Spore photoproduct lyase (EC18.104.22.168, SAM, SP lyase, SPL, SplB, SplG) is a radical SAMenzyme that repairs a particular kind of lesion that arises upon UV-radiation of bacterial DNA. This repair mechanism is one of the reasons for the resilience of certain bacterial spores. Through a series of radical reactions the photodimer, 3 5-thyminyl-5,6-dihydrothymine, is disconnected to give back two functional thymine rings.
^Susan C. Wang and Perry A. Frey (2007). "S-adenosylmethionine as an oxidant: the radical SAM superfamily". Trends in Biochemical Sciences32 (3): 101–10. doi:10.1016/j.tibs.2007.01.002. PMID17291766.Note that the SPL drawings are incorrect in this paper and the erratum
^Jeffrey M. Buis, Jennifer Cheek, Efthalia Kalliri, and Joan B. Broderick (2006). "Characterization of an Active Spore Photoproduct Lyase, a DNA Repair Enzyme in the Radical S-Adenosylmethionine Superfamily". Journal of Biological Chemistry281 (36): 25994–26003. doi:10.1074/jbc.M603931200. PMID16829680.