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  • 1
    Electronic Resource
    Electronic Resource
    Reaktionskinetische untersuchungen an einem makroporösen unquellbaren polystyrol: Abspaltung von nucleosiden und nucleotiden, die über p-anisyldiphenylmethylätherbindung an das polymerisat gebunden sind (1973)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 167 (1973), S. 171-182 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: A macroporous nonswellable copolymer of styrene and divinylbenzene (I) is converted to the polymeric derivative of p-anisyldiphenylmethyl chloride (VI) which reacts with the nucleosides dT(Ac) (VIIa), dbz6A(Ac) (VIIb) and the dinucleoside monophosphate dT-dT(Ac) (X) to form an ether bond. The rate of the cleavage of nucleotidic material from the carrier is studied as function of the kind of the protected or unprotected nucleoside or dinucleoside monophosphate, of the relation of VI to X in the loading reaction of the carrier and as a function of temperature. In order to enable comparable experiments in this heterogeneous reactions two values are introduced: the relative initial rate vrela which mainly describes the hydrolysis of the p-anisyldiphenylmethyl ether bond and the relative rate after one hour vrel1h which describes the diffusion phenomena taking place in the highly porous polymer.
    Notes: Ein makroporöses unquellbares Styrol-Divinylbenzol-Copolymerisat (I) wird in ein polymeres Derivat des p-Anisyldiphenylmethylchlorids (VI) übergeführt, das mit den Nucleosiden dT(Ac) (VIIa), dbz6A(Ac) (VIIb) und dem Dinucleosidmonophosphat dT-dT(Ac) (X) veräthert wird. Die Abspaltungsgeschwindigkeit von nucleotidischem Material vom Träger wird in Abhängigkeit von der Art des geschützten oder ungeschützten Nucleosids bzw. Dinucleosidphosphats, von dem bei der Beladung des Trägers vorliegen den Verhältnis von VI zu X und in Abhängigkeit von der Temperatur untersucht. Um vergleichende Untersuchungen dieser heterogenen Reaktionen durchführen zu können, werden zwei Größen eingeführt: die relative Anfangsgeschwindigkeit vrela beschreibt vorwiegend die Hydrolyse der p-Anisyldiphenylmethyläther-Bindung, die relative Geschwindigkeit nach einer Stunde vrel1h das komplexe Diffusionsgeschehen innerhalb des verzweigten Hohlraumsystems des Polymerisates.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1973.021670111
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  • 2
    Electronic Resource
    Electronic Resource
    The structure of the anticodon loop of tRNAPhe from yeast as deduced from spectroscopic studies on oligonucleotides (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 155-171 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The hexanucleotide Gm-A-A-Y-A-ψp excised from the anticodon loop of yeast tRNAPhe and its constituent oligonucleotides have been studied by ultraviolet absorption spectroscopy, static fluorescence, and circular dichroism. Gm-Ap has a melting point of 45°C and a high melting enthalpy when compared with G-Ap; hence 2′-O-methylation seems to stabilize stacking interactions. The nucleobase Y adjacent to the 3′-side of the anticodon triplet interacts stronger with its 3′-neighboring A than with its 5′-neighboring A. It is concluded that the base Y disconnects the stack of the anticodon itself from the stack of the anticodon stem, thereby setting a reading frame for the mRNA in the course of protein biosynthesis. From the opposite signs of the short-wavelength Cotton effects in the spectra of Gm-A-A-Y-Ap and Gm-A-A-Y, it is concluded that Y after removal of its 3′ neighbor undergoes a dramatic change in its conformation. The fluorescence of the nucleobase Y upon addition of Mg2+ is enhanced in oligonucleotides longer than two. An identical enhancement is observed for tRNAPhe, indicating that this Mg2+ effect is a property of an oligonucleotide segment and does not reflect conformational changes of the whole tRNA. The data presented here reveal that the basic structural features of the anticodon loop are already present in the hexanucleotide Gm-A-A-Y-A-ψp and are not determined by the overall structure of tRNA.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140112
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  • 3
    Electronic Resource
    Electronic Resource
    Spectroscopic properties of oligonucleotides excised from the anticodon region of phenylalanine tRNA from yeast (1973)
    New York : Wiley-Blackwell
    Biopolymers 12 (1973), S. 27-43 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ultraviolet absorption and static fluorescence properties of hexanucleotide (Gm-A-A-Y-A-ψp) and a dodecanucleotide (A-Cm-U-Gm-A-A-Y-A-ψ-m5C-U-Gp) excised from the anticodon region of phenylalanine tRNA from yeast have been studied with respect to temperature, pH, ionic strength, and Mg2+ concentration. At low temperature these oligomers have a largely stacked structure. Only the melting data of the dodecanucleotide in absence of Mg2+ fit a two-state model. From the different melting behavior of the oligonucleotides after excision of base Y, a rodlike structure of the hexanucleotide produced by stacking interactions can be concluded. The Y fluorescence increase produced by Mg2+ has been used to evaluate the binding equilibria between Mg2+ and the oligonucleotides. One strong binding site per oligonucleotide and a greater number of weak binding sites have been found. The fluorescence of the free base Y is not influenced by Mg2+. The dodecanucleotide enhances the ethidium fluorescence to the same extent as tRNAPhe and produces comparable shifts in the excitation and emission spectra. Therefore a double helical structure for this oligomer under the assay conditions is suggested. Only weak binding of ethidium to the hexanucleotide is observed, indicating that intercalation of the dye into its structure is not favored. The data show the decisive role of the nucleobase Y in maintaining a rigid stacked structure of the anticodon nucleotides. This structure is stabilized by high ionic strength, Mg2+, and ethidium.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1973.360120104
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