Telomeres are protein DNA complexes found at the ends of eukaryotic chromosomes. The human telomere sequence has a G-rich strand, (TTAGGG), complemented to a C-rich strand, (CCCTAA).  Previous studies of the G-rich strand indicate that this sequence folds into a distinct conformation, designated as a G quadruplex, where the GGG bases form G-tetrads while the TTA segments are found in loops joining the tetrads.  C-rich DNA has also been shown to form an unusual structure, under slightly acidic conditions, designated as the i-motif. For this aspect of the project, we are investigating the structure and stability of the conformation formed from (CCCTAA)4 in the presence of either Na+ or K+ at pH values ranging from 5.0 to 7.5. We will present circular dichroism (CD) spectroscopic determinations to demonstrate the pH induced formation of the i-motif for this sequence.  In addition, we will report results of the effect of a crowding agent (PEG) on the single strand to i-motif equilibrium.

Structural and thermodynamic studies of a DNA <i>?i</i>?-motif

245th National Meeting (2013)

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Structural and thermodynamic studies of a DNA ?i?-motif