Dynamic force spectroscopy of single DNA molecules
AUTOR(ES)
Strunz, Torsten
FONTE
The National Academy of Sciences
RESUMO
To explore the analytic relevance of unbinding force measurements between complementary DNA strands with an atomic force microscope, we measured the forces to mechanically separate a single DNA duplex under physiological conditions by pulling at the opposite 5′-ends as a function of the loading rate (dynamic force spectroscopy). We investigated DNA duplexes with 10, 20, and 30 base pairs with loading rates in the range of 16–4,000 pN/s. Depending on the loading rate and sequence length, the unbinding forces of single duplexes varied from 20 to 50 pN. These unbinding forces are found to scale with the logarithm of the loading rate, which is interpreted in terms of a single energy barrier along the mechanical separation path. The parameters describing the energy landscape, i.e., the distance of the energy barrier to the minimum energy along the separation path and the logarithm of the thermal dissociation rate, are found to be proportional to the number of base pairs of the DNA duplex. These single molecule results allow a quantitative comparison with data from thermodynamic ensemble measurements and a discussion of the analytic applications of unbinding force measurements for DNA.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=18024Documentos Relacionados
- DNA base pair resolution by single molecule force spectroscopy
- Beyond the conventional description of dynamic force spectroscopy of adhesion bonds
- Segmented nanofibers of spider dragline silk: Atomic force microscopy and single-molecule force spectroscopy
- Phase imaging of moving DNA molecules and DNA molecules replicated in the atomic force microscope.
- Atomic force microscopy of insulin single crystals: direct visualization of molecules and crystal growth.