Purine metabolism in primitive erythrocytes

1. 1. The activities of AMP kinase, GMP kinase, NDP kinase, PNPase and HGPRTase were determined in the erythrocytes of seal, eel, hagfish and dogfish. 2. 2. Erythrocytic NDP kinase activities were high and electrophoretically heterogeneous in all species examined. 3. 3. Patterns of nucleotide extracts of whole blood and erythrocytes in seal, sand dab, skate, hagfish, dogfish, nurse shark and stingray were similar when determined by high-pressure liquid chromatography. Patterns of the whole blood of eel and lemon shark, however, were strikingly different in containing large amounts of GDP and GTP.