Buy article online - an online subscription or single-article purchase is required to access this article.
structural communications
The crystal structure of the tetradecanucleotide sequence d(CCCCGGTACCGGGG)2 has been determined at 2.5 Å resolution in the tetragonal space group P41. This sequence was designed with the expectation of a four-way junction. However, the sequence crystallized as an A-DNA duplex and represents more than one full turn of the A-helix. The crystallographic asymmetric unit consists of one tetradecanucleotide duplex. The structural parameters of the A-type DNA duplex structure and the crystal-packing arrangement are described. One Mn2+ ion was identified with direct coordination to the N7 position of G13 and a water molecule at the major-groove side of the C2·G13 base pair.