Abstract:

i-Motif is formed from two parallel duplexes by intercalating with each other in an antiparallel orientation and each duplex is held together via hemiprotonated cytosine⁺-cytosine base pairs. However, a cell is crowded with various biomolecules and little is known about the properties of i-Motif under molecular crowding conditions until now. In the present study, we used human telomeric DNA sequence, [C₃TA₂]₃C₃, as a model system to investigate such problem by circular dichroism(CD) and UV absorbance spectroscopy. Based on the CD spectra, we found that there were no changes about the structure of i-Motif in the presence of polyethylene glycol(PEG). CD melting results showed that the thermal stability of i-Motif was increased under molecular crowding conditions compare to that in dilute buffer, which was further demonstrated by UV-melting results. This work suggests that molecular crowding could not affect the structure of i-Motif, which may depend on pH, while could enhance the thermal stability of i-Motif.

Key words: i-Motif; Molecular crowding; Polyethylene glycol(PEG)