Spink N, Nunn C M, Vojtechovsky J, Berman H M, Neidle S
Cancer Research Campaign Biomolecular Structure Unit, Institute of Cancer Research, Sutton, Surrey, United Kingdom.
Proc Natl Acad Sci U S A. 1995 Nov 7;92(23):10767-71. doi: 10.1073/pnas.92.23.10767.
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.
十聚体d(CGCAATTGCG)₂的晶体结构通过分子置换和重原子法相结合的方式得以解析，并在2.7埃分辨率下精修至R因子为20.2%。它不是一个完全碱基配对的双链体，而是具有一个由八个沃森-克里克碱基对组成的中央核心，两侧是未配对的末端鸟苷和胞嘧啶。这些在晶格中与相邻的十聚体双链体参与氢键排列。未配对的鸟苷结合在双链体小沟的G+C区域。胞嘧啶具有相对较高的流动性，尽管它们被限制在一个区域，在那里它们与G·C碱基对参与碱基配对三联体。双链区域中的5'-AATT序列具有狭窄的小沟，进一步证实了沟宽的序列依赖性。
