Force-induced structural transitions in cross-linked DNA films.
We report on the preparation and characterization of wet-spun films of sodium DNA in which intermolecular cross-links were introduced following formaldehyde treatment. Raman scattering shows that the DNA in moderately cross-linked films is mainly in the B conformation. Stretching experiments show a transition from plastic to elastomeric behavior with increasing exposure to the cross-linking agent. Elastomeric DNA films are strongly disordered. X-ray diffraction shows that stretching of moderately cross-linked films under controlled high humidity conditions results in increased molecular orientation as well as the appearance of meridional reflections at 7.4-7.8 and 8.2 angstroms. These reflections are not observed for any of the classical conformations associated with mixed sequence DNA, and may arise from extended base-pair stacking in a stretched DNA structure.
André
A
A
Universität Konstanz, Fachbereich Physik, 78457, Konstanz, Germany.
Fontaine-Vive
F
F
Möller
H M
HM
Fischer
T
T
Maret
G
G
Forsyth
V T
VT
Gisler
T
T
D003432:Cross-Linking Reagents / Q000737:chemistry*; D004247:DNA / Q000737:chemistry* / Q000648:ultrastructure*; D004548:Elasticity; D008567:Membranes, Artificial; D009690:Nucleic Acid Conformation; D044367:Phase Transition; D013314:Stress, Mechanical
D003432:Cross-Linking Reagents; D008567:Membranes, Artificial; D004247:DNA