pH-dependence of the UV absorbance at 297 nm, measured as proxy for i-motif formation,[60,61]for samples ofIM,IM*-3m, andIM+IM*-3moligonucleotides (not linked to star motifs). Increase inA297marks i-motif formation achieved at pH 6.16 for isolatedIMand 5.05 when alsoIM*-3mis present, with the difference ascribed to competition between duplex and i-motif formation. The transitional pH (pKA) values were calculated as the inflection points of sigmoidal fits. No response was observed in isolatedIM*-3m. The data are shown as mean standard error (shaded regions) of two experiments performed on two independently prepared samples, each consisting of three measurements.
