Abstract
Protection of Pseudomonas against gamma-radiation under anoxic conditions was seen with cysteine, glycerol, dimethyl sulfoxide, and thiourea. As the concentration of any of these increased, the dose-modifying factor tended to level off to a maximum value between 2.0 and 2.7. When used in combination, protection by pairs of compounds never exceeded these values. This is inter- preted as evidence that they all protect against the same component of radiation damage, probably either that due to the action of aqueous free radicals or that due to hydrogen abstraction.