Strained DNA is kinked by low concentrations of Zn2+

W. Han, M. Dlakic, Judy Zhu Yinwen Judy Zhu, Stuart Lindsay, R. E. Harrington

Research output: Contribution to journalArticlepeer-review

90 Scopus citations


A novel atomic force microscope with a magnetically oscillated tip has provided unprecedented resolution of small DNA fragments spontaneously adsorbed to mica and imaged in situ in the presence of divalent ions. Kinks (localized bends of average angle 78°) were observed in axially strained minicircles consisting of tandemly repeated d(A)5 and d(GGGCC[C]) sequences. The frequency of kinks in identical minicircles increased 4-fold in the presence of 1 mM Zn2+ compared with 1 mM Mg2+. Kinking persisted in mixed Mg2+/Zn2+ electrolytes until the Zn2+ concentration dropped below 100 μM, indicating that this type of kinking may occur under physiological conditions. Kinking appears to replace intrinsic bending, and statistical analysis shows that kinks are not localized within any single sequence element. A surprisingly small free energy is associated with kink formation.

Original languageEnglish (US)
Pages (from-to)10565-10570
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number20
StatePublished - Sep 30 1997


  • Atomic force microscopy
  • C mode mode
  • DNA kinking
  • DNA microcircles
  • Magnetic A

ASJC Scopus subject areas

  • General


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