Packing Features of the all-AT Oligonucleotide d(AAATTT) |
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| Authors: | N Valls A Santaolalla J L Campos J A Subirana |
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| Institution: | Departement d'Enginyeria Química , Universitat Politècnica de Catalunya , Av. Diagonal 647, E-08028 , Barcelona , Spain |
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| Abstract: | 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. |
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