Incorporation of Isotopic Formate into the Nucleotides of Ribo- and Desoxyribonucleic Acids¹

[14C]Formate labelling of bases of nucleic acids in respiring slices of rat tissues

“…The general pattern observed for slices of liver and spleen-good labelling of the purines of RNA, with lesser labelling of the pyrimidines, and good labelling of the purines and thymine of DNA, with lesser labelling of cytosine is in agreement with the in vitro experiments of Totter (1954) for bone marrow. Previously, a similar pattern was reported for various rat tissues after the injection of [14C]formate (Heinrich & Wilson, 1950;Totter, Volkin & Carter, 1951;Bendich et al 1953). In experiments of this type, the nucleic acid purines were found to be labelled in positions 2 and 8 (Heinrich & Wilson, 1950;Drysdale, Plaut & Lardy, 1951) and the thymine was labelled in the methyl group at position 5 (Totter et al 1951).…”

Human Leukocyte Metabolism in Vitro. I. Incorporation of Adenine-8-C14 and Formate-C14 Into the Nucleic Acids of Leukemic Leukocytes

“…A similar effect of exogenous uridine in CLL and acute leukemic leukocytes was not seen. 6. The effects of exogenous pyrimidines on thymine synthesis in CML leukocytes and of exogenous AIC on de novo purine synthesis indicate that leukemic leukocyte nucleic acid synthesis is determined, in part, by the availability of precursors of the nucleic acid bases.…”

“…The present studies were undertaken to explore further the in vitro nucleic acid metabolism of the morphologically different types of human leukemic leukocytes. Since the nucleic acid purines may be derived either from preformed purines or from purines synthesized by the cells (5,6), both pathways of purine utilization were assessed; preformed purine incorporation was studied with labeled adenine, while nucleic acid purine incorporation of formate-C14 was used to evaluate utilization of purines synthesized by the de novo pathway (6). Synthesis of deoxyribose nucleic acid (DNA) thymine could be evaluated concurrently in studies using formate-C14, since formate is a source of the methyl carbon required for the conversion of a uracil compound to thymine (6)(7)(8).…”

Part VIII. Folic acid antagonists

“…The additional unequivocal destinies for formate and for other carbon atoms from tetrahydrofolic acid cofactors are formylglutamate,40 the 2-position and 8-position of uric acid (and thus of the purine compounds from which uric acid is derived),41, 42 and the 5-methyl group of thymidylic acid. 43 Each of these reactions has unique features. In addition, vitamin Serine and glycine are freely interconvertible enzymatically in a reaction which involves N5-10 hydroxymethyltetrahydrofolic acid 45 (left, Fig.…”