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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 19 (1970), S. 384-389 
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Ergebnisse von Elektronen-Rechnungen für DNA-Basenpaare (ohne CI für den Grundzustand) werden mitgeteilt. Der erste Singulett- und Triplettzustand sind jeweils Zustände mit lokalisierter Anregung. Auch die Wechselwirkung mit mehrfach angeregten Konfigurationen ändert daran nichts. Ferner wird die Möglichkeit von UV-induzierten Mutationen diskutiert und die Resultate der Rechnungen mit Protonentransfer-Konstanten der Basenpaare verglichen.
    Abstract: Résumé Calculs des plus bas états électroniques π des paires de base du DNA avec la méthode SCF MO LCAO sans et avec interaction de configurations avec tous les monoexcités. On montre que le premier état excité singulet et le premier état excité triplet des deux paires dans l'approximation à une configuration sont les états où l'excitation est localisée sur l'une des deux bases. Dans le cas multiconfigurationnel on obtient qualitativement le même résultat. Discussion de la possibilité de mutations induites par irradiation UV, provoquées par transfert tunnel du proton dans les liaisons hydrogène. Les résultats du calcul sont comparés avec les constantes de transfert du proton dans les paires de bases.
    Notes: Abstract The results of calculations of the lowest π-electronic states of the DNA base pairs with the SCF MO LCAO method both without taking into account configuration interaction and taking into account all the singly excited configurations are presented. The first excited singlet state and the first triplet state of both pairs in a one-configurational approximation are shown to be the states where the excitation is localized on one of the bases. The calculations in a multi-configurational interaction give qualitatively the same result. The possibility of the UV irradiation-induced mutations, the mechanism of which is caused by the proton tunneling on the hydrogen bonds in DNA, is discussed. The results of calculations are compared with the proton transfer constants in the base pairs.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The results of calculations of the transition energies and polarization in nucleotide bases performed by the CNDO/S CI method are compared with experimental data for long-wavelength and vacuumabsorption bands. The calculations and the analysis of experimental data testify to the existence of n - π* transitions in the first absorption bands of the bases. The study of double-stranded polynucleotides and DNA hypochromism based on the theoretical electronic characteristics of the bases and perturbation theory is performed. The role of stacking and complementary interactions within the hypochromic effect is cleared up. Two mechanisms for the shift of the fluorescence band maximum are investigated: two-proton transfer along H bonds and excimer formation. The study of H-bond potential curves shows the disadvantage of two-proton phototautomerism in the nucleotide base pairs in contrast to model systems. The possibility of excimer state formation in stacked homo- and heterodimers of nucleotide bases is shown within the extended-Hückel treatment. The nature of excimer minimum for the excited-state potential curve is analyzed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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