Spectroscopic Studies on Binding of Cationic Pheophorbide-a Derivative to Model Polynucleotides

Ryazanova, Olga; Voloshin, Igor; Dubey, I. Ya.; Dubey, L. V.; Zozulya, Victor

doi:10.1007/978-3-540-69367-3_107

Cited by 6 publications

(16 citation statements)

References 21 publications

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“…As for the Zn TMPyP 3+ moiety of the conjugate, its emission quenches at the first poly(A)⋅poly(U) addition to 0.34 from initial, and it remains on this level in the P/D range from Table 1) was registered for complex of Zn(II)TMPyP 3+ -ImPzn with poly(A)⋅poly(U) (for its complex with poly(G) this value was equal to 3.1). Enhancement of the porphyrin emission under its binding to poly(G) at high polymer content was observed also for non-metallated TMPyP 3+ (Table 1, unpublished data), and earlier for Pheophorbide-a derivatives [50,51].…”

Section: Discussionmentioning

confidence: 63%

Binding of Metallated Porphyrin-Imidazophenazine Conjugate to Tetramolecular Quadruplex Formed by Poly(G): a Spectroscopic Investigation

et al. 2015

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The binding of telomerase inhibitor ZnTMPyP(3+)-ImPzn, Zn(II) derivative of tricationic porphyrin-imidazophenazine conjugate, to tetramolecular quadruplex structure formed by poly(G) was studied in aqueous solutions at neutral pH and near physiological ionic strength using absorption and polarized fluorescent spectroscopy techniques. Three binding modes were determined from the dependences of the fluorescence intensity and polarization degree for the porphyrin and phenazine moieties of the conjugate on molar polymer-to-dye ratio (P/D). The first one is outside electrostatic binding of positively charged porphyrin fragments to anionic phosphate groups of the polymer which prevails only at very low P/D values and manifests itself by substantial fluorescence quenching. It is suggested that the formation of externally bound porphyrin dimers occurs. The other two binding modes observed at high P/D are embedding of the ZnTMPyP(3+) moiety into the groove of poly(G) quadruplex accompanied by more than 3-fold enhancement of the conjugate emission, and simultaneous intercalation of the phenazine fragment between the guanine bases accompanied by the increase of its fluorescence polarization degree up to 0.25. Thus Zn(II) conjugate seems to be promising ligand for the stabilization of G-quadruplex structures since porphyrin binding to poly(G) is strengthened by additional intercalation of phenazine moiety.

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Section: Discussionmentioning

confidence: 63%

Binding of Metallated Porphyrin-Imidazophenazine Conjugate to Tetramolecular Quadruplex Formed by Poly(G): a Spectroscopic Investigation

et al. 2015

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“…This explains the fact that fluorescence band maximum is positioned in more shortwave region relatively to the longwave absorption band. It was shown that disintegration of the CatPheo-a dimers starts only at temperature more than 70 °C [9]. This process was accompanied by substantial increase in intensity of the dye absorption and emission.…”

Section: Resultsmentioning

confidence: 96%

“…Fluorescence polarisation degree measured in the band maximum is p = 0.015. Since at working concentration of 10 µM CatPheo-a is mainly in dimeric form [9], absorption bands can be attributed to the dye dimers, whereas emitting species is a monomer. This explains the fact that fluorescence band maximum is positioned in more shortwave region relatively to the longwave absorption band.…”

Section: Resultsmentioning

confidence: 99%

“…It was shown that CatPheo-a binds to all these polymers, but especially effective binding was observed in the case of quadruplex poly(G), evidently due to the structural features of the dye core which is appropriate for interaction with the G-tetrads through π -π stacking interactions. Two types of CatPheo-a complex with long four-stranded poly(G) were revealed depending on the relative phosphate-to-dye concentration ratio, P/D [9]. The first one predominating at high dye content (low P/D) and characterized by weakening of the dye emission was identified as external binding of the dye to phosphate backbone with self-stacking.…”

Section: Introductionmentioning

confidence: 99%

“…Spectroscopic properties of CatPheo-a, as well as the ways of its binding to model synthetic biopolymers of different secondary structures (single-strand inorganic polyphosphate, double-stranded poly(A)·poly(U), poly(G)·poly(C) polynucleotides and four-stranded poly(G) polynucleotides) were studied earlier at near-physiological ionic conditions using various spectroscopic techniques [8,9]. It was shown that CatPheo-a binds to all these polymers, but especially effective binding was observed in the case of quadruplex poly(G), evidently due to the structural features of the dye core which is appropriate for interaction with the G-tetrads through π -π stacking interactions.…”

Section: Introductionmentioning

confidence: 99%

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Spectroscopic study on binding of cationic Pheophorbide-ato antiparallel quadruplex Tel22

Ryazanova

Zozulya

Voloshin

et al. 2018

Preprint

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Binding of water-soluble cationic Pheophorbide-a derivative (CatPheo-a) to Na + -stabilized antiparallel quadruplex formed by 22-mer oligonucleotide d[AG 3 (T 2 AG 3 ) 3 ], a fragment of human telomeric DNA (Tel22, PDB ID: 143D), has been examined using experimental techniques of absorption and polarized fluorescent spectroscopy as well as absorption melting. The binding affinity of CatPheo-a to Tel22 was studied in titration experiments registering the dependence of the dye fluorescence intensity and polarization degree on molar phosphate-to-dye ratio (P/D). CatPheo-a was found to bind effectively to the quadruplex, and two competitive binding modes were detected. The first one predominates at the dye excess and results in the fluorescence quenching, whereas the second one is preferential at the biopolymer excess and results in the enhancement of pheophorbide emission.The effect of CatPheo-a on thermodynamic parameters of Tel22 quadruplex unfolding was estimated using a two-state model. It was found that CatPheo-a destabilizes the quadruplex structure of Tel22 slightly decreasing its 4→1 transition midpoint temperature, gives destabilizing increment into Gibbs standard free energy and 2-fold decrease in the equilibrium quadruplex folding constant at 37°C. In ethanol CatPheo-a exhibits 15% higher efficiency of singlet oxygen generation as compared to the parent Pheo-a compound that makes it a promising photosensitizer for photodynamic therapy.

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Pheophorbide–phenazinium conjugate as a fluorescent light-up probe for G-quadruplex structure

Ryazanova

Zozulya

Voloshin

et al. 2020

Journal of Molecular Structure

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Spectroscopic Studies on Binding of Cationic Pheophorbide-a Derivative to Model Polynucleotides

Cited by 6 publications

References 21 publications

Binding of Metallated Porphyrin-Imidazophenazine Conjugate to Tetramolecular Quadruplex Formed by Poly(G): a Spectroscopic Investigation

Binding of Metallated Porphyrin-Imidazophenazine Conjugate to Tetramolecular Quadruplex Formed by Poly(G): a Spectroscopic Investigation

Spectroscopic study on binding of cationic Pheophorbide-ato antiparallel quadruplex Tel22

Pheophorbide–phenazinium conjugate as a fluorescent light-up probe for G-quadruplex structure

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