Comparison of purine and pyrimidine metabolism in G1 and S phases of HeLa and Chinese hamster ovary cells

Detailed quantitative studies of purine and pyrimidine metabolism in G1 and S phases of synchronized HeLa and Chinese hamster ovary cells have been carried out. Concentrations of ribonucleoside triphosphates increased approximately in proportion to the increase in cell size as cells moved from G1 to S phase. Deoxyribonucleoside triphosphate concentrations were low in G1 phase and increased 2.5- to 10-fold in S phase. Pathways and rates of metabolism of radioactive adenine, guanosine, deoxyadenosine, deoxyguanosine, uridine, cytidine, deoxyuridine, deoxycytidine, and thymidine were determined by measuring the incorporation of each precursor into individual acid-soluble nucleotides and RNA and DNA bases. Cell-cycle or size-dependent differences were detected in many of the parameters studied.