Studies on the energy metabolism of opossum (Didelphis virginiana) erythrocytes--VI. De novo purine nucleotide biosynthesis is limited to the final steps of the pathway in vitro.

1. High pressure liquid radiochromatography was used to show the incorporation of [14C] formate with Z-compounds into ATP and GTP in opossum erythrocytes. 2. The use of Z-riboside with [14C] formate resulted in more extensive labeling of ATP than the Z-base/[14C] formate combination as substrates for nucleotide biosynthesis. 3. Substantial accumulation of ZMP and ZTP, but no ZDP was detected in the chromatograms. 4. ATP was unstable in red cells metabolizing in the presence of Z-compounds under an atmosphere of air as gas phase in these experiments.