Sun Hongxia

Study on catalytic oxidation of planar binuclear copper phthalocyanine on 2-mercaptoethanol

G-rich single-stranged DNA (5′-TTAG-GG-3′) adopted a G-quadruplex structure in buffer containing potassium ions. The spectroscopic feature and the interaction between methylene blue and G-qadruplex have been investigated by circular dichroism, and nuclear magnetic resonance spectroscopy. The UV-Vis absorption and fluorescence spectral results show that the fluorescence behavior of MB by single-stranded DNA fits Stern-Volmer static quenching equation very well and they formed 1: 1 complexes; dimeric G-quadruplexes were bound to MB with 1: 1 or 2: 1, and their equilibrium constants were 1.047×105 and 8.79×104 L/mol, respectively. Based on the above results and 1H-NMR spectral data, one may conclude that MB stacked either the terminal tetrads to form 1: 1 complexes or between two terminal tetrads of G-quadruplexes to form 1: 2 sandwich complexes with G-qudruplexes.