Abstract:
:We have explored the electromechanical properties of DNA on a nanometer-length scale using an electric field to force single molecules through synthetic nanopores in ultrathin silicon nitride membranes. At low electric fields, E < 200 mV/10 nm, we observed that single-stranded DNA can permeate pores with a diameter >/=1.0 nm, whereas double-stranded DNA only permeates pores with a diameter >/=3 nm. For pores <3.0 nm diameter, we find a threshold for permeation of double-stranded DNA that depends on the electric field and pH. For a 2 nm diameter pore, the electric field threshold is approximately 3.1 V/10 nm at pH = 8.5; the threshold decreases as pH becomes more acidic or the diameter increases. Molecular dynamics indicates that the field threshold originates from a stretching transition in DNA that occurs under the force gradient in a nanopore. Lowering pH destabilizes the double helix, facilitating DNA translocation at lower fields.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Heng JB,Aksimentiev A,Ho C,Marks P,Grinkova YV,Sligar S,Schulten K,Timp Gdoi
10.1529/biophysj.105.070672subject
Has Abstractpub_date
2006-02-01 00:00:00pages
1098-106issue
3eissn
0006-3495issn
1542-0086pii
S0006-3495(06)72298-6journal_volume
90pub_type
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