Untersuchung über die Biosynthese der Pterine bei Drosophila melanogaster

1. Larvae of the wild type of Drosophila melanogaster and of two mutants («trosy»)and («sepia») were fed with glycine‐ [2‐ 14 C], formate‐ [ 14 C] glucose‐ [U‐ 14 C], glucose‐(l‐ 14 C), glucose‐(6‐ 14 C), fructose ‐[U‐ 14 C] and DL ‐lactate‐ [1‐ 14 C]. After the hatching of the flies isoxanthopterine, drosopterine, sepiapterine and uric acid were isolated by paper chromatography and their specific activities were determined. The carbon atoms 8 and 9 of the pyrazine ring were isolated as oxalic acid after degradation of the pterine with chlorine followed by acid hydrolysis (method of W IELAND & T ARTTER ). The pyrimidine ring is not attacked by this process. This procedure was tested by the degradation of the synthetic isoxanthopterines‐ [8‐ 14 C] and ‐[5 14 C].