 The degree of unwinding varies depending on the intercalator; for example, ethidium cation (the ionic form of ethidium bromide found in aqueous solution) unwinds DNA by about 26°, whereas proflavine unwinds it by about 17°.This unwinding causes the base pairs to separate, or "rise", creating an opening of about 0.34 nm (3.4 Å).This unwinding induces local structural changes to the DNA strand, such as lengthening of the DNA strand or twisting of the base pairs.