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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 20 (1984), S. 155-160 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Four enzymes required for the biosynthesis of pencillins and cephalosporins by Streptomyces clavuligerus have been immobilized on an anion exchange resin. The capabilities of the system have been studied by circulation of reaction mixtures through the immobilized enzyme reactor. Within 30 min, all of the substrate δ-(l-α-aminoadipyl)-l-cysteinyl-d-valine is consumed and converted to a mixture of penicillins and cephalosporins. After 60 min the major antibiotic products are (iso)penicillin N and desacetylcephalosporin C. The activity of the immobilized enzyme reactor activity is stable to storage at temperatures below 4°C but activity is lost on repeated use.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The multi-subunit enzyme, δ-(L-α-aminoadipyl)-L-cysteinyl-D-valine (ACV) synthethase catalyses the first step in the biosynthetic pathway of the β-lactam antibiotic, cephamycin C. In batch fermentations of Streptomyces clavuligerus, ACV synthetaase activity appeared during the rapid growth phase. Over the same period the dissolved oxygen (DO) content of the medium was depleted to zero and remained there for nearly 10 h. Maintainance of the DO at saturation throughout the fermentation did not change the maximum ACV synthetaase specific activity, but did reduce the in-vivo stability of the enzyme. Oxygen saturation lowered the maximum intracellular ACV levels to one-sixth of those accumulated in the fermentor with no oxygen control, due principally to an improvement in the conversion of ACV to the penicillin N intermediate. Increased oxygenation also improved ACV conversion to cephamycin C, which demostrated that the activity of both an early and a later enzymatic step in cephamycin biosynthesis was limiting antibiotic production under restricted oxygen conditions. The later step, catalysing the conversion of penicillin N to cephamycin C, showed the greatest sensitivity to the oxygen state of the culture.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 30 (1989), S. 111-114 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary δ-(l-α-Aminoadipyl)-l-cysteinyl-d-valine (ACV) synthetase activity has been partially-purified from cell-free extracts of Streptomyces clavuligerus by ammonium sulfate precipitation. The salt precipitated enzyme was immobilized on an anion exchange resin and synthesis of ACV was observed by exposing the immobilized enzyme preparation to a reaction mixture containing l-α-aminoadipic acid, l-valine and l-cysteine in the presence of appropriate cofactors. Reaction mixtures containing l-α-aminobutyric acid(aB) in place of l-valine synthesized the ACV analog ACaB. Immobilized ACV synthetase can be reused, and after six cycles of reaction, 28.9% of original activity remains.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 31 (1989), S. 390-396 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary When grown in a chemically defined medium, Streptomyces clavuligerus excreted cephamycin C, in addition to other components, throughout most of the growth phase. Ferrous iron and oxygen are required for the biosynthesis of this antibiotic and the concentration of these cofactors was manipulated to maximize cephamycin C production. The iron content of the chemically defined medium was shown to be sub-optimal for antibiotic production and the addition of 130 μg/ml ferrous iron almost doubled the cephamycin C levels to 200 μg/ml. When dissolved oxygen was maintained at saturation levels, only 60–80 μg/ml cephamycin C was produced, and the intermediate penicillin N accumulated to high levels (50 μg/ml). This suggests that the high concentration of dissolved oxygen had a greater effect on the enzymes catalysing the conversion of penicillin N to cephamycin C, than on those involved in the earlier steps of the pathway leading to the formation of penicillin N.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature structural biology 3 (1996), S. 290-297 
    ISSN: 1072-8368
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] The structure of TEM-1 β-lactamase complexed with the inhibitor BLIP has been determined at 1.7 Å resolution. The two tandemly repeated domains of BLIP form a polar, concave surface that docks onto a predominantly polar, convex protrusion on the enzyme. The ability of BLIP to adapt to a ...
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Molecular genetics and genomics 214 (1988), S. 562-569 
    ISSN: 1617-4623
    Keywords: Isopenicillin-N synthase ; Streptomyces ; β-lactam antibiotics ; Sequence similarity ; Cloning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The genes coding for isopenicillin N synthase (IPNS) in Streptomyces jumonjinensis and S. lipmanii were isolated from recombinant phage lambda libraries using the S. clavuligerus IPNS gene as a heterologous probe. The S. jumonjinensis IPNS gene has an open reading frame coding for 329 amino acids, identical in size to that of the previously cloned S. clavuligerus IPNS gene. A partial nucleotide sequence was also determined for the S. lipmanii IPNS gene. Comparison of the predicted amino acid sequences of all three streptomycete IPNS proteins shows that they exhibit more than 70% similarity, close to that found in comparisons among fungal IPNS proteins and significantly greater than that found, approximately 60%, between Streptomyces and fungal IPNS proteins. We conclude that procaryotic and eucaryotic IPNS genes are subgroups of a single family of microbial IPNS genes. Hybridization probes prepared from IPNS genes of the above streptomycete species were used to detect analogous genes in eight other strains that included both penicillin and cephalosporin producers and non-producers. Each producer strain responded with all three probes implying the presence of an IPNS gene. Surprisingly, several non-producer strains also responded with one or two of the probes. Our results suggest that IPNS-related genes may be more prevalent in Streptomyces than previously believed.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 368 (1994), S. 657-660 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The molecular structure of BLIP was determined by the method of multiple isomorphous replacement (MIR; Fig. \b). It has been refined using data in the resolution range of 20.0 A to 2.1 A to an agreement index (/? = £ \\F0\ - \Fc\\/£ \F0\, where |F0| and |FC| and the measured and ...
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  • 8
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 359 (1992), S. 700-705 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The X-ray crystal structure of the molecular complex of penicillin G with a deacylation-defective mutant of the RTEM-1 β-lactamase from Escherichia coli shows how these antibiotics are recognized and destroyed. Penicillin G is covalently bound to Ser 70 Oγ as an ...
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 25 (1984), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Phosphate interference in the production of cephalosporins by Streptomyces clavuligerus had been associated with repression of expandase (desacetoxycephalosporin C synthetase) and inhibition of both expandase and cyclase (isopenicillin N synthetase). The present work shows that inhibition of enzyme action could be prevented by increasing the Fe2+ added to the cell-free reactions or to resting cells incubated with chloramphenicol. Since excess Fe2+ could not reverse phosphate interference of antibiotic synthesis in complete fermentations, it is clear that the major cause of the phosphate effect in fermentations is phosphate repression, rather than phosphate inhibition caused by Fe2+ deprivation.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 131 (1995), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract A survey of the total cellular DNA from five β-lactam antibiotic-producing Streptomyces spp. by pulsed field gel electrophoresis was conducted to investigate the presence of linear plasmids. Streptomyces clavuligerus NRRL 3585 contained two giant linear plasmids of 120 and 430 kb, in addition to the well-characterized 11.7 kb linear plasmid. Streptomyces griseus NRRL 3851 contained a single giant linear plasmid of 120 kb, and Streptomyces jumonjinensis NRRL 5741 contained two giant linear plasmids (220 and 280 kb), and two smaller linear plasmids. No plasmids were identified in Streptomyces cattleya NRRL 3841 or Streptomyces lipmannii NRRL 3584. Southern hybridization did not reveal any homology shared by these plasmids, and β-lactam antibiotic synthesis gene clusters were located on the chromosome.
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