Internal dynamics of superhelical DNA.

We present the first data on the temporal kinetics of monomer mean square displacements in DNA circles with defined degrees of superhelicity. The segmental dynamics of specifically labeled DNA plasmids with superhelical densities between 0 and -0.016 was assessed by fluorescence correlation spectroscopy. Introduction of superhelicity leads to progressively faster dynamics in the long time regime corresponding to the coil diffusion as observed previously by Langowski et al. [Biopolymers 34, 639 (1994)10.1002/bip.360340506], but also in the short time range corresponding to the segmental motion within the DNA coil.