Is enhanced free radical flux associated with increased intracellular proteolysis?

Intracellular proteolysis was measured in cultured cells during and after free radical attack. Radicals were generated firstly, throughout the aqueous phase by gamma irradiation and secondly, selectively, either extracellularly or intracellularly by chemical and enzymic methods. With both approaches, stimulation of proteolysis was observed in certain circumstances. Phenylhydrazine stimulated proteolysis at low concentration but inhibited at higher. Depletion of the antioxidant glutathione and inhibition of catalase also increased proteolysis.