Analysis of the ethidium bromide bound to DNA by photoacoustic and FTIR spectroscopy

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dc.contributor.authorBugs, M. R.
dc.contributor.authorCornelio, M. L.
dc.contributor.institutionUniversidade Estadual Paulista (Unesp)
dc.date.accessioned2014-05-20T15:27:19Z
dc.date.available2014-05-20T15:27:19Z
dc.date.issued2001-10-01
dc.description.abstractUnder physiological conditions B-form DNA is an exceedingly stable structure. However, experimental evidences obtained through nuclear magnetic resonance and fluorescence anisotropy suggest that the structure of the double helix fluctuates substantially. We describe photoacoustic phase modulation frequency measurements of ethidium bromide (Eb) with calf thymus, DNA. As in fluorescence phase modulation measurements, we used an intercalating dye as a probe; however, we monitored the triplet excited state lifetime at different ionic strengths. The triplet lifetime of Eb varied from about 0.30 ms, with no DNA present, to 20 ms, (at a DNA:Eb molar ratio of 5). With salt titration, this value falls, to about 2.0 ms. This result suggests, a strong coupling between the phenantridinium ring of the ethidium and the base pairs because of the stacking movement of the DNA molecule under salt effect. This, effect may be understood considering DNA as a polyelectrolyte. The counterions, in the solution shield the phosphate groups, reducing the electrostatic repulsion force between them, hence compacting the DNA molecule. The results from Fourier transform infrared demonstrated two important bands: 3187 cm(-1) corresponding to the symmetric stretching of the NH group of the bases, and 1225 cm(-1) corresponding to the asymmetric stretching of phosphate groups shifted toward higher wavenumbers, suggesting a proximity between the intercalant and base pairs and a modification of the DNA backbone state, both induced by salt accretion.en
dc.description.affiliationUniv Estadual Paulista, Inst Biociencias Letras & Ciências Exatas, Dept Fis, BR-15054000 São Paulo, Brazil
dc.description.affiliationUnespUniv Estadual Paulista, Inst Biociencias Letras & Ciências Exatas, Dept Fis, BR-15054000 São Paulo, Brazil
dc.format.extent512-520
dc.identifierhttp://dx.doi.org/10.1562/0031-8655(2001)074<0512:AOTEBB>2.0.CO;2
dc.identifier.citationPhotochemistry and Photobiology. Augusta: Amer Soc Photobiology, v. 74, n. 4, p. 512-520, 2001.
dc.identifier.doi10.1562/0031-8655(2001)074<0512:AOTEBB>2.0.CO;2
dc.identifier.issn0031-8655
dc.identifier.lattes3874425691257843
dc.identifier.urihttp://hdl.handle.net/11449/37326
dc.identifier.wosWOS:000171786700002
dc.language.isoeng
dc.publisherAmer Soc Photobiology
dc.relation.ispartofPhotochemistry and Photobiology
dc.relation.ispartofjcr2.214
dc.relation.ispartofsjr0,591
dc.rights.accessRightsAcesso restrito
dc.sourceWeb of Science
dc.titleAnalysis of the ethidium bromide bound to DNA by photoacoustic and FTIR spectroscopyen
dc.typeArtigo
dcterms.licensehttp://www.bioone.org/page/terms_of_use
dcterms.rightsHolderAmer Soc Photobiology
unesp.author.lattes3874425691257843
unesp.campusUniversidade Estadual Paulista (Unesp), Instituto de Biociências Letras e Ciências Exatas, São José do Rio Pretopt

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Artigos - Física - IBILCE