title: Folding transition into a loosely collapsed state in plasmid DNA as revealed by single-molecule observation.
abstract: The conformational transition of a plasmid DNA, pGEG.GL3 (12.5 kbp, circular), induced by spermine(4+) was studied through the observation of individual DNA by fluorescence microscopy. We deduced the change in the hydrodynamic radius R(H) from an analysis of the Brownian motion of single DNA molecules. R(H) decreases in a continuous manner with an increase in spermine(4+), in contrast to the large discrete on/off change for long linear DNA. Just after the transition to the collapsed state, a small number of DNA molecules tend to form an assembly, which disperses in the bulk solution without precipitation.
authors.affiliation: Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Yuko T
authors.initials: YT
authors.lastname: Sato
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Hamada
authors.forename: Koji
authors.initials: K
authors.lastname: Kubo
authors.forename: Ayako
authors.initials: A
authors.lastname: Yamada
authors.forename: Tsunao
authors.initials: T
authors.lastname: Kishida
authors.forename: Osam
authors.initials: O
authors.lastname: Mazda
authors.forename: Kenichi
authors.initials: K
authors.lastname: Yoshikawa
mesh_terms: D004247:DNA / Q000737:chemistry* / Q000378:metabolism*; D007834:Lasers; D009690:Nucleic Acid Conformation; D010957:Plasmids / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D004247:DNA