Role of molecular crowding in perturbing quadruplex-Watson Crick duplex equilibrium.

Herein, we address the sensitivity of the competitive equilibria between hoogsteen bonded quadruplex structure and hydrogen bonded Watson-Crick duplex structure. We used osmolytes as molecular crowding agents to mimick intracellular milieu and analysed their effect on Quadruplex-Duplex transition. We used telomeric quadruplex 5'Fluorescein-d[(G(3) TTA)(3) G(3)] as a model system and performed extensive Fluorescence Resonance Energy Transfer analysis for duplex formation in absence and presence of different concentrations of osmolytes (Glycerol and Ethylene Glycol). Overall the data shows that these molecular crowding agents stabilize quadruplex structure, delays duplex formation and thereby shifts the equilibrium towards quadruplex formation.