The effect of alkyltrimethylammonium ions on the thermostability of natural and modified DNA duplexes has been investigated. We have shown that the use of tetramethylammonium ions TMA+along with the chemical modification of duplexes allow the fine adjustment of T m and the possibility of obtaining several duplex systems with varied isostabilizedtemperatures, some of which show greater stability than those of natural DNA. This approach could be very useful for DNA sequencing by hybridization.
Centre de Biophysique Moléculaire, CNRS, Rue Charles Sadron, 45071 Orléans Cedex 02, France and Appligène-Oncor, Parc d'Innovation, Rue de Geiler de Kaysersberg, BP 72, 67402 Illkirch, France.