Structural investigations of DNA-polycation complexes.
Eur Phys J E Soft Matter
; 16(1): 17-28, 2005 Jan.
Article
en En
| MEDLINE
| ID: mdl-15688137
ABSTRACT
The internal structure of DNA-polycation complexes is investigated by synchrotron small-angle X-ray scattering (SAXS). Hexagonal packing of DNA is observed for DNA complexed with poly-L-lysine (PL), poly-L-arginine (PA), spermine (Sp), and linear and branched polyethyleneimine (lPEI and bPEI, respectively). Variations in the internal spacings and degree of long-range ordering are dependent on both polycation type and concentration of added salt. With increasing concentration of monovalent salt, a discontinuous phase transition is observed from compact to loose bundles and finally to an isotropic network phase. This salt-induced melting transition was found to be universal for all polyplexes studied and is in quantitative agreement with a simple free energy model based solely on electrostatic and entropic contributions. Using the osmotic stress method, bulk modulus (K) is measured for PL-DNA and PA-DNA polyplexes at various salt concentrations. With increasing osmotic force, we show that the salt-induced melting transition is shifted and compression in the loose bundle regime is in qualitative agreement with our model.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Poliaminas
/
ADN
/
Modelos Moleculares
/
Modelos Químicos
Tipo de estudio:
Qualitative_research
Idioma:
En
Revista:
Eur Phys J E Soft Matter
Asunto de la revista:
BIOFISICA
Año:
2005
Tipo del documento:
Article
País de afiliación:
Alemania