ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Lability of iron at the dinuclear centres of ferritin studied by competition with four chelators (1996)
    Springer
    JBIC 1 (1996), S. 49-60 
    Details
    ISSN: 1432-1327
    Keywords: Key words Ferritin ; Dinuclear iron ; 1 ; 10-Phenanthroline ; Desferrioxamine ; 3 ; 4-Dihydroxybenzaldehyde
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract  Ferritin molecules contain 24 polypeptide chains folded as four-helix bundles and arranged as a hollow shell capable of storing up to 4500 Fe(III) atoms. H chains contain ferroxidase centres which lie within the bundle, about 12 Å (1.2 nm) from the outside surface and 8 Å from the inner surface of the protein shell. Catalysis of Fe(II) oxidation precedes storage of Fe(III) as ferrihydrite, with the formation of μ-oxo-bridged Fe(III) dimers as intermediates. Factors influencing the movement of μ-oxo-bridged Fe(III) from the ferroxidase centre to the ferritin cavity are uncertain. Assistance by small chelators is one possibility. The aim of this investigation was to determine whether iron at the dinuclear centres of three ferritins (human H chain homopolymer, HuHF, the non-haem ferritin of Escherichia coli, EcFTN, and horse spleen ferritin, HoSF) is accessible to chelators. Forty-eight Fe(II) atoms/molecule were added to the apoferritins followed, 2 min later, by the addition of chelator (1,10-phenanthroline, 2,2-bipyridine, desferrioxamine or 3,4-dihydroxybenzaldehyde). Iron species were analysed by Mössbauer spectroscopy or visible absorbance. Competition between chelators and apoferritin for Fe(II) was also investigated. The main conclusions of the study are that: (1) dinuclear iron and iron in small iron-cores in HuHF and EcFTN is mobilisable by all four chelators; (2) the chelators penetrate the shell; (3) 3,4-dihydroxybenzaldehyde is the most efficient in mobilising Fe(III) but the least successful in competing for Fe(II); (4) Fe(III) is more readily released from EcFTN than from HuHF; (5) 2,2′-bipyridine aids the movement of Fe(III) from ferroxidase centre to core.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007750050022
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    The use of zinc(II) to probe iron binding and oxidation by the ferritin (EcFtnA) of Escherichia coli (1998)
    Springer
    JBIC 3 (1998), S. 682-688 
    Details
    ISSN: 1432-1327
    Keywords: Key words Dinuclear centre ; Diiron site ; Ferritin ; Iron oxidation ; Bacterial ferritin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract  The ferritin of Escherichia coli (EcFtnA) is similar to human H-chain ferritin (HuHF) in having 24 subunits, each containing a dinuclear site at which two iron atoms can be oxidised (the diiron centre). In EcFtnA, unlike HuHF, fluorescence quenching of Trp122, located near site A of the dinuclear centre, can be used to monitor metal binding (this tryptophan is absent from HuHF). Metal binding also perturbs the UV absorbance spectrum of Trp122 and that of Tyr24 (a conserved residue near site B of the dinuclear centre). Using UV-difference spectroscopy and fluorescence quenching it is shown that Fe(II) and Zn(II) bind at the same sites, A and B. Sequential stopped-flow studies of Fe(II) binding and oxidation also show that Zn(II) is an effective competitor of Fe(II) binding and an inhibitor of its oxidation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007750050282
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Molecular cloning of the fnr gene of Escherichia coli K12 (1981)
    Springer
    Molecular genetics and genomics 181 (1981), S. 95-100 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Mutations in the fnr gene of Escherichia coli have pleiotropic effects leading to deficiencies in the reduction of fumarate and nitrate, hydrogen production and the ability to grow anaerobically with fumarate or nitrate as terminal electron acceptors. Transducing phages (λfnr) carrying the wild-type fnr gene were isolated from populations of artificially-constructed recombinant lambda phages by their ability to complement the lesions of fnr mutants. The λfnr phages restored anaerobic growth with fumarate and nitrate as electron acceptors and, as prophages, they promoted normal synthesis of fumarate reductase, nitrate reductase and hydrogenase in fnr mutants. Five independently-isolated λfnr phages each contained a R.HindIII fragment (11.5 kilobases) that possessed three internal R.EcoRI targets and had inserted with the same orientation relative to the phage. A physical map of the fnr region was constructed by restriction analysis and flanking fragments were identified by DNA:DNA hybridization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00339011
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Molecular cloning of menaquinone biosynthetic genes of Escherichia coli K12 (1981)
    Springer
    Molecular genetics and genomics 181 (1981), S. 379-383 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A tranducing phage carrying some of the genes (men) defining the early stages of menaquinone biosynthesis was isolated from a pool of recombinant lambda phages that had been constructed from R.HindIII digests of E. coli DNA and the corresponding insertion vector. The lesions of menB and menC mutants were complemented by the phage but menD mutants were transduced either at low frequencies or not at all. This indicates that the transducing phage contains functional menB and menC genes but that only part of the menD gene had been cloned. The phage (λG68) was accordingly disignated γmenCB(D). Studies with the transducing phage enabled earlier mapping data (Guest 1979) to be reinterpreted in favour of the gene order nalA.... menC..menB..menD.... purF. Restriction analyses established the presence of a bacterial DNA fragment (11.5 kb) linked by a R.HindIII target to the right arm of the γ genome but fused to the left arm of the vector. Hybridization studies confirmed that the cloned DNA was derived from a larger R.HindIII fragment (21 kb). A physical map of the men region was constructed and some flanking and overlapping fragments were identified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425615
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Amplification of fumarate reductase synthesis with λfrdA transducing phages and orientation of frdA gene expression (1980)
    Springer
    Molecular genetics and genomics 179 (1980), S. 377-385 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Thermoinducible lysis-defective derivatives of λfrdA phages (λG1F and λG40F) carrying the fumarate marate reductase gene of Escherichia coli, inserted in each of two possible orientations, were used to amplify fumarate reductase synthesis and study the aerobic repression of frdA gene expression. Anaerobic induction of lysogens containing λfrdA cI ts Q −S− phages increased the fumarate reductase activities by up to 5 times the normal anaerobic level. Aerobic repression of frdA expression was overcome during aerobic induction and reductase activities up to twice the normal anaerobic level were produced. The rates and extents of amplification were dependent on the orientation of frdA in the λcI ts Q−S− derivatives but not in the corresponding λcI − N phages. Assays for the frdA-linked ampC gene product, β-lactamase, indicated that the intact ampC gene is not incorporated in the λfrdA phages. Autoradiographic analysis of the polypeptides synthesized by U.V.-irradiated bacteria infected with λfrdA phages confirmed the identification of a polypeptide (Mr=72,000) as the frdA gene product (the large subunit of fumarate reductase). No precursor form was detected but another polypeptide (Mr=26.000) encoded by the 4.9 kb R.HindIII fragment was detected. The corresponding gene (g26) could be the structural gene (frdB) for the small subunit of fumarate reductase. The directions of transcription of the cloned frdA and g26 genes were deduced for the transducing phages λG1F (λfrdA r) and λG40F (λfrdA 1) and were shown to be anticlockwise on the conventional Escherichia coli genetic map.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425468
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Transcription analysis of the sucAB, aceEF and lpd genes of Escherichia coli (1985)
    Springer
    Molecular genetics and genomics 200 (1985), S. 145-154 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Transcript mapping of the Escherichia coli sucAB, aceEF and lpd genes, encoding the five components of the pyruvate and 2-oxoglutarate dehydrogenase complexes, was carried out using single-stranded M13 probes. The sucA and aceE genes encode the specific dehydrogenase components (E1o, E1p), and the sucB and aceF genes encode the specific dihydrolipoamide acyltransferases (E2o, E2p). The common lipoamide dehydrogenase (E3) component is encoded by a single lpd gene adjacent to the aceEF genes. The sucAB, aceEF and lpd genes were all expressed on independent transcripts, and the promoters and terminators were identified. In addition, readthrough transcription from the sucAB genes to a downstream gene designated sucC, and from the aceEF genes to the adjacent lpd gene, was found. The relative levels of transcription of the suc, ace and lpd genes, and of the three different transcript types covering the ace-lpd region, were quantified using RNA from cells grown on different substrates. Most of the E3 components supplying the pyruvate dehydrogenase complex appear to be synthesised from ∼6415-base aceEF-lpd readthrough transcripts, but additional ∼4640-base aceEF transcripts terminating after the aceF gene provide a transcriptional basis for the observed stoichiometric excess of E1p and E2p relative to E3 in the assembled complex. Conversely most of the E3 components required for the 2-oxoglutarate dehydrogenase complex appear to be synthesised from the independent 1670-base lpd transcripts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00383328
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Genetic and physical characterization of lambda transducing phages (λfrdA) containing the fumarate reductase gene of Escherichia coli K12 (1980)
    Springer
    Molecular genetics and genomics 178 (1980), S. 409-418 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two types of fumarate reductase transducing phages, λfrdA, carrying the wild-type frdA gene but differing in the orientation of a R.HindIII fragment of bacterial DNA were isolated from populations of recombinant transducing phages by their ability to complement the lesions of frdA mutants of E. coli. In lysogens, the cloned frdA gene was controlled by its own promoter and was fully responsive to normal regulatory stimuli. The λfrdA phages would not complement the defects of succinate dehydrogenase (sdh) mutants. Genetic studies showed that the R.HindIII fragment contains ampA, the cis-acting regulatory locus for the chromosomal β-lactamase gene ampC. No evidence for the presence of other markers was detected but the bacterial segment could be extended to produce plaque-forming phage derivatives containing the amp operon and a gene concerned with bacteriophage morphogenesis, groE(mop). A physical map of the 4.9 kb R.HindIII fragment was constructed by restriction analysis and flanking fragments were identified by DNA: DNA hybridization analysis. The frdA region contained a single asymmetric R.EcoRI target 3.33 kb from one end and the orientation of the physical map with respect to the E. coli linkage map was established.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00270492
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...