Ten G N, Kadrov D M, Baranov V I
Biofizika. 2014 Jul-Aug;59(4):656-65.
The influence of hydrophilic and hydrophobic properties of the uracil elementary nucleic acids bases on its solubility and structure in aqueous solution was studied. Complexes of uracil with water molecules (from 1 to 14) were then calculated. The geometrical parameters of the hydrogen bridge of uracil and the changes in the frequency of valence vibrations of the bonds participating directly in hydrogen bond formation were calculated. It is shown that for the hydrogen bonds O(w)...HN(1) and O(w)...HN3 the hydrogen atom can tear, it may lead to tautomeric transformation of uracil. The results obtained having calculated the structure of uracil dimers, formed with the hydrogen bonds, in an isolated state and water solution, energy, dipole moments and the hydrogen bridge parameters made it possible to explain low solubility of uracil in water at room temperature. It is shown that water molecules with increase in their number are located mainly at one side of the plane of a pyrimidine uracil ring, that leads to the formation of stacking. Of two possible variants of stacking formation, the most profitable grouping is when a dipole moment of the formed dimer is equal to zero (anti-parallel stacking).
研究了尿嘧啶基本核酸碱基的亲水性和疏水性对其在水溶液中的溶解度和结构的影响。然后计算了尿嘧啶与水分子（1至14个）形成的配合物。计算了尿嘧啶氢键的几何参数以及直接参与氢键形成的键的价振动频率变化。结果表明，对于氢键O(w)...HN(1)和O(w)...HN3，氢原子可能会脱离，这可能导致尿嘧啶的互变异构转变。通过计算孤立状态和水溶液中由氢键形成的尿嘧啶二聚体的结构、能量、偶极矩和氢键参数，所得结果能够解释尿嘧啶在室温下在水中的低溶解度。结果表明，随着水分子数量的增加，水分子主要位于嘧啶尿嘧啶环平面的一侧，这导致了堆积的形成。在堆积形成的两种可能变体中，最有利的组合是形成的二聚体偶极矩等于零（反平行堆积）。
