Nucleic acid triple helices: Stability effects of nucleobase modifications

In the last years DNA triplexes have been the subject of a very intense research effort, which has been summarized in a vast number of books and reviews (see for example refs. [1-16]). After a general introduction to DNA polymorphism and the structure of triple helices, we will examine here general approaches to the stabilization of triple helices. Methods based in external binding to DNA and backbone modification will be briefly summarized, and the reader will be addressed to more specific reviews. Finally, we will survey strategies for triplex stabilization based on modification of nucleobases, paying particular attention to recent advances in the field.