Biosynthesis of nucleic acid purines. II. Role of hypoxanthine and xanthine compounds

Abstract

1. 1. Soluble extracts of rabbit bone marrow have been shown to convert C 14-labeled inosine and inosinic acid readily to compounds of adenine and guanine. No reaction occurred in the absence of added DPN. Free hypoxanthine-8-C 14 was utilized to an insignificant extent. 2. 2. Evidence has been presented indicating that inosine was phosphorylated to inosinic acid, and a compound tentatively identified as xanthosine phosphate was shown to be formed from inosinic acid with little change in specific activity. Xanthosine labeled with C 14 was converted to guanine. 3. 3. Addition of DPN was necessary to convert hypoxanthine and xanthine to the corresponding amino purines, reactions in which no oxidation of the purines was involved. DPN added to dialyzed extract oxidized inosinic acid to the xanthine level, but formation of adenine or guanine occurred only when boiled bone-marrow juice was added in addition to DPN.