This invention encompasses methods of preserving protein function by contacting a protein with a composition comprising one or more purine or pyrimidine nucleosides (such as e.g., adenosine or uridine) and an antioxidant (such as e.g., manganese). In addition, the invention encompasses methods of treating and/or preventing a side effect of radiation exposure and methods of preventing a side effect of radiotherapy comprising administration of a pharmaceutically effective amount of a composition comprising one or more purine or pyrimidine nucleosides (such as e.g., adenosine or uridine) and an antioxidant (such as e g., manganese) to a subject in need thereof. The compositions may comprise D. radiodurans extracts.
 The present invention arose in part from research funded by grant DE-FG02-04ER63918 from the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Remediation Research (BER), Environmental Remediation Sciences Program and by grant FA9559-07-1-0128 from the Air Force Office of Scientific Research. The Government has certain rights in the invention.