Takeda Y
J Biochem. 1985 Jun;97(6):1827-30. doi: 10.1093/oxfordjournals.jbchem.a135245.
X-ray studies on the complex of E. coli DNA with synthetic thermospermine in fibers were carried out. This complex showed the ordinary transition, except that it yielded a semicrystalline B-form at 66% r.h., suggesting good side-to-side interactions of the material due to some number of cross-bridges of tetramine. An idea of thymine methyl-neighbor base short contacts in A-form DNA is proposed to understand these structural changes of double helical DNA. On the assumption that the unstable A-conformation needs lateral interactions, the present X-ray results are well explained. This unstable factor is potentially of considerable biological interest in relation with DNA compaction.
对大肠杆菌DNA与合成热精胺在纤维中的复合物进行了X射线研究。该复合物显示出普通的转变，只是在相对湿度为66%时产生了一种半结晶的B型，这表明由于一定数量的四胺交叉桥，材料具有良好的侧向相互作用。为了理解双链DNA的这些结构变化，提出了A-DNA中胸腺嘧啶甲基邻碱基短接触的概念。假设不稳定的A构象需要侧向相互作用，那么目前的X射线结果就能得到很好的解释。这种不稳定因素在与DNA压缩相关方面可能具有相当大的生物学意义。
