Scientists observed one of the world's fastest chemical reactions for the first time, and gained insight into how DNA is damaged by ultraviolet light.

The researchers looked at what happens in DNA blocks when they are exposed to UV light, and what they do to protect themselves, Kiel University reported. The team found the molecules used to absorbed energy to set off a reaction that prevents the genes from being altered and destroyed.

The researchers used ultra short blasts of light to shoot base pairs guanine and cytosine, which were stimulated with UV light. During the electron-driven proton transfer process (EDPT), a hydrogen atom is displaced in the molecular compound. On the other hand, the base pair immediately returns to its original starting structure through the same process. This reaction strengthens DNA's resistance to light by orders of magnitude, creating a sort of "Sun protection" for DNA.

"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," said Professor Andrew Orr-Ewing of the University of Bristol.

The team also observed that in some circumstances, the base pairs were not able to return to their original situation. In the scenario, EDPT caused two hydrogen atoms to be displaced. 

"The product could be a mutagen precursor and lead to DNA damage," said Katharina Röttger from the English working group, who received her doctoral degree in Kiel. "We can only say that the potentially mutagen molecule survived our measurement time frame of one nanosecond (= a billionth of a second)."

In the future, the scientists hope to discover whether or not this process occurs in long strands of DNA.

The findings were published in a recent edition of the journal Angewandte Chemie International Edition.