Three pteridines have been isolated from the methane- or methanol-oxidizing bacterium Methylococcus capsulatus. Two of these are known compounds, 2-amino-6-carboxy-4-hydroxypteridine and 2-amino-4-hydroxy-6-methylpteridine. The third is shown by degradative and synthetic experiments to be l-threo-neopterin 2′:3′-phosphate. Labelling experiments show that both the pteridine moiety and phosphate residue are derived from a single GTP molecule. The possible metabolic significance of these compounds in methanol oxidation is discussed.
*Deceased May 1971.