Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Penn researcher shows that DNA gets kinky easily at the nanoscale

06.11.2006
Scientists have answered a long-standing molecular stumper regarding DNA: How can parts of such a rigid molecule bend and coil without requiring large amounts of force?

According to a team of researchers from the United States and the Netherlands, led by a physicist from the University of Pennsylvania, DNA is much more flexible than previously believed when examined over extremely small lengths. They used a technique called atomic force microscopy to determine the amount of energy necessary to bend DNA over nano-size lengths (about a million times smaller than a printed letter).

The findings, which appear in the November issue of the journal Nature Nanotechnology, illustrate how molecular properties often appear different when viewed at different degrees of magnification.

"DNA is not a passive molecule. It constantly needs to bend, forming loops and kinks, as other molecules interact with it," said Philip Nelson, a professor in Penn's Department of Physics and Astronomy in the School of Arts and Sciences. "But when people looked at long chunks of DNA, it always seemed to behave like a stiff elastic rod."

For example, DNA must wrap itself around proteins, forming tiny molecular structures called nucleosomes, which help regulate how genes are read. The formation of tight DNA loops also plays a key role in switching some genes off. According to Nelson, such processes were considered a minor mystery of nature, in part because researchers didn't have the tools of nanotechnology to examine molecules in such fine detail.

"Common sense and physics seemed to tell us that DNA just shouldn't spontaneously bend into such tight structures, yet it does," Nelson said. "In the conventional view of a DNA molecule, wrapping DNA into a nucleosome would be like bending a yardstick around a baseball."

To study DNA on the needed short length scales, Nelson and his colleagues used a technique called high-resolution atomic force microscopy to obtain a direct measurement of the energy it would take to bend lengths of DNA just a few nanometers long. The technique involves dragging an extremely sharp tip across the contours of the molecule in order to create a picture of its structure.

With this tool, Nelson and his colleagues measured the energies required to make various bends in DNA at lengths of five to 50 nanometers --- about a thousand times smaller than the diameter of a typical human cell.

''We found that DNA has different apparent properties when probed at short lengths than the entire molecule does when taken as a whole," Nelson said. ''Its resistance to large-angle bends at this scale is much smaller than previously suspected."

Nelson is also a member of Penn's Nano--Bio Interface Center, which explores how the fields of nanotechnology, biology and medicine all intersect.

"The nanoscale just happens to also be the scale at which cell biology operates," Nelson said. "We're entering an era when we are able to use the tools of nanotechnology to answer fundamental puzzles of biology."

Greg Lester | EurekAlert!
Further information:
http://www.upenn.edu

More articles from Physics and Astronomy:

nachricht Structured light and nanomaterials open new ways to tailor light at the nanoscale
23.04.2018 | Academy of Finland

nachricht On the shape of the 'petal' for the dissipation curve
23.04.2018 | Lobachevsky University

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: BAM@Hannover Messe: innovative 3D printing method for space flight

At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.

Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Industrial Maturity of Electrically Conductive Adhesives for Silicon Solar Cells Demonstrated

25.04.2018 | Power and Electrical Engineering

Electrode shape improves neurostimulation for small targets

25.04.2018 | Medical Engineering

Silicon as a new storage material for the batteries of the future

25.04.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>