The (6S,8R,11S) l,N 2-HNE-dGuo adduct of trans-4-hydroxynonenal (HNE) was incorporated into the duplex 5′-d(GCTAGCXAGTCC)-3′- 5′-d(GGACTAGCTAGC)-3′ [X = 6S,8R,11S) HNE-dG], in which the lesion was mismatched opposite dAdo. The (6S,8/?,115) adduct maintained the ring-closed 1,N 2- HNE-dG structure. This was in contrast to when this adduct was correctly paired with dCyd, conditions under which it underwent ring opening and rearrangement to diastereomeric minor groove cyclic hemiacetals [Huang, H., Wang, H., Qi, N., Lloyd, R. S., Harris, T. M., Rizzo, C. J., and Stone, M. P. (2008) J. Am. Chem. Soc. 130,10898-10906]. The (6S,8R,11S) adduct exhibited a synlanti conformational equilibrium about the glycosyl bond. The syn conformation was predominant in acidic solution. Structural analysis of the syn conformation revealed that X 7 formed a distorted base pair with the complementary protonated A 18. The HNE moiety was located in the major groove. Structural perturbations were observed at the neighbor C 6·G 19 and A 8·T 17 base pairs. At basic pH, the anti conformation of X 7 was the major species. The 1,N 2-HNE-dG intercalated and displaced the complementary A 18 in the 5′-direction, resulting in a bulge at the X 7·A 18 base pair. The HNE aliphatic chain was oriented toward the minor groove. The Watson - Crick hydrogen bonding of the neighboring A 8·T 17 base pair was also disrupted.
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