AGE-DEPENDENT AND RADIATION-DEPENDENT CHANGES IN CARBONYL CONTENT, SUSCEPTIBILITY TO PROTEOLYSIS, AND ANTIGENICITY OF SOLUBLE RAT-LIVER PROTEINS

Soluble liver proteins (SLP) from old and gamma-irradiated young rats were studied with respect to their carbonyl content, the rates of auto lysis and degradation by proteinase K, and their antigenicity for mice and compared with SLP from non-irradiated young animals. A significan t increase in the carbonyl level was found in SLP from old and gamma-i rradiated young rats as compared to SLP from intact young rats. The ra tes of SLP autolysis and proteolysis by proteinase K were increased in the same animal groups but did not correlate the carbonyl level. At t he same time, whereas the antigenicity for mice of SLP from old rats w as significantly higher than that of SLP from young rats, the antigeni city of SLP from gamma-irradiated rats did not differ from non-irradia ted animals. Enrichment of the diet with antioxidant and vitamin suppl ements (AVS) during one month before the irradiation caused a decrease in the radiation-induced carbonyl level in rat SLP. However, this rai sed antioxidant level in animal diet did not influence the rates of SL P autolysis and degradation by proteinase K and also did not alter the antigenicity of these proteins. The data allow us to suggest that the increase in autolysis, degradation by the exogenous proteinase, and a ntigenicity of SLP from old rats are determined not only by carbonyl f ormation in these proteins due to action of oxygen radicals but also b y other age-specific protein modifications. (C) 1997 Elsevier Science Inc.