title: The effect of spermine on plasmid condensation and dye release observed by fluorescence correlation spectroscopy.
abstract: We demonstrate that fluorescence correlation spectroscopy (FCS) can be employed to follow the conformational changes of DNA molecules induced by the addition of a cationic condensing compound (spermine). In our experiments the plasmid pHbetaAPr-1-neo (10 kbp; contour length 3.4 microm) was labeled with propidium iodide (PrIo) and then titrated with spermine to induce its condensation. When spermine was applied at concentrations above 5 microM (spermine/DNAphosphate=0.375), the diffusion time of the labeled plasmid dropped from 15 ms down to 3 ms (its diffusion coefficient, D, increased from 1.0x10(-12) m2/s to 6.0x10(-12) m2/s). The application of spermine was also accompanied by decreasing count rate and particle number, reflecting the dye's dissociation. The data presented show that FCS may become a valuable tool in studying supramolecular aggregate formation, especially when association is followed by a change in the hydrodynamic size of the resulting complex.
authors.affiliation: Department of Physics and Biophysics, Agricultural University, Wrocław, Poland.
authors.forename: Teresa
authors.initials: T
authors.lastname: Kral
authors.forename: Martin
authors.initials: M
authors.lastname: Hof
authors.forename: Marek
authors.initials: M
authors.lastname: Langner
mesh_terms: D004247:DNA / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry*; D007364:Intercalating Agents / Q000737:chemistry; D009690:Nucleic Acid Conformation / Q000187:drug effects; D010957:Plasmids / Q000737:chemistry*; D011419:Propidium; D013050:Spectrometry, Fluorescence; D013096:Spermine / Q000494:pharmacology*; D013194:Staining and Labeling
chemical_list: D005456:Fluorescent Dyes; D007364:Intercalating Agents; D013096:Spermine; D011419:Propidium; D004247:DNA