title: Improving the understanding of DNA-propanediyl-1,3-bis(dodecyldimethylammonium) dibromide interaction using thermodynamic, structural and kinetic approaches.
abstract: A kinetic, thermodynamic and structural study of the interaction of the gemini surfactant propanediyl-1,3-bis(dimethyldodecylammonium dibromide) (12-3-12.2Br) with calf thymus DNA was carried out at several ionic strengths (NaCl) in aqueous solutions. A new 12-3-12(2+)-selective membrane was prepared in order to gain insight into the factors that control the binding of 12-3-12.2Br to DNA. We used ethidium bromide (EB) as a fluorescence probe to follow the kinetics of the interaction by using the stopped-flow fluorescence technique. The results can be explained in terms of a reaction mechanism involving two consecutive reversible (fast and slow) steps. The fast step was attributed to the union/separation of the surfactant with/from the DNA polynucleotide. Changes in the kinetic constants in the forward and backward directions were discussed in terms of the Brönsted-Pitzer equation and of the increase in hydrophobic interactions of the surfactant tails as a consequence of salting-out effects, respectively. The slow step corresponds to a conformational change of the surfactant-DNA complex to a more compacted form. The equilibrium constant, calculated from the forward and reverse rate constants of these steps, agrees with the results obtained from potentiometric titration using a 12-3-12-(2+) selective electrode.
authors.affiliation: Department of Physical Chemistry, Faculty of Chemistry, University of Seville, C/Profesor García González, s/n, 41012, Sevilla, Spain. elia@us.es.
authors.forename: Elia
authors.initials: E
authors.lastname: Grueso
authors.forename: Edyta
authors.initials: E
authors.lastname: Kuliszewska
authors.forename: Rafael
authors.initials: R
authors.lastname: Prado-Gotor
authors.forename: Pilar
authors.initials: P
authors.lastname: Perez-Tejeda
authors.forename: Emilio
authors.initials: E
authors.lastname: Roldan
mesh_terms: D000818:Animals; D002417:Cattle; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D004996:Ethidium / Q000737:chemistry; D007700:Kinetics; D009994:Osmolar Concentration; D011407:Propane / Q000031:analogs & derivatives* / Q000737:chemistry; D012965:Sodium Chloride / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D013501:Surface-Active Agents; C000588802:propanediyl-1,3-bis(dimethyldodecylammonium dibromide); D012965:Sodium Chloride; D004247:DNA; C427203:calf thymus DNA; D004996:Ethidium; D011407:Propane