journal article
LitStream Collection
Determination of twist and handedness of a 39-base pair segment of DNA in solution
1983 Nature
doi: 10.1038/305070a0pmid: 6888552
For DNA in solution, there have been two methods for measuring the helical periodicity. One method1,2 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 method3,4 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 handedness5–7, 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 model8.