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Dual DNA binding mode of a turn-on red fluorescent probe thiazole coumarin

Turn-on fluorescent probes show enhanced emission upon DNA binding, advocating their importance in imaging cellular DNA. We have probed the DNA binding mode of thiazole-coumarin (TC) conjugate, a recently reported hemicyanine-based turn-on red fluorescent probe, using a number of biophysical techniq...

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Autores principales: Ganguly, Sudakshina, Ghosh, Debasis, Narayanaswamy, Nagarjun, Govindaraju, T., Basu, Gautam
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7497988/
https://www.ncbi.nlm.nih.gov/pubmed/32941495
http://dx.doi.org/10.1371/journal.pone.0239145
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author Ganguly, Sudakshina
Ghosh, Debasis
Narayanaswamy, Nagarjun
Govindaraju, T.
Basu, Gautam
author_facet Ganguly, Sudakshina
Ghosh, Debasis
Narayanaswamy, Nagarjun
Govindaraju, T.
Basu, Gautam
author_sort Ganguly, Sudakshina
collection PubMed
description Turn-on fluorescent probes show enhanced emission upon DNA binding, advocating their importance in imaging cellular DNA. We have probed the DNA binding mode of thiazole-coumarin (TC) conjugate, a recently reported hemicyanine-based turn-on red fluorescent probe, using a number of biophysical techniques and a series of short oligonucleotides. TC exhibited increased fluorescence anisotropy and decreased absorbance (~50%) at low [DNA]/[TC] ratio. Although the observed hypochromicity and the saturating value of [DNA base pair]:[TC] ratio is consistent with a previous study that suggested intercalation to be the DNA binding mode of TC, a distinctly different and previously unreported binding mode was observed at higher ratios of [DNA]:[TC]. With further addition of DNA, only oligonucleotides containing A(n)T(n) or (AT)(n) stretches showed further change—decreased hypochromicity, red shifted absorption peaks and concomitant fluorescence enhancement, saturating at about 1:1 [DNA]: [TC]. (1)H-NMR chemical shift perturbation patterns and H1’-H6/H8 NOE cross-peaks of the 1:1 complex indicated minor groove binding by TC. ITC showed the 1:1 DNA binding event to be endothermic (ΔH° ~ 2 kcal/mol) and entropy driven (ΔS° ~ 32 cal/mol/K). Taken together, the experimental data suggest a dual DNA binding mode by TC. At low [DNA]/[TC] ratio, the dominant mode is intercalation. This switches to minor groove binding at higher [DNA]/[TC], only for sequences containing A(n)T(n) or (AT)(n) stretches. Turn-on fluorescence results only in the previously unreported minor groove bound state. Our results allow a better understanding of DNA-ligand interaction for the newly reported turn-on probe TC.
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spelling pubmed-74979882020-09-24 Dual DNA binding mode of a turn-on red fluorescent probe thiazole coumarin Ganguly, Sudakshina Ghosh, Debasis Narayanaswamy, Nagarjun Govindaraju, T. Basu, Gautam PLoS One Research Article Turn-on fluorescent probes show enhanced emission upon DNA binding, advocating their importance in imaging cellular DNA. We have probed the DNA binding mode of thiazole-coumarin (TC) conjugate, a recently reported hemicyanine-based turn-on red fluorescent probe, using a number of biophysical techniques and a series of short oligonucleotides. TC exhibited increased fluorescence anisotropy and decreased absorbance (~50%) at low [DNA]/[TC] ratio. Although the observed hypochromicity and the saturating value of [DNA base pair]:[TC] ratio is consistent with a previous study that suggested intercalation to be the DNA binding mode of TC, a distinctly different and previously unreported binding mode was observed at higher ratios of [DNA]:[TC]. With further addition of DNA, only oligonucleotides containing A(n)T(n) or (AT)(n) stretches showed further change—decreased hypochromicity, red shifted absorption peaks and concomitant fluorescence enhancement, saturating at about 1:1 [DNA]: [TC]. (1)H-NMR chemical shift perturbation patterns and H1’-H6/H8 NOE cross-peaks of the 1:1 complex indicated minor groove binding by TC. ITC showed the 1:1 DNA binding event to be endothermic (ΔH° ~ 2 kcal/mol) and entropy driven (ΔS° ~ 32 cal/mol/K). Taken together, the experimental data suggest a dual DNA binding mode by TC. At low [DNA]/[TC] ratio, the dominant mode is intercalation. This switches to minor groove binding at higher [DNA]/[TC], only for sequences containing A(n)T(n) or (AT)(n) stretches. Turn-on fluorescence results only in the previously unreported minor groove bound state. Our results allow a better understanding of DNA-ligand interaction for the newly reported turn-on probe TC. Public Library of Science 2020-09-17 /pmc/articles/PMC7497988/ /pubmed/32941495 http://dx.doi.org/10.1371/journal.pone.0239145 Text en © 2020 Ganguly et al http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Ganguly, Sudakshina
Ghosh, Debasis
Narayanaswamy, Nagarjun
Govindaraju, T.
Basu, Gautam
Dual DNA binding mode of a turn-on red fluorescent probe thiazole coumarin
title Dual DNA binding mode of a turn-on red fluorescent probe thiazole coumarin
title_full Dual DNA binding mode of a turn-on red fluorescent probe thiazole coumarin
title_fullStr Dual DNA binding mode of a turn-on red fluorescent probe thiazole coumarin
title_full_unstemmed Dual DNA binding mode of a turn-on red fluorescent probe thiazole coumarin
title_short Dual DNA binding mode of a turn-on red fluorescent probe thiazole coumarin
title_sort dual dna binding mode of a turn-on red fluorescent probe thiazole coumarin
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7497988/
https://www.ncbi.nlm.nih.gov/pubmed/32941495
http://dx.doi.org/10.1371/journal.pone.0239145
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