Ab initio theoretical study of the structures of thymine glycol and dihydrothymine.
The structures of all diastereoisomers of 5,6-dihydroxy-5,6-dihydrothymine (thymine glycol) an 5,6-dihydrothymine, two important DNA lesions, have been optimized with ab initio quantum chemical methods at a 6-31 G level of calculations. The methyl group on C5 of thymine glycol shows a strong preference for a pseudo axial orientation. In contrast, in 5,6-dihydrothymine a pseudo equatorial methyl is preferred. Consequently, the thymine glycol lesion is much more bulky than 5,6-dihydrothymine. This observation may explain the different biological consequences observed for the two lesions.
Miaskiewicz
K
K
Biology and Chemistry Department, Pacific Northwest Laboratory, Richland, WA 99352.
Miller
J
J
Osman
R
R
D004247:DNA / Q000528:radiation effects; D004249:DNA Damage; D005609:Free Radicals; D013941:Thymine / Q000031:analogs & derivatives* / Q000737:chemistry
D005609:Free Radicals; C029389:thymine glycol; C042836:5,6-dihydrothymine; D004247:DNA; D013941:Thymine