Spectroscopic Characterization of i-motif Forming c-myc Derived Sequences Double-Labeled with Pyrene

In current studies we use the oligonucleotides based on c-myc sequence: CCC CAC CCT CCC CAC CCT CCC C (cmyc22) and CCC CAC CCT CCC CAC CCT CCC CA (cmyc22A) functionalized by pyrene moieties at both termini. Results of the circular dichroism (CD), UV absorption melting experiments, and steady-state fluorescence measurements of pyrene-modified i-motifs as well as their unlabeled precursors are presented and discussed here. The pyrene labels have a remarkable influence on i-motif stability which was deduced from CD spectra and confirmed by UV melting experiments. Both probes emit fluorescence band of pyrene monomer with intensity decreasing upon pH lowering. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10895-013-1184-z) contains supplementary material, which is available to authorized users.