Force-induced melting of the DNA double helix 1. Thermodynamic analysis

Ioulia Rouzina, Victor A. Bloomfield

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284 Scopus citations

Abstract

The highly cooperative elongation of a single B-DNA molecule to almost twice its contour length upon application of a stretching force is interpreted as force-induced DNA melting. This interpretation is based on the similarity between experimental and calculated stretching profiles, when the force-dependent free energy of melting is obtained directly from the experimental force versus extension curves of double- and single-stranded DNA. The high cooperativity of the overstretching transition is consistent with a melting interpretation. The ability of nicked DNA to withstand forces greater than that at the transition midpoint is explained as a result of the one-dimensional nature of the melting transition, which leads to alternating zones of melted and unmelted DNA even substantially above the melting midpoint. We discuss the relationship between force-induced melting and the B-to-S transition suggested by other authors. The recently measured effect on T7 DNA polymerase activity of the force applied to a ssDNA template is interpreted in terms of preferential stabilization of dsDNA by weak forces ∼7 pN.

Original languageEnglish (US)
Pages (from-to)882-893
Number of pages12
JournalBiophysical journal
Volume80
Issue number2
DOIs
StatePublished - 2001

Bibliographical note

Funding Information:
This work was supported in part by National Institutes of Health grant 28093.

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