Результаты поиска по 'cytosines':
Найдено статей: 3
  1. Kliuev P.N., Ramazanov R.R.
    The mechanism of dissociation of cytosine pairs mediated by silver ions
    Computer Research and Modeling, 2019, v. 11, no. 4, pp. 685-693

    The development of structured molecular systems based on a nucleic acid framework takes into account the ability of single-stranded DNA to form a stable double-stranded structure due to stacking interactions and hydrogen bonds of complementary pairs of nucleotides. To increase the stability of the DNA double helix and to expand the temperature range in the hybridization protocols, it was proposed to use more stable metal-mediated complexes of nucleotide pairs as an alternative to Watson-Crick hydrogen bonds. One of the most frequently considered options is the use of silver ions to stabilize a pair of cytosines from opposite DNA strands. Silver ions specifically bind to N3 cytosines along the helix axis to form, as is believed, a strong N3–Ag+–N3 bond, relative to which, two rotational isomers, the cis- and trans-configurations of C–Ag+–C can be formed. In present work, a theoretical study and a comparative analysis of the free energy profile of the dissociation of two С–Ag+–C isomers were carried out using the combined method of molecular mechanics and quantum chemistry (QM/MM). As a result, it was shown that the cis-configuration is more favorable in energy than the trans- for a single pair of cytosines, and the geometry of the global minimum at free energy profile for both isomers differs from the equilibrium geometries obtained previously by quantum chemistry methods. Apparently, the silver ion stabilization model of the DNA duplex should take into account not only the direct binding of silver ions to cytosines, but also the presence of related factors, such as stacking interaction in extended DNA, interplanar hydrogen bonds, and metallophilic interaction of neighboring silver ions.

    Keywords: DNA, cytosines, silver ions, QM / MM, free energy profile.
    Views (last year): 2.
  2. Yakushevich L.V.
    Biomechanics of DNA: rotational oscillations of bases
    Computer Research and Modeling, 2011, v. 3, no. 3, pp. 319-328

    In this paper we study the rotational oscillations of the nitrous bases forming a central pair in a short DNA fragment consisting of three base pairs. A simple mechanical analog of the fragment where the bases are imitated by pendulums and the interactions between pendulums — by springs, has been constructed. We derived Lagrangian of the model system and the nonlinear equations of motions. We found solutions in the homogeneous case when the fragment considered consists of identical base pairs: Adenine-Thymine (AT- pair) or Guanine-Cytosine (GC-pair). The trajectories of the model system in the configuration space were also constructed.

    Keywords: DNA, modeling, rotational oscillations of bases.
    Views (last year): 3. Citations: 2 (RSCI).
  3. Yakushevich L.V., Ryasik A.A.
    Dynamical characteristics of DNA kinks and antikinks
    Computer Research and Modeling, 2012, v. 4, no. 1, pp. 209-217

    In this article in the frameworks of the sine-Gordon mode we have calculated the dynamical characteristics of kinks and antikinks activated in the homogeneous polynucleotide chains each if them contains only one of the types of the bases: adenines, thymines, guanines or cytosines. We have obtained analytical formulas and constructed the graphs for the kink and antikink profiles and for their energy density in the 2D- and 3D-dimension. Mass of kinks and antikinks, their energy of rest and their size have been estimated. The trajectories of kink and antikink motion in the phase space have been calculated in the 2D- and 3D-dimension.

    Keywords: mathematical modeling, sine-Gordon equation, DNA-mobility, biophysics.
    Views (last year): 2. Citations: 7 (RSCI).

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