STUDY OF PROTEIN CARBONYLS IN SUBCELLULAR-FRACTIONS ISOLATED FROM LIVER AND SPLEEN OF OLD AND GAMMA-IRRADIATED RATS

Age- and gamma-irradiation-dependent accumulation of oxidatively modif ied proteins (measured as carbonyl level) was studied in cytoplasm, mi tochondria and nuclei isolated from spleen and liver of 4- and 26-mont h-old rats. The protein carbonyl levels significantly increased with a ge in all fractions studied. The carbonyl content was found to be two times higher in the nuclei than in the mitochondria and cytoplasm, whi ch may be related to an extensive modification of lysine and arginine residues in histone molecules. gamma-Irradiation of rats with 10 Gy ca used a rise of protein carbonyls only in their cytoplasm and mitochond ria, which was prevented in the animals fed with antioxidants and vita mins for a month before the irradiation. We observed an activation of histone-specific proteases in the nuclei of gamma-irradiated rats. The lack of carbonyl accumulation in the nuclear proteins isolated from t issues of gamma-irradiated animals may be explained by the degradation of oxidized histones by these proteases. (C) 1998 Elsevier Science Ir eland Ltd. All rights reserved.