Certain interrelationships in the metabolism of glycine and serine.

The utilization of L-serine-2,3-deuterio, 3-C4, N16 and glycine-2-C4, N15 for the biosynthesis of purines, thymine, and choline in the rat was described briefly in preliminary publications from this laboratory (1, 2). In the synthesis of the methyl groups of choline from the p-C14DaOH group of isotopically labeled serine it was later found (3) that t,he C14:D ratio was unaltered, indicating that carbon-hydrogen bonds were not broken. In order to gain a better understanding of the reactions involved in these conversions a more careful investigation was carried out, in the same animals, of the interrelationships in the metabolism of glycine and serine.