Formation Of Guanine Research Articles

The breakdown of ribonucleosides in extracts of the phytopathogenic organism Xanthomonas phaseoli.

Extracts of Xanthomonas phaseoli (XP8) degrade certain ribonucleosides readily by hydrolytic cleavage of the ribose moiety. Thus, uridine is converted to uracil and ribose, and cytidine to cytosine and ribose, with little deamination to uracil and ammonia taking place. Commercial adenosine is deaminated to inosine and ammonia without further significant cleavage. The data presented permit a choice to be made between the two theoretically possible pathways of guanosine degradation. With chromatographic evidence for xanthine but not for xanthosine and with spectrophotometric evidence for the intermediate formation of guanine, the mechanism of guanosine breakdown is described as being the result of hydrolytic cleavage to guanine and ribose followed by deamination to xanthine and ammonia.

Biosynthesis of nucleic acid purines. I. Formation of guanine from adenine compounds in bone marrow extracts

1. 1. The conversion of C 14-labeled adenine to guanine, which has previously been observed only in intact cells, has been found to occur in soluble extracts of rabbit bone marrow. 2. 2. The yield of guanine was increased 10–20-fold by using adenosine or adenosine 5′-phosphate as precursors in place of free adenine. 3. 3. The synthesis of guanine from adenine riboside or ribotide occurred only in the presence of added DPN. 4. 4. Inosine was an intermediate between adenosine and guanine. Evidence was presented that adenosine 5′-phosphate also passed, in part at least, through a hypoxanthine compound in its conversion to guanine.