INEFFICIENT DEGRADATION OF OXIDIZED REGIONS OF PROTEIN MOLECULES

We have previously shown that the intracellular half-life of endocytos ed oxidized albumin is much longer than that of native albumin.We now report that the regions of oxidized albumin which contain oxidation pr oducts (carbonyls and fluorophores), are less readily released as smal l degradation products by cell-free proteolysis than is the molecule o verall. We deduce that oxidized moieties in the polypeptide chain can confer localized resistance to enzymatic proteolysis. Such resistance to proteolysis may account for the intracellular accumulation of some endocytosed oxidized protein which we have previously observed.