Molecular design for the antigene method, chemical regulation of genetic expression based on the triplex formation

The triplex formation between the duplex and a single strand DNA has been shown to inhibit transcription at the specific DNA site, and expected as a new biological tool and a new therapeutic method in the so-called antigene strategy. However, native oligonucleotides can form triplexes only within the major groove of the homopurine-homopyrimidine stretch of DNA, and the triplex is destabilized either at a TA or a CG interrupting site. Despite a number of methods have been attempted to expand the limitation of triplex formation, this problem has not been generally solved. This review describes (1) molecular design to stabilize triplex at a TA or a CG interrupting site, including new recognition molecules which have been recently shown by the reviewer and coworkers to be specific toward each base pair. And (2) some method to enhance stability of triplexes with use of DNA binding molecules such as intercalators, cross-linking agents, and groove binders are also discussed.