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Spink, Neil, Nunn, Christine M., Vojtechovsky, Jaroslav, Berman, Helen M. and Neidle, Stephen (1995) Crystal structure of a DNA decamer showing a novel pseudo four-way helix-helix junction. Proceedings of the National Academy of Sciences of the United States of America, 92 (23). pp. 10767-10771. ISSN 0027-8424
The crystal structure of the decanucleotide d(CGCAATTGCG)2 has been solved by a combination of molecular replacement and heavy-atom procedures and has been refined to an R factor of 20.2% at 2.7 A. It is not a fully base-paired duplex but has a central core of eight Watson-Crick base pairs flanked by unpaired terminal guanosines and cytosines. These participate in hydrogen-bonding arrangements with adjacent decamer duplexes in the crystal lattice. The unpaired guanosines are bound in the G+C regions of duplex minor grooves. The cytosines have relatively high mobility, even though they are constrained to be in one region where they are involved in base-paired triplets with G.C base pairs. The 5'-AATT sequence in the duplex region has a narrow minor groove, providing further confirmation of the sequence-dependent nature of groove width.
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