CPL - Chalmers Publication Library
| Utbildning | Forskning | Styrkeområden | Om Chalmers | In English In English Ej inloggad.

IONIC-STRENGTH DEPENDENCE OF THE BINDING OF METHYLENE-BLUE TO CHROMATIN AND CALF THYMUS DNA

Per Hagmar (Institutionen för fysikalisk kemi) ; Stefan Pierrou (Institutionen för fysikalisk kemi) ; P. Nielsen ; Bengt Nordén (Institutionen för fysikalisk kemi) ; Mikael Kubista (Institutionen för fysikalisk kemi)
Journal of Biomolecular Structure & Dynamics (0739-1102). Vol. 9 (1992), 4, p. 667-679.
[Artikel, refereegranskad vetenskaplig]

The binding of the intercalating dye methylene blue (MB) to chromatin and to free DNA has been studied as a function of ionic strength at very low binding ratios (1 MB/400 DNA bases) using absorption spectroscopy. With increasing salt concentration MB is displaced from chromatin to a higher extent than from DNA. The free energy change for MB binding to chromatin is found to be approximately 5 kJ/mole lower than for binding to DNA. This difference can be explained by the reduced number of high affinity binding sites in chromatin due to the presence of histone proteins. The difference in binding energy is virtually independent of the degree of chromatin condensation and also of the valence of counter ions, suggesting that neither the affinity for, nor the number of intercalation sites in the linker DNA is markedly changed upon the salt-induced condensation. The unaffected thermodynamics of the linker binding suggests that factors such as DNA superhelicity and the electrostatic influence from the chromatosomes remain unchanged during chromatin condensation.

Nyckelord: ethidium-bromide, nucleic-acids, nucleosome, transitions, dichroism



Denna post skapades 2011-08-22.
CPL Pubid: 144684

 

Institutioner (Chalmers)

Institutionen för fysikalisk kemi (1900-2003)

Ämnesområden

Molekylärbiologi

Chalmers infrastruktur