The Effect of Ionizing Radiation on the Enzyme Desoxyribonuclease in the Dry State

Summary

The radiation sensitivity of the enzyme DNase in the dry state may be altered in the presence of added materials. In the presence of sodium chloride or sodium phosphate the radiation sensitivity of DNase is increased. This radiation sensitivity was found to vary, depending on the ph of the environment before freezing and drying. The addition of desoxyribonucleic acid was found to increase the radiation sensitivity above ph 6·5 and to decrease the sensitivity below ph 6·5. The radiation-sensitivity changes which occur in the presence of DNA include a specific decrease, dependent on the intact DNA-molecule, and a non-specific effect, in the presence of the degraded substrate or of intact RNA. The DNA-specific sensitivity change is probably a result of energy transfer from the enzyme to the substrate via the enzyme-substrate attachment site.