Exploring tiny forces with single molecule force spectroscopy

phys.org | 9/4/2019 | Staff
elio25elio25 (Posted by) Level 3
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In terms of space organization, DNA has powers rivaling Marie Kondo. A strand of DNA that is two meters long intricately folds itself into a cell nucleus only 10 microns across. (One of the hairs on your head has a diameter of 100 microns, and you can't see anything smaller than that without a microscope.) Everything that needs to happen biochemically for the DNA to function hinges upon the precise unpacking and unwinding of its strands from that tiny space.

But the study of DNA and other complex molecules often focuses not on their mechanical properties but on their chemical processes, noted Duke mechanical engineering and materials science professor Piotr Marszalek. While biochemical research has led to breakthrough applications like cloning, gene therapy and gene expression profiling, Marszalek said the intense focus on the single area has sometimes overshadowed the importance of mechanics in understanding the relationship between molecular structure and function.

Marszalek - Community - Researchers - Molecule - Force

Marszalek belongs to a community of researchers using single molecule force spectroscopy (SMFS) to study molecular structure, and the forces that stabilize these structures. Currently, there are three main approaches to SMFS: atomic force microscopy (AFM), which scans the surface of a molecule with a probe the size of a few atoms and is able to mechanically stretch these molecules; optical tweezers, which attract particles via focused lasers (and which earned their inventor, Arthur Ashkin, a Nobel Prize in physics); and magnetic tweezers, whose draw is so powerful that Marszalek warned me against handling them, for fear that my skin would be pinched between the magnetic cylinders and I would find them impossible to pry apart.

Each approach enables researchers to capture a single molecule—like DNA, or a bit of muscle or other protein—and slowly stretch it to observe what happens.


It doesn't just snap in half, as you might expect.

Polypeptide chains...
(Excerpt) Read more at: phys.org
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