Effects of salt concentration on spermidine-induced DNA folding transition

Abstract

The change on the higher order structure of individual giant double-strand DNA molecules as a function of salt and spermidine concentrations was investigated by single molecular observation with fluorescence microscopy in a wide range of concentration of NaCl, 1×10^<-6>-10^<-1>M. From the time successive fluorescent image, we evaluated the long-axis length and the hydrodynamic radius. I propose a scheme for two types of the folding transition manner of single DNAs.