title: Effects of superoxide dismutase, dithiothreitol and formate ion on the inactivation of papain by hydroxyl and superoxide radicals in aerated solutions.
abstract: Losses in enzyme activity and sulphydryl content have been studied in aerated papain solutions containing formate, superoxide dismutase and dithiothreitol. Both formate and dithiothreitol converted .OH to .O2-, whereas superoxide dismutase completely suppressed the inactivation by .O2-. Using results from all three systems, the fraction of .O2- reactions with papain that caused inactivation of the enzyme was 0.33 +/- 0.07. The results also showed that the fraction of .OH reactions, which cause inactivation of papain, is significantly higher in aerated than in oxygen-free solutions.
mesh_terms: D003037:Cobalt Radioisotopes; D004229:Dithiothreitol; D005561:Formates; D005609:Free Radicals; D005720:Gamma Rays; D010100:Oxygen; D010206:Papain / Q000528:radiation effects*; D012996:Solutions; D013482:Superoxide Dismutase
chemical_list: D003037:Cobalt Radioisotopes; D005561:Formates; D005609:Free Radicals; D012996:Solutions; D013482:Superoxide Dismutase; D010206:Papain; D010100:Oxygen; D004229:Dithiothreitol