Packing features of the all-AT oligonucleotide d(AAATTT).
Valls, N., Santaolalla, A., Campos, J.L., Subirana, J.A.(2007) J Biomol Struct Dyn 24: 547-552
- PubMed: 17508776 
- DOI: https://doi.org/10.1080/07391102.2007.10507143
- Primary Citation of Related Structures:  
2G1Z - PubMed Abstract: 
We describe the packing features of the oligonucleotide duplex d(AAATTT)2, as determined by X-ray diffraction. There is little information on sequences that only contain A and T bases. The present structure confirms that these sequences tend to pack as a helical arrangement of stacked oligonucleotides in a B conformation with Watson-Crick hydrogen bonding. Our results demonstrate that the virtual TA base step between stacked duplexes has a negative twist that improves base stacking. This observation is consistent with the low stability of TA base steps in B-form DNA.
Organizational Affiliation: 
Departament d'Enginyeria Quimica, Universitat Politecnica de Catalunya, Av. Diagonal 647, E-08028 Barcelona, Spain.