We used biophysics techniques to study the behavior of the single molecule human i-motif DNA structure as a function of the pH of its surroundings. We found that the molecule folds into a compact state around pH 6.0. We used FRET trace to observing the behavior of the molecule as it folds in a common imaging buffer of time-variant pH.
Dr. Hamza Balci
Förster resonance energy transfer (FRET) allows for observing behavior of single molecule processes. Two fluorescent molecules are attached to the ends of the biological structure. One molecule acts as the donor (Cy3), the other (Cy5) is an acceptor for the energy emitted from the donor molecule. The fraction of energy that is transferred depends on the distance between the molecules. Changes in the shape of the biological structure, accompanied by a change in the separation between donor and acceptor fluorophores, can be observed by FRET. The i-motif structure is a conformational switch which responds to the pH of its surrounding, attaining a compact structure at pH around 6.0. We used FRET techniques to study the folding and unfolding of the i-motif at different pH levels.