Phenotypes and circadian rhythm in utilization of formate in purine nucleotide biosynthesis de novo in adult humans

Evidence that mammalian liver introduces C8 and that C2 is introduced in a non-hepatic site would explain our results. Our data are not similar to those in non-mammalian organisms or cells in culture and are not consistent with the hypothesis that formate from folate-dependent metabolism in mitochondria is a major one carbon source for purine biosynthesis. Timing of peak 13C enrichment at C2 corresponds to maximal DNA synthesis in human bone marrow. Phenotypes may explain the efficacy (or lack of) of certain anticancer and immunosuppressive drugs.