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Abrupt buckling transition observed during the plectoneme formation of individual DNA molecules.

ABSTRACT: The response of single DNA molecules to externally applied forces and torques was directly measured using an angular optical trap. Upon overwinding, DNA buckled abruptly as revealed by a sharp extension drop followed by a torque plateau. When the DNA was held at the buckling transition, its extension hopped rapidly between two distinct states. Furthermore, the initial plectonemic loop absorbed approximately twice as much extension as was absorbed into the plectoneme upon each additional turn. The observed extension change after buckling and the postbuckling torque support a recent DNA elasticity model.

SUBMITTER: Forth S

PROVIDER: S-EPMC3019760 | biostudies-literature | 2008 Apr

REPOSITORIES: biostudies-literature

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Abrupt buckling transition observed during the plectoneme formation of individual DNA molecules.

Forth Scott S Deufel Christopher C Sheinin Maxim Y MY Daniels Bryan B Sethna James P JP Wang Michelle D MD

Physical review letters 20080408 14

The response of single DNA molecules to externally applied forces and torques was directly measured using an angular optical trap. Upon overwinding, DNA buckled abruptly as revealed by a sharp extension drop followed by a torque plateau. When the DNA was held at the buckling transition, its extension hopped rapidly between two distinct states. Furthermore, the initial plectonemic loop absorbed approximately twice as much extension as was absorbed into the plectoneme upon each additional turn. Th ...[more]

PMID: 18518075

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