Fourth rank immobile nucleic acid junctions.

An immobile nucleic acid junction composed of four dodecanucleotides has been designed according to principles of minimum symmetry aided by equilibrium calculations, and has been synthesized by automated phosphotriester techniques. We can demonstrate its tetrameric character and its 1:1:1:1 stoichiometry by gel electrophoresis. Thermal denaturation monitored by ultraviolet hyperchromism indicates that the complex is stable relative to its component arms. High resolution NMR spectroscopy suggests that this junction exists in more than one conformer at room temperature. The data from this junction are compared with the data from a similar junction composed of four hexadecanucleotides.