四聚体d（CpGpCpG）结晶为左手双螺旋结构。

Crawford J L, Kolpak F J, Wang A H, Quigley G J, van Boom J H, van der Marel G, Rich A

Proc Natl Acad Sci U S A. 1980 Jul;77(7):4016-20. doi: 10.1073/pnas.77.7.4016.

The structure of the tetramer d(CpGpCpG) has been solved by x-ray analysis in two different crystal forms with and without spermine cations. The molecules crystallize in hexagonal unit cells and they form a left-handed double helix of Z-DNA similar to that previously reported for the hexamer d(CpGpCpGpCpG). In the crystal lattice the molecules stack together to form a virtually continuous left-handed double helix in which every fourth phosphate group is missing. The stacking of bases upon each other is similar to that seen in the hexamer. However, the base pairs have a slightly different orientation in that the cytosine residues are slightly removed from the axis of the molecule compared to the position they occupy in the hexamer. The structures are similar in two crystal forms with and without spermine cations.

通过X射线分析，已在有和没有精胺阳离子的两种不同晶体形式下解析出四聚体d（CpGpCpG）的结构。这些分子在六边形晶胞中结晶，形成类似于先前报道的六聚体d（CpGpCpGpCpGpCpG）的Z-DNA左手双螺旋。在晶格中，分子堆叠在一起形成一个几乎连续的左手双螺旋，其中每隔四个磷酸基团缺失一个。碱基彼此之间的堆叠方式与六聚体中所见的相似。然而，碱基对的取向略有不同，与它们在六聚体中占据的位置相比，胞嘧啶残基从分子轴上略有偏移。有和没有精胺阳离子的两种晶体形式的结构相似。