DNA-spermine and DNA-lipid aggregate formation visualized by fluorescence correlation spectroscopy.
BACKGROUND
Fluorescence correlation spectroscopy (FCS) can be used for the determination of diffusion coefficients of single molecules. Since diffusion coefficients are correlated with size and shape of the labeled species, FCS provides information on conformational changes in plasmids aggregates.


METHODS
A 10-kbp plasmid stained with PicoGreen was condensed by spermine or liposomes formulated from cationic lipid and egg phosphatidylcholine.


RESULTS
The diffusion coefficient of DNA increases from 1.0 x 10(-12) m2/s to 3.2 x 10(-12) m2/s by the addition of spermine, whereas the addition of cationic liposomes leads to complexes characterized by diffusion coefficients with values ranging from 1.7 to 1.9 x 10(-12) m2/s.


CONCLUSIONS
FCS experiments allow determining the diffusion coefficients of DNA-containing aggregates which provide information regarding the topology and homogeneity of the aggregate.
Kral
Teresa
T
J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic. tek@ozi.ar.wroc.pl
Langner
Marek
M
Hof
Martin
M
D004247:DNA / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry; D006801:Humans; D008055:Lipids / Q000737:chemistry*; D009930:Organic Chemicals / Q000737:chemistry; D010957:Plasmids / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013096:Spermine / Q000737:chemistry*; D013194:Staining and Labeling
D005456:Fluorescent Dyes; D008055:Lipids; D009930:Organic Chemicals; C099476:PicoGreen; D013096:Spermine; D004247:DNA