XXXX . Oxidative modification in vivo and loss of phosphatase activity during aging.

@entity26 @entity544 @entity1251 @entity35 @entity13507 @entity6738
Oxidative modification of DNA, lipids, and proteins occurs as a consequence of reaction with free radicals and activated @entity26 . Oxidative modification of total cellular proteins has been described under many pathologic and experimental conditions, but no specific proteins have been identified as in vivo targets for oxidative modification. Utilizing an immunochemical method for detection of oxidatively modified proteins, we identified a protein in @entity35 liver that was highly oxidized. It was purified to homogeneity and identified as carbonic anhydrase, isozyme III. Its characteristics match those previously described for a protein that was lost during aging of the @entity35 , senescence marker protein-1. @entity1251 was purified from @entity35 aged 2, 10, and 18 months, and the proteins were characterized. All three preparations were highly oxidatively modified as assessed by their @entity6738 content. The enzyme has three known catalytic activities, and the specific activities for @entity544 hydration and for @entity13507 hydrolysis decreased during aging by approximately 30%. However, the third activity, that of a phosphatase, was virtually lost during aging. While the physiologic role of @entity1251 is unknown, we suggest that it functions in an oxidizing environment, which leads to its own oxidative modification.
