Development of adenylate kinase isoenzymes in rat liver.

Total adenylate kinase activity was determined in developing rat liver. The activity was 18 units/g wet weight of tissue in foetal liver; this increased to 41 units/g immediately after birth and continued increasing until adult activities of 150 units/g were reached after two weeks. The adenylate kinase activity was separated into four isoenzymes. Only isoenzymes II and III were observed in foetal rat liver. Isoenzyme II activity was 2 units/g in the foetal liver and increased to 25 units/g in adult liver. Adenylate kinase III activity was 20 units/g in the foetal liver and increased to 118 units/g in adult liver. The possible role that adenylate kinase might have in regulating the energy flow in the developing liver cell is discussed.