Abstract
Cyanine dyes have been widely applied in various biological systems owing to their specific photochemical properties. Assembly and disassembly process of cyanine dyes were constructed and regulated by special biomolecules. In this paper, dimeric cyanine dyes with different repeat units (oligo-oxyethylene) in linker (TC-Pn) (n = 3–6) were found to form H-aggregates or mixture aggregates in PBS. These aggregates could be disassembled into dimer and/or monomer by (TGnT) tetramolecular G-quadruplexes (n = 3–6, 8), which were affected by the linker length of dimeric cyanine dyes and layers of G-quartets. The 1H-NMR titration results suggest that the binding mode of dimeric cyanine dye with TGnT might be on both ends—stacking like a clip. This binding mode could clearly explain that matching structures between dimeric cyanine dyes and TGnT quadruplexes could regulate the disassembly properties of aggregates. These results could provide clues for the development of highly specific G-quadruplex probes.
Highlights
The G rich oligomers form four stranded structures maintained by stacked G-quartets
Tetramolecular G-quadruplexes (n = 3–6, 8), which were affected by the linker length of dimeric cyanine dyes and layers of G-quartets
Same TGnT G-quadruplex showed the capability for various disassembly chain. Owing to this structural change, we speculate that assembly and disassembly of dimeric cyanine aggregates of dimeric cyanine dyes (TC-P3, TC-P4 and TC-P5)
Summary
The G rich oligomers form four stranded structures maintained by stacked G-quartets. The building blocks of G-quadruplexes are structures known as G-quartets (Gq), which are planar association of four G bases held together by eight Hoogsteen hydrogen bonds. A clip-like binding mode of dimeric cyanine dye with parallel intramolecular G-quadruplexes was found by our previous study [17,18]. This binding mode involves two binding modes of terminal stacking and groove-embedding. Same TGnT G-quadruplex showed the capability for various disassembly chain Owing to this structural change, we speculate that assembly and disassembly of dimeric cyanine aggregates of dimeric cyanine dyes (TC-P3, TC-P4 and TC-P5). TG4T G-quadruplex with TC-P4 cyanine dye show that the binding mode should be clip-like, as our could be regulated by the layers of G-quartets. Result and Discussion dimeric cyanine dye was greatly affected by layers of d(TGnT) (abbreviated TGnT) G-quadruplexes
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