High-resolution structure of an extended A-tract: [d(CGCAAATTTGCG)]2.
Woods, K.K., Maehigashi, T., Howerton, S.B., Sines, C.C., Tannenbaum, S., Williams, L.D.(2004) J Am Chem Soc 126: 15330-15331
- PubMed: 15563130 
- DOI: https://doi.org/10.1021/ja045207x
- Primary Citation of Related Structures:  
1S2R - PubMed Abstract: 
The crystal structure of [d(CGCAAATTTGCG)]2 has been determined to 1.5 A resolution, representing the first high-resolution structure of this DNA fragment. The ion interactions are novel. A spermine molecule replaces a Mg2+ observed in analogous structures. Unlike lower-resolution structures, the minor groove is narrow and the major groove lacks extra Watson-Crick hydrogen bonds. In addition, a monolayer of solvent sites, including a "spine of hydration", is visible in the minor groove. The crystal of [d(CGCAAATTTGCG)]2 was grown from a solution containing spermine, magnesium, and lithium. The conformation recapitulates that of "monovalent-minus" DNA.
Organizational Affiliation: 
School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400, USA.