X-ray analyses of two DNA dodecamers containing N4-methoxy-cytosine paired with adenine or guanine. |
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| Authors: | M T Hossain T Hikima M Tsunoda T Chatake Y Ueno A Matsuda A Takénaka |
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| Affiliation: | Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Nagatsuda, Midori-ku, Yokohama, Kanagawa 226-8501, Japan. |
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| Abstract: | To investigate mismatch of base-pairings in relation to mutagenesis by oxyamines, crystal structures of two DNA dodecamers with the sequence d(CGCZAA TTmo4CGCG) (Z = A or G), containing N4-methoxy-cytosine (mo4C), have been determined by X-ray analysis. These dodecamers essentially form right-handed B-form duplexes, respectively. In the dodecamer with Z = A, the two mo4C residues are adapted in imino form with the anti methoxyl group to form pairs with A on the opposite strand in a manner of Watson-Crick fashion. While in the dodecamer with Z = G, one mo4C in amino form with the anti methoxyl group forms a normal Watson-Crick pair with G, but the other one in imino form with syn methoxyl conformation wobbles with G. Based on these results, possible mutation mechanism has been proposed. |
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