Anion interactions of cytosine nucleobase and its nucleosides: Detailed view from DFT study

The noncovalent interactions between cytosine nucleobase with some biological anions such as F-, Cl-. CN-, NO3-,SO42- and OH- and cytosine nucleosides (i.e., cytidine and deoxycytidine molecules) with F-, Cl-, CN- anions have been demonstrated by DFT study. The molecular geometries, energy properties, H-bonding patterns, dipole moments and charge distribution of these complexes were investigated with the B3LYP method in conjunction with the 6-311++G(d,p) basis set. It has been found that anions can interact with cytosine nucleobase forming hydrogen bonds. In general, these interactions occur via N-H. O-H and C-H substituents of cytosine, cytidine and deoxycytidine. The presence of anions near these molecules strongly affects the electron distribution in the base structure. From this study, a greater understanding of hydrogen bonding interactions involving DNA and RNA molecules will be obtained. These interactions could provide insight to an unrecognized control element in biological processes, providing new and intriguing opportunities of exploring the electrostatic effects on biological processes. (C) 2009 Elsevier B.V. All rights reserved.