title: Interplay between folding/unfolding and helix/coil transitions in giant DNA.
abstract: It has been well established that double-stranded DNA undergoes a melting, or helix/coil, transition into a single-stranded coil state with an increase in temperature. On the other hand, it has recently been found that, at a fixed temperature, long DNA, larger than several kilobase pairs, exhibits a discrete transition, or switching, between elongated and folded states, preserving its double-stranded structure, with the addition of various condensation agents, such as alcohol, hydrophilic polymer, multivalent cation, and cationic surfactant. In the present study, we examined the interplay between the folding/unfolding transition and the helix/coil transition in individual giant DNA molecules, by observing the conformation of single molecular chains with fluorescence microscopy. The results indicate that the helix-to-coil transition tightly cooperates with the unfolding transition in DNA.
authors.affiliation: Graduate School of Human Informatics, Nagoya University, Nagoya 464-8601, Japan. sergeyev@genebee.msu.su
authors.forename: S V
authors.initials: SV
authors.lastname: Mikhailenko
authors.forename: V G
authors.initials: VG
authors.lastname: Sergeyev
authors.forename: A A
authors.initials: AA
authors.lastname: Zinchenko
authors.forename: M O
authors.initials: MO
authors.lastname: Gallyamov
authors.forename: I V
authors.initials: IV
authors.lastname: Yaminsky
authors.forename: K
authors.initials: K
authors.lastname: Yoshikawa
mesh_terms: D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry*; D008856:Microscopy, Fluorescence; D009690:Nucleic Acid Conformation; D012997:Solvents; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013696:Temperature
chemical_list: D012997:Solvents; D004247:DNA