Altered brain phosphoglycerate kinase from aging rats

Pure phosphoglycerate kinase from old rat brain differs from the "young" enzyme as judged by its greater stability to heat and storage and its resistance to inactivation by protease. Moreover, inactivation of young compared to old brain phosphoglycerate kinase requires different amounts of monospecific antiserum raised against either the young form of muscle or liver phosphoglycerate kinase. Both young and old brain phosphoglycerate kinase are similar with respect to Vmax in the forward and backward directions, Km for different substrates, electrophoretic mobility and average molecular weight. Thus, the properties of young and old brain phosphoglycerate kinase that are similar and those that differ share a common pattern with their young and old counterparts from rat muscle and liver. Kinetic data and immunological response indicate that brain phosphoglycerate kinase is similar if not identical to the muscle enzyme rather than the liver enzyme.