Researchers observe one of the world's fastest chemical reactions for the first time.
UV radiation often damages our DNA. Researchers at Kiel University and The University of Bristol, Great Britain, have now seen for the first time what happens in DNA building blocks when they are stimulated by ultraviolet light, and what they do to prevent themselves from being destroyed.
The results show: the molecules use the absorbed energy to set off a completely harmless reaction which prevents the genes being altered. The study can be found in the current edition of the journal Angewandte Chemie (Applied Chemistry).
Our DNA contains the bases adenine, guanine, cytosine and thymine. The chemists used ultra short blasts of light to shoot base pairs guanine and cytosine which were stimulated with UV light. They were only able to reveal the protective molecular mechanism using this method of femtosecond spectroscopy, because the process happened within a few quadrillionths of a second.
During the so-called electron-driven proton transfer process (EDPT), a hydrogen atom is displaced within the molecular compound. The base pair, however, immediately returns to its original starting structure from the same procedure. "Nature uses the reaction to strengthen the DNA's resistance to light by orders of magnitude - it is sort of a sun protection for DNA", said Professor Friedrich Temps, head of the Kiel research team from the Institute of Physical Chemistry.
"The DNA building blocks themselves thereby relieve the cells' hugely complex and very slowly active repair mechanisms using enzymes. The discovery of these enzymes this year was awarded the Nobel Prize for Chemistry. Without the passive processes we observed, the cells' active repair mechanisms would be completely overloaded", added Professor Andrew Orr-Ewing, head of the team in Bristol.
In a few cases, however, the base pair was not able to return to the original situation. Here, EDPT caused two hydrogen atoms to be displaced. "The product could be a mutagen precursor and lead to DNA damage", explained Dr Katharina Röttger from the English working group, who received her doctoral degree in Kiel. Future experiments will have to show what then happens to this molecule. "We can only say that the potentially mutagen molecule survived our measurement time frame of one nanosecond (= a billionth of a second)", said Röttger.
The scientists now want to find out whether the same processes also occur in a long DNA strand. The many interactions within and between the molecules and in the hydrogen bridges make this undertaking more complicated, however. Extremely fast reactions are often covered up by slower ones. Professor Temps and Professor Orr-Ewing are confident that the analysis tools of their working groups will soon be able to solve this puzzle, too.
K. Röttger, H. J. B. Marroux, M. P. Grubb, P. M. Coulter, H. Böhnke, A. S. Henderson, M. C. Galan, F. Temps, A. J. Orr-Ewing, G. M. Roberts, "Ultraviolet Absorption Induces Hydrogen-Atom Transfer in G∙C Watson-Crick DNA Base Pairs in Solution", Angew. Chem. Int. Ed. 54, (2015). DOI: 10.1002/anie.201506940
Photos are available to download:
Caption: Katharina Röttger, Faculty prize winner for 2014 at Kiel University, investigated a chemical process in DNA base pairs, together with colleagues, using extremely short pulses of light.
Photo/Copyright: Jürgen Haacks, Kiel University
Caption: Friedrich Temps is developing methods in Kiel which can be used to observe ultra fast chemical processes.
Photo/Copyright: Denis Schimmelpfennig, Kiel University
Caption: The study from Kiel and Bristol will adorn the inside cover of Angewandte Chemie. It shows the process that was investigated on how DNA protects itself from ultraviolet radiation.
Figure/Copyright: Angewandte Chemie, John Wiley & Sons
The study was carried out within the Collaborative Research Centre 677 “Function by Switching”, where scientists investigate and create molecular switching processes: www.sfb677.uni-kiel.de.
Details, which are only a millionth of a millimetre in size: This is what the research focus "Kiel Nano, Surface and Interface Science – KiNSIS" at Kiel University has been working on. In the nano-cosmos, different laws prevail than in the macroscopic world - those of quantum physics. Through intensive, interdisciplinary cooperation between materials science, chemistry, physics, biology, electrical engineering, computer science, food technology and various branches of medicine, the research focus aims to understand the systems in this dimension and to implement the findings in an application-oriented manner. Molecular machines, innovative sensors, bionic materials, quantum computers, advanced therapies and much more could be the result. More information at www.kinsis.uni-kiel.de
Professor Dr Friedrich Temps
The Institute of Physical Chemistry
Tel.: +49 (0)431 880 7800
Dr. Boris Pawlowski | Christian-Albrechts-Universität zu Kiel
One step closer to reality
20.04.2018 | Max-Planck-Institut für Entwicklungsbiologie
The dark side of cichlid fish: from cannibal to caregiver
20.04.2018 | Veterinärmedizinische Universität Wien
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.
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...
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...
Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.
Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...
In the fight against cancer, scientists are developing new drugs to hit tumor cells at so far unused weak points. Such a “sore spot” is the protein complex...
13.04.2018 | Event News
12.04.2018 | Event News
09.04.2018 | Event News
20.04.2018 | Physics and Astronomy
20.04.2018 | Interdisciplinary Research
20.04.2018 | Physics and Astronomy