ACTIVATION OF OXIDIZED CYSTEINE PROTEINASES BY THIOREDOXIN-MEDIATED REDUCTION INVITRO

Activity of the cysteine adducts of the cysteine proteinases papain an d thaumatopain can be recovered by treatment with thioredoxin, thiored oxin reductase and NADPH. Recovery of proteinase activity did not occu r if any of the components of the thioredoxin system were omitted, or if thioredoxin or thioredoxin reductase were heat-inactivated. Such an enzyme-mediated process may be of significance in the recovery of cys teine proteinases inactivated by oxidative attack.