Purine biosynthesis in Helix aspersa: metabolic fate of labelled precursors

1. The hepatopancreas of terrestial snails actively synthesizes purines from labelled formic acid. 2. The guanine nucleotides are initially labelled to the highest specific activity followed by adenine and hypoxanthine. 3. The labelling patterns suggest that uric acid synthesis is the primary catabolic process for nitrogen excretion while guanine excretion is due to an inability to reutilize the base.