Ethidium Intercalation in Synthetic DNA and RNA duplexes. A Fluorescence Study.

Abstract

It is a well established fact that different helical conformations of DNA can be stabilized in acqueous solution by added salts or cosolvents, counterion type or temperature variations. In contrast with this manifestation of high flexibility by the DNA molecule, the RNA duplex exists in the A-form under most conditions. It is not clear whether this difference arises simply from the sugar conformation fixed in C3’-endo by the presence of the C2’-OH in RNA or also reflects the more rigid structure of the A-helix relative to that of the B-helix.