Structure of the DNA octanucleotide d(ACGTACGT)2

Wilcock, D. J., Adams, A., Cardin, C. J. ORCID: https://orcid.org/0000-0002-2556-9995 and Wakelin, L. P. G. (1996) Structure of the DNA octanucleotide d(ACGTACGT)2. Acta Crystallographica Section D - Biological Crystallography, 52 (3). pp. 481-485. ISSN 1399-0047 doi: 10.1107/S0907444995016052

Abstract/Summary

d(ACGTACGT), C78H84N30O32P7.20H2O, Mr (DNA) = 2170, tetragonal, P43212 (No 96), a = 42.845 (1), b = 42.845(1), c = 24.804 (1) Å, V = 45532.5 (2) Å3, z = 8,(MoK) = 0.71069 Å,µ(MoK) = 0.10 mm-1, T = 295 K, R = 0.18 for 1994 unique reflections between 5.0 and 1.9 Å resolution. The self-complementary octanucleotide d(ACGTACGT)2 has been crystallized and its structure determined to a resolution of 1.9 Å. The asymmetric unit consists of a single strand of octamer with 20 water molecules. It is only the second example of an octanucleotide having terminal A·T base pairs whose structure has been determined by X-ray crystallography. The sequence adopts the modified A-type conformation found for all octanucleotide duplexes studied to date with the helix bent by approximately 15° and an average tilt angle of 0°. Unusually the data collection was carried out using a 3 kW molybdenum sealed-tube source. The conformational details are discussed in comparison with other closely related sequences.