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Related Experiment Videos

Stretched DNA structures observed with atomic force microscopy

T Thundat1, D P Allison, R J Warmack

  • 1Health Sciences Research Division, Oak Ridge National Laboratory, TN 37831-6123.

Nucleic Acids Research
|October 11, 1994
PubMed
Summary
This summary is machine-generated.

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Atomic force microscopy revealed anomalous double-stranded DNA molecules with up to 80% increased contour lengths. These findings suggest DNA helix uncoiling without backbone breakage, challenging standard structural observations.

Area of Science:

  • Biophysics
  • Molecular Biology
  • Nanotechnology

Background:

  • Standard atomic force microscopy (AFM) images typically show relaxed double-stranded DNA (dsDNA) with minor contour length variations.
  • Plasmid and lambda DNA usually exhibit natural bends and kinks, with contour lengths within expected ranges.
  • Overlapping DNA molecules are generally observed only at very high concentrations.

Purpose of the Study:

  • To investigate anomalous DNA structures observed in AFM images.
  • To characterize the physical properties of unusually straightened and stretched DNA molecules.
  • To understand the mechanism behind observed DNA structural anomalies.

Main Methods:

  • Atomic Force Microscopy (AFM) imaging of DNA preparations.
  • Analysis of molecular contour lengths and heights.

Related Experiment Videos

  • Comparison of anomalous DNA structures with typical relaxed DNA conformations.

    • Main Results:

    • Observed DNA molecules with contour lengths increased by up to 80% compared to relaxed forms.
    • Anomalous molecules exhibited approximately half the height of normal relaxed DNA.
    • Some DNA molecules appeared to be in a transitional state between stretched and relaxed forms.

    Conclusions:

    • The observed DNA structural anomalies are consistent with helix uncoiling.
    • The uncoiling occurs without apparent breakage of the deoxyribose-phosphate backbone.
    • AFM can reveal non-standard DNA conformations under specific conditions.