Abstract

Mouse neuroblastoma clones N-18 and N-1E were found to incorporate radioactivity from [2-¹⁴C]guanosine into biopterin on its oxidation product, pterin-6-carboxylic acid. When similar incubations were carried out in the presence of [8-¹⁴C]guanosine little or no incorporation of radioactivity into the pterins occurred. These results indicate that the mammalian neuroblastoma cell line can synthesize biopterin from a purine precursor. The lack of incorporation of radioactivity into the pterins from [8-¹⁴C]guanosine indicates that the mammalian biosynthetic pathway may be similar to that found in bacteria.