Abstract
The fluorescence polarization anisotropies of ethidium intercalated in duplex DNAs containing 12 to 60 bp were measured and analyzed using a theory of deformable rods to obtain their hydrodynamic radii (R<SUB>H</SUB>). The apparent R<SUB>H</SUB> is 10.0 +/- 0.2 angstroms for 12 and 24 bp, but increases to 11.5 - 12.0 angstroms between 40 and 60 bp. This variation in R<SUB>H</SUB> is attributed to the presence of slowly relaxing bends in the DNA. Consequently, the static equilibrium persistence length must be much smaller than the dynamic persistence length (P<SUB>d</SUB>) defined by the dynamic (instantaneous) bending rigidity. We estimate that P<SUB>d</SUB> > 1000 angstroms. R<SUB>H</SUB> of a 48 bp duplex DNA is largely independent of NaCl concentration, which suggests that interionic forces do not much affect the rotational friction. However, R<SUB>H</SUB> depends significantly on the concentrations of other ions, especially Mg<SUP>2+</SUP> and Mn<SUP>2+</SUP>, which are believed to affect the hydration of DNA.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
