An X-ray study of the interaction of DNA with spermine.
An X-ray study of the interaction of DNA with spermine.
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DOI：
10.1016/0022-2836(69)90049-7
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发表时间：
1969-06
影响因子：
5.6
通讯作者：
M. Suwalsky;Wolfie Traub;U. Shmueli;Juan A. Subirana
中科院分区：
文献类型：
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作者：
M. Suwalsky;Wolfie Traub;U. Shmueli;Juan A. Subirana
四胺精胺与DNA形成复合物，从而保护DNA不变性和断裂。在不同相对湿度下拍摄DNA-精胺复合物的X射线纤维照片。在92%相对湿度下获得最详细的图案。它表明复合物具有与天然存在的B型DNA相同的螺旋参数，并且推测具有非常相似的构象。在76%及以下的相对湿度下，配合物为DNA C构型，分子间距离随样品水化程度而变化，但有一定的上限。分子模型的研究表明，精胺分子的四个基本基团也有可能与DNA分子上的磷酸基团形成氢键。精胺分子会穿过DNA的小凹槽，并将其两条链结合在一起。对DNA-精胺复合物的各种模型的强度计算表明，没有一种模型可以解释所观察到的X射线图案。然而，假设精胺在DNA的小凹槽中以及在分子间交联中，或者DNA和精胺之间的附着模式的种类更多，确实导致计算的和观察到的强度之间令人满意的一致性。
The tetramine spermine forms a complex with DNA, and thereby serves to protect it against denaturation and breakage.X-ray fibre photographs of the DNA-spermine complex were taken at various relative humidities. The most detailed pattern was obtained at 92% relative humidity. It shows the complex to have the same helical parameters as the naturally occurring B form of DNA, and presumably a closely similar conformation. However, at 76% and lower relative humidities, the complex conforms to the DNA C configuration.The intermolecular distance was found to vary with the degree of hydration of the specimen, but to have a definite upper limit. This and the range of intermolecular distance observed are consistent with spermine cross-links between DNA molecules.Studies of molecular models have shown that it is also possible for all four basic groups of a spermine molecule to make hydrogen bonds with phosphate groups on one molecule of DNA. The spermine molecules would lie across the small groove of the DNA and serve to bind its two strands together.Calculation of intensities for various models for the DNA-spermine complex indicates that no one model can account for the observed X-ray pattern. However, the assumption of spermine in the small groove of DNA as well as in intermolecular cross-links, or of an even greater variety of modes of attachment between DNA and spermine, does lead to satisfactory agreement between calculated and observed intensities.