Reactions of NO(2)Cl with imidazole: a model study for the corresponding reactions of guanine.
Reactions of nitryl chloride NO(2)Cl with imidazole, taken as a model for the guanine base of DNA, leading to the formation of 2-oxoimidazole (2-oxoIm), 2-chloroimidazole (2-chloroIm), and 2-nitroimidazole (2-nitroIm) corresponding to the 8-oxo, 8-chloro, and 8-nitro derivatives of guanine were studied at the B3LYP and MP2 levels of theory employing the 6-31+G* and AUG-cc-pVDZ basis sets in gas phase. In order to incorporate solvent effect, all the B3LYP/AUG-cc-pVDZ optimized structures were solvated in aqueous media at the B3LYP/AUG-cc-pVDZ and MP2/AUG-cc-pVDZ levels of theory using the polarizable continuum model (PCM). A single mechanism was found for the formation of 2-oxoIm, while two and three mechanisms were found for the formation of 2-nitroIm and 2-chloroIm respectively. Each of these reaction mechanisms involves two steps. The calculated barrier energies show that the formation of 2-nitroIm would occur more efficiently than those of 2-oxoIm and 2-chloroIm. It suggests that formation of 8-nitroguanine would be the main DNA lesion caused by NO(2)Cl, which is consistent with experimental observations.
Department of Physics, Banaras Hindu University, Varanasi, India.
P K
PK
Shukla
P C
PC
Mishra
D017606:Chlorine Compounds / Q000737:chemistry*; D006147:Guanine / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D009609:Nitrous Oxide / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry
D017606:Chlorine Compounds; D007093:Imidazoles; D006147:Guanine; C029899:imidazole; D009609:Nitrous Oxide; D010100:Oxygen