Book of Abstracts: Albany 2005
Structural Features of A-T Oligomers Studied by X-ray Crystallography
We reported some time ago (1) that the oligonucleotide d(ATATAT) crystallizes as a duplex with Hoogsteen base pairing. In an effort to find related structures, we have undertaken the study of oligonucleotides which only contain adenine and thymine in different sequences. Practically no data are available on crystal structures of this type. We have obtained crystal data on twelve additional sequences with different lengths (6 to 14 base pairs). Most of them have comparatively low resolution (3 to 6 Å), probably related to the high hydration observed. Nevertheless we have been able to determine their basic features in the crystals, which belong to two families:
b. Pseudohexagonal stacks of infinite columns of duplexes with no apparent lateral interactions. In several cases we have found that the unit cells contain many duplexes (up to 17) in the direction of the helical axis. In general, Watson-Crick base-pairs are present in these crystals.
References and Footnotes
1Department of Chemical Engineering