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Binding of singlet oxygen with a stacked guanine dimer
Author(s) -
Kushwaha P. S.,
Mishra P. C.
Publication year - 2004
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.20414
Subject(s) - guanine , dimer , molecule , chemistry , crystallography , bond length , solvation , density functional theory , singlet oxygen , computational chemistry , stereochemistry , oxygen , crystal structure , nucleotide , biochemistry , organic chemistry , gene
Geometry optimization calculations were performed using the B3LYP/6‐31+G* method on the complexes of 1 O 2 and 3 O 2 molecules with a stacked dimer of planar guanine, varying the distance (D) between the planes of the guanine molecules. In this process, geometries of the guanine molecules were held fixed, D was fixed at different values, while the bond lengths of 1 O 2 and 3 O 2 as well as their orientations with respect to the guanine molecules were optimized for each value of D. The complexes in their most stable geometries were solvated in water using the integral equation formalism of the polarized continuum model of the self‐consistent reaction field theory. In gas phase, the most stable complex between 1 O 2 and the guanine dimer (2G. 1 O 2 ) is formed when D is about 6 Å, while the most stable complex between 3 O 2 and the guanine dimer (2G. 3 O 2 ) is formed when D is about 3.75 Å. In the minimum total energy geometry of 2G. 1 O 2 , 1 O 2 is located between the guanine molecules, above the imidazole ring of one of them. However, in the minimum total energy geometry of 2G. 3 O 2 , 3 O 2 is located outside the stack of guanine molecules, near the amino group of one of them. The solvation calculations showed that in aqueous media, 1 O 2 would bind with the stacked guanine dimer more strongly than in gas phase, while 3 O 2 would not bind with the same. The mode of binding of 1 O 2 with the stacked guanine dimer is such that it seems that 1 O 2 would replace one basepair in DNA, as happens in the intercalative mode of binding of drugs and other molecules, and it can lead to the formation of 8‐oxoguanine that has a mutagenic nature. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005