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Tuesday, September 13, 2005 Possible Route to Repair UV Damage in Mammals Crystal structure of cyanobacterial DNA photolyase. Credit: Riken, Harima Institute Almost all forms of life on earth have an enzyme similar to photolyase, except mammals. Photolyase is an enzyme that can repair dimers in DNA. Dimers are when 2 juxtaposed nucleotides are excited by UV light and bond to one another. This causes problems in expression and replication of that segment of DNA. When this occurs in an oncogene, it leads to cancer. There is no known way to fix a dimer in mammals, since this function is taken care of by photolyase in other forms of life. Since until recently we did not know how it worked we could not replicate it. If scientists could replicates this enzyme, we could reduce the chances of cancer for long term space travel. We currently have a better understanding of how it works becuase of Dongping Zhong and other researchers at Ohio State University. The team of researchers used pulses of light to analyze steps in the repair (similar to using stop motion photography to see how a humming bird flaps its wings). A more detailed description of how photolyase works can be found here. (More info: Ohio State University) @ 12:24 EST