Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New study sheds light on 'dark states' in DNA

11.01.2007
Chemists at Ohio State University have probed an unusual high-energy state produced in single nucleotides -- the building blocks of DNA and RNA -- when they absorb ultraviolet (UV) light.

This is the first time scientists have been able to probe the "dark" energy state -- so called because it cannot be detected by fluorescence techniques used to study other high-energy states created in DNA by UV light.

The study suggests that DNA employs a variety of means to dissipate the energy it absorbs when bombarded by UV light.

Scientists know that UV light can cause genetic alterations that prevent DNA from replicating properly, and these mutations can lead to diseases such as cancer.

The faster a DNA molecule can dissipate UV energy, the lesser the chance that it will sustain damage -- so goes the conventional scientific wisdom. So the dark states, which are much longer lived than previously known states created by UV light, may be linked to DNA damage.
... more about:
»DNA »dissipate »picosecond

The existence of this dark energy state -- dubbed n(pi)* (pronounced "n-pi-star") -- had previously been predicted by calculations. Other experiments hinted at its existence, but this is the first time it has been shown to exist in three of the five bases of the genetic code -- cytosine, thymine and uracil.

The detection of this dark state in single bases in solution increases the chances that it may be found in the DNA double helix, said Bern Kohler, associate professor of chemistry at Ohio State and head of the research team.

The Ohio State chemists determined that, when excited by ultraviolet light, these three bases dissipate energy through the dark state anywhere from 10-50 percent of the time.

The rest of the time, energy is dissipated through a set of energy states that do fluoresce in the lab. These "bright" energy states dissipate the energy much faster, in less than one picosecond.

A picosecond is one millionth of one millionth of a second -- an inconceivably short length of time. Light travels at 186,000 miles per second, but in twenty picoseconds it would only travel just under a quarter of an inch. Still, a picosecond is not so fast compared to the speed of some chemical reactions in living cells.

In tests of single DNA bases, the dark state lasted for 10-150 picoseconds -- much longer than the bright state. The chemists reported their results in the Proceedings of the National Academy of Sciences.

"We want to know, what makes DNA resist damage by UV light?" said Kohler. "In 2000, we showed that single DNA bases can dissipate UV energy in less than one picosecond. But now we know that there are other energy states that have relatively long lifetimes."

"Now we see that there is a family of energy states in DNA responsible for energy dissipation, and this is a major correction in how we view DNA photostability."

Until now, the proposed dark energy state of DNA was a little like the dark matter in the universe – there was no direct way of probing it. The Ohio State chemists used a technique called transient absorption, which is based on the idea that molecules absorb light at specific wavelengths, and allows them to study events happening in less than a picosecond.

They found that DNA dissipates UV energy through the dark state 10-50 percent of the time, depending on which DNA base is excited, and whether a sugar molecule is attached to the base or not.

Next, Kohler's lab is investigating whether the dark state can be linked to DNA damage.

"What are the photochemical consequences of long-lived states? Are they precursors to some of the chemical photoproducts that we know cause damage? That's the Holy Grail in this field -- connecting our growing knowledge of the electronic states of DNA with the photoproducts that damage it," he said.

Kohler's coauthors include Carlos E. Crespo-Hernandez, a former postdoctoral researcher at Ohio State, and Patrick M. Hare, who just obtained his Ph.D. from the university and is about to begin a position as a postdoctoral researcher at the University of Notre Dame.

Bern Kohler | EurekAlert!
Further information:
http://www.osu.edu

Further reports about: DNA dissipate picosecond

More articles from Life Sciences:

nachricht Transport of molecular motors into cilia
28.03.2017 | Aarhus University

nachricht Asian dust providing key nutrients for California's giant sequoias
28.03.2017 | University of California - Riverside

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

OLED production facility from a single source

29.03.2017 | Trade Fair News

Transport of molecular motors into cilia

28.03.2017 | Life Sciences

A novel hybrid UAV that may change the way people operate drones

28.03.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>