title: Conformational changes of DNA in the presence of 12-s-12 gemini surfactants (s=2 and 10). Role of the spacer's length in the interaction surfactant-polynucleotide.
abstract: A multifaceted study on the interaction of calf-thymus DNA with two different cationic gemini surfactants alkanediyl-α-ω-bis(dodecyldimethyl-amonium)bromide, 12-s-12,2Br(-) (with s=2, G2, and 10, G10) was carried out. The measurements were done at different molar ratios X=[surfactant]/[DNA]. Results show two different conformational changes in DNA: a first compaction of the polynucleotide corresponding to a partial conformational (not total) change of DNA from an extended coil state to a globular state that happens at the lower molar ratio X. A second change corresponds to a breaking of the partial condensation, that is, the transition from the compacted state to a new more extended conformation (for the higher X values) different to the initial extension. According to circular dichroism spectra and dynamic light scattering measurements, this new state of DNA seems to be similar to a ψ-phase. Measurements confirm that interactions involved in the compaction are different to those previously obtained for the analog surfactant CTAB. X values at which the conformational changes happen depend on the length of the spacer in the surfactant along with the charge of the polar heads.
authors.affiliation: Department of Physical Chemistry, Faculty of Chemistry, University of Seville, c/Prof. García González n° 1, Sevilla 41012, Spain.
authors.forename: J P
authors.initials: JP
authors.lastname: García
authors.affiliation: Department of Physical Chemistry, Faculty of Chemistry, University of Seville, c/Prof. García González n° 1, Sevilla 41012, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Marrón
authors.affiliation: Department of Physical Chemistry, Faculty of Chemistry, University of Seville, c/Prof. García González n° 1, Sevilla 41012, Spain.
authors.forename: V I
authors.initials: VI
authors.lastname: Martín
authors.affiliation: Department of Physical Chemistry, Faculty of Chemistry, University of Seville, c/Prof. García González n° 1, Sevilla 41012, Spain.
authors.forename: M L
authors.initials: ML
authors.lastname: Moyá
authors.affiliation: Department of Physical Chemistry, Faculty of Chemistry, University of Seville, c/Prof. García González n° 1, Sevilla 41012, Spain. Electronic address: pcornejo@us.es.
authors.forename: P
authors.initials: P
authors.lastname: Lopez-Cornejo
mesh_terms: D000818:Animals; D002417:Cattle; D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry*; D007700:Kinetics; D008027:Light; D018625:Microscopy, Atomic Force; D008970:Molecular Weight; D009690:Nucleic Acid Conformation; D009691:Nucleic Acid Denaturation; D011119:Polynucleotides / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012542:Scattering, Radiation; D013050:Spectrometry, Fluorescence; D055672:Static Electricity; D013501:Surface-Active Agents / Q000737:chemistry*; D014783:Viscosity
chemical_list: D011119:Polynucleotides; D000644:Quaternary Ammonium Compounds; D013501:Surface-Active Agents; D004247:DNA; C427203:calf thymus DNA
keywords: AFM; Circular dichroism; DNA condensation; Gemini surfactant; Melting temperature