Packing features of the all-AT oligonucleotide d(AAATTT).
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.
Valls
N
N
Departament d'Enginyeria Quimica, Universitat Politecnica de Catalunya, Av. Diagonal 647, E-08028 Barcelona, Spain.
Santaolalla
A
A
Campos
J L
JL
Subirana
J A
JA
D000225:Adenine; D001483:Base Sequence; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides / Q000737:chemistry*; D013941:Thymine; D014961:X-Ray Diffraction
D009838:Oligodeoxyribonucleotides; D000225:Adenine; D013941:Thymine