Unraveling the Physics of DNA’s Double Helix:
Researchers at Duke University’s Pratt School of Engineering have uncovered a missing link in scientists’ understanding of the physical forces that give DNA its famous double helix shape.
“The stability of DNA is so fundamental to life that it’s important to understand all factors,” said Piotr Marszalek, a professor of mechanical engineering and materials sciences at Duke. “If you want to create accurate models of DNA to study its interaction with proteins or drugs, for example, you need to understand the basic physics of the molecule. For that, you need solid measurements of the forces that stabilize DNA.”
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They tugged on individual strands that were tethered at one end to gold and measured the changes in force as they pulled. The AFM technique allows precise measurements of forces within individual molecules down to one pico-Newton – a trillionth of a Newton. For a sense of scale, the force of gravity on a two-liter bottle of soda is about 20 Newtons, Marszalek noted.