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  • Crystallography, X-Ray  (3)
  • Organic Chemistry
  • 1995-1999  (4)
  • 1998  (4)
  • 1
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    A model for the mechanism of human topoisomerase I (1998)
    American Association for the Advancement of Science (AAAS)
    Details
    Publikationsdatum: 1998-03-21
    Beschreibung: The three-dimensional structure of a 70-kilodalton amino terminally truncated form of human topoisomerase I in complex with a 22-base pair duplex oligonucleotide, determined to a resolution of 2.8 angstroms, reveals all of the structural elements of the enzyme that contact DNA. The linker region that connects the central core of the enzyme to the carboxyl-terminal domain assumes a coiled-coil configuration and protrudes away from the remainder of the enzyme. The positively charged DNA-proximal surface of the linker makes only a few contacts with the DNA downstream of the cleavage site. In combination with the crystal structures of the reconstituted human topoisomerase I before and after DNA cleavage, this information suggests which amino acid residues are involved in catalyzing phosphodiester bond breakage and religation. The structures also lead to the proposal that the topoisomerization step occurs by a mechanism termed "controlled rotation."〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Stewart, L -- Redinbo, M R -- Qiu, X -- Hol, W G -- Champoux, J J -- CA65656/CA/NCI NIH HHS/ -- GM16713/GM/NIGMS NIH HHS/ -- GM49156/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1998 Mar 6;279(5356):1534-41.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Biomolecular Structure Center and Department of Biological Structure, School of Medicine, University of Washington, Seattle, WA 98195-7742, USA. emerald_biostructures@rocketmail.com〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9488652" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Amino Acid Sequence ; Arginine/chemistry/metabolism ; Binding Sites ; Catalysis ; Crystallography, X-Ray ; DNA/chemistry/*metabolism ; DNA Topoisomerases, Type I/*chemistry/*metabolism ; Humans ; Hydrogen Bonding ; *Models, Chemical ; Models, Molecular ; Molecular Sequence Data ; Nucleic Acid Conformation ; Oligodeoxyribonucleotides/chemistry/metabolism ; *Protein Conformation ; Protein Structure, Secondary ; Tyrosine/chemistry/metabolism
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Publiziert von American Association for the Advancement of Science (AAAS)
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
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    Inhibition of the hammerhead ribozyme cleavage reaction by site-specific binding of Tb (1998)
    American Association for the Advancement of Science (AAAS)
    Details
    Publikationsdatum: 1998-01-24
    Beschreibung: Terbium(III) [Tb(III)] was shown to inhibit the hammerhead ribozyme by competing with a single magnesium(II) ion. X-ray crystallography revealed that the Tb(III) ion binds to a site adjacent to an essential guanosine in the catalytic core of the ribozyme, approximately 10 angstroms from the cleavage site. Synthetic modifications near this binding site yielded an RNA substrate that was resistant to Tb(III) binding and capable of being cleaved, even in the presence of up to 20 micromolar Tb(III). It is suggested that the magnesium(II) ion thought to bind at this site may act as a switch, affecting the conformational changes required to achieve the transition state.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Feig, A L -- Scott, W G -- Uhlenbeck, O C -- GM-36944/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1998 Jan 2;279(5347):81-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9417029" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Binding Sites ; Binding, Competitive ; Catalysis ; Crystallography, X-Ray ; Magnesium/metabolism ; Models, Molecular ; Nucleic Acid Conformation ; RNA, Catalytic/*antagonists & inhibitors/chemistry/*metabolism ; Terbium/*metabolism/pharmacology
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Publiziert von American Association for the Advancement of Science (AAAS)
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
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    Crystal structures of human topoisomerase I in covalent and noncovalent complexes with DNA (1998)
    American Association for the Advancement of Science (AAAS)
    Details
    Publikationsdatum: 1998-03-21
    Beschreibung: Topoisomerases I promote the relaxation of DNA superhelical tension by introducing a transient single-stranded break in duplex DNA and are vital for the processes of replication, transcription, and recombination. The crystal structures at 2.1 and 2.5 angstrom resolution of reconstituted human topoisomerase I comprising the core and carboxyl-terminal domains in covalent and noncovalent complexes with 22-base pair DNA duplexes reveal an enzyme that "clamps" around essentially B-form DNA. The core domain and the first eight residues of the carboxyl-terminal domain of the enzyme, including the active-site nucleophile tyrosine-723, share significant structural similarity with the bacteriophage family of DNA integrases. A binding mode for the anticancer drug camptothecin is proposed on the basis of chemical and biochemical information combined with these three-dimensional structures of topoisomerase I-DNA complexes.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Redinbo, M R -- Stewart, L -- Kuhn, P -- Champoux, J J -- Hol, W G -- CA65656/CA/NCI NIH HHS/ -- GM49156/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1998 Mar 6;279(5356):1504-13.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Biomolecular Structure Center and Department of Biological Structure, Box 357742, School of Medicine, University of Washington, Seattle, WA 98195, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9488644" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Antineoplastic Agents, Phytogenic/metabolism/pharmacology ; Binding Sites ; Camptothecin/analogs & derivatives/metabolism/pharmacology ; Crystallography, X-Ray ; DNA/chemistry/*metabolism ; DNA Topoisomerases, Type I/*chemistry/genetics/metabolism ; *DNA-Binding Proteins ; Homeodomain Proteins/chemistry ; Host Cell Factor C1 ; Humans ; Hydrogen Bonding ; Integrases/chemistry ; Models, Molecular ; Mutation ; Nucleic Acid Conformation ; Octamer Transcription Factor-1 ; Oligodeoxyribonucleotides/chemistry/metabolism ; *Protein Conformation ; Protein Structure, Secondary ; Recombinant Proteins/chemistry ; Transcription Factors/chemistry ; Tyrosine/chemistry/metabolism
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Publiziert von American Association for the Advancement of Science (AAAS)
    Standort Signatur Erwartet Verfügbarkeit
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    AKTUELLE ARTIKEL
  • 4
    Digitale Medien
    Digitale Medien
    Extent of chiral inversion of the 2-arylpropionic acids by Cordyceps militaris (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 528-534 
    Details
    ISSN: 0899-0042
    Schlagwort(e): chiral inversion ; ibuprofen ; ketoprofen ; flurbiprofen ; indoprofen ; suprofen ; fenoprofen ; metabolism of 2-arylpropionic acids ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The fungus Cordyceps militaris has been previously shown to be capable of inverting the chirality of 2-phenylpropionic acid from its (R)-enantiomer to its (S)-antipode. The structure of this compound is similar to the 2-arylpropionic acid non-steroidal anti-inflammatory drugs, which have also been reported to undergo a similar chiral inversion process in mammals and man. We report here an investigation into the substrate specificity of the enzyme system present in C. militaris using pure enantiomers and racemates of ibuprofen and ketoprofen and racemates of indoprofen, suprofen, flurbiprofen, and fenoprofen and the structurally related compounds 2-phenylbutyric acid and 2-phenoxypropionic acid as substrates, using optimised incubation conditions developed for the inversion of 2-phenylpropionic acid. The results demonstrated that C. militaris is capable of inverting the chirality of all the compounds investigated, which suggests that the active sites of the enzymes are very flexible with regard to the molecular dimensions of the substrate molecule and the spatial occupation of the groups surrounding the chiral centre. Metabolism of all the substrates was observed but the rate of metabolism varied extensively depending on the substrate. Achiral HPLC analysis was used to detect any potential metabolites and the results suggested that the site of the metabolism appeared to be at the aliphatic side groups only, with the aromatic ring being left intact in all cases. These results suggest that C. militaris could be a valuable tool in the investigation of the prospective metabolic fates of new 2-arylpropionic acids during their development. Chirality 10:528-534, 1998. © 1998 Wiley-Liss, Inc.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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