of 12 with the suitably protected glycosyl bromide 9 of 2-azido-2-deoxy-D-glucose leads - in the presence of a heterogeneous silver catalyst - to the formation of the β-(1→6)-glycosidically linked disaccharide 14. It consists of two 2-azido-2-deoxy-D-glucose units. Partial deblocking of 14 furnishes 15. On glycosidation with KDO bromide this compound yields the trisaccharide 16, which contains a KDO unit in an α-(2→6) ketosidic bond. Reduction of the two azido groups followed by amidation with (R)-3-hydroxymyristic acid and further deblocking generates the trisaccharide α-KDO-(2→6)-β-D-GlcA-(1→6)-D-GlcA 20 with two 3-hydroxy fatty acid residues in an amidic linkage.
    Notes: Die Umsetzung des Pyranosylbromids 9 der 2-Azido-2-desoxy-D-glucose mit dem Akzeptor 12 führt bei Gegenwart eines heterogenen Silberkatalysators ohne Nachbargruppenbeteiligung unter Inversion zum β-(1→6)-glycosidisch verknüpften Disaccharid 14 aus zwei 2-Azido-2-desoxy-D-glucose-Einheiten. Nach partieller Entblockierung zu 15 ist die Anknüpfung eines KDO-Restes unter Bildung einer α-(2→6)-ketosidischen Bindung zum Trisaccharid 16 möglich. Nach Reduktion der Azidogruppen und Anknüpfung von (R)-3-Hydroxymyristinsäure-Resten gelangt man nach Entblockierung zum Trisaccharid α-KDO-(2→6)-β-D-GlcA-(1→6)-D-GlcA 20, das amidartig zwei 3-Hydroxyfettsäure-Reste gebunden enthält.
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  • 5
    ISSN: 0935-9648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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