Incorporation of Purine Analogs into the Nucleotide Pools of Human Erythrocytes

Abstract

For the past decade this laboratory has devoted much of its attention to an examination of various facets of purine metabolism in human erythrocytes. These cells do not have the complete pathway for the de novo synthesis of purines and do not make nucleic acids. On the other hand, they have an active nucleotide metabolism and contain the salvage enzymes, hypoxanthine-guanine phosphoribosyl transferase (HGPRTase), adenine phosphoribosyl transferase (APRTase) and adenosine kinase. In view of the fact that the activities of certain enzymes of purine metabolism are quite high (e.g., purine nucleoside phosphorylase occurs at a level of about 15 umolar units/ml of erythrocytes) and the total mass of erythrocytes in the adult human being is in excess of two liters, it appears that these cells play an important and perhaps not yet fully appreciated role in the whole body economy of purines in man. Therefore, we believe that the human erythrocyte provides a very useful model system for the examination of purine metabolism in man as well as for investigations of the action of certain purine and purine nucleoside antimetabolites, many of which are important in medicine.