Effect of ethidium bromide on deoxyribonucleic acid internal motions

Abstract
31P and 1H NMR were used to show that DNA internal motions are stopped or greatly hindered when ethidium bromide intercalates into DNA. The effect is localized to a 2 base pair long DNA region at the binding site and internal motions outside the binding site are nearly unaffected. Based upon the nearly independent behavior of bound and free DNA regions, it is concluded that in B-DNA individual base pairs experience internal motion which is independent of the motion of their neighbors.