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Michael R Wasielewski - One of the best experts on this subject based on the ideXlab platform.
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Solvent independent symmetry-breaking charge separation in terrylenediimide Guanine-Quadruplex nanoparticles.
The Journal of chemical physics, 2020Co-Authors: Natalia E Powers-riggs, Xiaobing Zuo, Ryan M Young, Michael R WasielewskiAbstract:G-Quadruplex assemblies are a promising tool for self-assembling π-stacked chromophore arrays to better understand their photophysics. We have shown that coupling a single Guanine moiety to terrylenediimide (TDI) produces a structure (GTDI) that self-assembles in tetrahydrofuran (THF) into a nearly monodisperse Guanine-Quadruplex structure having 16 π-stacked layers (GTDI4)16. The TDI surfaces were determined to have a high degree of cofacial overlap and underwent quantitative symmetry-breaking charge separation (SB-CS) upon photoexcitation. Here, we more deeply examine the relationship between solvent and aggregate formation and develop insights into structure-function relationships over a variety of solvent polarities and hydrogen-bonding capabilities. At high concentrations, GTDI assembles into Guanine-Quadruplex structures (GTDI4)16 in THF and toluene, as well as (GTDI4)9 in pyridine and benzonitrile. Transient absorption spectroscopy shows that SB-CS occurs in all solvents, regardless of their static dielectric constants, but the SB-CS yield is determined by structure. Solvent polarity independent SB-CS generation is also observed in GTDI films, where there is a complete absence of solvent.
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Symmetry-Breaking Charge Separation in a Nanoscale Terrylenediimide Guanine-Quadruplex Assembly.
Journal of the American Chemical Society, 2019Co-Authors: Natalia E Powers-riggs, Xiaobing Zuo, Ryan M Young, Michael R WasielewskiAbstract:Guanine-Quadruplex (G-Quadruplex) assemblies provide a useful platform for studying the spatial, structural, and photophysical effects of intermolecular interactions. Coupling a single Guanine moiety to terrylenediimide (TDI)—a chromophore with a large extended π-surface—produces a structure (GTDI) that assembles in plate-like tetramers, with the potential of undergoing tunable π-stacking. At high concentrations (3 × 10–3 M), GTDI self-assembles into a nearly monodisperse G-Quadruplex structure of 16 layers, with strong π-overlap between TDI moieties, observed by small- and wide-angle X-ray scattering. Transient absorption spectroscopy reveals that excitation of TDI in the G-Quadruplex results in symmetry-breaking charge separation to form ion pairs within the structure, owing to the strong π-overlap enforced by the hydrogen-bonding. These assemblies yield important insights into the interplay of noncovalent interactions in the assembly of ordered chromophoric arrays.
Natalia E Powers-riggs - One of the best experts on this subject based on the ideXlab platform.
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Solvent independent symmetry-breaking charge separation in terrylenediimide Guanine-Quadruplex nanoparticles.
The Journal of chemical physics, 2020Co-Authors: Natalia E Powers-riggs, Xiaobing Zuo, Ryan M Young, Michael R WasielewskiAbstract:G-Quadruplex assemblies are a promising tool for self-assembling π-stacked chromophore arrays to better understand their photophysics. We have shown that coupling a single Guanine moiety to terrylenediimide (TDI) produces a structure (GTDI) that self-assembles in tetrahydrofuran (THF) into a nearly monodisperse Guanine-Quadruplex structure having 16 π-stacked layers (GTDI4)16. The TDI surfaces were determined to have a high degree of cofacial overlap and underwent quantitative symmetry-breaking charge separation (SB-CS) upon photoexcitation. Here, we more deeply examine the relationship between solvent and aggregate formation and develop insights into structure-function relationships over a variety of solvent polarities and hydrogen-bonding capabilities. At high concentrations, GTDI assembles into Guanine-Quadruplex structures (GTDI4)16 in THF and toluene, as well as (GTDI4)9 in pyridine and benzonitrile. Transient absorption spectroscopy shows that SB-CS occurs in all solvents, regardless of their static dielectric constants, but the SB-CS yield is determined by structure. Solvent polarity independent SB-CS generation is also observed in GTDI films, where there is a complete absence of solvent.
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Symmetry-Breaking Charge Separation in a Nanoscale Terrylenediimide Guanine-Quadruplex Assembly.
Journal of the American Chemical Society, 2019Co-Authors: Natalia E Powers-riggs, Xiaobing Zuo, Ryan M Young, Michael R WasielewskiAbstract:Guanine-Quadruplex (G-Quadruplex) assemblies provide a useful platform for studying the spatial, structural, and photophysical effects of intermolecular interactions. Coupling a single Guanine moiety to terrylenediimide (TDI)—a chromophore with a large extended π-surface—produces a structure (GTDI) that assembles in plate-like tetramers, with the potential of undergoing tunable π-stacking. At high concentrations (3 × 10–3 M), GTDI self-assembles into a nearly monodisperse G-Quadruplex structure of 16 layers, with strong π-overlap between TDI moieties, observed by small- and wide-angle X-ray scattering. Transient absorption spectroscopy reveals that excitation of TDI in the G-Quadruplex results in symmetry-breaking charge separation to form ion pairs within the structure, owing to the strong π-overlap enforced by the hydrogen-bonding. These assemblies yield important insights into the interplay of noncovalent interactions in the assembly of ordered chromophoric arrays.
Michaela Vorlíčková - One of the best experts on this subject based on the ideXlab platform.
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CD Study of the G-Quadruplex Conformation.
Methods in molecular biology (Clifton N.J.), 2019Co-Authors: Iva Kejnovská, Daniel Renčiuk, Jan Palacký, Michaela VorlíčkováAbstract:Circular Dichroic (CD) spectroscopy is one of the most frequently used methods for Guanine Quadruplex studies and in general for studies of conformational properties of nucleic acids. The reason is its high sensitivity to even slight changes in mutual orientation of absorbing bases of DNA. CD can reveal formation of particular structural DNA arrangements and can be used to search for the conditions stabilizing the structures, to follow the transitions between various structural states, to explore kinetics of their appearance, to determine thermodynamic parameters, and also to detect formation of higher order structures. CD spectroscopy is an important complementary technique to NMR spectroscopy and X-ray diffraction in Quadruplex studies due to its sensitivity, easy manipulation of studied samples, and relative inexpensiveness. In this part, we present the protocol for the use of CD spectroscopy in the study of Guanine Quadruplexes, together with practical advice and cautions about various, particularly interpretation, difficulties.
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Guanine Quadruplex formation by rna dna hybrid analogs of oxytricha telomere g4t4g4 fragment
Biopolymers, 2008Co-Authors: Jitka Vondrušková, Jaroslav Kypr, Iva Kejnovská, Markéta Fialová, Michaela VorlíčkováAbstract:Using circular dichroism spectroscopy, gel electrophoresis, and ultraviolet absorption spectroscopy, we have studied Quadruplex folding of RNA/DNA analogs of the Oxytricha telomere fragment, G(4)T(4)G(4), which forms the well-known basket-type, antiparallel Quadruplex. We have substituted riboGuanines (g) for deoxyriboGuanines (G) in the positions G1, G9, G4, and G12; these positions form the terminal tetrads of the G(4)T(4)G(4) Quadruplex and adopt syn, syn, anti, and anti glycosidic geometries, respectively. We show that substitution of a single sugar was able to change the Quadruplex topology. With the exception of G(4)T(4)G(3)g, which adopted an antiparallel structure, all the RNA/DNA hybrid analogs formed parallel, bimolecular Quadruplexes in concentrated solution at low salt. In dilute solutions ( approximately 0.1 mM nucleoside), the RNA/DNA hybrids substituted at positions 4 or 12 adopted antiparallel Quadruplexes, which were especially stable in Na(+) solutions. The hybrids substituted at positions 1 and 9 preferably formed parallel Quadruplexes, which were more stable than the nonmodified G(4)T(4)G(4) Quadruplex in K(+) solutions. Substitutions near the 3'end of the molecule affected folding more than substitutions near the 5'end. The ability to control Quadruplex folding will allow further studies of biophysical and biological properties of the various folding topologies.
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Guanine Quadruplex formation by RNA/DNA hybrid analogs of Oxytricha telomere G4T4G4 fragment
Biopolymers, 2008Co-Authors: Jitka Vondrušková, Jaroslav Kypr, Iva Kejnovská, Markéta Fialová, Michaela VorlíčkováAbstract:Using circular dichroism spectroscopy, gel electrophoresis, and ultraviolet absorption spectroscopy, we have studied Quadruplex folding of RNA/DNA analogs of the Oxytricha telomere fragment, G(4)T(4)G(4), which forms the well-known basket-type, antiparallel Quadruplex. We have substituted riboGuanines (g) for deoxyriboGuanines (G) in the positions G1, G9, G4, and G12; these positions form the terminal tetrads of the G(4)T(4)G(4) Quadruplex and adopt syn, syn, anti, and anti glycosidic geometries, respectively. We show that substitution of a single sugar was able to change the Quadruplex topology. With the exception of G(4)T(4)G(3)g, which adopted an antiparallel structure, all the RNA/DNA hybrid analogs formed parallel, bimolecular Quadruplexes in concentrated solution at low salt. In dilute solutions ( approximately 0.1 mM nucleoside), the RNA/DNA hybrids substituted at positions 4 or 12 adopted antiparallel Quadruplexes, which were especially stable in Na(+) solutions. The hybrids substituted at positions 1 and 9 preferably formed parallel Quadruplexes, which were more stable than the nonmodified G(4)T(4)G(4) Quadruplex in K(+) solutions. Substitutions near the 3'end of the molecule affected folding more than substitutions near the 5'end. The ability to control Quadruplex folding will allow further studies of biophysical and biological properties of the various folding topologies.
Anne Petitjean - One of the best experts on this subject based on the ideXlab platform.
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Going Platinum to the Tune of a Remarkable Guanine Quadruplex Binder: Solution- and Solid-State Investigations.
Angewandte Chemie (International ed. in English), 2020Co-Authors: Caitlin E. Miron, Laura M. Van Staalduinen, Alana M. M. Rangaswamy, Mickey Chen, Yushi Liang, Zongchao Jia, Jean-louis Mergny, Anne PetitjeanAbstract:Guanine Quadruplex recognition has gained increasing attention, inspired by the growing awareness of the key roles played by these non-canonical nucleic acid architectures in cellular regulatory processes. We report here the solution and solid-state studies of a novel planar platinum(II) complex that is easily assembled from a simple ligand, and exhibits notable binding affinity for Guanine Quadruplex structures, while maintaining good selectivity for Guanine Quadruplex over duplex structures. A crystal structure of this ligand complexed with a telomeric Quadruplex confirms double end-capping, with dimerization at the 5' interface.
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Going Platinum to the Tune of a Remarkable Guanine Quadruplex Binder: Solution‐ and Solid‐State Investigations.
Angewandte Chemie International Edition, 2020Co-Authors: Caitlin Miron, Laura M. Van Staalduinen, Mickey Chen, Yushi Liang, Zongchao Jia, Jean-louis Mergny, Alana Rangaswamy, Anne PetitjeanAbstract:Guanine Quadruplex recognition has gained increasing attention, inspired by the growing awareness of the key roles played by these non-canonical nucleic acid architectures in cellular regulatory processes. We report here the solution and solid-state studies of a novel planar platinum(II) complex that is easily assembled from a simple ligand, and exhibits notable binding affinity for Guanine Quadruplex structures, while maintaining good selectivity for Guanine Quadruplex over duplex structures. A crystal structure of this ligand complexed with a telomeric Quadruplex confirms double end-capping, with dimerization at the 5' interface.
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An Improved Route for the Synthesis of Guanine Quadruplex Ligand Phen-DC3
Synlett, 2018Co-Authors: Caitlin E. Miron, Anne PetitjeanAbstract:The recognition of noncanonical DNA and RNA architectures such as Guanine Quadruplexes by small molecule ligands has become a promising strategy for anticancer and antiviral applications in recent years, leading to an exponential increase in the number of Quadruplex ligands reported in the literature. There is consequently a need for ‘benchmark’ compounds which can be used as controls to facilitate comparisons between novel and previously reported ligands. One candidate for this role is Phen-DC3, which binds with high affinity and selectivity to Guanine Quadruplexes. To encourage its use in this role, an alternate synthetic route for the production of Phen-DC3 that may be more appropriate for implementation on a large scale is reported. This pathway eliminates the need for several hazardous reagents and increases the overall synthetic yield from 21% to a maximum of 43%.
Xiaobing Zuo - One of the best experts on this subject based on the ideXlab platform.
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Solvent independent symmetry-breaking charge separation in terrylenediimide Guanine-Quadruplex nanoparticles.
The Journal of chemical physics, 2020Co-Authors: Natalia E Powers-riggs, Xiaobing Zuo, Ryan M Young, Michael R WasielewskiAbstract:G-Quadruplex assemblies are a promising tool for self-assembling π-stacked chromophore arrays to better understand their photophysics. We have shown that coupling a single Guanine moiety to terrylenediimide (TDI) produces a structure (GTDI) that self-assembles in tetrahydrofuran (THF) into a nearly monodisperse Guanine-Quadruplex structure having 16 π-stacked layers (GTDI4)16. The TDI surfaces were determined to have a high degree of cofacial overlap and underwent quantitative symmetry-breaking charge separation (SB-CS) upon photoexcitation. Here, we more deeply examine the relationship between solvent and aggregate formation and develop insights into structure-function relationships over a variety of solvent polarities and hydrogen-bonding capabilities. At high concentrations, GTDI assembles into Guanine-Quadruplex structures (GTDI4)16 in THF and toluene, as well as (GTDI4)9 in pyridine and benzonitrile. Transient absorption spectroscopy shows that SB-CS occurs in all solvents, regardless of their static dielectric constants, but the SB-CS yield is determined by structure. Solvent polarity independent SB-CS generation is also observed in GTDI films, where there is a complete absence of solvent.
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Symmetry-Breaking Charge Separation in a Nanoscale Terrylenediimide Guanine-Quadruplex Assembly.
Journal of the American Chemical Society, 2019Co-Authors: Natalia E Powers-riggs, Xiaobing Zuo, Ryan M Young, Michael R WasielewskiAbstract:Guanine-Quadruplex (G-Quadruplex) assemblies provide a useful platform for studying the spatial, structural, and photophysical effects of intermolecular interactions. Coupling a single Guanine moiety to terrylenediimide (TDI)—a chromophore with a large extended π-surface—produces a structure (GTDI) that assembles in plate-like tetramers, with the potential of undergoing tunable π-stacking. At high concentrations (3 × 10–3 M), GTDI self-assembles into a nearly monodisperse G-Quadruplex structure of 16 layers, with strong π-overlap between TDI moieties, observed by small- and wide-angle X-ray scattering. Transient absorption spectroscopy reveals that excitation of TDI in the G-Quadruplex results in symmetry-breaking charge separation to form ion pairs within the structure, owing to the strong π-overlap enforced by the hydrogen-bonding. These assemblies yield important insights into the interplay of noncovalent interactions in the assembly of ordered chromophoric arrays.