Twofold Concentration Research Articles

Some aspects of pteridine biosynthesis in amphibians

Abstract 1. 1. Five pteridines (sepiapterin, biopterin, hynobius-blue, isoxanthopterin and 2-amino-4-hydroxypteridine) and three purines (adenine, hypoxanthine and guanine) were extracted from homogenized Rana sylvatica larvae and identified. 2. 2. Glycine-(u.l.)-C14, when injected into Rana sylvatica larvae, was incorporated into the five pteridines and the three purines. 3. 3. Hypophysioprivic Rana sylvatica larvae showed a twofold concentration increase of all five pterdines after intermedin treatments and, at the same time, adenine and hypoxanthine concentrations decreased, while guanine remained at essentially the same concentration. 4. 4. A scheme for the biosynthetic interconversion of pteridines in hypophysioprivic Rana sylvatica larvae has been proposed. These pathways appear to be altered after intermedin treatments, and the alternateve pathways have been indicated. 5. 5. Hynobius-blue is proposed to have the same structure as tetrahydrobiopterin or tetrahydrosepiapterin. 6. 6. The free purines do not appear to be converted to integumental pteridines in hypophysioprivic Rana sylvatica larvae.