Iwamoto S, Hsu M T
Nature. 1983;305(5929):70-2. doi: 10.1038/305070a0.
For DNA in solution, there have been two methods for measuring the helical periodicity. One method examines the ladder of discrete bands formed in the electrophoretic pattern of supercoiled DNA. Such a ladder is assumed to reflect the set of differently linked covalently closed molecules. The other method measures the lengths of partial nuclease digestions of DNA segments affixed to flat surfaces. Neither method, however, is able to measure the absolute handedness. X-ray diffraction of DNA oligonucleotides can determine the handedness, but the DNA must necessarily be crystallized. We have developed a new method for determining the helical parameters of a segment of DNA in solution. It is the first non-crystallographic method that can directly determine both the helical periodicity and the absolute handedness of DNA. The results obtained using this method are consistent with the classical Watson-Crick right-handed double helical model.
对于溶液中的DNA，有两种测量螺旋周期性的方法。一种方法是检查超螺旋DNA电泳图谱中形成的离散条带阶梯。这种阶梯被认为反映了一组不同连接的共价闭合分子。另一种方法是测量固定在平面上的DNA片段的部分核酸酶消化长度。然而，这两种方法都无法测量绝对手性。DNA寡核苷酸的X射线衍射可以确定手性，但DNA必须结晶。我们开发了一种新方法来确定溶液中一段DNA的螺旋参数。这是第一种能够直接确定DNA螺旋周期性和绝对手性的非晶体学方法。使用该方法获得的结果与经典的沃森-克里克右手双螺旋模型一致。
