Calorimetric and dynamic light-scattering investigation of cationic surfactant--DNA complexes.
By means of combined calorimetric and dynamic light-scattering measurements, we have investigated the conformational behavior of DNA chains after thermal melting in the presence of a cationic surfactant at different concentrations, up to a surfactant-to-phosphate group molar ratio close to unity. Both the specific heat capacity, C(ex)(p) and the hydrodynamic radius R of the DNA chains provide support for the existence of two structural arrangements with different thermal stabilities, coexisting in the bulk solution. Although a component remains an elongated unfolded DNA chain originated in the thermal denaturation, the second component, consisting of DNA-surfactant complexes, assumes a compact structure with an average size of about 80 nm, whose thermal denaturation occurs at temperatures higher than 100 degrees C.
Marchetti
S
S
Dipartimento di Fisica, Universita' di Firenze, Via G. Sansone, I-50019 Sesto Fiorentino, Firenze, Italy.
Onori
G
G
Cametti
C
C
D000818:Animals; D002152:Calorimetry, Differential Scanning; D002412:Cations / Q000737:chemistry; D002417:Cattle; D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry; D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry*; D008027:Light; D013501:Surface-Active Agents / Q000737:chemistry*; D044366:Transition Temperature
D002412:Cations; D002593:Cetrimonium Compounds; D013501:Surface-Active Agents; D004247:DNA; C427203:calf thymus DNA; D000077286:Cetrimonium