G-rich single-stranded DNA (5′-TTAG-GG-3′) adopted a G-quadruplex structure in buffercontaining potassium ions. The spectroscopic featureand the interaction between methylene blue andG-quadruplex have been investiga...G-rich single-stranded DNA (5′-TTAG-GG-3′) adopted a G-quadruplex structure in buffercontaining potassium ions. The spectroscopic featureand the interaction between methylene blue andG-quadruplex have been investigated by circular di-chroism, and nuclear magnetic resonance spectros-copy. The UV-Vis absorption and fluorescence spec-tral results show that the fluorescence behavior ofMB by single-stranded DNA fits Stern-Volmer staticquenching equation very well and they formed 1︰1complexes; dimeric G-quadruplexes were bound toMB with 1︰1 or 2︰1, and their equilibrium constantswere 1.047×105 and 8.79×104 L/mol, respectively.Based on the above results and 1H-NMR spectraldata, one may conclude that MB stacked either theterminal tetrads to form 1︰1 complexes or betweentwo terminal tetrads of G-quadruplexes to form 1︰2sandwich complexes with G-qudruplexes.展开更多
文摘G-rich single-stranded DNA (5′-TTAG-GG-3′) adopted a G-quadruplex structure in buffercontaining potassium ions. The spectroscopic featureand the interaction between methylene blue andG-quadruplex have been investigated by circular di-chroism, and nuclear magnetic resonance spectros-copy. The UV-Vis absorption and fluorescence spec-tral results show that the fluorescence behavior ofMB by single-stranded DNA fits Stern-Volmer staticquenching equation very well and they formed 1︰1complexes; dimeric G-quadruplexes were bound toMB with 1︰1 or 2︰1, and their equilibrium constantswere 1.047×105 and 8.79×104 L/mol, respectively.Based on the above results and 1H-NMR spectraldata, one may conclude that MB stacked either theterminal tetrads to form 1︰1 complexes or betweentwo terminal tetrads of G-quadruplexes to form 1︰2sandwich complexes with G-qudruplexes.
