Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Molecular Sunscreen: How DNA Protects Itself from UV Light

22.06.2015

X-ray pulses from the Linac Coherent Light Source probe the molecular dynamics of photoexcitation.

X-rays from the Linac Coherent Light Source were used to measure the ultrafast response of DNA nucleobases to ultraviolet light. Researchers found that the UV excited state in the nucleobase thymine decays rapidly, harmlessly dissipating the potentially destructive UV energy.


Image courtesy of Markus Guehr

Nucleobases (shown here is thymine) encode genetic information inside DNA. Even isolated nucleobases have a sophisticated mechanism protecting them from the destructive influence of ultraviolet light.

The Impact

The experimental findings give new insight on how the nucleobases inside DNA protect themselves from damage induced by ultraviolet light. In addition, the experimental scheme developed will be useful for probing the ultrafast dynamics of other classes of molecules in biology, chemistry and physics.

Summary

Disentangling the underlying ultrafast motion of electrons and nuclei of the photoexcited molecule is challenging using current spectroscopic approaches. Researchers at SLAC approached this problem by investigating how DNA, which absorbs light very strongly, protects itself by dissipating the UV energy as heat instead of breaking the chemical bonds that hold the DNA together. By using an ultrafast x-ray pulse, an innermost electron from a thymine molecule, a so-called core electron, is stripped away, resulting in an atom with a vacancy in its core level, resulting in a “core hole.”

The atom, now unstable, fills the core hole with an outer electron, and an electron is emitted via a process known as the Auger effect. Measurement of the kinetic energy of the Auger electrons reveals information about the dynamics.

This experimental scheme, called time-resolved Auger spectroscopy, allowed scientists to distinguish between the movement of the atomic nuclei and the changes in the distribution of electrons from an element specific point of view. Using this strategy for the DNA nucleobase thymine, researchers observed that the oxygen Auger spectrum shifts initially toward high kinetic energies due to the stretching of a single carbon-oxygen bond.

The Auger spectrum then shifts toward lower kinetic energies within 200 fs to an electronic relaxed state, which allows the UV energy to dissipate as heat rather than damaging the DNA. This newly developed tool should provide a window to view the motions of electrons in many areas of chemistry, biology and physics.

Funding

This work was supported by the AMOS program within the Chemical Sciences, Geosciences, and Biosciences Division of the Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy. M. G. acknowledges funding via the Office of Science Early Career Research Program through the Office of Basic Energy Sciences, U.S. Department of Energy. R. F. thanks the Swedish Research Council, the Göran Gustafsson Foundation (UU/KTH), and the Knut and Alice Wallenberg Foundation, Sweden for financial support.

The main part of the experimental research was carried out at the Linac Coherent Light Source (LCLS) at the SLAC National Accelerator Laboratory. LCLS is an Office of Science User Facility operated for the U.S. Department of Energy Office of Science by Stanford University. Other portions of this research were carried out at the Advanced Light Source, which is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

Publications

McFarland, BK, et al., “Ultrafast X-ray Auger Probing of Photoexcited Molecular Dynamics.” Nature Communications 5, 4235 (2014). [DOI: 10.1038/ncomms5235]

Contact Information
Kristin Manke
kristin.manke@science.doe.gov

Kristin Manke | newswise
Further information:
http://www.science.doe.gov

More articles from Life Sciences:

nachricht Symbiotic bacteria: from hitchhiker to beetle bodyguard
28.04.2017 | Johannes Gutenberg-Universität Mainz

nachricht Nose2Brain – Better Therapy for Multiple Sclerosis
28.04.2017 | Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik IGB

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>