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Scanning tunneling microscopy of nucleic acids.
G Lee1, P G Arscott, V A Bloomfield
1Department of Chemical Engineering and Materials Science Interfacial, University of Minnesota, Minneapolis 55455.
Science (New York, N.Y.)
|April 28, 1989
Summary
Scanning tunneling microscopy (STM) precisely measured nucleic acid structures like DNA and RNA. STM revealed subtle structural changes, including helical pitch variations, crucial for understanding molecular function.
Area of Science:
- Biophysics
- Molecular Biology
- Nanotechnology
Background:
- The Scanning Tunneling Microscope (STM) offers high-resolution imaging capabilities.
- Understanding the precise three-dimensional structure of nucleic acids is fundamental to molecular biology.
Purpose of the Study:
- To utilize STM for quantitative analysis of nucleic acid structural parameters.
- To investigate the effects of dehydration on nucleic acid structure.
- To demonstrate STM's ability to detect fine structural modulations.
Main Methods:
- Employing STM to image poly(rA).poly(rU) and DNA fibers.
- Utilizing 2D Fourier transforms and topographic profiles for pitch measurement.
- Analyzing localized regions for variations in helical pitch.
Main Results:
- Measured helical pitches were approximately 7% smaller than standard A-form RNA and B-form DNA dimensions, consistent with mild dehydration.
- Extensive dehydration resulted in up to 19% structural shrinkage.
- STM detected local helical pitch variations as small as 1 angstrom.
Conclusions:
- STM provides precise measurements of nucleic acid structural parameters like helical pitch and interhelical spacing.
- Dehydration significantly impacts nucleic acid dimensions, a factor observable with STM.
- STM's resolution enables visualization of functionally relevant modulations in nucleic acid structure.