New finding could lead to sunburn-healing drugs
By Ben Coxworth
July 27, 2011
While there may be medications that help soothe sunburnt skin, when it comes to healing that skin ... well, we pretty much have to just wait for our bodies to do that on their own. Recent research conducted at Ohio State University, however, suggests that an actual healing treatment for sunburn may be on the way. It all comes down to some new understandings about an enzyme named photolyase.
Plants and some animals have naturally-occurring photolyase in their systems, although humans and other mammals do not. When DNA molecules are exposed to too much ultraviolet radiation, their atoms can become over-excited, and accidentally bond in ways that result in molecular injuries known as dimers. A dimer is shaped like a ring and is attached to the side of the molecule, where it keeps the DNA from replicating properly. In organisms lucky enough to possess photolyase, the enzyme rips open the dimer in two places, restoring the DNA molecule to its unharmed state. Led by Prof. Dongping Zhong, an Ohio State team decided to take a closer look at the process, to see if it could be applied to a medication.
Using a high-speed strobing laser, they discovered that the two breaks occurred 90 trillionths-of-a-second apart from one another - it had previously been assumed that they occurred simultaneously. This is because the one electron that is ejected from the photolyase first causes a break in the chemical bond on the near side of the dimer, but then travels around its outer edge to cause the second break.
"The enzyme needs to inject an electron into damaged DNA - but how?" said Zhong. "There are two pathways. One is direct jump from the enzyme across the ring from one side to the other, which is a short distance. But instead the electron takes the scenic route. We found that along the way, there is another molecule that acts as a bridge to speed the electron flow, and in this way, the long route actually takes less time."
Now that Zhong and his Ohio State colleagues better understand the DNA-repairing process, they are hoping that synthetic photolyase could be produced, and incorporated into drugs or lotions for use on human sunburn victims.
The research was recently published in the journal Proceedings of the National Academy of Sciences.