Polymorphism and resolution of oncogene promoter quadruplex-forming sequences.

We report the separation of several quadruplex species formed by ten promoter sequences by Size Exclusion Chromatography (SEC). Modification at the 5' or 3' ends or in loop regions of quadruplex forming sequences has become the standard technique for dealing with quadruplex polymorphism. However, conformations produced employing this method or by other means of artificially shifting the equilibrium may not represent the species that are present in vivo. This method enables an unperturbed view of the structural polymorphism inherent to quadruplex formation. Separation via SEC facilitates studies on quadruplex structure and biophysical properties without the need for sequence modification.